comparative assessment of miscibility and degradability on pet/pla and pet/chitosan blends

7/23/2019 Comparative assessment of miscibility and degradability on PET/PLA and PET/chitosan blends

1/15

Comparative assessment of miscibility and degradability onPET/PLA and PET/chitosan blends

A.M. Torres-Huerta a,, D. Palma-Ramrez b, M.A. Domnguez-Crespo a, D. Del Angel-Lpez a,D. de la Fuente c

a Instituto Politcnico Nacional, CICATA-Altamira, Km. 14.5 Carretera Tampico-Puerto Industrial Altamira, 89600 Altamira, Tamps, Mexicob PMTA of CICATA-Altamira, IPN, Km. 14.5 Carretera Tampico-Puerto Industrial Altamira, 89600 Altamira, Tamps, Mexicoc Centro Nacional de Investigaciones Metalrgicas, CENIM (CSIC), Av. Gregorio del Amo 8, 28040 Madrid, Spain

a r t i c l e i n f o

Article history:

Received 4 August 2014Received in revised form 18 October 2014Accepted 23 October 2014Available online 6 November 2014

Keywords:

PET/PLAPET/chitosanBlendsMiscibility

Degradability

a b s t r a c t

This work reports the synthesis and miscibility of PET/PLA and PET/chitosan blends as wellas their degradation in real soil environment (6 months) and in accelerated weathering(1200 h). For this purpose, commercial polyethylene terephthalate (PET) and recycledPET (R-PET) were used as polymer matrixes and extruded with different amounts of poly-lactic acid (5, 10 and 15 wt-%) or chitosan (1, 2.5 and 5 wt-%) to form filaments. Differentcharacterization techniques such as X-ray diffraction (XRD), Fourier transform infraredspectroscopy (FTIR), differential scanning calorimetry/thermogravimetric analysis (DSC/TGA) and scanning electron microscopy (SEM) were used before and after degradation pro-cess. The results indicate weak interactions between blend components suggesting second-ary bonds by hydrogen bridges or by electrostatic forces. The miscibility of chitosan in both

PET matrixes is lower in comparison with PLA; the saturation of PLA into polymer matrixeswas reached up to an amount of 10 wt-% whereas longer amounts of 5 wt-% of chitosanbecome rigid and brittle. The best performance in the miscibility and degradation processwas found for PET/chitosan (95/5) which is comparable with commercial bottles of BioPETunder similar experimental conditions.

2014 Elsevier Ltd. All rights reserved.

1. Introduction

The long-lasting petroleum polymers have been widelyused provoking that the waste of this kind of polymerstakes a very long time to be broken down. Nowadays, thisindiscriminate use of petroleum-based polymers hascaused a big pollution problem [1,2]. To reduce thisproblem, it has been used biodegradable polymers fromrenewable sources like collagen, keratin, gluten, milk pro-teins, soy proteins, polysaccharides like starch, cellulosederivatives, chitosan, alginate, carrageenan, pectins. These

biodegradable polymers have a short-lifetime because ofare ideal for short-time applications such as; disposablepackages, agricultural mulches, horticultural pots, etc[36]. They are also naturally degradable when disposedin the environment. Despite its advantages, many of thesekinds of polymers exhibit poor thermal stability, low steamand gas barrier and low mechanical properties, makingthem unsuitable for other applications [7,8]. Therefore,the general trend is to combine the mechanical, barrierand thermal properties of petroleum based polymers withthe biodegradability properties of renewable polymers,resulting in the production of polymeric materials withcontrolled lifetime. The designed materials must be resis-tant during their use and must have short time degradationat the end of their useful life [4,9].

http://dx.doi.org/10.1016/j.eurpolymj.2014.10.016

0014-3057/2014 Elsevier Ltd. All rights reserved.

Corresponding author. Tel.: +52 8332600125x87510; fax: +528332600125x87521.

E-mail addresses: [email protected], [email protected](A.M. Torres-Huerta).

European Polymer Journal 61 (2014) 285299

Contents lists available at ScienceDirect

European Polymer Journal

j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c at e / e u r o p o l j
http://dx.doi.org/10.1016/j.eurpolymj.2014.10.016mailto:[email protected]:[email protected]:[email protected]://dx.doi.org/10.1016/j.eurpolymj.2014.10.016http://www.sciencedirect.com/science/journal/00143057http://www.elsevier.com/locate/europoljhttp://www.elsevier.com/locate/europoljhttp://www.sciencedirect.com/science/journal/00143057http://dx.doi.org/10.1016/j.eurpolymj.2014.10.016mailto:[email protected]:[email protected]://dx.doi.org/10.1016/j.eurpolymj.2014.10.016http://-/?-http://-/?-http://crossmark.crossref.org/dialog/?doi=10.1016/j.eurpolymj.2014.10.016&domain=pdf


2/15

The most favorable packaging material for disposablesoft drink bottles is polyethylene terephthalate (PET), akind of semicrystalline, thermoplastic polyester with highstrength and transparency properties as well as excellentbarrier properties. Unfortunately, most of these beveragebottles are used only once and then discarded, which inev-itably generates serious environmental problems (whitepollution) [10]. Therefore, recycling the discarded PETpolymer along with obtaining biodegradable PET-basedblends are efficient approaches to reduce the resourcesconsumption and to protect the environment at the sametime [11]. The recycling of post-consumer packaging mate-rials into direct food contact packaging applications wasnot possible, because of the lack of knowledge about thecontamination of packaging polymers during first use orrecollection. However, for PET the situation is much favor-able: due to its inert character, recycling technologies havebeen developed to establish a bottle-to-bottle recycling ofpost-consumer PET bottles[12].

On the other hand, most biodegradable polymers arethermoplastics (e.g. poly(lactic acid), poly(hydroxyalkano-ate), poly(vinyl alcohol)) [9]. Among them, poly(lactic acid)(PLA) is a bio-based polymer obtained from renewablesources mainly from corn and starch[13]. PLA is an aro-matic polyester and has several applications, for example,is used for films, extrusion-thermoformed containers andmedical applications for tissue engineering, bone recon-struction and controlled delivery systems[14]. The use ofPLA in beverage bottles is limited due to its poor oxygenbarrier and low mechanical properties[15]. Another inter-esting biodegradable polymer is chitosan, a biopolymerderived from chitin, a natural compound from crustaceanshells; chitosan has the ability to form semipermeablefilms and, in recent years, the efforts have been intensifiedto develop chitosan films and its application in food pack-ing[16]. Biodegradable copolymers of PET and aliphaticpolyesters have been synthesized, such as poly(lactic acid),poly(b-hydroxyalkanoate), poly(e-caprolactone) andpoly(butylene succinate) in order to obtain a degradablepolymer with a faster degradation rate [17,18].Additionally, physical mixtures of conventional andbiodegradable phases have been studied[19]. To our bestknowledge, few researches are focused in determine theeffects on physicochemical, structural and morphologicalproperties as well as degradation time of blends PET/PLAor PET/Chitosan. In this work, the issue has been investi-gated from different perspectives and the results arediscussed in the terms of the quantities of biodegradablepolymers that were added in two different matrixes com-mercial PET and recycled PET during extrusion process.

2. Experimental

2.1. Materials and processing

During the first set of experiments, it was used a com-mercial PET (CLEARTUF-MAX2, lot no. 1008-03219) pro-vided as pellets by M&G Polymers Company whereas inthe second step recycled PET (R-PET) was obtained fromdiscarded bottles after they were washed, dried and cut

into flakes. The polylactic acid pellets, PLA-2002D (contain-ing 4.4 wt-% in average of isomer D), (batch: YA0828b131)and chitosan (low molecular weight, with a deacetylationdegree P75%) were purchased from NatureWorks LLC,USA and Sigma Aldrich, respectively. Before processing,the raw materials were dried at 60 C during 24 h in anoven (Thermolyne). Different amounts of PLA (5, 10 and15 wt-%) or chitosan (1, 2.5 and 5 wt-%) and commercialPET or R-PET were hand mixed previous to extrusion pro-cess. It is important to mention that, initially, we tried toadd into the polymer matrix the same quantities of chito-san or PLA (5, 10 and 15 wt-%), unfortunately, we observedthat synthesized samples with chitosan become rigid andbrittle, regarding the chitosan polymer is a brittlenessmaterial, however, this characteristic depend if the mate-rial is derived of fungal biomass, crustacean shell andinsect cuticles[20,21]. Thus, after several experiments wefound that an optimal percentage to evaluate chitosan isless than 5 wt-%. Blends with a filaments shape (1 mm indiam. 200 cm length) were obtained in a single-screwextruder (C.W. Brabender) with L/D ratio of 25:1 and fourheating zones: feeding (225C), compression (237.5 C),distribution (260 C), and finally, the extrusion die(225 C).

2.2. Characterization

Structural characterization of the polymer blends wascarried out using a Bruker D8 Advance diffractometer from2h= 560(Cu Ka, k = 0.154 nm) and a rate of 1.5 /min.

The Fourier Transform Infrared Spectroscopy (FT-IR)spectra were recorded with a Nicolet FT-IR spectrometer(Magna System 550) equipped with an attenuated totalreflectance (ATR) accessory between 2000 and 650 cm1

at an optical resolution of 4 cm1 (40 scans).Simultaneous thermal analysis was carried out in a

Labsys Evo, Setaram instrument, which was used in theDSC/TGA configuration with the sample and reference cru-cibles made ofa-Al2O3. Sample amount in the crucible wasabout 10 mg. The samples were firstly heated at 40 C andhold for 2 min and subsequently, the measurements werecarried out in the range of 40300 C to evaluate thermaldegradation under argon atmosphere with a heating rateof 10 C/min. Then, the samples were hold at 300 C for2 min followed by a cooling with the same rate. It is wellknown that peak temperature is influenced by the scanrate; however, in this case such displacement was consid-ered neglected. It is also important to mention that DSCheating was intentionally evaluated from 40 C to 300 Cin order to observe the total degradation of these samples.After accelerating weathering tests, DSC/TGA analysis werealso conducted on the samples with similar procedure andheating rate but using a temperature range from 40 C to500 C.

In order to dissolve the biopolymer phase and to evalu-ate the dispersion in the different matrixes (PET and R-PET)as well as evaluate the morphology of the as-preparedsamples, the polymer blends were solubilized in chloro-form and acetic acid for PLA and chitosan, respectively.The dissolved samples were observed by SEM to analyzethe cross section of the blends; before characterization,

286 A.M. Torres-Huerta et al. / European Polymer Journal 61 (2014) 285299
http://-/?-http://-/?-http://-/?-


3/15

the samples were dried at 40 C for 24 h and then coatedwith an AuPd thin film. SEM micrographs were acquiredusing SEM JEOL 6300 series apparatus operating at 15 kV.

2.3. Accelerated weathering

Accelerated weathering tests were carried out in a QUV

accelerated weathering chamber Model QUV/Se whichuses UV-B lamps (313 nm and 0.63 W/m2) as radiationsource. During these experiments, PET, R-PET, commercialbottles of BioPET (B-PET), PLA and all the as-preparedblend samples were exposed to the UV radiation using anexposure time of 1200 h with UV/Condensation cycles of8/4 h at 60 C/50 C for their further characterization.Additionally, the average weight loss mass was evaluatedduring 300 h, 600 h, 900 h and 1200 h. General process toobtain commercial bottles of BioPET (B-PET) considersthe reaction of bio-terephthalic acid with pretroleum-derive ethylene glycol or bio-terephthalic acid in combina-tion with bio-ethylene glycol[22].

2.4. Degradation in soil

The polymer blends were buried in a commercialcompost and exposed to the environment in Altamira,Tamaulipas Mxico for 6 months where the averagetemperatures varies from 30 C to 40 C with an averageof relative humidity of 80%. To analyze the effecton the deg-radation by adding the biopolymers, DSC/TGA analysiswere recorded to compare with the results of the as-pre-pared blends.

3. Results and discussion

3.1. Characterization of as-prepared polymer blends after

extrusion

Since, the final properties of the materials stronglydepend on the induced microstructure which can be gov-erned by the complex thermo-mechanical history; it is ofprime interest to observe and to understand the develop-ment of the crystalline phase. Fig. 1ac shows X-Ray dif-fraction patterns of the polymer blends with chitosan orPLA starting from commercial PET and recycled PET at dif-ferent weight ratios. As a reference, it is also presented thediffractograms of raw materials. The commercial PET(Fig. 1a) displays a well-defined triclinic structure; inagreement with PDF # 00-050-2275 file, the strong peaksare observed at 2h degrees of 16.19, 17.2, 21.3, 22.36and 25.5which correspond to 0 11; 010; 111; 110and (100) planes, respectively. On the other hand, R-PETshows a diffraction pattern with a wide peak. In general,the diffraction peaks of semicrystalline polymers are broadand made up of the amorphous phase and reflections of thecrystalline planes. The diffraction pattern of R-PET revealsa semicrystalline structure with a peak characteristicreflection corresponding to the plane with a Miller index(100) at 2h= 25.5[23].

Selected XRD patterns of chitosan shows two peaks, at8.14 and 18.58, which are commonly refer as a semicrys-

talline phase. Different works reported only one peak forchitosan at 2h ca. 20; however, the crystallinity or morepacking in the main chain of our commercial chitosanwas modified using a deacetylation process. In such case,the first reflection is associated with two different kind ofcrystals; according to Hwang et. al.[24]the first peak at510 has a unit cell characterized by a = 7.76, b = 10391,c= 10.30 and b= 90 whereas the second peak at1825 was characterized by a= 4.4, b= 10.0, c= 10.30 andb = 90[24,25]. PLA samples display an orthorhombicstructure with a strong peak of two overlapped signalsca. 16.5as well as lower intensity peaks around, 19and22. The intensities match with the (110), (200), (203),

10 20 30 40 50 60

PLA

Chitosan

PET

R-PET

(100)

(110)

(111)

(010)

(011)

(203)

(201)

(111)

(002)

(100)

(110)

(200)

{

{

(300)

(112)

(102)

(210)In

tensity(a.u.)

2 (degrees)

{

(a)

PET/PLA 85/15

PET/PLA 90/10

PET/PLA 95/5

R-PET/PLA 85/15

R-PET/PLA 90/10

R-PET/PLA 95/5

Intensity

(a.u.)

2(degrees)

(b)(100)

(110)

(111)

(010)

(011)

(100)

(110)

(111)

(010)

(011)

PET/Chitosan 95/5

PET/Chitosan 97.5/2.5

PET/Chitosan 99/1

R-PET/Chitosan 95/5

R-PET/Chitosan 97.5/2.5

R-PET/Chitosan 99/1

Intensity(a.u.)

(c)

10 20 30 40 50 60

10 20 30 40 50 60

2(degrees)

Fig. 1. X-ray diffraction patterns for (a) Raw materials (b) PET/and R-PET/PLA (c) PET/and R-PET/chitosan.

A.M. Torres-Huerta et al. / European Polymer Journal 61 (2014) 285299 287
http://-/?-http://-/?-http://-/?-http://-/?-


4/15

(201), (111) and (102), (210) planes, respectively; PDF #00-054-1917 file.

The XRD patterns of polymer blends with PLA or chito-san were also analyzed and the results are shown in Fig. 1band c. From the X-Ray diffraction patterns, it is seen thatthe spectra are quite similar resembling the XRD PET pat-tern. The observed reflections could indicate a weak inter-action when the chitosan or PLA are added to the PETmatrixes. It can be also observed that the signal of mainpeak at 25.5 (100) shows a slightly decrease with therelation of PLA or chitosan; the same trend is detectedfor the intensity of (0 11 and (01 0) planes. Similar resultshave been previously reported; i.e. the increasing of theamount of biopolymer reduces the intensity of the diffrac-tion peaks[25], characterizing the spectra as semicrystal-line phases.

The most important point to highlight is that duringextrusion process a recrystallization of R-PET blends wasobtained. It is well known that the semycristalline poly-mers have a metastable nanophase structure, where thevarious nanophases can be occur like crystal, liquid, glassor mesophases. The structure is determined by the self-organization, crystallization and vitrification and it isestablished during the material processing depending ofits thermal and mechanical history [26,27]. Thus, theblends crystallized after the extrusion process as a resultof the absence of the cooling system in the extraction zoneof the die, which stimulates the formation of polymericcrystals.

FT-IR spectra were recorded in order to investigate thechemical structure of the raw materials and to study thecharacteristic signals of the blends after extrusion.Fig. 2ac shows the FT-IR spectra of raw materials andas-obtained polymer blends at the proposed compositions.FT-IR spectra show typical absorption bands of amorphousor semi-crystalline PET similar to those reported in the lit-erature, except for the variation of the background due tothe film thickness dependent optical effects caused byreflections from polymer surface and polymer/substrateinterface. FT-IR spectra of PET and R-PET (Fig. 2a) showthe main absorption bands as follows: at 3626 cm1 isthe OAH stretching, 3432 OAH stretching of ethylene gly-col end group, 3060 cm1 due to the aromatic CAH stretch-ing, 29652906 cm1 is correlated with the aliphatic CAHstretching, 25581961 cm1 aromatic summation band,1723 cm1 (C@O stretch), 16191510 cm1 aromatic skel-eton stretching band, 14601341 CH

2deformation band,

12661102 cm1 C(O)AO stretching of ester group,1018 cm1 (1,4 aromatic substitution), 963 cm1 OACH2stretching of ethylene glycol segment in PET, 869 cm1

CAH deformation of two adjacent coupled hydrogens onan aromatic ring and finally, at 730 cm1 is presented theband associated with the out of plane deformation of thetwo carbonyl substituents on the aromatic ring.

On the other hand, the FTIR spectrum of PLA was classi-fied into five regions, which corresponds to the followingpeaks band assignment: ACAHA stretching (2994.2 and2985 cm1), AC@O ester carbonyl (1746.2 cm1), ACAHAdeformation (1451.3, 1383 and 1358 cm1), ACAOAstretching (1266, 1178, 1127, 1077 and 1039 cm1) andACACA stretching (867 cm1). In chitosan, the NAH

stretching occurs in the 3438 cm1 region overlapping theOH stretch from the carbohydrate ring. The other peaksband assignment corresponds to ACAHA stretching in2884 cm1, amide I, amide II and NAH bending vibrationsof amine and amide II (1656, 1597 cm1), ACH2 bending(1425 cm1), ACH3symmetrical deformation (1386 cm

1),CAN stretching vibrations overlap the vibrations of carbo-hydrate ringACAOACA (1154 cm1) and skeletal vibrationof CAO stretching (1029 cm1)[13,2834].

FTIR spectra of PET/PLA and R-PET/PLA blends areshown in Fig. 2b; where it is seen a strong absorption bandbetween 1768 cm1 and 1670 cm1, attributed to thesuperposition of the carbonyl stretching of PET and PLA.It is well known that a reaction between these materialsresulted in significant alterations in the bands, normallyassociated with the formation of new bonds; in thisrespect, some researchers have been reported the shift ofthe bands as result of esterification in polymers blends ofPoly carbonate (PC)/PET, Bisphenol A-PC /Poly trimethyl-ene terephthalate and in blends of poly vinylphenol(PVPh)/poly vinylpyrrolidone (PVP) [3537]. The non-displacement of the commented bands can be related withanother kind of interactions between polymers, probablyhydrogen bonds interaction.

In the combinations produced with PET/chitosan orR-PET/chitosan, it was not possible to observe the chitosanphase or an important displacement in the wavenumber orbonds (Fig. 2c). This might be due to the used of low chito-san amounts which are under the limit detection of theequipment (65%). Recent reports demonstrated that thehydrophilic character of chitosan can provoke a stronginteraction between the components forming the polymerblend[38,39]. However, in our case FT-IR spectra did notshow appreciable modifications in the evaluated range(Fig. 2a), suggesting that chitosan is physically integratedto the polymer matrix.

One of the most common methods used to estimatepolymerpolymer compatibility is to determine the glasstransition temperature (Tg) of the blend and compare withthe Tg of the component polymers. If one of the compo-nents is crystalline, the reduction in melting temperature(Tm) can be used to investigate the blend compatibility[4043]. Then, estimating the changes in the Tm of theblends, it is possible to study the miscibility of the blendsif one of the components is crystalline in nature.

Table 1displays the results of DSC thermograms of theraw materials and polymer blends with different quanti-ties of PLA or chitosan. Specifically, PET is characterizedby a glass transition temperature (65140 C) and meltingtemperature (240265 C)[44,45]. However, the commer-cial PET used in this work displayed a glass transition tem-perature about 82 C and two melting temperatures at126 C and 243 C. The first Tm is a result of the additivesthat are commonly used during PET processing, which itis expected do not affect the degree of crystallinity,whereas the second Tm matched well with the value forPET[44].

From these results, it can be noticeable that Tg cannotbe detected in all compositions, which can be explainedby considering that PET can be prevented from crystalliz-ing by very fast cooling, and so obtained in completely



5/15

amorphous form [45]. However, in our laboratory setup,the cooling was carried out at room temperature whichallows the formation of more crystalline regions.Crystallinity of PET is usually induced by thermal crystalli-zation and/or by stress or strain induced crystallization.Specifically, as it is the case, thermally induced crystalliza-tion occurs when polymer is heated above Tg and notquenched rapidly enough. In this condition, the polymerturns opaque due to spherulitic structure generated bythermal crystallization aggregates of non-oriented poly-mers[44].

A slightly increase in the melting point of PET or R-PETcan be obtained by adding both biopolymers and remainfairly constant ca. 250 C when the biopolymers are misci-ble in the matrix. Interestingly, the saturation of PLA intopolymer matrixes was reached up to an amount of10 wt-%, longer quantities than this value provoke twophases in the polymer blend which in turn show a secondmelting temperature (158 C). Similar works highlighted

4000 3500 3000 2500 2000 1500 1000

(a)

N-H

C-H

CH2

C-C

C-CC-O

CO

O-H and N-H

C-H

C-H

C-H

C-H

chitosan

PLA

R-PET

PET

Absorban

ce(%)

CH1,4

C-N

CH2

CO

=Phenyl group CH1,4

CO

CH2

C-C

C-C

Amide I and II

C=O

C=O

C=O

Wavenumber (cm-1)Wavenumber (cm-1)

COC

C-O

3000 2500 2000 1500 10003000 2500 2000 1500 1000

PET/PLA 95/5

(b)

PET/PLA 90/10

PET/PLA 85/15

R-PET/PLA 95/5

R-PET/PLA 90/10

PET signalsC=O PLA

Absorbance(%)

R-PET/PLA 85/15

C=O PET

3000 2500 2000 1500 1000

(c)PET/chitosan 99/1

PET/chitosan 97.5/2.5

PET/chitosan 95/5

R-PET/chitosan 99/1

R-PET/chitosan 97.5/2.5

Absorbance(%)

Wavenumber (cm -1)

R-PET/chitosan 95/5

Wavenumber (cm-1)

Fig. 2. ATR- FTIR for (a) Raw materials (b) PET/and R-PET/PLA (c) PET/and R-PET/chitosan.

Table 1

Thermal transitions obtained for as-prepared selected blends using PLA and

chitosan with PET and R-PET.

Sample Tg (C) Tm (C) Tc (C)

PET 82 126, 243 201R-PET 245 205PLA 69 161 126Chitosan 88 188 PET/PLA 95/5 250 200PET/PLA 90/10 250 202PET/PLA 85/15 250,158 205R-PET/PLA 95/5 250 198R-PET/PLA 90/10 250 201R-PET/PLA 85/15 250,158 202PET/chitosan 99/1 248 197PET/chitosan 97.5/2.5 249 197PET/chitosan 95/5 251 203R-PET/chitosan 99/1 248 208R-PET/chitosan 97.5/2.5 250 207R-PET/chitosan 95/5 250 208



6/15

the importance of the crystallinity on polymers blends,indicating that stable values in the melting point can bereached for higher quantities of PLA in PET/PLA amorphousblends produce from casting solution [46]. However, in ourstudy miscible phases are only obtained with amountsunder 15 wt-% using semi-crystalline biopolymer (PLA).The endothermic peak observed at 126 C for commercialPET is missed in the DSC spectra of blends extruded at260 C, corroborating the presence of small quantities ofadditives.

Table 1 also shows that by increasing the amount of PLAinto the PET or R-PET matrixes slightly increases the crys-tallization temperature (Tc) from 198 C to 205 C. Similartendency can also see for PET/Chitosan or R-PET/Chitosanpolymer blends with a range of Tc between 197 C and208 C. Comparing the crystallization temperatures valuesin the polymer blends, it can be mentioned that all thesamples have an affinity to preserve Tc value of the PETmatrix (PET or R-PET) and the small differences in the ther-mal properties can be associated with a slightly decreasedof the molecular weight of PLA during the processing blendor to the capacity of chitosan to act as nucleating agentpromoting a faster crystallization of PET in combinationwith the crystallinity of the materials.

Dissolution of selected phases in a polymer blend withsuitable solvents is an etching method for morphologyevaluation of polymer blends[47]. Chloroform and aceticacid etching allows the removal of PLA and chitosan toimprove the analysis and reveal the morphology of dis-persed biodegradable polymer. Fig. 3a-l shows typicalSEM observations of PET/PLA, R-PET/PLA, PET/chitosanand R-PET/chitosan. By comparison, SEM micrographs ofthe different compositions of PET with PLA are also shown(Fig. 3bg). All compositions exhibit a droplet (holes)-matrix with heterogeneous structure; i.e. homogenouslydispersed PLA domains are found in PET matrix. The meandiameter of the PLA agglomerates is ranged from 0.02 lmto 1.9 lm (in PET) and 0.52.1 lm (in R-PET). In contrastto PET/PLA blends, the behavior of PET/chitosan blendswas quite different. From Fig. 3hl, cavities were notobserved in ratios of 99/1 and 97.5/2.5. Additionally, PET/Chitosan 95/5 was observed to have some agglomeratesof chitosan which were not dissolved by acetic acid.

Thus, green polymers were integrated in PET and R-PETmatrixes uniformly but the size of agglomerates that formthe filaments varies with the amount of biopolymer. Theseholes after etching demonstrate that such integration isestablished of semi-spherical shape with a size fluctuatingbetween 0.4 and 4.31 lm. Similar morphology has alsobeen observed with previous reports in different polymerblends using chitosan as biodegradable component[48].

3.2. Polymer blends degradation under accelerated

weathering

It has been well recognized that the weight loss of poly-meric blends can indicate the resistance to degradationprocess in a material. Thus, weight loss percentage hasbeen used to estimate the degradation of as obtained poly-mers. Total weight loss% was calculated from the followingequation:

Weight loss% WiWr

Wi1

where Wiand Wrrepresent the initial and residual weightsof the specimens, respectively.

Fig. 4shows the trend of the weight loss% of as-pre-pared samples using PLA or chitosan and monitored during1200 h under accelerated weathering. For comparison, theraw materials (except chitosan powders) and an additionalsample that consist of a commercial BioPET specimen(B-PET) were evaluated.

The evolution of weight loss indicate that only 600 h ofUV irradiation were required to initiate the degradation ofPLA, at this time, the green polymer became brittle and itwas difficult to handle as a consequence of being frag-mented and degraded by UV light from lamps[49]. In gen-eral at 600 h, the blends showed slightly more weight losspercent in comparison with the raw materials.

Intervals between 1.12 and 2.23 wt-% of weight loss intheblends were founddepending ontheamount of biopoly-mer and kind of matrix (commercial or recycled PET). Theresults can divided in two tendencies; (i) the degradationprocess of polymer blends augment as the biopolymer con-centration increases independently of the matrix; and (ii)the highest weight loss of polymer blends was obtainedwhen it is used a recycled PET matrix, which may be associ-ated to the loss properties during the reprocessing. Thepolymer reprocessing provoked that the blend displayedweaker and fragile material more susceptible to degrada-tion than commercial PET [5052]. Additionally, it is widelyknown that amorphous regions in polymers degrade moreeasily than crystalline zones[53,54], i.e. in semicrystallinepolyesters, degradation first occurs in the amorphousdomains and subsequent in the crystalline regions [55].The weight lossof the amorphous R-PET wasapproximately1.40%after 1200 hourswhich was higher than that obtainedfor commercial PET (ca. 0.97%).

On the other hand, it is noteworthy that there were notfound important differences between the weight loss of R-PET (1.4%) and B-PET (1.5%), in spite of the last one isobtained from natural resources.

Weight loss percentages were used to calculate the deg-radation rate according to Eq.(2)

Degradation rateKW

ATD 2

whereKis a constant of conversion units to mm/year,Wisthe weight loss (g), A is the area exposed (cm2), T is thetime (h) and D is the density of the material (g cm3).The degradation rate of PET/PLA, PET/chitosan, R-PET/PLAand R-PET/chitosan blends are shown inFig. 5corroborat-ing the weight loss and FT-IR analyses.

By comparing a six year natural weathering study with a20,000 h accelerated weathering report, it has been shownthat there is a rough relationship of approximately 1000 hof accelerated QUV weathering being equal to one year ofnatural exposure. On the other hand, a rough correlationused in the paint and coatings industry is 5001500 h ofaccelerated exposure equaling approximately 1 year of reallife exposure [56]. Thus, a relationship of 1000 h



7/15

accelerated weathering equaling to a year of natural weath-ering is used as a conservative data in this work[57].

Table 2indicates the lifetime prediction of the synthe-sized materials studied in this work. The results estimatethat commercial PET will totally decompose in about125 years whereas R-PET and B-PET decomposes in 76and 86 years, respectively. As previously mentioned, thisis consistent with the strong dependency of beingsemicrystalline B-PET and amorphous R-PET. From overallsamples, R-PET blends with chitosan (95/5) and PLA (85/15) were found to degrade faster than the others composi-

tions after 45 and 54 years, respectively.

3.2.1. Characterization of degraded polymer blends subjected

to weathering chamber

It is well known that environmental factors, such astemperature, UV radiation and humidity are the maincauses of the degradation in polymer materials [58].Generally, the degradation is noticed as changes in thephysical integrity and the loss of the structural proper-ties due to molecular bond scission [59]. Structuralchanges in all polymer blends were monitored by ana-lyzing the region of absorption bands (between2000 cm1 and 650 cm1) where susceptible bonds to

degradation are located.

(a)

PET

(b)

PET/PLA 95/5 PET/PLA 90/10

(c) (d)

(e) (f) (g)

(h) (i) (j)

(k) (l)

PET/PLA 85/15

R-PET/PLA 95/5 R-PET/PLA 90/10 R-PET/PLA 85/15

PET/chitosan 99/1PET/chitosan

97.5/2.5 PET/chitosan 95/5

R-PET/chitosan 99/1R-PET/chitosan

97.5/2.5

10 m

5 m 5 m 5 m

5 m 5 m 5 m

5 m 5 m 5 m

5 m 5 m R-PET/chitosan 95/5 5 m

(m)

Fig. 3. Morphological features of selected blends using PLA and chitosan with PET and R-PET.

http://-/?-


8/15

Fig. 6shows the FTIR spectra of (a) PET/PLA, (b) R-PET/PLA, (c) PET/chitosan and (d) R-PET/chitosan blends afterbeing exposed to accelerate weathering for 1200 h. Usingcommercial PET or R-PET as matrix in the polymer blendsand PLA in different weight ratios (Fig. 6a and b), the fol-lowing observations can be drawn: (i) it is seen that C@Obands were divided into multiple peaks; probably, due tothe characteristics of each matrix, i.e. the vibrations aremore intense in the commercial PET than that observedfor R-PET. This splitting is commonly used to distinguishbetween the crystalline (lower frequency) and amorphous(higher frequency) phase [60]; (ii) the broader signalobserved around 1700 cm1 indicates the beginning ofphoto-oxidation and degradation in the amorphous poly-ester backbones [61]. The peak in 1747 cm1 at higherwavenumber is encountered more defined than the bandin the amorphous phase; therefore it can be inferred thatthe crystalline phase related to the C@O prevails afteraccelerated weathering. Amorphous phase in the polymerblends is less densely packed and therefore more suscepti-ble to degradation than crystalline regions[62].

The C@O stretching band of the amorphous part of PLAafter the treatment also appears at higher wavenumber(1760 cm1) [63]. In carbonyl containing compounds the(C@O) peaks are well known to shift to higher wavenum-bers, as the electron-withdrawing effect of the /-substitu-ent is larger[64]. This may explain the observations wherecrystalline structure has shorter bonds length than in typ-ical amorphous structures. Characteristic ester bondsappear at 1318 cm1 and 1180 cm1 for PET and PLA,respectively; which become broad and weak after degrada-tion process due to the chain scission of the CAO bondscaused by the UV light and humidity. In the same way,the common CH

2bands (vibration of ethylene units) that

initially appeared at 1410 cm1 and 1340 cm1 are joinedto form a new broad peak after degradation processbetween 1470 and 1420 cm1 [30,65]. Our results seemsto be in good agreement with Liang and coworkers whoseindicate that amorphous CH2 bending mode is found at1455 cm1 corroborating that the degradation processhas begun[66]. Similar behavior was obtained with poly-ester bands between 1120 cm1 and 1100 cm1 character-istic of CAO bonds[67]; i.e. after 1200 h of exposure, thenew band is a combination of crystalline and amorphousphases due to the breakdown of the main bonds ofpolyester.

On the other hand, FT-IR spectra of degraded PET/chito-san blends (Fig. 6c) show very small bands, indicating thetypical splitting of the C@O signals with a shift of the sig-nals to higher wavenumbers[68,69]. A noticeable changein the band intensities is also observed, particularly,ethylene vibrations (CH2) in the wavenumber range from1478 to 1400 cm1 and CAO bonds in the range of1198954 cm1. Finally, the splitting bands correlatedwith crystalline-amorphous phase are missing for R-PET/chitosan (Fig. 6d) polymer blends.

Table 3shows the thermal properties obtained by DSCanalyses of polymer blends after degradation. CommercialPET displays a decrease of Tc from 201 C to 170 C with aTm that remains fairly constant. R-PET presented a similarbehavior with a decrease of Tc from 205 C to 156 C, a new

0 200 400 600 800 1000 1200 1400

0,0

0,5

1,0

1,5

2,0

2,5

3,0

95/5

90/10

85/15

95/590/10

85/15

Time (h)

Weight

loss(%)

PET/PLA

R-PET/PLA

95/5

PLA

PET/chitosan

99/1

97.5/2.5

PLA

B-PET

B-PET

R-PET

R-PET

PET

99/1

97.5/2.5

95/5

PET

R-PET/chitosan

Fig. 4. Weight loss% of PET, R-PET, B-PET, PLA and blends underaccelerated weathering.

0,0 1,0x10-3

2,0x10-3

3,0x10-3

4,0x10-3

Blends

Degradation velocity (mm/year)

PET/PLA 85/15

PET/PLA90/10

PET/PLA 95/5

R-PET/PLA 85/15

R-PET/PLA90/10

R-PET/PLA 95/5

PET/chitosan 95/5

PET/chitosan 97.5/2.5

PET/chitosan 99/1

R-PET/chitosan 95/5

R-PET/chitosan 97.5/2.5

R-PET/chitosan 99/1

Fig. 5. Degradation rate of blends under accelerated weathering.

Table 2

Lifetime prediction of raw materials and blends.

Sample Lifetime prediction (year)

PET 125R-PET 86B-PET 76PET/PLA 95/5 107PET/PLA 90/10 103PET/PLA 85/15 76R-PET/PLA 95/5 91R-PET/PLA 90/10 58R-PET/PLA 85/15 54PET/Chitosan 99/1 143PET/Chitosan 97.5/2.5 93PET/Chitosan 95/5 60R-PET/Chitosan 99/1 56R-PET/Chitosan 97.5/2.5 55

R-PET/Chitosan 95/5 45



9/15

peak appear at about 227 C and a Tm that remains con-stant. The crystallization temperature of the PET andR-PET was found lower than before the weather chambertests. The observed shifts in the Tcs were directly corre-

lated with the disentangled and break of the molecules inthe amorphous phase as well as some crystalline regions.

An unexpected feature was observed in blends or PET/PLA 95/5 and 90/10 at 152 C where the existence of the

2000 1800 1600 1400 1200 1000 800

PET-PLA 95/5

(a)

PET-PLA 85/15

PET-PLA 90/10

Absorbance(%)

C-O

17001747 C=O(a)

Wavenumber (cm-1)

C=O(c)

R-PET/PLA 85/15

R-PET/PLA 90/10

R-PET/PLA 95/5

(b)

Abs

orbance(%)

Wavenumber (cm-1)

PET/chistosan 97.5/2.5

PET/chistosan 99/1

(c)

Absorbance(%

)

C=O (a)

Wavenumber (cm-1)

1746 1715

1700

C=O (c)

CH2

C-OPET/chistosan 95/5 R-PET/Chitosan 95/5

R-PET/Chitosan 97.5/2.5

R-PET/Chitosan 99/1

(d)

Absorbance(%

)

Wavenumber (cm-1)

2000 1800 1600 1400 1200 1000 800 2000 1800 1600 1400 1200 1000 800

2000 1800 1600 1400 1200 1000 800

Fig. 6. FTIR spectra of: (a) PET/PLA, (b) R-PET/PLA, (c) PET/chitosanand (d) R-PET/chitosan blends after being exposed to accelerated weathering for 1200 h.

Table 3

Thermal properties of raw materials and blends after being subjected to accelerated weathering.

Sample Tm(PLA)(C) Tg(chitosan)(C) Tc (C) Tm(PET) (C) Td(chitosan)(C) Td(PLA)(C) Td(PET)(C)

PET 170 248 R-PET 156 227,245 PLA 120 150 Chitosan * * * * * * *

PET/PLA 95/5 152 205 243 370 424,436PET/PLA 90/10 152 202 242 370 424PET/PLA 85/15 155 200 244 370 421

R-PET/PLA 95/5 152 194 241 370 422R-PET/PLA 90/10 152 180 243 370 422R-PET/PLA 85/15 152 180 239 370 422PET/Chitosan 99/1 115, 184 240 340 420PET/Chitosan 97.5/2.5 117, 165 191 242 343 421PET/Chitosan 95/5 117, 171 190 249 344 R-PET/Chitosan 99/1 241 340 422R-PET/Chitosan 97.5/2.5 R-PET/Chitosan 95/5 240 422

* Since chitosan was used as powder, DSC data after accelerated weathering was not included.



10/15

melting point corresponding to PLA as well as the endo-thermic peak at 370 C corroborates that the degradationof PLA is taking place even with low PLA concentrations[70].

In Chitosan, there are several glass transition tempera-ture values, this variability could be attributed to differentfactors like physical state, molecular weight and de-acety-lation degree[71]. From theTable 3, when chitosan wasadded to polymer matrixes two glass transition tempera-tures appear, one at 115 and 117 C from the plasticizedchitosan as a result of the water supplied in the weatheringtest, and the second one at 165 and 171 C attributed toincrease of the molecular movement due to dissociationof hydrogen bonds and starting of molecular scissions[72]. The DSC studies of the blends with chitosan alsoshowed a degradation temperature at 340 C. Thisendothermic peak can be attributed to the degradation ofchitosan [68,73]and its effect into the PET matrix. Thus,both PLA and chitosan biopolymers induce the scission ofPET bonds, producing shorter fragments and therefore,provoking the PET degradation at 420 C[74].

Thermal stability of the polymer blends afteraccelerated weathering and weight loss as a function oftemperature was analyzed by TGA (Fig. 6ad).

From Fig. 7a and c, it is seen that commercial PET beforeweathering decompose at 360 C and at 500 C presents14% of residual weight. Similar results were obtained forR-PET before weathering (Fig. 7b and d) which decomposesat 356 C leaving 13.8% of residual weight (500 C). TheTGA analyses showed that the chain scission of the esterbonds (degradation of the polymer backbone) occurred inthis interval of temperatures[75]. InFig. 7a and b, it canbe seen that the initial step of PLA degradation starts atlower temperatures than PET, at around of 307 C leavingnegligible residue (2-wt%) above 397 C. This is explaineddue to when PLA is exposed to elevated temperatures(370 C), undergoes thermal degradation, leading to theformation of lactide monomers[76].

From the blends TGA studies, is clearly shown that PLAhas strong effect to increase the degradation on bothmatrixes (PET and R-PET) (Fig. 7a and b). The initial decom-position temperature of PET/PLA (Fig. 7 a) is reduced as thecontent of PLA is increased in the blends, showing values of287 C, 250 C and 150 C with a residual weight of 17, 16.5and 13-% at 500 C, for the PET/PLA weight ratios of 95/5,90/10 and 85/15, respectively. On the contrary, R-PET/PLAblends (Fig. 7 b) show an increase in the total mass percent-age in the range of 250327 C which was correlated with

100 200 300 400 500

0

20

40

60

80

100(a)

PLA

PET

PET/PLA (85/15)

PET/PLA (95/5)

PET/PLA (90/10)

50 100 150 200 250 300 350 400 450 5000

20

40

60

80

100

Temperature (C)

(b)

PLA

R-PET

R-PET/PLA (85/15)

R-PET/PLA (95/5)

R-PET/PLA (90/10)

0

20

40

60

80

100(c)

PETPET/Chitosan (99/1)

PET/Chitosan (95/5)

PET/Chitosan (97.5/2.5)

100 200 300 400 500

0

20

40

60

80

100

Weightloss(%

)

R-PETR-PET/Chitosan (99/1)

R-PET/Chitosan (95/5)

R-PET/Chitosan (97.5/2.5)

(d)

100 200 300 400 500

Temperature (C)

Temperature (C) Temperature (C)

Weightloss(%)

Weigh

tloss(%)

Weightloss(%)

Fig. 7. TGA thermograms of: (a) PET/PLA, (b) R-PET/PLA, (c) PET/chitosan and (d) R-PET/chitosan blends after being exposed to accelerated weathering for1200 h.

http://-/?-http://-/?-


11/15

the evaporation of additives used during the production ofR-PET. The first stage of degradation changed to 300 C,327 C and 50 C, with a residual weight of 19%, 20% at500 C and 100-% at 466 C, for the weight ratios of 95/5,90/10 and 85/15, respectively. The TGA analyses evidencedthat the incorporation of PLA and the accelerated weather-ing conditions decreases significantly the thermal stabilityof the blends.

In the case of blends with chitosan (Fig. 7c and d), non-appreciable changes were observed in the temperature

where degradation starts, however, a reduction in the mass

loss can be observed as the amount of chitosan isincreased. The first degradation step varies with the weightratios of 99/1, 97.5/2.5 and 95/5 at 276 C, 305 C and311 C with a final weight of 16, 19 and 20.5 wt-%, respec-tively. Similar trend is again observed for R-PET/chitosanpolymer blends obtaining degradation temperatures about367 C, 299 C and 273 C with a final weight of 16.5, 18.6and 20.6 wt-%, respectively, under the same weight ratios.Then, even though chitosan enhances slightly the thermalstability, reduces the degradation process in comparison

with PLA.

10 m10 m

10 m10 m10 m

10 m10 m10 m

10 m10 m10 m

(a)

PET/PLA 95/5

(b)

PET/PLA 90/10 PET/PLA 85/15

(c)

(d) (e) (f)

(g) (h) (i)

(j) (k)

R-PET/PLA 95/5 R-PET/PLA 90/10 R-PET/PLA 85/15

PET/chitosan 99/1PET/chitosan

97.5/2.5 PET/chitosan 95/5

R-PET/chitosan 99/1R-PET/chitosan

97.5/2.5 10 m

R-PET/chitosan

95/5

(l)

100 m

Fig. 8. PET/PLA, R-PET/PLA, PET/chitosan and R-PET/chitosan blends with different weight ratios after 900 h of accelerated weathering.

http://-/?-


12/15

Fig. 8al shows micrographs of representative weath-ered blends after 1200 h. The micrographs of the weath-ered filaments evidenced rough surfaces caused by theeffects of the UV light and water that simultaneously causesurface microcracks; initially, microcracks or fissures wereformed due to the breaking of the backbone CAO bondsand thereafter are dispersed in different points of the sur-face. The morphology was quit affected by the PLA amount,producing further degradation. For damage accumulation,some regions are so weakened that cracking formationstarts microcracks and expanding over all surface of fila-ments (inset ofFig. 8c). Thus, in presence of PLA and afterthis biodegradable polymer begins to degrade, PET startsthe disintegration process in ACAOA and AC@O bonds[77], which are produced from cleavage at CAC bonds ofthe main polymer chain[78]. InFig. 9, it is shown a pro-posed model for photo-oxidative degradation of polymerblends where are illustrated the chemical alterations andcrack formation during weathering test.

By comparison of the morphologies of PLA and chitosan,it is shown that chitosan blends presented small quantityof microcracks (Fig. 8gl); however, some deep holesformed by the swelling of chitosan powders were also evi-dent. The swelling may be caused by the water used in theQUV camera, leaving away the chitosan particles whichproduce the microcracks[79]. In this case, the photo-oxi-dation process of PET/chitosan blends occurs due to alter-ations such as cross-linking and chains scission; i.e. theformation of carboxylic groups increasing the amount ofpolar groups on the surface during and after irradiationtime point out both the photo-oxidation of chitosan andchanges of its structure. Additional groups such as OH,OOH, CO can also contribute to the rapid degradation ofchitosan with the subsequent swelling and cracks forma-tion and in consequence, eventually, the PET disintegration[80].

3.3. Degradation of polymer blends in soil

From studies of PET degradation, kinetic models havereported, based on accelerated experiments of hydrolyticdegradation and the life time of PET was found in the rangefrom 16 to 48 years[80,81]. Unfortunately, there are fewstudies about the degradation in soil of PET[82,83]. The

degradation of the blends was measured by monitoring

the plastic weight loss during 6 months under real fieldconditions (Fig. 10). It can be noticed that the semicrystal-line (commercial) and amorphous (recycled) PET as well asPET from biodegradable bottle did not show importantvariations in their weight after six months. It means thatdegradation takes a long time for some samples eventhough with some amounts seems to be that the materialdisintegration has started. For example, PET/PLA 95/5 andPET/Chitosan 99/1 blends remained without changes dur-ing all the time, whereas R-PET/PLA (90/10), R-PET/PLA(85/15), PET/Chitosan (95/5) and R-PET/Chitosan (95/5)blends showed certain degradation. It is also seen thatR-PET/chitosan (95/5) blends exhibited the highest loss

weight in comparison with the other polymer blends.Hence, degradation in soil is favored when higher amountsof chitosan or PLA are added to PET matrixes and fromthese the degradation is accelerated with R-PET.Accelerated QUV weathering tests were found to be consis-tent with those obtained under real field conditions. Toprove these observations thermogravimetric analyses ofthe samples were also evaluated (Fig. 11ad). The decom-position temperature (Td) is shifted to low values as PLAcontent is increased. Similarly, PET/chitosan with a 95/5weight ratio showed a displacement up to reach aTdabout

Fig. 9. Proposed model for photo-oxidative degradation of PET/PLA polymer blend.

0.000

0.001

0.002

0.003

0.004

Blends after 6 months

PET/Chitosan(95/5

)

PET/Chitosan(97.5/2.5)

PET/Chitosan(99/1

)

R-PET/PLA(85/15)

R-PET/PLA(95/5)

R-PET/PLA(90/10)

PET/PLA(85/15)

PET/PLA(90/10)

PET/PLA(95/5)

Weigh

tLoss(%)

R-PET/Chitosan(95/5)

R-PET/Chitosan(97.5/2.5)

R-PET/Chitosan(99/1)

Fig. 10. Degradation trends for PET/PLA, R-PET/PLA, PET/Chitosan, R-PET/chitosan blends in soil.



13/15

384 C whereas with other ratios the decomposition tem-perature remains fairly constant, corroborating the lossweight in soil.

According to the above results, the addition of higheramounts of PLA or chitosan on both PET matrixes canmodified its degradation mechanism. PLA degradation attemperature between 3040 C and 80-% of humiditycould be due to the chemical hydrolysis that provokes thateventually the PET/PLA blends cleavage and degrades; sim-ilarly chitosan is degraded by the oxygen presence due tothe interaction in the water drop/surface of the blend sam-ples interface.

4. Conclusions

Blends of commercial and recycled PET/PLA and -/Chitosan were prepared by extrusion process at 250 C toanalyze the miscibility and degradability as a function ofbiopolymer content. The following conclusions can bedrawn:

After extrusion process, XRD patterns and infrared spec-tra analysis showed a weak interaction between PETmatrixes and biodegradable polymers suggesting type sec-ondary bonds by hydrogen bridges or by electrostaticforces. In independence of the amount of biodegradablepolymers, their semi-crystalline character helps to therecrystallization of R-PET during the extrusion reprocess-

ing, which in turn is affected by two factors: quenchedtemperature and mobility of the biopolymer fraction. Themiscibility of the polymer-biopolymer blends is indepen-dent of the PET matrix and the saturation with PLA isreached with 10 wt-%, whereas for chitosan all the compo-sitions display an adequate miscibility. SEM analysisshowed that the green polymers were uniformly distrib-uted into the polymer matrixes, but the mean diameterof the agglomerates and their dissolution varied with theamount and kind of the biopolymer. The acceleratingweathering tests indicate that the interaction betweenPET and chitosan favors more the degradation rate in com-parison with PET/PLA blends, which it is thermally more

stable. The best performance was obtained for PET/chito-san polymer blend with a 95/5 weight ratio where an esti-mate time of about 45 years is required for its degradation.Finally, all the results obtained from various analyses indi-cate that the differences in the thermal stability and degra-dation rate suggest a certain degree of interaction betweenblend components which are comparable to commercialbottles of BioPET, which uses higher amounts of biopoly-mer materials.

Acknowledgements

D. Palma-Ramrez is grateful for her postgraduatefellowship to CONACYT, COFAA and SIP-IPN. The authors

100 200 300 400 5000

20

40

60

80

100

Temperature (C)

Weightloss(%)

PLA

PET

PET/PLA (85/15)

PET/PLA (95/5)

PET/PLA (90/10)

(a)

0

20

40

60

80

100

Temperature (C)

PLA

R-PET

R-PET/PLA (85/15)

R-PET/PLA (95/5)

R-PET/PLA (90/10)

(b)

0

20

40

60

80

100

PET/Chitosan (99/1)

PET/Chitosan (97.5/2.5)

Temperature (C)

Weightloss(%)

PET

PET/Chitosan (95/5)

(c)

100 150 200 250 300 350 400 450 500

0

20

40

60

80

100


R-PET/Chitosan(97.5/2.5)

R-PET


Temperature (C)

Weightloss(%)

(d)

100 200 300 400 500

100 200 300 400 500

Weight

loss(%)

Fig. 11. Thermograms for (a) PET/PLA, (b) R-PET /PLA, (c) PET/chitosan and (d) R-PET/chitosan in composting for 6 months.

http://-/?-http://-/?-http://-/?-


14/15

are also grateful for the financial support provided byCONACYT through the CB2009-132660 and CB2009-133618 projects and to IPN through SIP 2014-0164 and2014-0992 projects and SNI-CONACYT. The authors alsothank M.E.A.E. Rodrguez-Salazar and ROMFER SA CVindustries for their technical support.

Appendix A. Supplementary material

Supplementary data associated with this article can befound, in the online version, at http://dx.doi.org/10.1016/

j.eurpolymj.2014.10.016.

References

[1] Ivar do Sul JA, Costa MF. The present and future of microplasticpollution in the marine environment. Environ Pollut2014;185:35264.

[2] Tian H, Gao J, Hao J, Lu L, Zhu C, Qiu P. Atmospheric pollutionproblems and control proposals associated with solid wastemanagement in China: a review. J Hazard Mater 2013;252253:14254.

[3]Kasetaite S, Ostrauskaite J, Grazuleviciene V, Svediene, BridziuvieneD. Camelina oil- and linseed oil-based polymers withbisphosphonate crosslinks. J Appl Polym Sci 2014;131:18.

[4] Rubio-Anaya M, Guerrero-Beltrn JA. Polmeros utilizados para laelaboracin de pelculas biodegradables. Temas Selectos deIngeniera de Alimentos 2012;6:17381.

[5] Garrison TF, Kessler MR, Larock RC. Effects of unsaturation anddifferent ring-opening methods on the properties of vegetable oil-based polyurethane coatings. Polymer 2014;4:100411.

[6] Lpez OV, Castillo LA, Garca MA, Villar MA, Barbosa SE. Foodpackaging bags based on thermoplastic corn starch reinforced withtalc nanoparticles. Food Hydrocolloids 2014. http://dx.doi.org/10.1016/j.foodhyd.2014.04.021.

[7]Petersson L, Kvien I, Oksman K. Structure and thermal properties ofpoly(lactic acid)/cellulose whiskers nanocomposite materials.Compos Sci Technol 2007;67:253544.

[8]Qu P, Gao Y, Wu G-F, Zhang L-P. Nanocomposites of poly(lactic acid)

reinforced with cellulose nanofibrils. Bioresources 2010;5:181123.[9]Choudhary P, Mohanty S, Nayak SK, Unnikrishnan L. Poly(L-lactide)/

polypropylene blends, evaluation of mechanical, thermal, andmorphological characteristics. J Appl Polym Sci 2011;121:322337.

[10] Zhu M, Li S, Li Z, Lu X, Zhang S. Investigation of solid catalysts forglycolysis of polyethylene terephthalate. Chem Eng J2012;185:16877.

[11] Girija BG, Sailaja RRN, Madras G. Thermal degradation andmechanical properties of PET blends. Polym Degrad Stab2005;90:14753.

[12] Welle F. Twenty years of PET bottle to bottle recycling anoverview. Resour Conserv Recycl 2011;55:86575.

[13] Garlotta D. A literature review of poly (lactic acid). J Polym Environ2001;9:6384.

[14] Tokiwa Y, Calabia B. Biodegradability and biodegradation ofpoly(lactide). Appl Microbiol Biotechnol 2006;72:24451.

[15] Auras RA, Harte B, Selke S, Hernndez R. Mechanical, physical, and

barrier properties of poly(lactide) films. J Plastic Film Sheeting2003;19:12335.

[16] Bautista-Baos S, Hernndez-Lauzardo AN, Velzquez del Valle MG,Hernndez-Lpez M, Ait-Barka E, Bosquez-Molina E, et al. Chitosanas a potential natural compound to control pre and postharvestdiseases of horticultural commodities. Crop Prot 2006;25:10818.

[17] Kint D, Muoz-Guerra S. A review on the potential biodegradabilityof poly(ethylene terephthalate). Polym Int 1999;48:34652.

[18] Siracusa V, Rocculi P, Romani S, Dalla Rosa M. Biodegradablepolymers for food packaging: a review. Trends Food Sci Technol2008;19:63443.

[19] Zou H, Yi C, Wang L, Xu W. Crystallization, hydrolytic degradation,and mechanical properties of poly (trimethylene terephthalate)/poly(lactic acid) blends. Polym Bull 2010;64:47181.

[20] Malgorzata J, Kensuke S, Pierre G, Eric G. Influence of chitosancharacteristics on polymer properties, I: crystallographic properties.Polym Int 2003;52:198205.

[21] Hua H, Changsheng L, Wenjing W. Preparation and characterizationof chitosan/PEG/gelatin composites for tissue engineering. J ApplPolym Sci 2009;114:12205.

[22] US Patent 2013037546. Methods of preparing para-xylene frombiomass, Search International and National Patent Collections.

[23] Xavier Nunes RA, Costa VC, De Araujo Calado VM, Tavares Branco JR.Wear, friction, and microhardness of a thermal sprayed PET poly(ethylene terephthalate) coating. Mater Res 2009;12:1215.

[24] Hwang KT, Kim JT, Jung ST, Cho GS, Park HJ. Properties of chitosan-based biopolymer films with various degrees of deacetylation and

molecular weights. J Appl Polym Sci 2003;89:347684.[25] Samuels RJ. Solid state characterization of the structure of chitosan

films. J Polym Sci 1981;19:1081105.[26] Righetti MC, Tombari E, Angiuli M, Di Lorenzo ML. Enthalpy-based

determination of crystalline, mobile amorphous and rigidamorphous fractions in semicrystalline polymers poly(ethyleneterephthalate). Thermochim Acta 2007;462:1524.

[27] Wunderlich B. Reversible crystallization and the rigidamorphousphase in semicrystalline macromolecules. Prog Polym Sci2003;28:383450.

[28] Holland BJ, Hay JN. The thermal degradation of PET and analogouspolyesters measured by thermal analysis-Fourier transform infraredspectroscopy. Polymer 2002;43:183547.

[29] Prasad SG, De A, De U. Structural and optical investigations ofradiation damage in transparent PET polymer films. Int J Spectrosc2011;1:17.

[30] Drobota M, Aflori M, Barboiu V. Protein immobilization on

Poly(ethylene terephthalate) films modified by plasma andchemical treatments. Digest J Nanomater Biostruct (DJNB)2010;5:3542.

[31] Boerio FJ, Bahl SK, McGraw GE. Vibrational analysis of polyethyleneterephthalate and its deuterated derivatives. J Polym Sci Polym PhysEd 1976;14:102946.

[32] Miyake A. The infrared spectrum of polyethylene terephthalate. I.The effect of crystallization. J Polym Sci 1959;38:47995.

[33] Cristina B, Xavier D, Serge E. Characterization of poly(ethyleneterephthalate) used in commercial bottled water. IOP Conf Series:Mater Sci Eng 2009;5:15.

[34] Zhao Q, Jia Z, Li X, Ye Z. Surface degradation of unsaturated polyesterresin in Xe artificial weathering environment. Mater Des2010;31:445760.

[35] Al-Jabareen A, Illesca S, Maspotch MLI, Santana OO. Effects ofcomposition and transesterification catalysts on the physico-chemical and dynamic properties of PC/PET blends rich in PC. J

Mater Sci 2010;45(24):662333.[36] Na SK, Kong BG, Choi C, Jang MK, Nah JW. Transesterification and

compatibilization in the blends of bisphenol-A polycarbonate andpoly(trimethylene terephthalate). Macromol Res 2005;13(2):8895.

[37] Kuo SW, Chang FC. Significant thermal property and hydrogenbonding strength increase in poly(vinylphenol-co-vinylpyrrolidone)copolymer. Polymer 2003;44(10):302130.

[38] Shieh YT, Yang YF. Significant improvements in mechanical propertyand water stability of chitosan by carbon nanotubes. Eur Polym J2006;42:316270.

[39] Rueda DR, Secall T, Bayer RK. Differences in the interaction of waterwith starch and chitosan films as revealed by infrared spectroscopyand differential scanning calorimetry. Carbohydr Polym1999;40:4956.

[40] Adoor SG, Manjeshwar LS, Krishna Rao KSV, Naidu B, AminabhaviTM. Solution and solid-state blend compatibility of poly(vinyl

alcohol) and poly(methyl methacrylate). J Appl Polym Sci2006;100:241521.

[41] Jawalkar SS, Adoor SG, Sairam M, Nadagouda MN, Aminabhavi TM.Molecular modeling on the binary blend compatibility of poly(vinylalcohol) and poly(methyl methacrylate): an atomistic simulationand thermodynamic approach. J Phys Chem B 2005;109:1561120.

[42] Feng L, Bian X, Li G, Chen Z, Cui Y, Chen X. Determination of ultra-low glass transition temperature via differential scanningcalorimetry. Polym Testing 2013;32:136872.

[43] MacKnight WJ, Karasz FE, Fried JR. Solid state transition behavior ofblends. Chapter 5. Polym Blends 1978:185242.

[44] Demirel B, Yaras AH, Elcicek BF. Crystallization behavior of PETmaterials. Bil Enst Dergisi Cilt 2011;13:2635.

[45] Strobl G. The Physics of Polymers: Concepts for Understanding TheirStructures and Behavior. Berlin, Germany: Springer; 1997.

[46] Chen H, Pyda M, Cebe P. Non-isothermal crystallization of PET/PLAblends. Thermochim Acta 2009;492:616.

http://dx.doi.org/10.1016/j.eurpolymj.2014.10.016http://dx.doi.org/10.1016/j.eurpolymj.2014.10.016http://refhub.elsevier.com/S0014-3057(14)00368-1/h0005http://refhub.elsevier.com/S0014-3057(14)00368-1/h0005http://refhub.elsevier.com/S0014-3057(14)00368-1/h0005http://refhub.elsevier.com/S0014-3057(14)00368-1/h0010http://refhub.elsevier.com/S0014-3057(14)00368-1/h0010http://refhub.elsevier.com/S0014-3057(14)00368-1/h0010http://refhub.elsevier.com/S0014-3057(14)00368-1/h0010http://refhub.elsevier.com/S0014-3057(14)00368-1/h0015http://refhub.elsevier.com/S0014-3057(14)00368-1/h0015http://refhub.elsevier.com/S0014-3057(14)00368-1/h0015http://refhub.elsevier.com/S0014-3057(14)00368-1/h0020http://refhub.elsevier.com/S0014-3057(14)00368-1/h0020http://refhub.elsevier.com/S0014-3057(14)00368-1/h0020http://refhub.elsevier.com/S0014-3057(14)00368-1/h0025http://refhub.elsevier.com/S0014-3057(14)00368-1/h0025http://refhub.elsevier.com/S0014-3057(14)00368-1/h0025http://dx.doi.org/10.1016/j.foodhyd.2014.04.021http://dx.doi.org/10.1016/j.foodhyd.2014.04.021http://dx.doi.org/10.1016/j.foodhyd.2014.04.021http://refhub.elsevier.com/S0014-3057(14)00368-1/h0035http://refhub.elsevier.com/S0014-3057(14)00368-1/h0035http://refhub.elsevier.com/S0014-3057(14)00368-1/h0035http://refhub.elsevier.com/S0014-3057(14)00368-1/h0035http://refhub.elsevier.com/S0014-3057(14)00368-1/h0040http://refhub.elsevier.com/S0014-3057(14)00368-1/h0040http://refhub.elsevier.com/S0014-3057(14)00368-1/h0045http://refhub.elsevier.com/S0014-3057(14)00368-1/h0045http://refhub.elsevier.com/S0014-3057(14)00368-1/h0045http://refhub.elsevier.com/S0014-3057(14)00368-1/h0050http://refhub.elsevier.com/S0014-3057(14)00368-1/h0050http://refhub.elsevier.com/S0014-3057(14)00368-1/h0050http://refhub.elsevier.com/S0014-3057(14)00368-1/h0055http://refhub.elsevier.com/S0014-3057(14)00368-1/h0055http://refhub.elsevier.com/S0014-3057(14)00368-1/h0055http://refhub.elsevier.com/S0014-3057(14)00368-1/h0060http://refhub.elsevier.com/S0014-3057(14)00368-1/h0060http://refhub.elsevier.com/S0014-3057(14)00368-1/h0060http://refhub.elsevier.com/S0014-3057(14)00368-1/h0065http://refhub.elsevier.com/S0014-3057(14)00368-1/h0065http://refhub.elsevier.com/S0014-3057(14)00368-1/h0070http://refhub.elsevier.com/S0014-3057(14)00368-1/h0070http://refhub.elsevier.com/S0014-3057(14)00368-1/h0075http://refhub.elsevier.com/S0014-3057(14)00368-1/h0075http://refhub.elsevier.com/S0014-3057(14)00368-1/h0075http://refhub.elsevier.com/S0014-3057(14)00368-1/h0075http://refhub.elsevier.com/S0014-3057(14)00368-1/h0080http://refhub.elsevier.com/S0014-3057(14)00368-1/h0080http://refhub.elsevier.com/S0014-3057(14)00368-1/h0080http://refhub.elsevier.com/S0014-3057(14)00368-1/h0080http://refhub.elsevier.com/S0014-3057(14)00368-1/h0080http://refhub.elsevier.com/S0014-3057(14)00368-1/h0085http://refhub.elsevier.com/S0014-3057(14)00368-1/h0085http://refhub.elsevier.com/S0014-3057(14)00368-1/h0090http://refhub.elsevier.com/S0014-3057(14)00368-1/h0090http://refhub.elsevier.com/S0014-3057(14)00368-1/h0090http://refhub.elsevier.com/S0014-3057(14)00368-1/h0090http://refhub.elsevier.com/S0014-3057(14)00368-1/h0095http://refhub.elsevier.com/S0014-3057(14)00368-1/h0095http://refhub.elsevier.com/S0014-3057(14)00368-1/h0095http://refhub.elsevier.com/S0014-3057(14)00368-1/h0100http://refhub.elsevier.com/S0014-3057(14)00368-1/h0100http://refhub.elsevier.com/S0014-3057(14)00368-1/h0100http://refhub.elsevier.com/S0014-3057(14)00368-1/h0105http://refhub.elsevier.com/S0014-3057(14)00368-1/h0105http://refhub.elsevier.com/S0014-3057(14)00368-1/h0105http://refhub.elsevier.com/S0014-3057(14)00368-1/h0115http://refhub.elsevier.com/S0014-3057(14)00368-1/h0115http://refhub.elsevier.com/S0014-3057(14)00368-1/h0115http://refhub.elsevier.com/S0014-3057(14)00368-1/h0120http://refhub.elsevier.com/S0014-3057(14)00368-1/h0120http://refhub.elsevier.com/S0014-3057(14)00368-1/h0120http://refhub.elsevier.com/S0014-3057(14)00368-1/h0120http://refhub.elsevier.com/S0014-3057(14)00368-1/h0125http://refhub.elsevier.com/S0014-3057(14)00368-1/h0125http://refhub.elsevier.com/S0014-3057(14)00368-1/h0130http://refhub.elsevier.com/S0014-3057(14)00368-1/h0130http://refhub.elsevier.com/S0014-3057(14)00368-1/h0130http://refhub.elsevier.com/S0014-3057(14)00368-1/h0130http://refhub.elsevier.com/S0014-3057(14)00368-1/h0130http://refhub.elsevier.com/S0014-3057(14)00368-1/h0135http://refhub.elsevier.com/S0014-3057(14)00368-1/h0135http://refhub.elsevier.com/S0014-3057(14)00368-1/h0135http://refhub.elsevier.com/S0014-3057(14)00368-1/h0140http://refhub.elsevier.com/S0014-3057(14)00368-1/h0140http://refhub.elsevier.com/S0014-3057(14)00368-1/h0140http://refhub.elsevier.com/S0014-3057(14)00368-1/h0145http://refhub.elsevier.com/S0014-3057(14)00368-1/h0145http://refhub.elsevier.com/S0014-3057(14)00368-1/h0145http://refhub.elsevier.com/S0014-3057(14)00368-1/h0150http://refhub.elsevier.com/S0014-3057(14)00368-1/h0150http://refhub.elsevier.com/S0014-3057(14)00368-1/h0150http://refhub.elsevier.com/S0014-3057(14)00368-1/h0150http://refhub.elsevier.com/S0014-3057(14)00368-1/h0155http://refhub.elsevier.com/S0014-3057(14)00368-1/h0155http://refhub.elsevier.com/S0014-3057(14)00368-1/h0155http://refhub.elsevier.com/S0014-3057(14)00368-1/h0160http://refhub.elsevier.com/S0014-3057(14)00368-1/h0160http://refhub.elsevier.com/S0014-3057(14)00368-1/h0165http://refhub.elsevier.com/S0014-3057(14)00368-1/h0165http://refhub.elsevier.com/S0014-3057(14)00368-1/h0165http://refhub.elsevier.com/S0014-3057(14)00368-1/h0165http://refhub.elsevier.com/S0014-3057(14)00368-1/h0170http://refhub.elsevier.com/S0014-3057(14)00368-1/h0170http://refhub.elsevier.com/S0014-3057(14)00368-1/h0170http://refhub.elsevier.com/S0014-3057(14)00368-1/h0175http://refhub.elsevier.com/S0014-3057(14)00368-1/h0175http://refhub.elsevier.com/S0014-3057(14)00368-1/h0175http://refhub.elsevier.com/S0014-3057(14)00368-1/h0175http://refhub.elsevier.com/S0014-3057(14)00368-1/h0180http://refhub.elsevier.com/S0014-3057(14)00368-1/h0180http://refhub.elsevier.com/S0014-3057(14)00368-1/h0180http://refhub.elsevier.com/S0014-3057(14)00368-1/h0180http://refhub.elsevier.com/S0014-3057(14)00368-1/h0185http://refhub.elsevier.com/S0014-3057(14)00368-1/h0185http://refhub.elsevier.com/S0014-3057(14)00368-1/h0185http://refhub.elsevier.com/S0014-3057(14)00368-1/h0190http://refhub.elsevier.com/S0014-3057(14)00368-1/h0190http://refhub.elsevier.com/S0014-3057(14)00368-1/h0190http://refhub.elsevier.com/S0014-3057(14)00368-1/h0195http://refhub.elsevier.com/S0014-3057(14)00368-1/h0195http://refhub.elsevier.com/S0014-3057(14)00368-1/h0195http://refhub.elsevier.com/S0014-3057(14)00368-1/h0195http://refhub.elsevier.com/S0014-3057(14)00368-1/h0200http://refhub.elsevier.com/S0014-3057(14)00368-1/h0200http://refhub.elsevier.com/S0014-3057(14)00368-1/h0200http://refhub.elsevier.com/S0014-3057(14)00368-1/h0200http://refhub.elsevier.com/S0014-3057(14)00368-1/h0205http://refhub.elsevier.com/S0014-3057(14)00368-1/h0205http://refhub.elsevier.com/S0014-3057(14)00368-1/h0205http://refhub.elsevier.com/S0014-3057(14)00368-1/h0205http://refhub.elsevier.com/S0014-3057(14)00368-1/h0205http://refhub.elsevier.com/S0014-3057(14)00368-1/h0210http://refhub.elsevier.com/S0014-3057(14)00368-1/h0210http://refhub.elsevier.com/S0014-3057(14)00368-1/h0210http://refhub.elsevier.com/S0014-3057(14)00368-1/h0215http://refhub.elsevier.com/S0014-3057(14)00368-1/h0215http://refhub.elsevier.com/S0014-3057(14)00368-1/h0220http://refhub.elsevier.com/S0014-3057(14)00368-1/h0220http://refhub.elsevier.com/S0014-3057(14)00368-1/h0225http://refhub.elsevier.com/S0014-3057(14)00368-1/h0225http://refhub.elsevier.com/S0014-3057(14)00368-1/h0230http://refhub.elsevier.com/S0014-3057(14)00368-1/h0230http://refhub.elsevier.com/S0014-3057(14)00368-1/h0230http://refhub.elsevier.com/S0014-3057(14)00368-1/h0230http://refhub.elsevier.com/S0014-3057(14)00368-1/h0230http://refhub.elsevier.com/S0014-3057(14)00368-1/h0225http://refhub.elsevier.com/S0014-3057(14)00368-1/h0225http://refhub.elsevier.com/S0014-3057(14)00368-1/h0220http://refhub.elsevier.com/S0014-3057(14)00368-1/h0220http://refhub.elsevier.com/S0014-3057(14)00368-1/h0215http://refhub.elsevier.com/S0014-3057(14)00368-1/h0215http://refhub.elsevier.com/S0014-3057(14)00368-1/h0210http://refhub.elsevier.com/S0014-3057(14)00368-1/h0210http://refhub.elsevier.com/S0014-3057(14)00368-1/h0210http://refhub.elsevier.com/S0014-3057(14)00368-1/h0205http://refhub.elsevier.com/S0014-3057(14)00368-1/h0205http://refhub.elsevier.com/S0014-3057(14)00368-1/h0205http://refhub.elsevier.com/S0014-3057(14)00368-1/h0205http://refhub.elsevier.com/S0014-3057(14)00368-1/h0200http://refhub.elsevier.com/S0014-3057(14)00368-1/h0200http://refhub.elsevier.com/S0014-3057(14)00368-1/h0200http://refhub.elsevier.com/S0014-3057(14)00368-1/h0200http://refhub.elsevier.com/S0014-3057(14)00368-1/h0195http://refhub.elsevier.com/S0014-3057(14)00368-1/h0195http://refhub.elsevier.com/S0014-3057(14)00368-1/h0195http://refhub.elsevier.com/S0014-3057(14)00368-1/h0195http://refhub.elsevier.com/S0014-3057(14)00368-1/h0190http://refhub.elsevier.com/S0014-3057(14)00368-1/h0190http://refhub.elsevier.com/S0014-3057(14)00368-1/h0190http://refhub.elsevier.com/S0014-3057(14)00368-1/h0185http://refhub.elsevier.com/S0014-3057(14)00368-1/h0185http://refhub.elsevier.com/S0014-3057(14)00368-1/h0185http://refhub.elsevier.com/S0014-3057(14)00368-1/h0180http://refhub.elsevier.com/S0014-3057(14)00368-1/h0180http://refhub.elsevier.com/S0014-3057(14)00368-1/h0180http://refhub.elsevier.com/S0014-3057(14)00368-1/h0180http://refhub.elsevier.com/S0014-3057(14)00368-1/h0175http://refhub.elsevier.com/S0014-3057(14)00368-1/h0175http://refhub.elsevier.com/S0014-3057(14)00368-1/h0175http://refhub.elsevier.com/S0014-3057(14)00368-1/h0175http://refhub.elsevier.com/S0014-3057(14)00368-1/h0170http://refhub.elsevier.com/S0014-3057(14)00368-1/h0170http://refhub.elsevier.com/S0014-3057(14)00368-1/h0170http://refhub.elsevier.com/S0014-3057(14)00368-1/h0165http://refhub.elsevier.com/S0014-3057(14)00368-1/h0165http://refhub.elsevier.com/S0014-3057(14)00368-1/h0165http://refhub.elsevier.com/S0014-3057(14)00368-1/h0160http://refhub.elsevier.com/S0014-3057(14)00368-1/h0160http://refhub.elsevier.com/S0014-3057(14)00368-1/h0155http://refhub.elsevier.com/S0014-3057(14)00368-1/h0155http://refhub.elsevier.com/S0014-3057(14)00368-1/h0155http://refhub.elsevier.com/S0014-3057(14)00368-1/h0150http://refhub.elsevier.com/S0014-3057(14)00368-1/h0150http://refhub.elsevier.com/S0014-3057(14)00368-1/h0150http://refhub.elsevier.com/S0014-3057(14)00368-1/h0150http://refhub.elsevier.com/S0014-3057(14)00368-1/h0145http://refhub.elsevier.com/S0014-3057(14)00368-1/h0145http://refhub.elsevier.com/S0014-3057(14)00368-1/h0145http://refhub.elsevier.com/S0014-3057(14)00368-1/h0140http://refhub.elsevier.com/S0014-3057(14)00368-1/h0140http://refhub.elsevier.com/S0014-3057(14)00368-1/h0140http://refhub.elsevier.com/S0014-3057(14)00368-1/h0135http://refhub.elsevier.com/S0014-3057(14)00368-1/h0135http://refhub.elsevier.com/S0014-3057(14)00368-1/h0135http://refhub.elsevier.com/S0014-3057(14)00368-1/h0130http://refhub.elsevier.com/S0014-3057(14)00368-1/h0130http://refhub.elsevier.com/S0014-3057(14)00368-1/h0130http://refhub.elsevier.com/S0014-3057(14)00368-1/h0130http://refhub.elsevier.com/S0014-3057(14)00368-1/h0125http://refhub.elsevier.com/S0014-3057(14)00368-1/h0125http://refhub.elsevier.com/S0014-3057(14)00368-1/h0120http://refhub.elsevier.com/S0014-3057(14)00368-1/h0120http://refhub.elsevier.com/S0014-3057(14)00368-1/h0120http://refhub.elsevier.com/S0014-3057(14)00368-1/h0115http://refhub.elsevier.com/S0014-3057(14)00368-1/h0115http://refhub.elsevier.com/S0014-3057(14)00368-1/h0115http://refhub.elsevier.com/S0014-3057(14)00368-1/h0105http://refhub.elsevier.com/S0014-3057(14)00368-1/h0105http://refhub.elsevier.com/S0014-3057(14)00368-1/h0105http://refhub.elsevier.com/S0014-3057(14)00368-1/h0100http://refhub.elsevier.com/S0014-3057(14)00368-1/h0100http://refhub.elsevier.com/S0014-3057(14)00368-1/h0100http://refhub.elsevier.com/S0014-3057(14)00368-1/h0095http://refhub.elsevier.com/S0014-3057(14)00368-1/h0095http://refhub.elsevier.com/S0014-3057(14)00368-1/h0095http://refhub.elsevier.com/S0014-3057(14)00368-1/h0090http://refhub.elsevier.com/S0014-3057(14)00368-1/h0090http://refhub.elsevier.com/S0014-3057(14)00368-1/h0090http://refhub.elsevier.com/S0014-3057(14)00368-1/h0085http://refhub.elsevier.com/S0014-3057(14)00368-1/h0085http://refhub.elsevier.com/S0014-3057(14)00368-1/h0080http://refhub.elsevier.com/S0014-3057(14)00368-1/h0080http://refhub.elsevier.com/S0014-3057(14)00368-1/h0080http://refhub.elsevier.com/S0014-3057(14)00368-1/h0080http://refhub.elsevier.com/S0014-3057(14)00368-1/h0075http://refhub.elsevier.com/S0014-3057(14)00368-1/h0075http://refhub.elsevier.com/S0014-3057(14)00368-1/h0075http://refhub.elsevier.com/S0014-3057(14)00368-1/h0070http://refhub.elsevier.com/S0014-3057(14)00368-1/h0070http://refhub.elsevier.com/S0014-3057(14)00368-1/h0065http://refhub.elsevier.com/S0014-3057(14)00368-1/h0065http://refhub.elsevier.com/S0014-3057(14)00368-1/h0060http://refhub.elsevier.com/S0014-3057(14)00368-1/h0060http://refhub.elsevier.com/S0014-3057(14)00368-1/h0055http://refhub.elsevier.com/S0014-3057(14)00368-1/h0055http://refhub.elsevier.com/S0014-3057(14)00368-1/h0055http://refhub.elsevier.com/S0014-3057(14)00368-1/h0050http://refhub.elsevier.com/S0014-3057(14)00368-1/h0050http://refhub.elsevier.com/S0014-3057(14)00368-1/h0050http://refhub.elsevier.com/S0014-3057(14)00368-1/h0045http://refhub.elsevier.com/S0014-3057(14)00368-1/h0045http://refhub.elsevier.com/S0014-3057(14)00368-1/h0045http://-/?-http://refhub.elsevier.com/S0014-3057(14)00368-1/h0040http://refhub.elsevier.com/S0014-3057(14)00368-1/h0040http://-/?-http://refhub.elsevier.com/S0014-3057(14)00368-1/h0035http://refhub.elsevier.com/S0014-3057(14)00368-1/h0035http://refhub.elsevier.com/S0014-3057(14)00368-1/h0035http://-/?-http://dx.doi.org/10.1016/j.foodhyd.2014.04.021http://dx.doi.org/10.1016/j.foodhyd.2014.04.021http://-/?-http://refhub.elsevier.com/S0014-3057(14)00368-1/h0025http://refhub.elsevier.com/S0014-3057(14)00368-1/h0025http://refhub.elsevier.com/S0014-3057(14)00368-1/h0025http://-/?-http://refhub.elsevier.com/S0014-3057(14)00368-1/h0020http://refhub.elsevier.com/S0014-3057(14)00368-1/h0020http://refhub.elsevier.com/S0014-3057(14)00368-1/h0020http://-/?-http://refhub.elsevier.com/S0014-3057(14)00368-1/h0015http://refhub.elsevier.com/S0014-3057(14)00368-1/h0015http://refhub.elsevier.com/S0014-3057(14)00368-1/h0015http://-/?-http://refhub.elsevier.com/S0014-3057(14)00368-1/h0010http://refhub.elsevier.com/S0014-3057(14)00368-1/h0010http://refhub.elsevier.com/S0014-3057(14)00368-1/h0010http://refhub.elsevier.com/S0014-3057(14)00368-1/h0010http://-/?-http://refhub.elsevier.com/S0014-3057(14)00368-1/h0005http://refhub.elsevier.com/S0014-3057(14)00368-1/h0005http://refhub.elsevier.com/S0014-3057(14)00368-1/h0005http://-/?-http://dx.doi.org/10.1016/j.eurpolymj.2014.10.016http://dx.doi.org/10.1016/j.eurpolymj.2014.10.016http://-/?-


15/15

[47] Nisha P, Moghe N, Riccobono O, Tyagi S, Rajagopalan S. Novelapproaches in microstructure evaluation of polymer blends. MicroscMicroanal 2005;11(suppl. S02):21101.

[48] Correlo VM, Boesel LF, Bhattacharya M, Mano JF, Neves NM, Reis RL.Properties of melt processed chitosanand aliphatic polyester blends.Mater Sci Eng: A 2005;403:5768.

[49] Muthukumar T, Aravinthan A, Mukesh D. Effect of environment onthe degradation of starch and pro-oxidant blended polyolefins.Polym Degrad Stab 2010;95:198893.

[50] Krcalk M, Pospisil L, Slouf M, Mikesova J, Sikora A, Simonik J, et al.

Effect of glass fibers on rheology, thermal and mechanical propertiesof recycled PET. Polym Compos 2008;29:91521.

[51] Pawlak A, Plutaa MB, Morawieca J, Galeskia A, Pracellab M.Characterization of scrap poly(ethylene terephthalate). Eur Polym J2000;36:187584.

[52] Spinac MAS, De Paoli MA. Characterization of poly(ethyleneterephtalate) after multiple processing cycles. J Appl Polym Sci2001;80:205.

[53] Tudorachi N, Cascabal CN, Rusu M, Pruteanu M. Testing of polyvinylalcohol and starch mixtures as biodegradable polymeric materials.Polym Testing 2000;19:78599.

[54] Huang SJ, Ho LH, Huang MT, Koenig MF, CameronJA. Similarities anddifferences between biodegradation and non-enzymaticdegradation. Stud Polym Sci 1994;12:310.

[55] Anderson JM, Shive MS. Biodegradation and biocompatibility of PLAand PLGA microspheres. Adv Drug Deliv Rev 1997;28(1):524.

[56] Martin D, Eng P. Advanced thin film geomembrane technology for

biocell liners and covers (available from Layfield Geosynthetics andIndustrial Fabrics Ltd) (2005).

[57] Wagner N, Ramsey B. QUV accelerated weathering study: analysis ofpolyethylene film and sheet samples. Technical Document by GSELining Technology, Inc., 2003. Houston, TX, USA

[58] Andrady AL, HamidHS, Torikai A. Effects of climate change and UV-Bon materials. Photochem Photobiol Sci 2003;2:6872.

[59] Fischer HR, Semprimosching C, Mooney C, Rohr T, Ernst RH,Verkuijlen MHW. Degradation mechanism of silicone glues underUV irradiation and options for designing materials with increasedstability. Polym Degrad Stab 2013;98:7206.

[60] Andanson JM, Kazarian SG. In situ ATR-FTIR spectroscopy ofpoly(ethylene terephthalate) subjected to high-temperaturemethanol. Macromol Symp 2008;265:195204.

[61] Zhang WR, Hinder SJ, Smith R, Lowe C, Watts JF. An investigation ofthe effect of pigment on the degradation of a naturally weatheredpolyester coating. J Coat Technol Res 2011;8:32942.

[62] Mai F, Habibi Y, Raquez JM, Dubois P, Feller JF, Peijs T, et al.Poly(lactic acid)/carbon nanotube nanocomposites with integrateddegradation sensing. Polymer 2013;54:681823.

[63] Zhang J, Sato H, Tsuji H, Noda I, Ozaki Y. Differences in theCH3. . .O@C interactions among poly(l-lactide), poly(l-lactide)/poly(d-lactide) stereocomplex, and poly(3-hydroxybutyrate)studied by infrared spectroscopy. J Mol Struct 2005;735:24957.

[64] Shimizu T, Ohkawa Tanaka Y, Kutsumizu S, Yano S. StructuralStudies of Poly(1H,1H-fluoroalkyl alpha fluoroacrylate)s by infraredspectroscopic analysis. Macromolecules 1996;29:35404.

[65] Dieval F, Khoffi F, Mir R, Chaouch W, Le Nouen D, Chakfe N, et al.Long-term biostability of pet vascular prostheses. Int J Polym Sci2012;2012:114.

[66] Liang CY, Krimm S. Infrared spectra of high polymers: Part IX.Polyethylene terephthalate. J Mol Spectrosc 1959;3:55474.

[67] Donelli I, Freddi G, Nierstrasz VA, Taddei P. Surface structure andproperties of poly-(ethylene terephthalate) hydrolyzed by alkali andcutinase. Polym Degrad Stab 2010;95:154250.

[68] De Britto D, Campana-Filho SP. Kinetics of the thermal degradationof chitosan. Thermochim Acta 2007;465:7382.

[69] Pierg M, Ostrowska-Czubenko J, Gierszewska-Druzynska M.Thermal degradation of double crosslinked chitosan membranes.Prog Chem Appl Chitin Derivatives XVII 2012:6774.

[70] Arrieta MP, Lpez J, Ferrndiz S, Peltzer A. Characterization of PLA-limonene blends for food packaging applications. Polym Testing2013;32:7608.

[71] Zhang L, Kosaraju SL. Biopolymeric delivery system for controlledrelease of polyphenolic antioxi-dants. Eur Polym J 2007;43:295666.

[72] Mucha M, Pawlak A. Thermal analysis of chitosan and its blends.Thermochim Acta 2005;427:6976.

[73] Fernandes LL, Resende CX, Tavares DS,Soares GA, Castro LO, GanjeiroJM. Cytocompatibilityof chitosan and collagen-chitosan scaffolds fortissue engineering. Polmeros 2011;21(1):16.

[74] Chen DQ, Wang YZ, Hu XP, Wang DY, Hai M, Yang B. Flame-retardantand anti-dripping effects of a novel char-forming flame retardant forthe treatment of poly(ethylene terephthalate) fabrics. Polym Degrad

Stab 2005;88:34956.[75] Turnbull L, Liggat JJ, MacDonald WA. Thermal degradation chemistry

of poly(ethylene naphthalate) a study by thermal volatilisationanalysis. Polym Degrad Stab 2013;98:224458.

[76] Lim LT, Auras R, Rubino M. Processing technologies for poly(lacticacid). Prog Polym Sci 2008;33:82052.

[77] Babanalbandi A, Hill DJT, ODonnell JH, Pomery PJ, Whittaker A. Anelectron spin resonance study on gamma-irradiated poly(L-lacticacid) and poly(D, L-lactic acid). Polym Degrad Stab1995;50:297304.

[78] Copinet A, Bertrand C, Govindin S, Coma V, Couturier Y. Effects ofultraviolet light (315 nm), temperature and relative humidity on thedegradation of polylactic acid plastic films. Chemosphere2004;55:76373.

[79] Matuana LM, Jin S, Stark NM. Ultraviolet weathering of HDPE/wood-flour composites coextruded with a clear HDPE cap layer. PolymDegrad Stab 2011;96:97106.

[80] Eubeler JP, Bernhard M, Knepper TP. Environmental biodegradationof synthetic polymers II. Biodegradation of different polymer groups.TrAC Trends Anal Chem 2010;29:84100.

[81] Mller RJ, Kleeberg I, Deckwer WD. Biodegradation of polyesterscontaining aromatic constituents. J Biotechnol 2001;86:8795.

[82] Radulovic J. Degradation of polyethylene terephthalate in naturalconditions. Sci Techn Rev LVI 2006:4551.

[83] Platt DK, Rapra L. Technology: biodegradable polymers: MarketReport Rapra Technology (2006).

http://refhub.elsevier.com/S0014-3057(14)00368-1/h0235http://refhub.elsevier.com/S0014-3057(14)00368-1/h0235http://refhub.elsevier.com/S0014-3057(14)00368-1/h0235http://refhub.elsevier.com/S0014-3057(14)00368-1/h0240http://refhub.elsevier.com/S0014-3057(14)00368-1/h0240http://refhub.elsevier.com/S0014-3057(14)00368-1/h0240http://refhub.elsevier.com/S0014-3057(14)00368-1/h0245http://refhub.elsevier.com/S0014-3057(14)00368-1/h0245http://refhub.elsevier.com/S0014-3057(14)00368-1/h0245http://refhub.elsevier.com/S0014-3057(14)00368-1/h0250http://refhub.elsevier.com/S0014-3057(14)00368-1/h0250http://refhub.elsevier.com/S0014-3057(14)00368-1/h0250http://refhub.elsevier.com/S0014-3057(14)00368-1/h0250http://refhub.elsevier.com/S0014-3057(14)00368-1/h0250http://refhub.elsevier.com/S0014-3057(14)00368-1/h0255http://refhub.elsevier.com/S0014-3057(14)00368-1/h0255http://refhub.elsevier.com/S0014-3057(14)00368-1/h0255http://refhub.elsevier.com/S0014-3057(14)00368-1/h0260http://refhub.elsevier.com/S0014-3057(14)00368-1/h0260http://refhub.elsevier.com/S0014-3057(14)00368-1/h0260http://refhub.elsevier.com/S0014-3057(14)00368-1/h0265http://refhub.elsevier.com/S0014-3057(14)00368-1/h0265http://refhub.elsevier.com/S0014-3057(14)00368-1/h0265http://refhub.elsevier.com/S0014-3057(14)00368-1/h0270http://refhub.elsevier.com/S0014-3057(14)00368-1/h0270http://refhub.elsevier.com/S0014-3057(14)00368-1/h0270http://refhub.elsevier.com/S0014-3057(14)00368-1/h0275http://refhub.elsevier.com/S0014-3057(14)00368-1/h0275http://refhub.elsevier.com/S0014-3057(14)00368-1/h0290http://refhub.elsevier.com/S0014-3057(14)00368-1/h0290http://refhub.elsevier.com/S0014-3057(14)00368-1/h0295http://refhub.elsevier.com/S0014-3057(14)00368-1/h0295http://refhub.elsevier.com/S0014-3057(14)00368-1/h0295http://refhub.elsevier.com/S0014-3057(14)00368-1/h0295http://refhub.elsevier.com/S0014-3057(14)00368-1/h0300http://refhub.elsevier.com/S0014-3057(14)00368-1/h0300http://refhub.elsevier.com/S0014-3057(14)00368-1/h0300http://refhub.elsevier.com/S0014-3057(14)00368-1/h0305http://refhub.elsevier.com/S0014-3057(14)00368-1/h0305http://refhub.elsevier.com/S0014-3057(14)00368-1/h0305http://refhub.elsevier.com/S0014-3057(14)00368-1/h0310http://refhub.elsevier.com/S0014-3057(14)00368-1/h0310http://refhub.elsevier.com/S0014-3057(14)00368-1/h0310http://refhub.elsevier.com/S0014-3057(14)00368-1/h0315http://refhub.elsevier.com/S0014-3057(14)00368-1/h0315http://refhub.elsevier.com/S0014-3057(14)00368-1/h0315http://refhub.elsevier.com/S0014-3057(14)00368-1/h0315http://refhub.elsevier.com/S0014-3057(14)00368-1/h0315http://refhub.elsevier.com/S0014-3057(14)00368-1/h0315http://refhub.elsevier.com/S0014-3057(14)00368-1/h0315http://refhub.elsevier.com/S0014-3057(14)00368-1/h0320http://refhub.elsevier.com/S0014-3057(14)00368-1/h0320http://refhub.elsevier.com/S0014-3057(14)00368-1/h0320http://refhub.elsevier.com/S0014-3057(14)00368-1/h0325http://refhub.elsevier.com/S0014-3057(14)00368-1/h0325http://refhub.elsevier.com/S0014-3057(14)00368-1/h0325http://refhub.elsevier.com/S0014-3057(14)00368-1/h0330http://refhub.elsevier.com/S0014-3057(14)00368-1/h0330http://refhub.elsevier.com/S0014-3057(14)00368-1/h0335http://refhub.elsevier.com/S0014-3057(14)00368-1/h0335http://refhub.elsevier.com/S0014-3057(14)00368-1/h0335http://refhub.elsevier.com/S0014-3057(14)00368-1/h0340http://refhub.elsevier.com/S0014-3057(14)00368-1/h0340http://refhub.elsevier.com/S0014-3057(14)00368-1/h0340http://refhub.elsevier.com/S0014-3057(14)00368-1/h0345http://refhub.elsevier.com/S0014-3057(14)00368-1/h0345http://refhub.elsevier.com/S0014-3057(14)00368-1/h0345http://refhub.elsevier.com/S0014-3057(14)00368-1/h0345http://refhub.elsevier.com/S0014-3057(14)00368-1/h0350http://refhub.elsevier.com/S0014-3057(14)00368-1/h0350http://refhub.elsevier.com/S0014-3057(14)00368-1/h0350http://refhub.els

comparative assessment of miscibility and degradability on pet/pla and pet/chitosan blends

Documents