parchment-like paper using water hyacinth pulp · 2016. 1. 11. · mari el:philippine journal of...

Philippine Journal of Science141 (2): 179-185, December 2012ISSN 0031 - 7683Date Received: 20 Sept 2011

Key Words: Cobb values, fiber formation, tensile index

*Corresponding author: [email protected]

179

Erlinda L. Mari

Parchment-Like Paper Using Water Hyacinth Pulp

Forest Products Research and Development InstituteDepartment of Science and Technology

College, Laguna

Water hyacinth pulps, obtained by open-vessel cooking of fresh, air-dried, and ground water hyacinth stems, were mixed with abaca and wastepaper pulps to form handsheets. The handsheets had natural glaze and those from pure hyacinth pulps were fairly translucent, with Cobb values of 38-40 g/m2 that compare well with commercial parchment paper. Compared with either pure abaca or pure wastepaper pulp, replacement with water hyacinth pulp by 25 to 75% significantly improved burst index and tensile index, suggesting better formation and bonding of fibers. Inversely, however, any amount of the soft and short-fibered hyacinth pulp with either pulp reduced tear index, understandably because this property is dependent more on fiber length. With wastepaper pulp, water hyacinth pulp improves the tensile property to a level comparable with that of paper from abaca pulp as well as parchment paper.

INTRODUCTIONLocal studies on the pulp and papermaking potential of water hyacinth conducted in the late seventies (Zerrudo et al. 1978, 1979) followed the conventional method of pulping at high temperature and pressure using steam-heated closed digesters. Results of these studies concluded that depithed water hyacinth stalks may be pulped satisfactorily by any conventional process but the low pulp yields and low initial freeness of the pulp negate its use for ordinary paper. However, the high water resistance, non-porous, and oil-proof properties of the paper produced suggest that water hyacinth pulps may be used for specialty papers such as the parchment type of papers. Much earlier references cited by the authors also mention similar results.

The cooking method used, however, is capital intensive and energy consuming for a material with very low dry solid content of only about 5 %. The use of water hyacinth for pulp and papermaking, thus, did not prosper this way.

Interestingly, water hyacinth is already widely used in handmade papermaking (HMP) in Kenya (http://www.unep.org/roa 2008) and Bangladesh (http://www. Bangladesh.com/ 2008) and is also becoming an alternative fiber material for HMP in some regions of the Philippines where it is abundant.

HMP makes use of different non-wood fibers, such as abaca, cogon, banana fiber, which are pulped by cooking in open vessels under open-fire, unlike the steam-heated closed digester method of cooking. Considering that water hyacinth is similar to these non-wood fibers, its abundance and the reported water resistance of its pulp is an encouragement for its use particularly for special or high end HMP, such as for parchment, lamp shades, or special packaging. This should compensate for the very low dry solid content (about 5 %, green basis) that discourages serious consideration.

Problems arising in the use of water hyacinth need to be addressed, however. When used as fresh, the material is very bulky that a 200-L drum usually used for cooking can accommodate only a fraction of the usual load of dry fibers.

Mari EL: Parchment Paper from Water HyacinthPhilippine Journal of ScienceVol. 141 No. 2, December 2012

180

Thus, air-drying prior to cooking would be advantageous; but this would require large space and additional time for drying. Moreover, water hyacinth material, even when dried, cannot be stored for a long time because it is easily attacked by fungi.

Incidentally, in a previous study aimed at taking advantage of the mucilaginous property of water hyacinth (Mari et al. 2010), water content of the plant’s stems was mechanically extracted and successfully used as formation aid in making handsheets from equal proportions of abaca and wastepaper pulp. The extract significantly increased the tensile strength of the resulting handsheets while residual mass after extraction can be used for other purposes.

Considering the above information, this study evaluated the suitability of water hyacinth pulp for specialty handmade paper using this residual mass and compared the results with those from the fresh and air-dried stalks. The evaluation focused specifically on the strength properties and water resistance of standard laboratory handsheets from pure water hyacinth pulp and in mixture with either abaca or wastepaper pulp. Proportional cost of water hyacinth as raw material in comparison with abaca was also estimated based on pulp yield and purchase cost of raw material. Results from this study will significantly add to the considerations (advantages and disadvantages) in using water hyacinth as a raw material for paper.

MATERIALS AND METHODS

MaterialsThe fiber materials were commercial semi-bleached abaca pulp, bond paper trimmings, and water hyacinth stems from three preparations prior to pulping, namely, fresh (F), air dried (D), and the residual mass (G) after the extraction of the stems’ juice.

Preparation of pulps The commercial semi-bleached abaca pulp lap and bond paper trimmings were simply disintegrated into pulp.

The water hyacinth materials were separately cooked with NaOH at 15% chemical charge (based on oven-dry mass) in an 80-L vessel for two hours. The cooked fibers were squeezed off residual cooking chemical, washed with water, and then disintegrated in the valley beater. The pulp was bleached with 5% calcium hypochlorite for 30 minutes and washed thoroughly.

Pulp FreenessThe freeness of water hyacinth, abaca, and wastepaper pulps, singly or in combination with each other, was measured following the standard ISO 5267-2:2001 (ISO 2003).

Preparation of handsheets Moisture contents of the pulps were determined to calculate the respective oven-dry mass. The three pulp materials were then mixed at the following proportions on oven-dry basis:

Pulp Proportions

Abaca (A) Wastepaper (W) Water Hyacinth (F, D, G)

10075502500000

0000

1007550250

02550750255075100

Testing and evaluation of properties of handsheetsHand sheets were tested for Cobb, burst, tensile, and tear strength properties in accordance with the standard procedures, ISO 535, ISO 2758, ISO 1924-2, and ISO 1974, respectively (ISO 2003). For burst test, 10 sample data were obtainable; the rest, only 5 sample data per treatment.

Analysis of variance (ANOVA) in completely randomized design (CRD) and Duncan Multiple Range Test (DMRT) were conducted to evaluate the effect of the different proportions of pulps on the handsheets.

Estimation of costsEstimation of cost was limited to the cost of abaca and water hyacinth materials based only on their respective pulp yield and purchase cost.

RESULTS AND DISCUSSION

Pulp FreenessThe freeness of pulp is a measure of the rate at which a dilute suspension of pulp may be drained (ISO 5267-2:2001 (ISO 2003). It is a measure used in controlling the beating operation as it relates to the speed at which paper could be made as well as the corresponding changes in strength of paper from the beaten pulps.

Figure 1 shows the freeness values in Canadian Standard Freeness (CSF) mL of pulp stocks from different proportions of water hyacinth (F only), abaca, and wastepaper pulps.

In this study, the freeness of the water hyacinth pulps after disintegration was measured first. Pulp G’s freeness could not be determined as water could hardly drain. Pulps F and


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D (no longer shown) had very low freeness, which indicate the pulps’ very fine nature and the probable cohesion or pulling together of the hemicelluloses and other softened substances in the pulp as the water is drained. In view of this, it was decided that the other materials (abaca and wastepaper) would also no longer be beaten to clearly

show the difference when water hyacinth pulp is partly substituted to these materials. This is limited to this study only and does not necessarily suggest elimination of beating for other purposes.

As Figure 1 shows, 100% abaca pulp had the highest freeness value of 674 CSF mL, followed by wastepaper pulp wit 473 CSF mL. Partial substitution with water hyacinth pulp caused proportional decrease in the values.

Tables 1 and 2 show the results of ANOVA on the properties of handsheets from different proportions of hyacinth pulp (F, D, and G) with abaca and wastepaper pulps, respectively. Incidentally, no hand sheet was successfully formed with 100% pulp from ground (G) hyacinth stems, as the pulp slurry could not drain. Thus, instead of factorial in CRD with type of hyacinth pulp and pulp ratio as variables, ANOVA in simple CRD was conducted for each pulp combination with only pulp ratio as the variable. Data indicate highly significant effect of the treatments on all properties.

Figures 2 and 3 illustrate the property mean values. In both figures, the left set of data is with abaca and water

Figure 1. Freeness values of different pulp stocks.Note: A – abaca; W – wastepaper; FH – fresh water hyacinth

Table 1. ANOVA on the properties of handsheets from different proportions of water hyacinth and abaca pulps.

F:A pulp mixtures

Source of Variation Mean Square

DF Burst Index DF Tear Index Tensile Index Cobb

TreatmentErrorTotal

44549

5.554**0.584

42024

1241.650**31.478

292.525**64.425

4254.421**54.422

R-square, %Coefficient of variation

45.819.158

88.822.758

47.616.301

94.08.227

D:A pulp mixtures



TreatmentErrorTotal

44549

6.267**0.380

42024

1035.651**23.144

321.869*92.616

4603.824**62.214


59.413.819

89.924.778

41.019.381

93.79.506

G:A pulp mixtures



TreatmentErrorTotal

33639

3.786**0.244

31619

920.751**31.104

532.801*101.353

806.006**114.113


56.310.984

84.722.769

49.619.063

57.011.116

** - Statistically significant at 1 % probability level * - Statistically significant at 5 % probability level ns – not significant

F, D, G - pulps from fresh, air-dried and ground hyacinth stalks, respectively.A and W - pulps from abaca and wastepaper, respectively.


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hyacinth combinations; the right set, for wastepaper and water hyacinth combinations. Values for parchment paper cross as a horizontal line for comparison purposes.

Figure 2 shows the burst index (upper graph) and tensile index (lower graph) of the different pulp combinations. Compared with hand sheet from pure abaca pulp, combining with hyacinth pulp from 25 to 75% resulted in an improvement in both burst and tensile indices with the best results around 50 A: 50H. Burst index significantly improved by 7 to 39% and tensile index by 52 to 58%, suggesting better formation and bonding of fibers that may be attributed to the hyacinth pulp acting as dry strengthening agent. The tendency to decrease from a peak with more hyacinth pulp indicates a limitation. Nonetheless, even a 75% substitution with hyacinth pulp is comparable with parchment paper.

With wastepaper, burst and tensile indices almost continuously increased by 20 to 183% and 65 to 141 %, respectively, with an increase in the proportion of hyacinth pulp. Wastepaper is secondary fiber that could have undergone several recycling. With each recycling, fiber properties suffer degradation (Kleinau 1993; Mari et al. 2011). Despite the degraded wastepaper fibers, 75 %

substitution with hyacinth pulp improved burst and tensile properties comparable with those of abaca and hyacinth pulp in the same proportion.

Figure 3 (upper graph) on the other hand, shows that any amount of hyacinth pulp reduced tear index, whether with abaca or wastepaper combinations. This is understandable because this property is dependent more on fiber length. Handsheets from abaca registered the highest tear index. This is not unexpected as abaca fiber (about 6 mm in length) has been recorded with outstanding tear strength (Atchison 1993). In this study fiber dimensions were not measured. However, the tear index data decreasing with addition of hyacinth pulp suggests that the fibers of water hyacinth (about 1.53 mm in length according to Zerrudo et al. 1978), may be much shorter than the already degraded wastepaper.

Regarding water resistance, Figure 3 (lower graph) shows the parchment paper with a Cobb value of 40 g/m2. Values for the handsheets from pure water hyacinth pulp come in very close at 38-40 g/m2. These are almost the same values by which the diploma and waterleaf papers (Cobb values 35.1 and 40.1 g/m2, respectively) from pure water hyacinth pulp (prepared by closed vessel alkaline sulfite pulping) are considered water resistant (Zerrudo et al.

Table 2. ANOVA on the properties of handsheets from different proportions of water hyacinth and wastepaper pulps.

F:W pulp mixtures



TreatmentErrorTotal

44549

3.900**0.114

42024

48.855**0.887

439.024**27.994

2847.453**15.578


75.217.394

91.713.065

75.816.482

97.34.925

D:W pulp mixtures



TreatmentErrorTotal

44549

9.465**0.242

42024

52.643**0.848

685.823**13.635

2601.355**12.166


77.717.640

92.513.263

90.99.337

97.74.826

G:W pulp mixtures



TreatmentErrorTotal

33639

5.815**0.077

31619

47.123**0.725

572.204**35.091

1966.796**104.878


86.312.774

92.411.048

75.417.109

77.911.161

** - Statistically significant at 1 % probability level * - Statistically significant at 5 % probability level ns – not significant

F, D, G - pulps from fresh, air-dried and ground hyacinth stalks, respectively.A and W - pulps from abaca and wastepaper, respectively.


183

Figure 2. Burst and Tensile properties of handsheets from different proportions of water hyacinth (H) pulp with abaca (A) or wastepaper (W) pulps compared with parchment paper.

Note: MD and CD – machine and cross directions, respectively

Figure 3. Tear and Cobb properties of handsheets from different proportions of water hyacinth (H) pulp with abaca (A) or wastepaper (W) pulps compared with parchment paper.

1979). This implies that with the closeness in Cobb values, the pulping process has no remarkable effect on the self-sizing ability of the generated water hyacinth pulp to impart water resistance on the formed paper.

Self-sizing occurs when “resins and extractives with low softening point are redistributed on the fiber material by surface diffusion or by gas-phase diffusion and condensation” (Eklund and Lindstrom 1991). In this case, self-sizing may have been due to redistribution of the hemicelluloses and dissolved substances in water hyacinth fibers.

Interestingly, however, this ability is adversely affected by the introduction of any amount of other pulps to the material. Thus, the Cobb values significantly increased for the handsheets from water hyacinth pulp combined with even the least amount of either abaca or wastepaper pulp. The result indicates that the abaca or wastepaper pulp served to break the relatively hydrophobic bonds probably formed by self-sizing in water hyacinth pulp sheet.

The introduction of other fibers into the system may have broken this reorientation of molecules on the boundary surface thereby opening hydrophilic surfaces on the sheet resulting in poor water resistance. This self-sizing effect is also manifested in the translucent appearance and natural glaze of the handsheets from pure water hyacinth pulp similar to parchment paper. Figure 4 shows the SEM micrographs of handsheets from pure hyacinth pulp and 50A:50H pulp combination. The former shows a smooth surface of partly dissolved fibers while the latter has the more visible but well-laid abaca fibers (A) partly overlaid by the partly dissolved, translucent hyacinth (H) fibers.

Incidentally, although no handsheet was formed with the pulp (G) from ground stems, the preceding data indicate a trend where there seems to be not much difference among the pulps from the three methods of preparation for water hyacinth stems. Pulp yield was also around 30% for all three. It may be inferred that it is indeed possible to extract


184

Figure 4. SEM micrographs of handsheets.Note: Abaca (A) and water hyacinth (H) fibers as indicated by arrows

first the juice from water hyacinth for use as formation aid (Mari et al. 2010), and then pulp the residual mass for mixing with other pulps. This will lessen the difficulty in pulping large volumes of fresh water hyacinth stems and do away with pre-drying.

Estimation of costsDespite the seemingly huge volume of water hyacinth obtainable from bodies of water, production of paper from pure water hyacinth pulp, though technically feasible, has not progressed to commercial production of paper. This study also confirmed the technical feasibility of producing parchment-like paper from pure water hyacinth pulp. It further showed the technical feasibility of mixing water hyacinth pulp with either wastepaper or abaca pulp to produce handsheets with strength properties better than either the pure abaca or wastepaper.

The use of water hyacinth pulp appears to be more feasible for handmade papermaking as the fiber requirement is smaller. The non-fibrous portion may be disposed

with other compost materials or as animal feeds in neighboring areas. Furthermore, production shall not be limited to the processing and use of pure water hyacinth pulp. The use of ground stems after extraction of juice is worthy of consideration to simplify pulping. Although not estimated in this study, it is believed that the cost of energy due to grinding and extraction may be possibly recovered from the use of the juice as formation aid for other pulp materials. The water hyacinth pulp shall also be in combination with wastepaper or other fibers.

Table 3 shows cost estimates for the raw materials for a production capacity of 200 sheets per day at 25 days per month. For a 44-gram 24” x 36” sheet, the total pulp requirement per month would be 220 kg of dry pulp. Based on a PhP10/kg cost of fresh water hyacinth (which is actually for labor cost for collection), increasing the proportion of water hyacinth pulp results in a more costly material due to its low recovery. Thus, handmade paper from water hyacinth may be recommended for special end-use due to its natural glaze, greater tensile strength

Table 3. Cost estimates for abaca and water hyacinth raw materials (based on pulp yield) at different pulp proportions.

Fiber Raw Material (FRM)

Estimated Pulp Yield, %

FRMCost/kg, PhP

Pulp (Abaca:Hyacinth),kg / FRM Cost

100:0 PhP 75:25 PhP 50:50 PhP0:100 PhP

Abaca 60 30 367 11000 275 8250 184 5500 0 0

Water Hyacinth 30 10 0 0 330 3300 660 6600 1330 13300

Total Cost 11000 11550 12100 13300

Difference from 100% Abaca +5% +10% +21%

HV10.00 kV

mag 500 x

WD10.0 mm

400 μmDry Water hyacinth - Abaca

HV10.00 kV

mag 500 x

WD10.0 mm

400 μmDry Water hyacinth - Abaca


185

and water resisting property (from 50 % proportion and up) but probably at higher price to compensate for the additional cost due to lower recovery.

It is a sad reality that although water hyacinth is considered a “pest,” there is definite cost for its collection and use as raw material.

CONCLUSIONS AND RECOMMENDATIONSThe residual mass after extraction of juice from water hyacinth stalks can be pulped but the low freeness or poor drainage of the resulting pulp prevents it from forming into paper. Low freeness is an indication of short fibers. However, the pulp, similar to those from the fresh and air-dried stalks, can be used in mixture with abaca or wastepaper pulps for sufficient freeness to produce paper.

Compared with either pure abaca or wastepaper pulp, replacement with water hyacinth pulp by 25 to 75% significantly improves burst index and tensile index, indicating better formation and bonding of fibers due to the water hyacinth pulps’ self-sizing ability.

Inversely, any amount of the soft and short-fibered hyacinth pulp combined with either abaca or wastepaper pulp reduces tear index, understandably because this property is dependent more on fiber length.

Water hyacinth pulp’s self-sizing ability is manifested more by the natural glaze, translucent appearance and Cobb values of 38-40 g/m2 of handsheets from the pure pulp that are comparable with commercial parchment paper. The water resistance imparted by this self-sizing ability is, however, adversely affected by the presence of any amount of other fiber material combined with water hyacinth pulp.

The use of water hyacinth pulp for handmade paper requires careful consideration on processing, end use, and price to compensate for the additional cost due to low pulp yield of water hyacinth stems. Extraction of juice (before pulping) for use as formation aid for other pulps may recover some of the additional cost when hyacinth pulp from the residual mass itself is combined with other pulps.

The results of the study can help in the pro-active control of the damage brought by of uncontrolled growth of water hyacinth through proper utilization.

ACKNOWLEDGEMENTThe author is grateful to FPRDI staff, namely, Messrs. Cesar Austria, Anniver Ryan P. Lapuz, Mario Ramos, Raul A. Felismino, Justino C. Buendia and Ms. Jasmin B. del

Rio, for the assistance during the experiments; Ms. Adela S. Torres and Mildred M. Fidel, for some suggestions; and Ms. Socorro Dizon, for the statistical analyses of data.

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EKLUND D, LINDSTROM T. 1991. Chapter VIII. Water penetration and internal sizing. In: paper Chemistry. An Introduction. 1st English Edition. Finland: DT Paper Science Publications. p. 203-215.

KLEINAU JH. 1993. Secondary fibers and recycling. In: Pulp and Paper Manufacture. Vol. 3. Secondary Fibers and Non-Wood Pulping. Hamilton F, Leopold B, eds. Joint Textbook Committee of the Paper Industry, TAPPI USA and CPPA & Canada.p.127-131.

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