unsaturated polyester resin composites containing bentonites modifield with silesquioxanes

Unsaturated Polyester Resin Composites Containing BentonitesModied with SilsesquioxanesMariusz Oleksy* and Henryk Galina

Faculty of Chemistry, Rzeszow University of Technology, 35-959 Rzeszow, Al. Powstan cow Warszawy 6, Poland

ABSTRACT: Unsaturated polyester (UP) resins were lled with up to 3 wt % of bentonites modied with silsesquioxanes(POSS). The eects on mechanical properties and ammability changes of the composites obtained therefrom are presented.The mechanical properties of cured resins were improved; the tensile strength and Charpy impact strength increased by up to44% and 59%, respectively, compared to unmodied resins. The cured resins had a typical clay nanocomposite structure withlayer-like morphology, as observed in scanning electron microscopy (SEM) photomicrographs of brittle fractures, an absence ofX-ray diraction pattern (because of the smectic structure of clays), and exfoliated structure, as evidenced by transmissionelectron microscopy (TEM) examination. The presence of POSS-modied bentonites in cured UP resins improved their ameresistance, as exemplied by the increase in the limiting oxygen index, from 17.2 for unlled resin to 25.2 for the resin containing3 wt % of Wyoming bentonite modied with POSS.

INTRODUCTIONThe progress in organic composite materials involves applicationof better and better modiers that, even when used in smallquantities, provide materials with unique properties includingimproved ame resistance and thermal stability. Some attentionas potential ame retardants attracted polyhedral oligomericsilsequioxanes (POSS).1 Their specicity is the structureconsisting of a polyhedral (most often cubic) inorganicsiliconoxygen core with organic substituents in the vertices.The core size is 0.5 nm, and the size of the entire moleculeseldom exceeds 13 nm.The most important limitation of a wide use of these

compounds is their still rather large price. If, however, POSSderivatives containing quaternary ammonium groups are used asmodiers of layered aluminosilicates and the latter are then usedas polymer llers,2,3 the price starts to have a less-important role.4

The main advantage of aluminosilicates themselves, as well asthose modied with silsesquioxane salts, is their relatively highthermal stability, with the temperature of the start ofdecomposition often exceeding 300 C. Recently, a series ofpapers have been published,411 where POSS were used for themodication of clays. The thus-modied aluminosilicates werethen used as nanollers for several types of polymers, includingpolylactide,7 polyamide 12,8,9 poly(butylene terephthalate),10

epoxy resins,11,12 polystyrene,8,1316 and polyurethanes.17

Our previous experience on nanocomposites with syntheticresins as matrices1821 made us to try to prepare bentonitesmodied with quaternary ammonium salt containing POSS andused them as llers of a commercial unsaturated polyester resin.Here, we report on the results.

EXPERIMENTAL SECTIONMaterials. The following materials were used: (i) Wyoming

bentonite (BW) andUkrainian bentonite (BU), both supplied byCETCO-Poland; (ii) selected quaternary ammonium derivativesof octasilsesquioxanes (POSS1 and POSS2) provided by thegroup of Professor Marciniec from University of Poznan, Poland

(the formulas and names are presented in Table 1); (iii)commercial unsaturated polyester resin Polimal 109 (UP109);(iv) cobalt(II) naphtenate (2% styrene solution); and (v)Luperox K-1 (solution of methylethylketone hydroperoxide indibutyl phthalate). Items (iii), (iv), and (v) were kindly providedby Chemical Plants, Organika-Sarzyna-Ciech, in NowaSarzyna, Poland.Modication of Bentonites with POSS Ammonium

Salts.Modication of smectic clays with POSS ammonium saltswas carried out using the following procedure.21 First, thebentonite was mixed with water to obtain a suspensioncontaining 810 wt % of clay. Then, POSS1 or POSS2 in theform of 50% solution in ethanol was introduced dropwise to theclay suspension preheated to 70 C. The amount of introducedPOSS1 or POSS2 per 100 g of air-dry bentonite was 35 or 40 g,respectively. The suspension containing POSS then wasvigorously stirred for 3 h, while slowly increasing the temperatureto 80 C. In the second stage of modication, the temperaturewas further increased to 90 C and the suspension stirred foranother 3 h. The mixture then was cooled to room temperaturewithin 1 h with continuous stirring. The precipitate was freedfrom water excess by evaporating (POSS1) or by ltering undervacuum on a Buchner funnel (POSS2), rinsing it several timeswith distilled water. The resulting wet solid was dried at 100120C in an oven with forced air circulation, until its humidity fellbelow 0.5 wt %.Dried modied bentonite was grinded in an impact and then in

a ball mill and sieved through a sieve with the mesh size of 0.065mm. The grain size distribution was measured using a MasterSizer HydroMU2000 (Malvern) at 20 C. Prior tomeasurement,the particles were ultrasonically dispersed in isopropanol.

Received: December 13, 2012Revised: April 3, 2013Accepted: April 22, 2013Published: April 22, 2013

Article

pubs.acs.org/IECR

2013 American Chemical Society 6713 dx.doi.org/10.1021/ie303433v | Ind. Eng. Chem. Res. 2013, 52, 67136721

Thermal Studies by Dierential Scanning Micro-calorimetry (DSC). The DSC measurements were made on a822e apparatus (Mettler Toledo), in the temperature range of50500 C at a heating rate of 10 C/min in a nitrogenatmosphere.Preparation of Compositions Containing Unsaturated

Polyester (UP) Resin and Bentonites Modied with POSS.A general-use commercial unsaturated polyester (UP) resin,Polimal 109 (Sarzyna, Poland), was used. The resin was mixedwith 1.0, 2.0, or 3.0 wt % of bentonite BW or BU modied withPOSS1 or POSS2. The compositions were premixed using amechanical stirrer at the rate of 500 min1, placed in hermeticglass jars, and further homogenized in an ultrasonic mixer for 15min at 50 C. The compositions then were mixed at the sametemperature (50 C) in a high-speed homogenizer equipped witha turbine-like mixing blade 50 mm in diameter. The time ofmixing was 30 min at a rate of 8000 rpm. Finally, thecompositions were homogenized for 10 min, using a high-speed shear grinder rotating at the rate of ca. 1000 s1. Thiscomplex procedure (temperature and duration of homogeniza-tion stages) was adopted after years of experience in order toprovide the best possible homogenization of bentonites, whilereducing styrene evaporation and preserving integrity ofbentonite platelets.The platelet sizes were estimated from wide-angle X-ray

scattering (WAXS) diractograms, using the Scherer equation.The thus-prepared compositions were kept in a refrigerator (4C) until further use.

Specimen for Mechanical Testing. The UP compositionscontaining modied bentonite were cured using Luperox K-1 (2wt %) (commercial solution of methylethylketone hydroper-oxide in dibutyl phthalate) and cobalt accelerator (0.4 wt %), asrecommended by the resin producer. The compositions thenwere degassed and cast into silicone molds prepared, accordingto ISO Standard 527-1:1998 in a laboratory vacuum oven(VAKUUM UHG 400, Schuechl, Germany). The samples werekept at room temperature for 24 h and post-cured at 80 C for 2h.Two days later, the samples were mechanically tested, using

the procedures described in the respective standards.Morphology and structure of Modied Bentonites and

Composites. The morphology of bentonites, both plain andthose modied with POSS, as well as that of brittle fractures ofcured composites were analyzed by scanning electron micros-copy (SEM) (Model Jeol 234a, JEOL, Japan). The fractures wereobtained after impact breaking the samples cooled in dry ice. Themorphology of composites was also examined using a trans-missionmicroscope (TeslaModel BS 500, accelerating voltage of90 kV). Ultrathin specimens were cut using a Tesla microtomeequipped with freshly shaped glass knifes. They were collectedon acetone/water solution and placed on the standard coppermicromesh.The chemical structure of the composites was also analyzed

using a Fourier transform infrared (FT-IR) microscope (NicoletiN10 MX) in order to check the uniformity of distribution of the

Table 1. Silsesquioxanes Used for Bentonite Modication

Industrial & Engineering Chemistry Research Article

dx.doi.org/10.1021/ie303433v | Ind. Eng. Chem. Res. 2013, 52, 671367216714

silicon-containing components on the sample surface. Thediagnostic band was that at 1045 cm1.The distance between platelets in bentonites before and after

modication and in the composites was evaluated by WAXS,according to Braggs law. ADron 234 diractometer (made in theformer Soviet Union) with a molybdenum lamp (K at =0.7124 ) was used. The samples had a form of round plates 25mm in diameter and 2 mm thick.Mechanical Testing. The tensile strength was measured

using a testing machine (Instron, Model 5967) with anelongation rate of 2 mm/min, according to ISO Standard 527-1:1998. The Rockwell hardness was measured using a dierenttesting machine (Zwick, Model 3106) according to EN Standard10109-1 standard. The penetrator load was 358 N. An averagefrom at least 10 measurements was taken as the result. Charpyimpact resistance was determined using a hammer of impactenergy of 1 J, according to PN-EN ISO Standard 148-1:2010.Flammability of Composites. The limiting oxygen index

(LOI) was measured, according to EN ISO Standard 4589-3 at25 C, using a device from Fire Testing Technology, Ltd.(England) to determine the LOI. The ammability ofcomposites was measured according to Polish Standard PN-82/C-89023. A sample in the form of a beam was weighed and itsdimensions measured. A line perpendicular to its long axis wasdrawn 80 mm from the end to be ignited. The sample was thenclamped horizontally at the other end and the free end wasexposed to a ame from a gas burner for 60 s. After the burnerwas removed, the time until the ame died out or reached themarked line was measured. The remaining part of the beam wasweighed, and the length of the remaining unburned part wasmeasured. Themeasurements were made for at least 5 samples ofeach composition. The results were the averages of the length ofburned sample and the time of burning.

RESULTS AND DISCUSSIONModication Process. In order to assess the eectiveness of

clay modication procedure, thermal (DSC) and X-ray analyseswere made. The DSC curves of unmodied Wyoming (BW) andUkrainian (BU) bentonites and those for bentonites modiedwith POSS1 and POSS2 are shown in Figure 1. In thethermograms, clear endothermic peaks can be seen in temper-ature ranges of 250300 C and 400430 C, and 225260 Cand 380440 C, respectively. The eects are related to thermaldecomposition of the modiers. No peaks in these temperatureranges are present in the thermograms of unmodied bentonites.The only endotherms on the thermogram of plain bentonites, at80130 C, are related to water release from the aluminosili-cates. The same eect occurs also for the modied bentonites,but at slightly lower temperature (60100 C).The nal verication of the bentonite modication was

provided by WAXS analysis. The samples had the form ofpowdered ller and disks cast using UP composites containingthe ller. The distances between platelets were calculated usingthe Bragg equation.Figures 2 and 3 present diractograms of unmodied and

modied BW and BU bentonites, respectively. The distancebetween platelets in Wyoming bentonite increased from 12.4 for unmodied to ca. 18.4 and 16.4 for the same claymodied with POSS1 and POSS2, respectively. For Ukrainianbentonite, the distances increased from 13.1 to 17.9 and 18.1 ,for POSS1 and POSS2, respectively.The relatively large separation of platelets in the modied

bentonites results in organophilization, in addition to facilitating

penetration of the polymer chains or the growth of (macro)-radicals between platelets. This, on the other hand, providesexcellent distribution of ller particles in the resin.The grain size distribution for the modied bentonite powders

was measured. The results are shown in Figure 4 and collected inTable 2.

Figure 1.DSC curves for (a) unmodied BW and (b) BU, as well as forthose modied with POSS1 (BWPOSS1, BUPOSS1) and POSS2(BWPOSS2, BUPOSS2).

Figure 2.WAXS curves for unmodied Wyoming bentonite (BW) andthose for bentonite modied with silsesquioxanes (BWPOSS1 andBWPOSS2).



As can be seen in Table 2, the grain-size distributions ofunmodied and modied bentonites are quite dierent. Thefraction of grains >10 m in size increases inmodied bentonites,particularly for those containing POSS2, relative to the size ofunmodied aluminosilicates. One should bear in mind, however,that, before use, the bentonite llers have micrometer-sizedgrains. The grains disintegrate into nanosized platelets or theirsmall aggregates only after dispersion in UP resin by using themultistage homogenization procedure and after curing.Morphology of Modied Bentonites. The morphology of

bentonite grains after modication with POSS were studied bySEM. Some results are presented in Figure 5. In Figure 5a, onecan observe a lamellar structure consisting of thin layers orderedin regular packets. After modication with POSS1 the structurechanges and a thin opaque layer appears on the surface oflamellae. In the case of BW modied with POSS2, agglomeratesof broken platelets glued together with the modier seem to

prevail. This latter structure does not seem to facilitatehomogenization of the ller within the resin. A similar imageof bonded small disintegrated platelets was observed for theother bentonite (BU).To summarize the observations on the bentonite modication,

one may state that replacing POSS1 by POSS2 rather negativelyaects the surface of grains, thermal stability, and theinterlamellar distances between platelets in modied bentonites,at least in the case of BW bentonite.Compositions of UP Containing Fillers. The composi-

tions of unsaturated polyester resin with Wyoming and

Figure 3. WAXS curves for unmodied Ukrainian bentonite (BU) andthose for bentonite modied with silsesquioxanes (BUPOSS1 andBUPOSS2).

Figure 4. Diagram of the grain size distribution for BWPOSS1.

Table 2. Grain Size Distribution of Unmodied and ModiedBentonites

Distribution of Grain Sizes (%)

bentonite 0.51 m 15 m 510 m 1050 m 50100 m

BW 4.1 13.4 20.4 30.6 31.5BWPOSS1 3.5 10.6 18.3 33.2 34.4BWPOSS2 2.6 9.3 17.4 31.8 38.9BU 3.2 13.6 20.6 31.4 31.2BUPOSS1 3.0 10.1 18.0 34.1 34.8BUPOSS2 2.1 8.8 16.9 30.6 41.6

Figure 5. SEMphotomicrograph of (a) unmodiedWyoming bentonite(BW), (b) BW modied with POSS1, and (c) BW modied withPOSS2.



Ukrainian bentonites modied with POSS1 and POSS2 werefound to be easy to homogenize and the ller formed very stabledispersion in the resin (practically no sedimentation). Our earlierexperience with the methods of dispersing bentonite ller withinpolymer matrices19 have let us select proper homogenizingprocedures consisting of several stages. Consequently, moreuniform compositions were obtained than those previouslyprepared; the compositions were more transparent than thosedescribed previously. We found the homogenization temper-ature (50 C) to be an optimal one to reduce viscosity of thecompositions and, hence provide better homogenization of thesystems. This temperature was still safe from the point of view ofreactivity and shelf stability of the resin.Morphology and Structure of Nanocomposites. The

SEM photomicrographs of UP composites containingBWPOSS1 and BWPOSS2 llers indicate that their brittlefractures have shattered surfaces with at fragments of resin thatare dicult to distinguish from bentonite platelets. Thismorphology suggests a good compatibility of organophilizedbentonite with the resin.The structure of UP composite containing 3 wt % of

BWPOSS1 (Figure 6b) is characteristic for a nanocomposite.Unfortunately, in the case of the other composite UP +BWPOSS2 (Figures 6c and 6d), one can notice the evidentpresence of ller agglomerates. This suggests that micro-composites rather than nanocomposites are formed, at least in

some regions. This explains the somewhat-worse properties ofthe composites lled with BWPOSS2.In the composite containing 3 wt % BWPOSS1, the peak at 2

5 is no longer present in WAXS diractograms, compared tothat in the WAXS diractogram of the pure ller (Figure 7a).This conrms the presence of an exfoliated structure (i.e., astructure with bentonite platelets dispersed in a polymer matrix).In the WAXS curves of composites containing 3 wt %

BWPOSS2 (Figure 7b), the peak corresponding to 2 is locatedclose to that of the ller (i.e., BWPOSS2). This means that thedistance between platelets in the bentonite has not changed.Hence, no exfoliation took place and only microcomposites wereformed, as already concluded from SEM photomicrographs.The microphotographs of ultrathin slices of UP composite

containing BWPOSS1 ller observed in transmissionmicroscopeseem to conrm that exfoliated nanocomposites23 were obtained.In Figure 8a, one can observe platelets of modied bentonite0.52 nm thick, each of which is well-separated from the others.On the other hand, in Figure 8b, a microphograph of a slice ofcomposite UP + 3% BWPOSS2 is shown with evidently noexfoliated structure of bentonite.The surface of cast specimens of UP composites was examined

using infrared (IR) microscopy in order to assess the distributionuniformity of modied aluminosilicates within composites. Theapparatus was set to the 1045 cm1 band characteristic vibrationsof SiOSi bonds. For the UP + 3% BWPOSS2 composites,

Figure 6. SEM photomicrographs of (a) unlled cured UP resin, (b) cured UP resin lled with 3 wt % BWPOSS1, and (c, d) cured UP resin lled with 3wt % BWPOSS2.



silicate agglomerates approximately several dozen micrometersin size can be seen in the photomicrographs (see Figure 9c). Onthe surface of composites containing BWPOSS1 (Figure 9b), theareas of high IR adsorption are much smaller (1020 m).This seems to be more evidence of the poor miscibility of

BWPOSS2 with a UP resin and, hence, insucient intercalation

of the clay galleries by polymer chains. As a result, the bentonitegrains preserve their initial sizes (of the order of micrometers).To summarize, the results of structure examinations by using

SEM, TEM, WAXS, and IR spectroscopy indicate that it waspossible to obtain a nancomposite for the system consisting ofcommercial unsaturated polyester resin with 3 wt % ofBWPOSS1 ller. In the case of the other ller, BWPOSS2,which also was used in the amount of 3 wt %, microcompositesrather than nanocomposites were obtained.Mechanical Properties of Composites. The results of

mechanical testing of the UP composites are collected in Table 3.Static Tensile Strength. The presence of BWPOSS1,

BWPOSS2, BUPOSS1, or BUPOSS2 llers in cured commercialUP resin Polimal 109 clearly improved the toughness of thematerial. Both the tensile strength and Youngmodulus increased.For the composite with UP matrix containing 3 wt % ofBWPOSS1 ller the tensile strength and Young modulusincreased by as much as 44% and 33%, respectively (see Table 3).Somewhat worse improvement of the tensile properties was

recorded for composites containing BWPOSS2 ller. Noimprovement was observed by increasing the amount of ller(Table 3). This result was probably related to the tendency of theller to agglomerate and form a microcomposite (as shown alsoby WAXS, SEM, TEM, and IR mapping measurements).With the Ukrainian bentonites, the improvements of the static

mechanical properties were by 6%34.5% and 3.8%26.5% fortensile strength and Young modulus, respectively, for UPcomposites containing BWPOSS1. For BWPOSS2, therespective improvements were 2%21% for tensile strengthand 3.8%12.6% for Youngmodulus. The values increased as theamount of ller increased (see Table 3).

Rockwell Hardness. The results shown in Table 2 indicatethat the hardness of composites was dependent on all the factorsthat have been varied in this work, i.e., the type and amount ofller. Generally, the hardness of UP composites lled with bothbentonites modied with POSS1 and POSS2 was slightlyreduced, compared to that of the unlled UP. The mostsignicant eect was observed for the composites modied withPOSS1 (the Rockwell hardness decreased by 1.4%6.5%).Hence, the resin containing modied bentonite slightly softened,compared to unmodied cured UP resin. The smallest hardness

Figure 7. WAXS curves recorded for cured composites: (a) UP + 3%BWPOSS1 and (b) UP + 3% BWPOSS2.

Figure 8. TEM photomicrographs of ultrathin slices of UP composite containing 3 wt % of (a) BWPOSS1 and (b) BWPOSS2.



reduction (0.4%2.9%) was noticed for the composites lledwith BUPOSS2.

Charpy Impact Resistance. As follows from the valuescollected in Table 3, the presence of all types of llers studied inthis work was advantageous from the point of view of impactresistance. Again, themost spectacular changes were observed for

UP composites containing BWPOSS1. The important factor isthe amount of ller. The greatest increase of the unnotchedCharpys impact resistance, by as much as 59%, was observed forthe cured polyester resin lled with 3 wt % of BWPOSS1. Asomewhat-worse eect was observed for the other bentonite(BU) that was also modied with POSS1 (3 wt %). In this case,

Figure 9. Surface maps of UP composites showing the intensity of IR adsorption at the band of 1045 cm1, characteristic for SiOSi vibrations: (a) IRspectrum of bentonite, (b) surface adsorption map for UP + BWPOSS1 composites, and (c) surface adsorption map for UP + BWPOSS2 composites.

Table 3. Eect of the Amount of Filler on the Tensile Strength, Young Modulus, Charpy Impact Resistance, and RockwellHardness of CuredCommercial Unsaturated Polyester Resin (UP) Filled with (a) BWPOSS1 and BWPOSS2 or (b) BUPOSS1 andBUPOSS2a

(a) UP Composites Containing BW Bentonite Modied with POSS

UP BWPOSS1 BWPOSS2

property 0.0 wt % 1.0 wt % 2.0 wt % 3.0 wt % 1.0 wt % 2.0 wt % 3.0 wt %

tensile strength [MPa] 60.4 4.7 67.1 3.8 74.2 2.6 86.9 4.3 64.6 4.2 69.3 3.8 74.3 5.6Young modulus [MPa] 3960 25 4256 31 4932 19 5267 26 4187 23 4325 27 4600 18Charpys impact resistance [kJ/m2] 5.6 0.9 6.7 0.8 7.8 0.6 8.9 0.2 6.2 0.3 6.9 0.8 7.3 0.7Rockwell hardness [MPa] 49.3 4.7 48.6 1.9 47.4 2.5 46.3 4.2 48.8 2.1 47.9 0.4 47.2 0.9

(b) UP Composites Containing BU Bentonite Modied with POSS

UP BUPOSS1 BUPOSS2

property 0.0 wt % 1.0 wt % 2.0 wt % 3.0 wt % 1.0 wt % 2.0 wt % 3.0 wt %

tensile strength [MPa] 60.4 4.7 63.9 2.5 72.5 3.3 81.3 3.1 61.2 4.2 68.4 3.3 72.9 3.7Young modulus [MPa] 3960 25 4112 19 4798 31 5009 26 4110 18 4231 22 4460 21Charpys impact resistance [kJ/m2] 5.6 0.9 6.3 0.6 7.3 0.4 8.0 0.5 6.0 0.2 6.7 0.5 7.0 0.3Rockwell hardness [MPa] 49.3 4.7 48.9 2.3 48.1 1.2 47.4 3.1 49.1 1.3 48.6 1.2 47.9 0.5

aThe standard deviation for each value also is shown.



the increase of impact resistance was 43%, with respect to that ofunmodied polyester resin. As expected, the weakest eect ofbrittleness improvement was observed for the compositescontaining bentonites (BW or BU) modied with POSS2.To summarize the results of static mechanical testing, one can

state that much better properties than those of the nativepolyester resins had the composites lled with up to 3 wt %bentonites modied with silsesquioxane quaternary ammoniumderivative POSS1 (recall Table 1). Replacement of the modierwith POSS2 made the composites less mechanically improved.From among the two bentonites studied, clearly the better eectswere obtained for Wyoming bentonite, compared to those forUkrainian bentonite. All the results are presented in Table 3.The Eect of Bentonites Modied with POSS on the

Flammability of UP Composites. The limiting oxygennumber measurements for the cured UP composites indicateda generally advantageous eect of POSS modied bentonites onthe reduction of ammability of these materials. As can be seen inFigure 10, in all cases, the limiting oxygen index (LOI) of the

samples increased monotonically as the amount of llerincreased. These results show that the lowest concentration ofoxygen in a mixture with nitrogen necessary to support sampleburning was higher than that for unmodied polyester resin. Thebest result (LOI = 22.7%) was obtained for the compositecontaining 3 wt % BWPOSS1.Flammability of UP Composites Containing Bentonites

Modied with POSS Fillers. According to literature data,15

nanollersin particular, modied bentonitesmay act as reretardants for composites. Hence, one of the objectives of thiswork was to verify whether the preparation methods that we haveused indeed lead to composites based on a polyester matrix ofreduced ammability. Flammability tests showed that compo-sites containing 3 wt %BWPOSS1 or BUPOSS1 were indeed lessammable than plain cured UP resins. The test involvedweighing the unburned part of specimen beam. The results, inthe form of relative weight loss of burned sample in reference tothat of unmodied resin, are presented in Figure 11. Similar tothat observed with the other physical properties, the best eect ofammability reduction was observed for bentonites modiedwith POSS1. A similar conclusion could be drawn from the timeof burning measured in another standard ammability test (seeFigure 12). Hence, the results indicate that the cured UP resinslled with well-distributed bentonites modied with POSS llers

in the form of quaternary ammonium compounds can beconsidered as starting materials for hybrid composites of reducedammability or self-extinguishing materials.

CONCLUSIONSThe following conclusions are reached from the research:

The organolized llers (BWPOSS1, BWPOSS2, BU-POSS1, and BUPOSS2) used for modication of acommercial unsaturated polyester (UP) resin mix wellwith the resin and had no tendency to sediment.

BWPOSS1 ller added to UP evidently improved themechanical properties of cured resin. Tensile strengthincreased by 44%, Young modulus increased by 33%, andunnotched impact resistance increased by 59%.

All UP composites obtained in this work had improvedame resistance. The best reduction of ammability wasobtained for unsaturated polyesters lled with BWPOSS1.

AUTHOR INFORMATIONCorresponding Author*Tel.: + 48 17865 1223. Fax: +48 17 854 3655. E-mail: [email protected].

NotesThe authors declare no competing nancial interest.

Figure 10. Limiting oxygen number (LOI) values measured for UPcomposites containing BW and BU bentonites modied with POSSllers.

Figure 11. Relative change of burned part of the sample in ammabilitytest, versus the amount of bentonite in UP composites.

Figure 12. Relative burning time of sample beams, versus the amount ofBW and BU bentonites modied with POSS1 and POSS2.



ACKNOWLEDGMENTSThe study was carried out as a part of the project,Silsesquioxanes as Nanollers and Modiers in PolymerComposites (under Grant No. WND-POIG.01.03.01-30-173/09, co-nanced by the European Union, within the EuropeanFund for Regional Development).

REFERENCES(1) Yei, D. R.; Kuo, S. W.; Su, Y. Ch.; Chang, F. Ch. Enhanced thermalproperties of PS nanocomposites formed from inorganic POSS-treatedmontmorillonite. Polymer 2004, 45, 2633.(2) Zhao, F.;Wan, Ch.; Bao, X.; Kandasubramanian, B.Modification ofmontmorillonite with aminopropylisooctyl polyhedral oligomericsilsequioxane. J. Colloid Interface Sci. 2009, 333, 164.(3) Zak, P.; Marciniec, B.; Majchrzak, M.; Pietraszuk, C. HighlyEffective Synthesis of Functionalized Cubic Silsesquioxanes. J. Organo-met. Chem. 2011, 696, 887.(4) Lee, J. H.; Jeong, Y. G. Preparation and Crystallization Behavior ofPolylactide Nanocomposites Reinforced with POSS-modified Mont-morillonite. Fibers Polym. 2011, 12, 180.(5) Perrin, F. X.; Bruzaud, S.; Grohens, Y. Structure and thermalbehaviour of polyhedral oligomeric silsesquioxane modified montmor-illonite. Appl. Clay Sci. 2010, 49, 113.(6) Zhao, F.; Bao, X.; McLauchlin, A. R.; Gu, J. Effect of POSS onmorphology and mechanical properties of polyamide 12/montmor-illonite nanocomposites. Appl. Clay Sci. 2010, 47, 249.(7) Fox, D. M.; Harris, R. H., Jr.; Bellayer, S.; Gilman, J. W.; Gelfer, M.Y.; Hsaio, B. S.; Maupin, P. H.; Trulove, P. C.; De Long, H. C. Thepillaring effect of the 1,2-dimethyl-3(benzyl ethyl iso-butyl POSS)imidazolium cation in polymer/montmorillonite nanocomposites.Polymer 2011, 52, 5335.(8) McLauchlin, A.; Bao, X.; Zhao, F. Organoclay polybutyleneterephthalate nanocomposites using dual surfactant modified mont-morillonite prepared by the masterbatch method. Appl. Clay Sci. 2011,53, 749.(9) Liu, H.; Zhang, W.; Zheng, S. Montmorillonite intercalated byammonium of octaaminopropyl polyhedral oligomeric silsesquioxaneand its nanocomposites with epoxy resin. Polymer 2005, 46, 157.(10) Teo, J. K. H.; Toh, Ch. L.; Lu, X. Catalytic and reinforcing effectsof polyhedral oligomeric silsesquioxane (POSS)-imidazolium modifiedclay in an anhydride-cured epoxy. Polymer 2011, 52, 1975.(11) Fu, H. K.; Huang, Ch. F.; Huang, J. M.; Chang, F. Ch. Studies onthermal properties of PS nanocomposites for the effect of intercalatedagent with side groups. Polymer 2008, 49, 1305.(12) Fu H. K.; Huang Ch. F.; Huang J. M.; Chang F. Ch. PropertiesEnhancement of PS Nanocomposites through the POSS Surfactants. J.Nanomater. 2008, Article ID 739613.(13) Kuo, S. W.; Chang, F.Ch. POSS related polymer nanocomposites.Prog. Polym. Sci. 2011, 36, 1649.(14) Samakande, A.; Hartmann, P. C.; Cloete, V.; Sanderson, R. D. Useof acrylic based surfmers for the preparation of exfoliated polystyreneclay nanocomposites. Polymer 2007, 48, 1490.(15) Sarier, N.; Onder, E. Organic modification of montmorillonitewith low molecular weight polyethylene glycols and its use inpolyurethane nanocomposite foams. Thermochim. Acta 2010, 510, 113.(16) Oleksy, M.; Heneczkowski, M.; Galina, H. Chemosetting ResinsContaining Fillers. I. Unsaturated Polyester Resin CompositionsContaining Modified Smectites. J. Appl. Polym. Sci. 2005, 96, 793.(17) Oleksy, M.; Budzik, G.; Heneczkowski, M.; Markowski, T.Composites of Nanobent lled polyurethane resins (in Pol.). Polimery(Warsaw, Pol.) 2010, 55, 194.(18) Galina, H.; Heneczkowski, M.; Oleksy, M.; Oliwa, R.; Mossety-Leszczak, B. Polish Patent Application P-395821, 2011.(19) Galina, H.; Heneczkowski, M.; Oleksy, M.; Oliwa, R.; Marciniec,B.; Dutkiewicz, M. Polish Patent Application P-397541, 2012.(20) LeBaron, P. C.; Wang, Z.; Pinnavaia, T. J. Polymer-layered silicatenanocomposites: An overview. Appl. Clay. Sci. 1999, 15, 11.

(21) Gobiewski, J.; Rozan ski, A.; Gaski, A. Study on the process ofpreparation of polypropylene nanocomposite with montmorillonite (inPol.). Polimery (Warsaw, Pol.) 2006, 51, 374.(22) Need to add ref 22 or remove citation for ref 22 that appearsshortly after the Figure 1 citation in the Results and Discussion section.



unsaturated polyester resin composites containing bentonites modifield with silesquioxanes

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