Effects of Blend Ratio of PVA-Chitosan-Glycerol Films on their Mechanical Properties

by

Chezza Marie A. Cruz Abiegael C. Dabu Elbenson P. Rescober

An Undergraduate Research Report Submitted to the School of Chemical Engineering and Chemistry in Partial Fulfilment of the Requirements for the Degree Bachelor of Science in Chemical Engineering

Mapúa Institute of Technology March 2006

APPROVAL SHEET

This is to certify that we have supervised the preparation of and read the undergraduate research report, entitled Effects of Blend Ratio of PVA-Chitosan-Glycerol Films on their Mechanical Properties, prepared by Chezza Marie A. Cruz, Abiegael C. Dabu, and Elbenson P. Rescober and that the said report has been submitted for final examination by the Oral Examination Committee.

Manuel R. De Guzman Course Coordinator

Ruth R. Aquino Research Adviser

As members of the Oral Examination Committee, we certify that we have examined this report and hereby recommend that it be accepted as a partial fulfillment of the requirements for the Degree Bachelor of Science in Chemical Engineering.

Carlo Gutierrez Panel Member 1

Rochelle P. Dineros Panel Member 2

Arvin Niele B. Arugay Panel Member 3

This undergraduate research report is hereby approved and accepted by the School of Chemical Engineering and Chemistry as a partial fulfillment of the requirements for the Degree Bachelor of Science in Chemical Engineering.

Alvin R. Caparanga

Luz L. Lozano Dean, School of Chemical Engineering and Chemistry

Chair, Chemical Engineering

ii

ACKNOWLEDGEMENT

We would like to extend our deepest gratitude to our dear advisers, Engr. Ruth Aquino, Engr. Manuel R. De Guzman and Engr. Rhoda B. Leron for providing us the support we need to complete this study. Likewise, we would like to thank the following persons: Mr. Gether Coloma, Ms. Charina Malolot, Ms. Joy Bonus, Ms. Jailene Esperanza, Ms. Andrea De Guzman, Ms. May Carabeo, Ms. Winnie Revil and Mr. Jolly Bilangdal, for their innumerable help to our group; Mr. Rico Maritinez and Mr. Eusebio Aralar, for their assistance in all our laboratory needs; Engr. Joel Rodriguez of TRIMC Testing Laboratory, for his assistance in the mechanical testing of our plastic films; Our dear classmates, for all their sound advice as well as their considerable suggestions; And most of importantly, our beloved parents, for serving as our constant driving force and motivation in all our undertakings. We deeply appreciate the endless love and support that you have always shown us. For this important achievement, we give back all the glory and praises to the omnipotent Almighty Father.

Chezza Marie A. Cruz Abiegael E. Dabu Elbenson P. Rescober

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TABLE OF CONTENTS

TITLE PAGE

i

APPROVAL PAGE

ii

ACKNOWLEDGEMENT

iii

TABLE OF CONTENTS

iv

LIST OF TABLES

vi

LIST OF FIGURE

vii

ABSTRACT

viii

Chapter 1: INTRODUCTION

1

Chapter 2: LITERATURE REVIEW

4

2.1

PVA-Chitosan Blend Film

2.2

Incorporation of Plasticizers

Chapter 3: EFFECTS OF BLEND RATIO OF PVA-CHITOSAN-GLYCEROL BLEND FILMS ON THEIR MECHANICAL PROPERTIES

4 12

16

Abstract

16

Introduction

16

Methodology

19

Extraction of Chitin

19

Film Formation without Plasticizer

21

Mechanical Testing

22

Film Formation with Plasticizer

22

Results and Discussion

23

iv

Mechanical Test on Films without glycerol

23

Mechanical Test on Films with glycerol

26

Conclusion

29

References

29

Chapter 4: CONCLUSION

30

Chapter 5: RECOMMENDATION

31

REFERENCES

32

APPENDIX

36

v

LIST OF TABLES

Table 1: PVA-chitosan Blend Film Formation without Plasticizer Table 2: PVA-chitosan Blend Film Formation with Plasticizer Table 3: Mechanical Properties of PVA-Chitosan Films (without glycerol) Table 4: Film properties of Polyethylene Films Table 5: Mechanical Properties of Sample A (with glycerol)

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21 22 23 26 26

LIST OF FIGURES

Figure 1: Mean Tensile Strength of PVA-Chitosan Films (without glycerol) Figure 2: Mean Percentage elongation at break of PVA-Chitosan Films (w/o glycerol) Figure 3: Chemical structure of (a) chitosan and (b) PVA Figure 4: Mean Tensile Strength of PVA-Chitosan Films (with glycerol) Figure 5: Mean Percentage elongation at break of PVA-Chitosan Films (with glycerol)

23 24 25 27 27

Figure A.1: IR spectra of Chitosan

39

vii

ABSTRACT

Plastic waste disposal becomes a serious problem because of its high volume of solid wastes and its inalterability over a very long period of time. This study covered the production of plastic films using different ratios of PVA and chitosan. It focused on the investigation of the effects of incorporating glycerol as plasticizer. Blend ratio of polyvinyl alcohol and chitosan and glycerol films were subjected to mechanical property testing using universal testing machine. It was noted that increasing the amount of PVA also increased the mean tensile strength and percentage elongation of the plastic films. Addition of glycerol as plasticizer affected the mechanical properties of the plastic film to a significant increase of percent elongation and a decrease in tensile strength. Sample A with 1.8g PVA and 0.2g chitosan gave the best ratio having the highest tensile strength and percentage elongation among the five samples. The 9:1 ratio of PVA to chitosan gave the best ratio in terms of higher mean tensile strength and percentage elongation.

Keywords: polyvinyl alcohol, chitosan, glycerol, tensile strength, elongation

viii

1 Chapter 1

INTRODUCTION

Plastic waste disposal becomes a serious problem because of its high volume of solid wastes and its inalterability over a very long period of time. Today, pyrolysis is a common method to get rid of non-biodegradable plastics, but this unfortunately leads to high emission of CO2. One approach to solve this problem is to use biodegradable materials instead of non-biodegradable polymers, e.g. in packaging. These materials have the potential to reduce environmental pollution by lowering the solid disposal waste and reducing the need for pyrolysis. Hence, there is a need to search for a material that can be used for the production of biodegradable plastics. One of the possible materials in the development of the biodegradable plastic film is chitosan. Chitosan, a copolymer of glucosamine and Nacetyglucosamine units linked by 1-4 glucosidic bonds, is obtained by N-deacetylation of chitin. It can be produced from shellfish waste of seafood industry. This copolymer has excellent oxygen and carbon dioxide barrier properties and interesting bacteriostatic properties. Carapace and shells of black tiger shrimp were more suitable sources of chitin (34.9% and 36.3%) than other sources, such as blue crab, red crab, brine shrimp and horseshoe crab which contained a relatively low chitin content ranging from 14.9-27.6% (Benjakul et al., 1993). Several studies have already been conducted to investigate the significance of chitosan production as an alternative resource material such as a packaging polymer. Studies done were intended to utilize the properties inherent in chitosan to develop an outstanding packaging material. An example of such studies is the one conducted by Park et al. (2000) on

1

2 the characteristics of PVA and chitosan blend films. One of the findings was that the mechanical properties (tensile strength, elongation), water vapor permeability, O2 of PVA and chitosan blended films were affected by acidic type, chitosan viscosity and various mixture ratios. The tensile strength of PVA films was 145Mpa. The tensile strength of PVA and chitosan in citric acid blended films was between 13-35MPa and was generally lower than those of blended films with chitosan dissolved in the other acidic solutions. The elongation of the blended films was higher than those of chitosan films and lower than PVA films. A study conducted by Bodmeier and Remunan (1996) investigated on the mechanical properties and water vapor transmission of properties of polysaccharide films made from sodium alginate and hydroxypropyl me cellulose (HPMC) dissolved in different types and concentrations of acids. Water vapor permeability ranged from 3.64 to 6.56 gmm/hm2 KPa., tension force from 7.23 to 48.3 MPa and elongation percentage from 22.9 to 167.02 were obtained. Polysaccharide films two percent with 0.3 % tween 80 produced films that showed the lowest permeability value. Polysaccharide films with 0.6 % glycerol had the highest percentage of elongation, polysaccharide films with 0.6% tween 80 improved the hydrophobicity of the chitosan film in 1.14 times. The highest value for tension force was found for chitosan with 0.6% of tween 60. The water vapor transmission rate through plasticized films increased with glycerol concentrations. Unfortunately, there are some limitations to the application of chitosan film in packaging and these are due to its high sensitivity to moisture (Törnqvist, 2000). Therefore chitosan must be associated with a moisture resistant polymer that will not affect the overall biodegradability of the plastic. One interesting option is to blend chitosan with polyvinyl

2

3 alcohol. PVA is one of the most widely used polymers because of its excellent mechanical properties. It is a water-soluble synthetic polymer with excellent film forming characteristic and emulsifying capability (Park et al., 2000). On the studies made on the mechanical properties of polyvinyl alcohol and chitosan films, there was no concrete result on the effect of the blend ratio of the two materials on their mechanical property and with the addition of glycerol as plasticizer. The objective of this study was to determine the effect of blend ratio and plasticizer addition to the mechanical properties of PVA-chitosan blend films. It also aimed to determine the PVA-chitosan ratio that yields the blend film of good mechanical strength (tensile strength and percentage elongation). The PVA to chitosan ratios to produce the plastic films were limited as the researchers were only after establishing the effect of the said components on the mechanical properties of the material specifically tensile strength and elongation. The study involved the determination of the effect of plasticizer addition on the mechanical properties of the blend films including the extraction of chitin and its conversion to chitosan, formation of the plastic film and the testing of its mechanical properties such as tensile strength and percentage elongation. This study was conducted in order to create alternative materials, which could be viable enough in replacing plastic materials that persist in the environment as nonbiodegradable solid wastes.

3

4 Chapter 2

LITERATURE REVIEW

Plastic waste disposal becomes a serious problem because of its high volume of solid wastes and its inalterability over a very long period of time. Therefore there is a need to search for a material that can be used for the production of biodegradable plastics. One of the possible materials in the development of the biodegradable plastic film is chitosan. Park et al. (2000) studied about the characteristics of PVA and chitosan blend films and the type of solvent to be used. In the study conducted on the mechanical properties of polyvinyl alcohol and chitosan films, there was no concrete result on the effect of the blend ratio of the two materials on their mechanical property and the addition of glycerol as plasticizer.

2.1 PVA-Chitosan and Polysaccharide Blend Films

Several studies have already been conducted to investigate the significance of chitosan production as an alternative resource material for several valuable products. In fact, most of these studies were done intending to utilize the properties inherent in chitosan to develop outstanding packaging materials. An example of such studies is the one conducted by Park et al. (2000) on the characteristics of PVA and chitosan blend films. This study aimed to prepare new functional degradable films by blending various viscosity chitosan and PVA materials to measure the mechanical properties and barrier (O2 and CO2) of the resulting films. Chitosan of different viscosities was used which was then dissolved in four different acidic solutions with PVA having different mixture ratios. The dried blend films were then analyzed. The tensile

4

5 strength of PVA films was 145MPa. The tensile strength of PVA and chitosan in citric acid blended films was between 13-35MPa and was generally lower than those of blended films with chitosan dissolved in the other acidic solutions. The elongation of the blended films was higher than those of chitosan films and lower than PVA films. Another example is the study conducted by Bodmeier and Remunan (1996) on the mechanical properties and water vapor transmission of properties of polysaccharide films made from sodium alginate and hydroxypropyl me cellulose (HPMC) dissolved in different types and concentrations of acids. Water vapor permeability ranged from 3.64 to 6.56 g mm/hm2 KPa, tension force from 7.23 to 48.3 MPa and elongation percentage from 22.9 to 167.02 were obtained. polysaccharide films two percent with 0.3 % tween 80 produces films that showed the lowest permeability value. Polysaccharide films with 0.6 % glycerol has the highest percentage of elongation, polysaccharide films with 0.6 % tween 80 improved the hydrophobicity of the chitosan film in 1.14 times. The highest value for tension force was found for chitosan with 0.6 % of tween 60. The water vapor transmission rate through plasticized films increased with glycerol concentrations. Tanveer et al. (2000) investigated the suitability of chitosan films prepared using two different solvents, acetic acid (chitosan-AA) and lactic acid (chitosan-LA), for wound dressing. Chitosan films demonstrated significantly different mechanical and bioadhesive strength properties. Chitosan-LA was more soft, flexible, pliable and bioadhesive when compared to chitosan-AA films. Furthermore, chitosan-LA did not cause erythema, edema and systemic toxicity. Hence, Chitosan-LA film was suitable to be used in the management of wound healing and skin burn.

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6 Aydinli et al. (2003) determined the mechanical (tensile strength and elongation) properties, the optical (haze and luminous transmittance) properties of locust bean gum (LBG) based edible films containing polyethylene glycol with different molecular weights as a plasticizer and investigated the thermal properties of the LBG polymer, which had broad application areas in which thermal treatments were applied. Tensile strength and elongation decreased, but there was no regular relationship between the molecular weight of the polyethylene glycol and the tensile strength of the films. It was concluded from the results of the mechanical and optical measurements that the most suitable plasticizer among the polyethylene glycol plasticizers with different molecular weights was polyethylene glycol 200 and that the maximum level for its use was 0.6 mL/0.7 g LBG in edible film formulations. Result obtained from the study of Retuert et al. (2000) on the effect of thermal treatments of chitosan films with different molecular weights, but with a similar acetylation degree, carried out by microhardness was found that the hardness of films prepared from both type of chitosan was similar, of approximately 190 MPa. This suggested that this property was almost independent from the molecular weight in a wide range. The hardness increased notably with a moderate heating (60 °C) reaching a constant value of about 450 MPa after 60 minutes at this temperature. This was attributed to the loss of water and the formation of new intermacromolecular bonds leading to a more compact network. The increase of hardness was accompanied by an increase in the fragility of the films. Xiao et al. (2001) prepared blend films from chitosan and polyacrylamide solutions. The structure and physical properties of the resulting blend films were analysized by FTinfrared spectra (FT-IR), wide angle X-ray diffraction (WAXD), thermo-gravimetric analysis

6

7 (TGA), scanning electron microscopy (SEM), and by tensile tester. The results showed the occurrence of intermolecular interactions between chitosan and polyacrylamide through hydrogen bond formation. The thermal stability and mechanical properties were improved by blending chitosan with polyacrylamide. It was worth noting that the blend film exhibited the greatest tensile strength 68 MPa and highest thermal stability when the polyacrylamide content in the blends was around 20 wt%. Polysaccharide films such as corn starch films evaluated its film forming ability and mechanical stress-strain properties was the study made by Palviainen et al. (2001). Free films were prepared from high-amylose corn, corn and waxy corn starches, using sorbitol and glycerol as plasticizers. The amylose content of the starch film formers affected both the tensile strength and the elongation. The elongations were under 5% for even the plasticized starches, and in most cases, no plasticization effect was seen by either of the plasticizers. Dissolution of native corn starch film-coated tablets (weight gain 1%) did not differ from uncoated ones. A study by Mangala et al. (2003) developed chitosan/polyvinyl alcohol and determined its good swelling and mechanical properties to determine if it could be good burn dressings. Blend membranes of chitosan and polyvinyl alcohol were prepared in different compositions (1:1, 1:3 and 3:1 v/v) by using solvent-casting technique and their morphological properties were studied. The prepared membranes were characterized for their mechanical properties and intermolecular reactions by FT-IR spectroscopy. The swelling behavior of membranes was studied in various pH media (2.1 and 7.4). Broad-spectrum antibiotic. Gentamicin was incorporated into the membranes and ts in vitro release profiles was studied in phosphate buffered saline (PBS) pH 7.4 using reciprocating thermostatic

7

8 water bath and analyzing the sample spectrophotometrically. Cast films presented good swelling and mechanical properties, which made them good candidates as burn dressings. The film-forming ability of chitosan and binary mixtures of chitosan and native amylose corn starch was evaluated with free films prepared by a casting/solvent evaporation method by Cervera et al. (2003). Unplasticized and plasticized free chitosan films in aqueous acetic acid and respective films containing a mixture of chitosan and native amylose starch in acetic acid were prepared. Glycerol, sorbitol, and i-erythritol were used as plasticizers. A plasticizer concentration of 20% wt/wt (of the polymer weight) was sufficient to obtain flexible films with all samples tested. Incorporation of native amylose corn starch into chitosan films improved the consistency and the mechanical properties of the films. Ferdous et al. (2003) mechanical properties like tensile strength (TS), elongation at break (Eb) of chitosan film. Five formulations were developed with 2-ethyl-2-hydroxymethyl-1,3-propandiol-tri-methacrylate (EHMPTMA), a tri-functional acrylic monomer and 2-ethylhexyl acrylate (EHA), a mono-functional acrylic monomer in the presence of photoinitiator (2%). The films were soaked in those monomer formulations in dissimilar soaking times and irradiated under UV radiation at different radiation intensities for the improvement of the properties of chitosan film. The cured films were then subjected to various characterization tests like TS, Eb, polymer loading (PL), water uptake, gel content etc. The formulation, containing 25% EHMPTMA and 73% EHA showed the best performance at 10th UV passes of UV radiation for 4 min soaking time. The bioblend film PVA/chitosan performed better physico-mechanical properties rather than PVA/polyethylene oxide (PEO).

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9 Jeong et al. (2004) investigated on the preparation and properties of polyvinyl alcohol and chitosan blend films. Variation of the physicochemical properties of the blend films was investigated through to several analysis methods. The mechanical properties of the blend films were increased with increasing chitosan content in both dry and wet states. The blend film including 15 wt% chitosan exhibited unusually high tensile strength. Examination of antibacterial properties revealed that bacterio-static ratios of all blend samples containing chitosan more than 10 wt% were greater than 99.9 %. Moisture regain was increased with increasing chitosan content but the degree of swelling was decreased. Up to chitosan content 15 wt%, the melting and crystallization temperature of blend films was increased with chitosan content. The blends containing chitosan content 10 and 15 wt% gave melting temperature 229 and 228, respectively. However, the melting temperature was decreased if chitosan content exceeded 20 wt%. Wang et al. (2004) used chitosan and polyvinyl alcohol to form a semiinterpenetrating polymeric network with glutaraldehyde as the cross-linker. The addition of PVA improved the mechanical properties of the hydrogel. However, PVA tended to leach out at longer swelling times in the acidic medium due to hydrolysis of the gel networks, Schiff’s base. The molecular weight and degree of deacetylation of the chitosan were 612 kDa and 72 %, respectively. The chitosan was essential for hydrogel formation through Schiff’s base reaction between the amino groups of the chitosan and the aldehyde groups of the glutaraldehyde. The study investigated by Bravin et al. (2004) determined the effect of different types of surfactant (glycerol monostearate, tween 60, and tween 80) on water vapor permeability (WVP), tensile strength (TS), percentage elongation at breaking (E), and

9

10 structure of an emulsified edible film composed of cornstarch, methylcellulose, and cocoa butter or soybean oil. Results showed that the effects of independent variables on WVP, TS, and E were dependent on surfactant and lipid type. The presence of emulsifier significantly decreased the WVP of cocoa butter films but did not improve the barrier or mechanical properties of soybean oil-based film. Films made up of chitosan-anionic starch and two types of clay prepared by casting method using polyethylene glycol as a plasticizer and their mechanical and water permeation properties were evaluated by Rodriguez et al. (2004). A decrease in both the tensile strength and percent elongation was observed. The water vapor permeability was significantly different for two clay types used in this study during a storage time of 60 days. Trujilllo et al. (2004) prepared biodegradable films via method of solvent casting from modified starch, chitosan and polyvinyl alcohol by cross-linking, whereas, polyethylene glycol was used as a plasticizer. Films were evaluated for their mechanical property (tensile strength and elongation) and vapor barrier properties under storage conditions for up to a three month period. A decrease in both the tensile strength and percentage elongation from 27.46 to 21.51 MPa and 7.09% to 4.91%, respectively, was observed over the storage period. The water permeation capacity of film was 1.45 x 10-7 g/hm2mmHg on day one, and reduced to 1.10 x 10-7 g/hm2mmHg by day 30. A research conducted by Chi et al. (2004) showed that addition of oregano essential oil (OEO) resulted in increased thickness of chitosan films from 0.107 to 0.306 and 0.425 mm with 0, 1, and 2% OEO, respectively. Mechanical properties of the films were significantly altered by addition of OEO and after application on the meat product. Tensile

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11 strength of pure chitosan films (105.66 N/mm2) decreased to 28.18 and 17.35 N/mm2 in the films with 1 and 2% OEO. Amylose films blended with chitosan, which were free from additives such as acid, salt, and plasticizer, were prepared by casting mixtures of an aqueous solution of an enzymatically synthesized amylose and that of water-soluble chitin (44.1% deacetylated). Suzuki et al. (2005) observed that the presence of a small amount of chitin (less than 10%) increased significantly the permeability of gases (N2, O2, CO2, C2H4) and improved the mechanical parameters of amylose film; particularly, the elastic modulus and elongation of the blend films were larger than those of amylose or chitin films. Films from blends of oppositely charged biopolymers were prepared by Rutiaga et al. (2005). About 50 mm thick cast films containing blends of oppositely charged biopolymers such as anionic starch-chitosan, and cationic starch-pectin were fabricated. The tensile strength and elongation at break (%) of the films were evaluated as well as their capacity to degrade in compost. Anionic starch-chitosan films had much superior tensile strength and elongation compared to cationic starch-pectin, suggesting that the ionic bonds formed between anionic starch and positively charged groups in chitosan polymer were much more stable and stronger. Initially, both films lost about 36% weight within 96 hours, which also correlated well with the loss in the characteristic absorption peaks in the infrared region of the spectrum typical of biopolymers. One difference of our study with those previously mentioned was that the plastic to be made from chitosan would be extracted only from a single source, which would be subsequently blended with PVA of various proportions. In this study, chitosan would be dissolved only in acetic acid. The researchers would also make use of a film casting/solvent

11

12 evaporation method to make the blend films. Glycerol would be the only plasticizer to be added to the film.

2.2 Incorporation of Plasticizers to the Plastic Film

Plasticizer is defined as a material incorporated in a plastic to increase its workability and flexibility. Plasticizers function by reducing the brittleness of plastics and permitting its sufficient flow under the influence of heat and pressure. Plasticizers basically reduce the intermolecular vander waals forces between polymers, which make the plastics flexible and reduces its stiffness. Kim et al. (2001) found out that plastics compounded with plasticizers usually become more flexible, the modulus and the tensile strength were reduced, and provide better elongation. However, due to the fact that plasticizers are not held permanently to the resin, the exposure plastics’ to water and other agents may partly extract these components. Since many plasticizers exude in humid environment, these may also cause unwanted effects on the plastic articles. Plasticizers may also impart its biological properties to a relatively inert synthetic polymer, which may lead to fungal and bacterial attacks. The compatibility of the plasticizer with the resin must also be considered. A given plasticizer may be compatible with a resin only for such a while but may result in rapid loss of plasticizer as ageing period progresses. It is therefore necessary that the quantity of plasticizer that must be added to a resin be limited up to the reasonable performance (Fleck, 1949). Studies conducted by Shaw et al. (1997) determined the effect of soya oil and glycerol on physical properties of whey protein isolate edible films. Increasing the proportion

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13 of soya oil or glycerol in the film formulations resulted in lower tensile strength and young's modulus and higher percentage elongation. Water vapor permeability and film solubility decreased with increased oil-protein ratios, but increased with increasing plasticizer-protein ratios. Film opacity increased with increasing soya oil concentration and decreased with increasing plasticizer:protein ratio. Another study conducted by Shaw et al. (1997) which determined the mechanical and moisture transport properties of a whey protein based edible films showed that films with low plasticizers level were good moisture barriers. Films containing 35, 50 or 70 g/100g glycerol had water vapour transfer rates of 0.264 ±0.004, 0.283 ±0.018 or 0.312 ±0.027 gh1m-2 respectively. Increasing the glycerol concentration from 35 to 70 g/100g increased the film elongation values from 10.7% to 46.5% respectively. Film tensile strength decreased from 6.9 ± 2.5 MPa to 2.4 ± 0.9 MPa as glycerol concentrations increased from 35 to 70 g/100g respectively. Plasticizers concentration is thus an important parameter in determining the functional properties of edible films. Rulande et al. (2000) found out that extrusion manufacture of starch-based thermoplastics such as biodegradable packaging materials glycerol was an effective additive as a plasticizer, that is, to diminish the brittle nature of the product and to provide the desired extent of flexibility. However, the addition of glycerol might also affect the gelatinization behavior of the starch-water mixture, and hence processing conditions for producing a homogeneously gelatinised starch-based material were required. The effect of glycerol on the gelatinisation of wheat starch was studied using differential scanning calorimetry (DSC). As expected, water acted as a plasticizer in that the onset temperature for gelatinisation (T0) decreased with increasing moisture content. Glycerol, however, increased T0. It was shown

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14 that the T0 of starch-glycerol-water mixtures might be predicted on the basis of the effective moisture content of the starch fraction of these mixtures resulting from the relative speed of moisture absorption by glycerol and starch respectively. Plasticizers are usually added to improve the mechanical and conditional (thermomechanical) quality of film coatings. Different molecular weights and concentrations of polyethylene glycol were incorporated as plasticizers in hydroxypropylmethylcellulose (HPMC) films. Thermomechanical and mechanical properties of cast films were tested using tensile and dynamic mechanical thermal analysis (DMTA) testing, respectively. Honary et al. (2002) showed that addition of plasticizer caused a decrease in both mechanical and thermomechanical properties, but lower grades had more effect than higher molecular weights and concentrations. Conclusion was drawn that combining different grades of plasticizers to optimize mechanical and thermomechanical properties was more efficient than using different concentrations of plasticizers. Suyatma et al. (2005) determined the effect of hydrophilic plasticizers on mechanical surface properties of chitosan films. Chitosan films were plasticized with four hydrophilic compounds, namely, glycerol, ethylene glycol, poly(ethylene glycol), and propylene glycol. Plasticization improved the chitosan ductility, and typical stress-strain curves of plasticized films had the features of ductile materials, except the film made with 5% polyethylene glycol that exhibited as a brittle polymer and showed an antiplasticization effect. The elongation of plasticized films decreased with the storage time, which was due to the recrystallization of chitosan and the loss of moisture and plasticizer from the film matrix. It was found out that glycerol and polyethylene glycol were more suitable as chitosan plasticizers than ethylene glycol and propylene glycol by taking into account their

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15 plasticization efficiency and storage stability. Furthermore, a plasticizer concentration of 20% (w/w) with glycerol or propylene glycol seemingly was sufficient to obtain flexible chitosan film with a good stability for 5 months of storage.

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16 Chapter 3

EFFECTS OF BLEND RATIO OF PVA-CHITOSAN-GLYCEROL ON THEIR MECHANICAL PROPERTIES

Abstract Plastic waste disposal becomes a serious problem because of its high volume of solid wastes and its inalterability over a very long period of time. This study covered the production of plastic films using different ratios of PVA and chitosan. It focused on the investigation of the effects of incorporating glycerol as plasticizer. Blend ratio of polyvinyl alcohol and chitosan and glycerol films were subjected to mechanical property testing using universal testing machine. It was noted that increasing the amount of PVA also increased the mean tensile strength and percentage elongation of the plastic films. Addition of glycerol as plasticizer affected the mechanical properties of the plastic film to a significant increase of percent elongation and a decrease in tensile strength. Sample A with 1.8g PVA and 0.2g chitosan gave the best ratio having the highest tensile strength and percentage elongation among the five samples. The 9:1 ratio of PVA to chitosan gave the best ratio in terms of higher mean tensile strength and percentage elongation.

Keywords: polyvinyl alcohol, chitosan, glycerol, tensile strength, elongation

Introduction

Plastic waste disposal becomes a serious problem because of its high volume of solid wastes and its inalterability over a very long period of time. Today, pyrolysis is a common method to get rid of non-biodegradable plastics, but this unfortunately leads to high emission of CO2. One approach to solve this problem is to use biodegradable materials instead of non-biodegradable polymers, e.g. in packaging. These materials have the potential to reduce environmental pollution by lowering the solid disposal waste and reducing the need for pyrolysis. Hence, there is a need to search for a material that can be used for the production of biodegradable plastics. One of the possible materials in the development of the biodegradable plastic film is chitosan. Chitosan, a copolymer of glucosamine and N-

16

17 acetyglucosamine units linked by 1-4 glucosidic bonds, is obtained by N-deacetylation of chitin. It can be produced from shellfish waste of seafood industry. This copolymer has excellent oxygen and carbon dioxide barrier properties and interesting bacteriostatic properties. Carapace and shells of black tiger shrimp were more suitable sources of chitin (34.9% and 36.3%) than other sources, such as blue crab, red crab, brine shrimp and horseshoe crab which contained a relatively low chitin content ranging from 14.9-27.6% (Benjakul et al., 1993). Several studies have already been conducted to investigate the significance of chitosan production as an alternative resource material such as a packaging polymer. Studies done were intended to utilize the properties inherent in chitosan to develop an outstanding packaging material. An example of such studies is the one conducted by Park et al. (2000) on the characteristics of PVA and chitosan blend films. One of the findings was that the mechanical properties (tensile strength, elongation), water vapor permeability, O2 of PVA and chitosan blended films were affected by acidic type, chitosan viscosity and various mixture ratios. The tensile strength of PVA films was 145Mpa. The tensile strength of PVA and chitosan in citric acid blended films was between 13-35MPa and was generally lower than those of blended films with chitosan dissolved in the other acidic solutions. The elongation of the blended films was higher than those of chitosan films and lower than PVA films. A study conducted by Bodmeier and Remunan (1996) investigated on the mechanical properties and water vapor transmission of properties of polysaccharide films made from sodium alginate and hydroxypropyl me cellulose (HPMC) dissolved in different types and concentrations of acids. Water vapor permeability ranged from 3.64 to 6.56

17

18 gmm/hm2 KPa., tension force from 7.23 to 48.3 MPa and elongation percentage from 22.9 to 167.02 were obtained. Polysaccharide films two percent with 0.3 % tween 80 produced films that showed the lowest permeability value. Polysaccharide films with 0.6 % glycerol had the highest percentage of elongation, polysaccharide films with 0.6% tween 80 improved the hydrophobicity of the chitosan film in 1.14 times. The highest value for tension force was found for chitosan with 0.6% of tween 60. The water vapor transmission rate through plasticized films increased with glycerol concentrations. Unfortunately, there are some limitations to the application of chitosan film in packaging and these are due to its high sensitivity to moisture (Törnqvist, 2000). Therefore chitosan must be associated with a moisture resistant polymer that will not affect the overall biodegradability of the plastic. One interesting option is to blend chitosan with polyvinyl alcohol. PVA is one of the most widely used polymers because of its excellent mechanical properties. It is a water-soluble synthetic polymer with excellent film forming characteristic and emulsifying capability (Park et al., 2000). On the studies made on the mechanical properties of polyvinyl alcohol and chitosan films, there was no concrete result on the effect of the blend ratio of the two materials on their mechanical property and with the addition of glycerol as plasticizer. The objective of this study was to determine the effect of blend ratio and plasticizer addition to the mechanical properties of PVA-chitosan blend films. It also aimed to determine the PVA-chitosan ratio that yields the blend film of good mechanical strength (tensile strength and percentage elongation). The PVA to chitosan ratios to produce the plastic films were limited as the researchers were only after establishing the effect of the said components on the mechanical

18

19 properties of the material specifically tensile strength and elongation. The study involved the determination of the effect of plasticizer addition on the mechanical properties of the blend films including the extraction of chitin and its conversion to chitosan, formation of the plastic film and the testing of its mechanical properties such as tensile strength and percentage elongation. This study was conducted in order to create alternative materials, which could be viable enough in replacing plastic materials that persist in the environment as nonbiodegradable solid wastes.

Methodology

Material preparation

The shell waste of the black tiger shrimp was washed repeatedly with water until thoroughly cleaned and tray dried at 70○C for 5 hours. The dried carapace was subjected to size reduction using a blender. It was weighed and placed in a 1000 mL beaker.

Deproteinization

Using a solid to solvent ratio 1:6 (w/v), the black tiger shrimp shells were soaked in a 1.0 M NaOH 100○C for 1 hour. The particles were filtered and washed to neutrality with water, then will be dried and weighed.

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20 Demineralization

The deproteinized shells were treated with 1.25 M HCl. The mixture was continuously stirred at room temperature for 30 minutes. The demineralized particles were filtered and washed to neutrality with tap water and dried. The weight of chitin obtained was noted. The demineralized particles were sealed and stored at room temperature until used.

Deactylation of chitin to chitosan

The chitin was subjected into alkaline hydrolysis using 50% NaOH solution with the solid to solvent ratio of 1:15 (wt/vol) for 4 hours using a rotary evaporator at 1000C. The obtained chitosan product was successively washed with water until it became neutral and then it was dried. To increase the degree of deactylation the alkaline hydrolysis was repeated using 15% NaOH solution 1:15 (wt/vol) for 1 hour using a hotplate set at 100oC. It was washed with water to neutrality and dried. This was placed in a beaker sealed and stored at room temperature until used. Small amount of the sample was apportioned to for IR analysis to confirm the identity of the product.

IR analysis

Samples of chitosan were analyzed in the laboratory of De la Salle University College of Chemical and Engineering using the Magna-IR Spectro 550 Nicolet. IR spectra of chitosan can be found in Appendix.

20

21 Film formation of polyvinyl alcohol-chitosan blends

On a basis of 2 gram-blends, different PVA to chitosan ratios were prepared. Table 1 summarizes the ratios of the amount of PVA to the amount of chitosan used in the experiment.

Table 1 PVA-Chitosan Blend Film Formation without Plasticizer %PVA-%Chitosan

Sample Code

Weight of PVA (g)

Weight of Chitosan (g)

90-10 80-20 70-30

A B C

1.8 1.6 1.4

0.2 0.4 0.6

60-40

D

1.2

0.8

50-50

E

1.0

1.0

Chitosan was dissolved in a 100 mL of 1% acetic acid solution. The solution was heated to 50○C. PVA was added while being continuously stirred until a homogenous mixture was obtained. The solution was poured and spread evenly on a pyrex plate. It was cast dried in an oven at 60○C for 2 hours. The completely dried plastic was gently peeled off.

Mechanical testing

Plastic films measuring 100 mm X 15 mm were prepared. Three pieces per sample, having a mean thickness difference of ±0.002 were submitted at the Laboratory Department of Titan Industrial Manufacturing Corporation for tensile strength and percentage elongation tests. The equipment used was the Universal Testing Machine (Shimadzu Autograph AGS 500D). The data collected was treated graphically having the blend ratio of chitosan-PVA in the x-axis while the mean tensile strength and the percent elongation in the y-axis.

21

22 Addition of plasticizer

Among the films that were produced, the best ratio of polyvinyl alcohol:chitosan depending on the mechanical properties was selected. This was prepared again with the addition of varying amounts (w/w ratios) of glycerol as plasticizer. Table 2 summarizes the %PVA-%chitosan with the grams of glycerol used in the experiment. Samples of these films with plasticizer were also submitted to the Titan Industrial Manufacturing Corporation Laboratory Department for testing. The data collected was treated graphically having the blend ratio of chitosan-PVA-glycerol in the x-axis the mean tensile strength and the percent elongation in the y-axis.

Table 2 PVA-Chitosan Blend Film Formation with Plasticizer Sample Code

%PVA-%Chitosan

Grams of Glycerol per 10 grams of PVA-chitosan

XG1 XG2 XG3 XG4 XG5

90-10 90-10 90-10 90-10 90-10

10 20 30 40 50

Results and Discussion

Mechanical testing

Table 3 shows the mechanical properties of PVA-chitosan blend films (without glycerol) obtained from Titan Industrial Manufacturing Corporation Testing Laboratory. Figure 1 illustrates the relationship between chitosan-PVA ratios and its mechanical tensile strength while figure 2 shows the relationship between film ratios and percentage elongation.

22

23

Table 3 Mechanical Properties of PVA-Chitosan Films (without glycerol) Sample Code

Weight of Chitosan (g)

Weight of PVA (g)

Mean Tensile Strength (MPa)

Mean % Elongation at Break

Mean Thickness (mm)

A

0.2

1.8

17.42

21.40

0.102

B

0.4

1.6

15.09

18.80

0.105

C

0.6

1.4

12.35

13.70

0.102

D

0.8

1.2

10.13

7.40

0.103

E

1.0

1.0

8.01

3.60

0.106

Mean Tensile Strength, MPa

20

15

10

5

0 0

10-90

20-80

30-70

40-60

50-50

Chitosan-PVA, %

Figure 1 Mean Tensile Strength of PVA-Chitosan Films (without glycerol)

23

24

Mean Elongation at break, %

25 20 15 10 5 0 0

10-90

20-80

30-70

40-60

50-50

Chitosan-PVA, %

Figure 2 Mean Percentage elongation at break of PVA-Chitosan Films (without glycerol) It can be glanced from Table 3 the values for tensile strength range from 8.01 to 17.42 MPa. Based on the results, sample A showed the highest tensile strength with 17.42 MPa. Further, it is noticed that the percentage elongation of the plastic films decreased with a decreasing polyvinyl alcohol content. Sample A registered the highest percentage elongation (21.40%) as compared to other plastic samples. Figures 1 and 2 show that 10% chitosan with 90% PVA film gave the best ratio having the highest tensile strength and percentage elongation among the five samples. It is noticed that increased amount of PVA increased both the tensile strength and percentage elongation of the plastic films. Decreased amount of PVA in the film made the plastic brittle and stiff which lower its mechanical property values, but increased amount of PVA made the plastic more flexible incorporating higher tensile strength and elongation. Addition of polyvinyl alcohol improved the mean tensile strength and percentage elongation of the plastic film due to its water-soluble synthetic polymer with excellent film-

24

25 forming and emulsifying capability. The unique cationic nature of chitosan (Figure 3.a) when dissolved in an anionic derivative such as PVA (Figure 3.b) achieved a homogeneous blend in an aqueous environment. The positively charged polysaccharide chitosan moved towards the negatively charged of the hydroxyl group of the polyvinyl alcohol which improved the tensile strength and elongation of the plastic film that might due to the occurrence of intermolecular interactions between chitosan and polyvinyl alcohol through hydrogen bond formation. Increasing the amount of PVA resulted in a higher degree of intra- and intermolecular hydrogen bonding due to anionic property of the hydroxyl group.

(a)

(b)

Figure 3 Chemical structure of (a) chitosan and (b) PVA

It was worth noting that the blend film exhibited the greatest tensile strength 17.42 MPa when the polyvinyl alcohol content in the blends was around 90 wt%. Among the five plastic samples 90-10 ratio gave the best ratio in terms of higher mean tensile strength and percentage elongation. But samples B and C having a mean tensile strength of 15.09 and 12.35 MPa and percentage elongation of 18.80% and 13.70% have comparable values to Table 4 of LDPE (Low Density Polyethylene) and MDPE (Medium Density Polyethylene), summarizing film properties of polyethylene films from the handbook of plastics and elastomers by Harper, 1975.

25

26 Table 4 Film Properties of Polyethylene Films Propety

Low Density

Medium Density

High Density

Thickness Range , mm

0.00762 and up

0.00762 and up

0.01016 and up

Tensile Strength, MPa

10.34 to 20.68

13.79 to 24.13

16.55 to 44.82

Elongation, %

100 to 700

50 to 650

10 to 650

Table 5 shows the mechanical properties of PVA-chitosan films incorporated with different amounts of glycerol as plasticizer obtained from Titan Industrial Manufacturing Corporation Testing Laboratory. Figure 4 illustrates the relationship between chitosan-PVAglycerol ratios and its mechanical tensile strength while figure 5 shows the relationship between film ratios and percentage elongation.

Table 5 Mechanical Properties of Sample A (with glycerol) Sample Code

Grams of Glycerol per 10 grams of PVA-chitosan (g)

Mean Tensile Strength (MPa)

Mean % Elongation at Break

Mean Thickness (mm)

XG1

10

10.85

49.70

0.116

XG2

20

9.72

57.80

0.116

XG3

30

7.87

62.60

0.118

XG4

40

77.40

0.117

XG5

50

5.94 5.28

89.40

0.119

26

Mean Tensile Strength, MPa

27

20 15 10 5 0 0

10

20

30

40

50

Glycerol, g

Mean Elongation at break, %

Figure 4 Mean Tensile Strength of PVA-Chitosan Films (with glycerol)

90 80 70 60 50 40 30 20 10 0 0

10

20

30

40

50

Glycerol, g

Figure 5 Mean Percentage elongation at break of PVA-Chitosan Films (with glycerol)

From Tables 4 and 5, percentage elongation of the plastic films, originally 21.40% (without glycerol), was improved due to the addition of plasticizer. The elongation values range from 49.70% to 89.40%. While the mean tensile strength, originally 17.42 MPa 27

28 (without plasticizer) decreased to 10.85 up to 5.28 MPa with an increasing plasticizer content. Figure 4 shows that as the amount of plasticizer increased in the film formulations composed of chitosan and polyvinyl alcohol, the mean tensile strength values of the films decreased.

On the other hand, Figure 5 shows that as the amount of plasticizer were

increased in the film formulations, the percentage elongation values of the films increased. In a study in which plasticizer based locust bean gum, polysaccharide films, were investigated (Aydinli et al., 2003), it was determined that the effect of the amount of plasticizer used on the tensile strength and elongation of locust bean gum films was such that, when the concentration of the plasticizer was raised, tensile strength was found to decrease and elongation was found to increase. In our chitosan-PVA films, it was also a decrease in tensile strength and an increase in elongation as the level of plasticizer increased. The hydrophilic nature of chitosan-PVA films necessitates the use of polar plasticizers such as glycerol for better compatibility. It is thought that glycerol reduces the intermolecular vander waals forces between polymers, which makes the plastics flexible and reduces its stiffness (Kim et al., 2001). Glycerol (Figure 6) reduces the rigidity network of the intermolecular bonding of chitosanpolyvinyl alcohol films, producing a less ordered film structure and increasing the ability of movement of polymer chains.

Figure 6 Chemical Structure of Glycerol

28

29 With its three hydroxyl groups of glycerol, it makes a moisturizing and lubricant effect that diminishes the brittle nature of the film and provides improved results in elongation. These results show that the addition of plasticizer significantly improved the percentage elongation while the tensile strength decreased with increasing plasticizer content because increasing the amount of plasticizer will make the plastic very flexible making the plastic very soft and pliable.

Conclusion

The mechanical test showed decreased amount of chitosan and increased amount of PVA improved the tensile strength and percentage elongation of the plastic films. Addition of glycerol as plasticizer from PVA-chitosan film affected the mechanical properties of the plastic film to a significant increase of percent elongation and a decrease in tensile strength. The 9:1 ratio of PVA to chitosan gave the best ratio in terms of higher mean tensile strength and percentage elongation. Ten grams of glycerol as plasticizer to the PVA-chitosan blend film is the only sample that meets the mean tensile strength requirement for LDPE.

References

Aydinli M., M. Tutas, A. Bozdemir (2003). Mechanical and Light Transmittance Properties of Locust Bean Gum Based Edible Films. Turk J Chem, Volume 28 (2), 163-171. Benjakul, S. and P. Sophanodara (1993). Chitosan Production from Carapace and Shell of Black Tiger Shrimp (Penaeus Monodon). ASEAN Food Journal. Volume 8 (4), 145-148.

29

30 Bravin B., D. Peressini, A. Sensidoni (2004). Influence of emulsifier type and content on functional properties of polysaccharide lipid-based edible films. Agric Food Chem Journal, Volume 52 (21), 6448-6455. Bodmeier, R. and C. Remunan (1996). Mechanical and Water Vapor Transmission Properties of Polysaccaharide Films. Chemical Abstracts. Cervera, M., J. Heinämäki, K. Krogars, A. Jörgensen, M. Karjalainen, I. Colarte, and J. Yliruusi (2003). Solid-State and Mechanical Properties of Aqueous Chitosan-Amylose Starch Films Plasticized With Polyols. Pharmaceutical Technology, Volume 20 (2), 521-526. Chi, S., S. Zivanovic, J. Weiss, and F.A. Draughon (2004). Physico-chemical properties of chitosan films enriched with oregano essential oils. Dept. of Food Science & Technology, Univ. of Tennessee. Coupland, J.N., F.J. Monahan, E.D. O’Riordan, M. O’Sullivan and N. Shaw (2000). Effect of glycerol content on the moisture sorption properties of a whey protein based edible film. Department of Agriculture and Food. Ferdous S., I. Mustafa, and M. Khan (2003). Study on Mechanical Properties of Photocured Films of Chitosan/PVA and PEO/PVA Blend with Acrylic Monomers. Journal of Macromolecular Science. Volume 40 (8), 817-832. Fleck, RH. (1949). Plastics–Scientific and Technological. 2nd ed., Chemical Publishing Co. Inc., New York. Harper, C.A. (1975). Handbook of Plastics and Elastomers. McGraw-Hill, USA. Hernandez, M.P., A. Kanavouras, P.K.W. Ng, and R. Gavara (2003). Development and Characterization of Biodegradable Films made from wheat gluten protein fractions. Journal of Agricultural and Food Chemistry,Volume 51 (8), 7647-7654. Honary, S. and H. Orafai (2002). The Effect of Different Plasticizer Molecular Weights and Concentrations on Mechanical and Thermomechanical Properties of Free Films Drug. 34 Development and Industrial Pharmacy, Volume 28 (6), 711 – 715. Jeong, M.G., D.S. Kim, Y.H. Choi, B.G. Kim, K.S. Lee and T.W. Son (2004). Preparation and Properties of Poly(vinyl alcohol)/Chitosan Blend Films. Polymer(Korea). Volume 28 (3), 253-262. Kim, K.M., C.L. Weller, M.A. Hanna, and A. Gennadios (2001). Characterization of SPI films plasticized with aqueous and crystalline sorbitol. Materials Science Research and Development, Banner Pharmacaps Inc.

30

31 Mangala, E., T.S. Kumar, S. Baskar, and K. Panduranga Rao (2003). Development of chitosan/polyvinyl alcohol blend membranes as burn dressings. Trends Biomate. Artif. Organs. Volume 17 (1), 34-40. Palviainen, P., J. Heinämäki, P. Myllärinen, R. Lahtinen, Jouko Yliruusi, and P. Forssell (2001). Corn Starches as Film Formers in Aqueous-Based Film Coating. Pharmaceutical Development and Technology, Volume 6 (3), 353-361. Park, S.Y., S.T. Jung, and K.S. Marsh (2000). Characteristics (Mechanical Properties) of PVA and Chitosan Blending Films. Packaging Science, Clemson University. Retuert, J., S. Fuentes, G. Gonzalez and R. Benavente (2000). Thermal Effect on the Microhardness of Chitosan Films. Departamento de Química. Facultad de Ciencias, Universidad de Chile. Rodriguez, H.D., S.H. Imam, L.J. Galan, M.O. Rutiaga, and K.N. Arevalo, (2004). Mechanical Properties and Water Vapor Permeability of Biodegradable Films from Natural Polymers. Bioenvironmental Polymer, Volume 24 (5), 64-66. Rulande, P.G., G.R. Nashed, and P.A. Sopade (2000). The plasticisation effect of glycerol and water on the gelatinization of wheat starch. Division of Chemical Engineering, University of Queensland, St Lucia. Rutiaga, M.O., Galan, L.J., Morales, L.H., Gordon, S.H., Imam, S.H., Nino, K.A. (2005). Mechanical Property and Biodegradability of Cast Films Prepared from Blends of Oppositely Charged Biopolymers. Polymers and the Environment, Volume 13 (2), 185-191. Shaw, N.B., F. J. Monahan, E.D. O'Riordan, and M. O'Sullivan (1999). Effect of soya oil and glycerol on physical properties of whey protein isolate edible films. Food Science, University College Dublin. Shaw, N.B. Shaw N.B., F. J. Monahan, E.D. O'Riordan, and M. O'Sullivan (1997). Mechanical and moisture transport properties of a whey protein based edible film. Department of Agriculture and Food, Dublin. Suyatma, N.E., L. Tighzert, and Copinet A, V. Coma (2005). Effects of hydrophilic plasticizers on mechanical, thermal, and surface properties of chitosan films. Agric Food 35 Chem Journal, Volume 53 (10), 3950-3957. Suzuki, S., K. Shimahashi, J. Takahara, M. Sunako, T. Takaha, K. Ogawa, and S. Kitamura (2005). Effect of addition of water-soluble chitin on amylose film. Biomacromolecules. Volume 6 (6), 3238-3242.

31

32 Tanveer A.K., K.P. Khiang, and H.S. Ch'ng (2000). Mechanical, Bioadhesive Strength and Biological Evaluations of Chitosan films for Wound Dressing. Pharm Pharmaceut Sci Journal. Volume 12 (3), 120-128. Trujilllo, E.R., L.J. Galan, S.H. Imam, M.O. Rutiaga, and N.K. Areval (2004). Mechanical, Physical and Vapor Barrier Properties of Biobased Films. Bioenvironmental Polymer. Volume 25 (6), 100-106. Törnqvist, J. (2000). Water-resistant chitosan and wey films. Materials and Manufacturing Engineering / Polymer Engineering. Wang T., M. Turhan, and S. Gunasekaran (2004). Selected properties of pH-sensitive, biodegradable chitosan-poly(vinyl alcohol) hydrogel. Polymer International. Volume 53 (3), 911-918. Xiao, C., L. Weng, Y. Lu, and L. Zhang (2001). Blend Films from chitosan and polyacrylamide solutions. Journal of Macromolecular Science, Volume 38 (8), 761-771.

32

Chapter 4

CONCLUSION

The mechanical test showed decreased amount of chitosan and increased amount of PVA improved the tensile strength and percentage elongation of the plastic films. Addition of glycerol as plasticizer from PVA-chitosan film affected the mechanical properties of the plastic film to a significant increase of percent elongation and a decrease in tensile strength. The 9:1 ratio of PVA to chitosan gave the best ratio in terms of higher mean tensile strength and percentage elongation. Ten grams of glycerol as plasticizer to the PVA-chitosan blend film is the only sample that meets the mean tensile strength requirement for LDPE.

33

Chapter 5

RECOMMENDATION

To further improve the properties of the plastic film, the addition of other suitable additives may be experimented. A comparative study of different plasticizers such as sorbitol and polyethylene glycol may be conducted by future researchers in order to determine the most compatible plasticizer which could be blended with PVA and chitosan. Water vapor transmission of the PVA-chitosan-glycerol films can also be done to test its water permeation property.

34

REFERENCES

Aydinli M., M. Tutas, A. Bozdemir (2003). Mechanical and Light Transmittance Properties of Locust Bean Gum Based Edible Films. Turk J Chem, Volume 28 (2), 163-171. Benjakul, S. and P. Sophanodara (1993). Chitosan Production from Carapace and Shell of Black Tiger Shrimp (Penaeus Monodon). ASEAN Food Journal. Volume 8 (4), 145-148. Bravin B., D. Peressini, A. Sensidoni (2004). Influence of emulsifier type and content on functional properties of polysaccharide lipid-based edible films. Agric Food Chem Journal, Volume 52 (21), 6448-6455. Bodmeier, R. and C. Remunan (1996). Mechanical and Water Vapor Transmission Properties of Polysaccaharide Films. Chemical Abstracts. Cervera, M., J. Heinämäki, K. Krogars, A. Jörgensen, M. Karjalainen, I. Colarte, and J. Yliruusi (2003). Solid-State and Mechanical Properties of Aqueous Chitosan-Amylose Starch Films Plasticized With Polyols. Pharmaceutical Technology, Volume 20 (2), 521-526. Chi, S., S. Zivanovic, J. Weiss, and F.A. Draughon (2004). Physico-chemical properties of chitosan films enriched with oregano essential oils. Dept. of Food Science & Technology, Univ. of Tennessee. Coupland, J.N., F.J. Monahan, E.D. O’Riordan, M. O’Sullivan and N. Shaw (2000). Effect of glycerol content on the moisture sorption properties of a whey protein based edible film. Department of Agriculture and Food. Ferdous S., I. Mustafa, and M. Khan (2003). Study on Mechanical Properties of Photocured Films of Chitosan/PVA and PEO/PVA Blend with Acrylic Monomers. Journal of Macromolecular Science. Volume 40 (8), 817-832. Fleck, RH. (1949). Plastics–Scientific and Technological. 2nd ed., Chemical Publishing Co. Inc., New York. Harper, C.A. (1975). Handbook of Plastics and Elastomers. McGraw-Hill, USA. Hernandez, M.P., A. Kanavouras, P.K.W. Ng, and R. Gavara (2003). Development and Characterization of Biodegradable Films made from wheat gluten protein fractions. Journal of Agricultural and Food Chemistry,Volume 51 (8), 7647-7654. Honary, S. and H. Orafai (2002). The Effect of Different Plasticizer Molecular Weights and Concentrations on Mechanical and Thermomechanical Properties of Free Films Drug. Development and Industrial Pharmacy, Volume 28 (6), 711 – 715.

35

36 Jeong, M.G., D.S. Kim, Y.H. Choi, B.G. Kim, K.S. Lee and T.W. Son (2004). Preparation and Properties of Poly(vinyl alcohol)/Chitosan Blend Films. Polymer(Korea). Volume 28 (3), 253-262. Kim, K.M., C.L. Weller, M.A. Hanna, and A. Gennadios (2001). Characterization of SPI films plasticized with aqueous and crystalline sorbitol. Materials Science Research and Development, Banner Pharmacaps Inc. Mangala, E., T.S. Kumar, S. Baskar, and K. Panduranga Rao (2003). Development of chitosan/polyvinyl alcohol blend membranes as burn dressings. Trends Biomate. Artif. Organs. Volume 17 (1), 34-40. Palviainen, P., J. Heinämäki, P. Myllärinen, R. Lahtinen, Jouko Yliruusi, and P. Forssell (2001). Corn Starches as Film Formers in Aqueous-Based Film Coating. Pharmaceutical Development and Technology, Volume 6 (3), 353-361. Park, S.Y., S.T. Jung, and K.S. Marsh (2000). Characteristics (Mechanical Properties) of PVA and Chitosan Blending Films. Packaging Science, Clemson University. Retuert, J., S. Fuentes, G. Gonzalez and R. Benavente (2000). Thermal Effect on the Microhardness of Chitosan Films. Departamento de Química. Facultad de Ciencias, Universidad de Chile. Rodriguez, H.D., S.H. Imam, L.J. Galan, M.O. Rutiaga, and K.N. Arevalo, (2004). Mechanical Properties and Water Vapor Permeability of Biodegradable Films from Natural Polymers. Bioenvironmental Polymer, Volume 24 (5), 64-66. Rulande, P.G., G.R. Nashed, and P.A. Sopade (2000). The plasticisation effect of glycerol and water on the gelatinization of wheat starch. Division of Chemical Engineering, University of Queensland, St Lucia. Rutiaga, M.O., Galan, L.J., Morales, L.H., Gordon, S.H., Imam, S.H., Nino, K.A. (2005). Mechanical Property and Biodegradability of Cast Films Prepared from Blends of Oppositely Charged Biopolymers. Polymers and the Environment, Volume 13 (2), 185-191. Shaw, N.B., F. J. Monahan, E.D. O'Riordan, and M. O'Sullivan (1999). Effect of soya oil and glycerol on physical properties of whey protein isolate edible films. Food Science, University College Dublin. Shaw, N.B. Shaw N.B., F. J. Monahan, E.D. O'Riordan, and M. O'Sullivan (1997). Mechanical and moisture transport properties of a whey protein based edible film. Department of Agriculture and Food, Dublin. Suyatma, N.E., L. Tighzert, and Copinet A, V. Coma (2005). Effects of hydrophilic plasticizers on mechanical, thermal, and surface properties of chitosan films. Agric Food Chem Journal, Volume 53 (10), 3950-3957.

36

37 Suzuki, S., K. Shimahashi, J. Takahara, M. Sunako, T. Takaha, K. Ogawa, and S. Kitamura (2005). Effect of addition of water-soluble chitin on amylose film. Biomacromolecules. Volume 6 (6), 3238-3242. Tanveer A.K., K.P. Khiang, and H.S. Ch'ng (2000). Mechanical, Bioadhesive Strength and Biological Evaluations of Chitosan films for Wound Dressing. Pharm Pharmaceut Sci Journal. Volume 12 (3), 120-128. Trujilllo, E.R., L.J. Galan, S.H. Imam, M.O. Rutiaga, and N.K. Areval (2004). Mechanical, Physical and Vapor Barrier Properties of Biobased Films. Bioenvironmental Polymer. Volume 25 (6), 100-106. Törnqvist, J. (2000). Water-resistant chitosan and wey films. Materials and Manufacturing Engineering / Polymer Engineering. Wang T., M. Turhan, and S. Gunasekaran (2004). Selected properties of pH-sensitive, biodegradable chitosan-poly(vinyl alcohol) hydrogel. Polymer International. Volume 53 (3), 911-918. Xiao, C., L. Weng, Y. Lu, and L. Zhang (2001). Blend Films from chitosan and polyacrylamide solutions. Journal of Macromolecular Science, Volume 38 (8), 761-771.

37

APPENDIX

39 Appendix

IR ANALYSIS

IR (Magna-IR Spectro 550 Nicolet from De La Salle University) analysis was conducted in order to identify the functional groups present in the chitosan sample. The presence of hydroxyl group was indicated by the major IR bands at 3200-3800 cm-1 region. The band signal of the amino group present was registered at 1560-1940 cm-1 region.

Figure 1.1 IR spectra of Chitosan

39