Progress 01/01/07 to 12/31/11
Outputs
OUTPUTS: Two commercially available biopolyesters, i.e., poly(lactic acid) (PLA) and polyhydroxyalkanoates) (PHAs) were investigated in this study. While the potential for biobased PLA and PHAs to replace some petroleum-based polymers in various applications is tremendous, great challenges also lie ahead. PHB and PHBV copolymers with low 3-hydroxyvalerate comonomer contents possess the levels of strength and modulus comparable to that of various grade polypropylenes, while PLA has high strength and modulus comparable to that of polystyrene. However, both PLA and PHAs are inherently brittle, which greatly inhibits wide applications. For the past five years, we have made great efforts to investigate various means for solving the problems biobased polyester materials encounter during processing and application and to introduce novel approaches for development of high performance biobased polyester materials. The ultimate goals of the project are to develop economically viable and environmentally sound technologies for biobased polyester products. Specifically, we have advanced the investigation in the following aspects. 1. Studied nucleation and crystallization of PHBV in the presence of various nucleating agents; 2. Developed novel high performance (high strength and toughness) PHBV/bamboo fiber composites using bamboo pulp fibers; 3. Developed formulation and processing techniques for wood plastics using wood flour and PHB or PHBV polymers; 4. Collaborated with Metabolix in developing a proprietary compatiblization technology for PHA/starch blends and PHA/wood flour composites; 5. Elucidated the toughening mechanisms of binary PLA blends and PLA nanocomposites; 6. Developed a novel PLA ternary blend system through reactive extrusion for supertoughened PLA materials; 7. Developed novel PLA/soy protein (SP) blends in which SP was used as a plastic-like component in compounding; 8. Developed a new processing technology for PLA/sugar beet pulp composites to have enhanced performance of the products; 9. Introduced in situ fibrillation of PLA for reinforcing starch plastics. The research results are fruitful. So far, the results from this project have been published in twenty-one (21) journal papers and four (4) book chapters. In addition, three (3) more manuscripts are under review. A number of oral and poster presentations were given at different national and international conferences. One joint patent with Metabolix is under application. PARTICIPANTS: Dr. Jinwen Zhang (PI) oversees the whole project and directly advises his graduate students and postodc who participate in different parts of the whole project. Dr. Long Jiang is involved in advising graduate students and undertakes characterization of polymer blends. Dr. Hongzhi Liu, postdoc at WSU, is focusing on studies of morphology of the blends and toughening of PLA. Miss Feng Chen, of WSU, PhD student in the Materials Science Program, mainly undertakes the study of soy protein blends. Mr. Bo liu, PhD student in the Materials Science Program, mainly undertakes the study of foaming processing technology. Miss Jia Cheng, PhD student in the Materials Science Program, is working on the preparation of reactive compatibilizers and characterization of the blends. TARGET AUDIENCES: U.S. corn growers will be the immediate beneficiaries of the investigation by finding new applications of PLA and PHAs in a market dominated by petroleum-based plastics, because both polymers are corn starch-based. This research will also result in new value-added applications for products from other sectors in the agricultural industry, such as soybean and forestry. The general public will benefit from the results, because the biobased polymers (PLA & PHAs) and natural polymers are environmentally friendly and renewable; and their products are biodegradable and compostable after use. In addition, the findings from this project will advance the knowledge base of bioplastics and stimulate future developments within the biobased plastic materials industry. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
We introduced a novel toughening method for PHB and PHBVs by using a fiber whose yield strain was comparable or slightly smaller than that of the matrix polymer but has a much higher strain at break. The fiber used was bamboo pulp fiber. It was noted that the bamboo fiber toughened the polymer by bridging the cracks of the matrix, which prevented and delayed the propagation of the microcracks. We further discovered that adding an appropriate nucleating agent would further increase the toughness, strength and modulus of the polymer/bamboo fiber composites. A proper compatibilizing approach is particularly needed when mixing the hydrophobic polyesters with the highly hydrophilic natural fibers, natural polymers or mineral nanofillers. We have successfully used polymeric methene diphenyl diisocyanate (pMDI) as a coupling agent to improve the PHA and PLA composites with natural fibers and composites. Because pMDI is very sensitive to moisture, its use requires thorough drying of the natural fibers, polymers and mineral fillers. We have introduced a novel compatibilizer, i.e., poly(2-ehtyl-2-oxazoline) (PEOX), for the compounding of PLA with SP as a plastic-like component. When SP, starch and sugar beep pulp (SBP) are compounded as a plastic-like component with PHAs and PLA, water is necessary in the formulation. In this case, pMDI is not suitable. MA grafted PHAs or PLAs are used in this situation. In addition, PEOX was found to be an effective compatiblizer for the plastic-like SP to mix with those polymers. PEOX was identified as a compatibilizer for SP blends in a granted US patent by the PI. We also introduced a creative dual compatibilization method in which poly(2-ethyl-2-oxazoline) (PEOX) was first used during the compounding step because it was water compatible and resulted in fine dispersion of SPC. pMDI as a co-compatibilizer was applied in the subsequent processing step, e.g., injection molding or extrusion for products. Our research results elucidated the toughening mechanisms of binary PLA blends and PLA nanocomposites with nanoclay and nano-CaCO3. However, almost all conventional binary blends displayed good ductility but still had very poor impact strength. We developed a novel ternary blend system that comprised PLA, an epoxy-containing elastomer and a zinc ion-containing ionomer. The zinc ions catalyzed the reactive compatibilization and elastomer crosslinking. In many cases, supertoughened PLA blends were achieved. Another important contribution in this project was the introduction of a novel concept and method for the preparation of SP/polymer blends, i.e., compounding SP as a plastic-like component. Later on this concept was also expanded to sugar beep pulp. We have demonstrated that the morphology of the blends and consequently the properties could be greatly manipulated by this method. The results achieved not only provide practical solutions to some existing problems but also are contributions to the knowledge base.
Publications
- 13. Long Jiang; Jinwen Zhang. 2009. Toughening of Poly(lactic acid), in "Encyclopedia of Polymer Composites: Properties, Performance and Applications"(ISBN: 978-1-60741-717-0), eds.: Mikhail Lechkov and Sergej Prandzheva. Chapter 34, pp 991 -1008, Nova Science Publishers, Inc. (2009)
- 14. Linshu Liu; David R. Coffin; C.-K. Liu; Peter H. Cooke; Kevin B. Hicks; F. Lee; Jinwen Zhang. 2008. Sugar beet pulp and poly(lactic acid) composites using methylene diphenyl diisocyanate as coupling agent. Polym. Res. J. 2008, 2, 115-126.
- 12. Bo Liu; Long Jiang; Jinwen Zhang. 2011. Study of effects of processing aids on properties of poly(lactic acid)/soy protein blends, Journal of Polymer and the Environment 2011, 19, 239 - 247.
- 1. Bo Liu; Jinwen Zhang. 2011. Performance enhancement of poly (lactic acid)/soy protein concentrate blends by formation of SPC network, submitted
- 2. Rui Zhu; Hongzhi Liu; Jinwen Zhang. 2011. Effects of Functionality and Concentration of Maleated Poly(lactic acid) (PLA) on Morphology and Properties of PLA/Soy Protein Composites, Submitted.
- 3. Wenjia Song; Hongzhi Liu; Feng Chen; Jinwen Zhang. 2011. Effects of ionomer characteristics on reactions and properties of poly(lactic acid) ternary blends prepared by reactive blending, submitted.
- 4. Weili Li; David R. Coffin; Tony Z. Jin; Nicolas Latona; Cheng-Kung Liu; Bo Liu; Jinwen Zhang; and LinShu Liu. 2001. Biodegradable composites from polyester and sugar beet pulp with antimicrobial coating for food packaging, Journal of Applied Polymer Science 2011, in press.
- 5. Long Jiang; Meng-Hsin Tsai; Scott Anderson; Michael P. Wolcott; Jinwen Zhang. 2011. Development of Biodegradable Polymer Composites Comprising Bacterial Polyester Produced from Municipal Waste Effluent, Bacterial Cell Mass, and Cellulosic Fiber, in "Sustainable Production of Fuels, Chemicals and Fibers from Forest Biomass", eds.: Zhu, J., et al. Chapter 14, pp 367 - 391. ACS Symposium Series, 2011.
- 6. Long Jiang; Jinwen Zhang. 2011. Biodegradable and biobased Polymers, in "Applied Plastics Engineering Handbook: Processing and Materials (ISBN: 9781437735147)", ed., Myer Kutz, Elsevier, Chapter 9, pp.145-158 (2011).
- 7. Jinwen Zhang; Feng Chen. 2011. Development of novel soy protein-based polymer blends, in "Green Polymer Chemistry: Biocatalysis and Biomaterials", eds: H. N. Cheng; Richard A. Gross. Chapter 4, pp 45-57. ACS Symposium Series, Vol. 1043 (ISBN13: 9780841225817; eISBN: 9780841225824) (2011).
- 8. Hongzhi Liu; Li Guo; Xiaojie Guo; Jinwen Zhang. 2011. Effects of reactive blending temperature on impact toughness of poly(lactic acid) ternary blends, Polymer 2012, doi:10.1016/j.polymer.2011.12.036
- 9. Bo Liu; Long Jiang; Jinwen Zhang. 2011. Extrusion foaming of poly (lactic acid)/soy protein concentrate blends, Macromolecular Materials & Engineering 2011, 296, 835 - 842.
- 10. Hongzhi Liu; Jinwen Zhang. 2011. Research progress in toughening modification of poly(lactic acid) (PLA), 2011, Journal of Polymer Science: Part B Polymer Physics 2011, 49, 1051 -1083.
- 11. Hongzhi Liu; Wenjia Song; Feng Chen; Li Guo; Jinwen Zhang. 2011. Interaction of microstructure and interfacial adhesion on impact performance of polylactide (PLA) ternary blends, Macromolecules 2011, 44, 1513 - 1522.
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Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: For the past year, we have made great effort to investigate various means for solving the problems that biopolyester materials encounter during processing and application and to develop novel approaches for high performance materials. The two commercially available biopolyesters, i.e., poly(lactic acid) (PLA) and polyhydroxyalkanoates) (PHAs), were both used in our study. Specifically, we have advanced the investigation in the following aspects: 1. Development of PHA/bamboo fiber composite: a. Investigate the reinforcing and toughening effects of bamboo fiber for PHBV. 2. Investigation of a novel PLA ternary blend system for high impact performance; a. Study the effects of blending temperature on reactive interfacial compatibilization and vulcanization of the rubber during compounding; b. Study tensile and impact properties of reactively compounded PLA ternary blends. 3. Development of a novel processing technique for soy protein concentrate (SPC) blends: a. Process SPC as plastic in blending with other thermoplastic polymers; b. Study effects of plasticization, shear and composition on plastic behavior of SPC during compounding; c. Study the effects of processing aids on rheological and mechanical properties and morphology; d. Study the different effects of water and glycerol on phase structure of PLA/SPC blends. Three oral presentations of the results were given at: (1) Two presentations, one on processing technology of PLA/SPC blends and the other on PLA toughening, at the International Symposium on Polymers and the Environment: Emerging Technology and Science & the 2010 BioEnvironmental Polymer Society (BEPS) Annual Meeting (Toronto, Canada, Oct. 12016, 2010); (2) one presentation at American Institute of Chemical Engineer (AICHE) annual meeting (Salt Lake City, Nov 7 -11, 2010). In addition, one poster was displayed at the BEPS meeting, and one poster was displayed at the 2010 Washington State University Academic Showcase. PARTICIPANTS: Dr. Jinwen Zhang (PI), supervised the whole project, directly advised his graduate students and the postdoc who participated in different parts of the entire project. Dr. Long Jiang, was involved in advising graduate students, and undertook characterization of polymer blends. Dr. Xiaoqing Liu, mainly undertook the chemical modification of PLA, PHAs for compatibilizer application. Dr. Hongzhi Liu, postdoc at WSU, focused on studies of morphology of the blends and toughening of PLA. Miss Feng Chen of WSU, PhD student in Materials Science Program, mainly undertook the study of soy protein blends. Mr. Bo Liu, PhD student in Materials Science Program, mainly undertook the study of foaming processing technology. Miss Jia Cheng, PhD student in Materials Science Program, worked on the preparation of reactive compatibilizers and characterization of the blends. TARGET AUDIENCES: U.S. corn growers will be the immediate beneficiaries of the investigation by finding new applications of PLA and PHAs in a market dominated by petroleum-based plastics, because both polymers are corn starch-based. This research will also result in new value-added applications for products from other sectors in the agricultural industry, such as soybean and forestry. The general public will benefit from the results, because the biobased polymers (PLA & PHAs) and natural polymers are environmentally friendly and renewable; and their products are biodegradable and compostable after use. In addition, the findings from this project will advance the knowledge base of bioplastics and stimulate future developments within the biobased plastic materials industry. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
We provided further evidence and analysis which shows that bamboo pulp fiber (BPF) had both reinforcing and toughening effects for poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). The unique toughening effect of BPF was due to the similar yield strain but much higher strain at break of BPF with respect to that of PHBV. This finding may provide important guidance in design and materials selection of biocomposites when high impact is required. PLA has received the most extensive investigation among various biobased polymers which are intended for plastic applications. The brittleness of PLA is a major obstacle for its broad application. Most PLA blends in the literature displayed satisfactory improvement on tensile toughness (or ductility) but had little effect on improving impact toughness. We introduced a novel and creative approach in which PLA was blended with rubber containing epoxy functional groups and an ionomer containing zinc ions to solve this problem. The PLA ternary blends demonstrated not only high tensile toughness but also high impact toughness. In fact, supertoughness was achieved at some compositions. We believe we have introduced a breakthrough approach for PLA toughening. We further investigated the new technology of processing SP as plastic in blending with other thermoplastic polymers which our group first introduced. Particularly, the investigation was focused on (1) improving tensile properties of the blends, (2) processing aids on rheological and mechanical properties, (3) SP plasticization and shear stress on SP phase structure and (4) the different effects of water and glycerol co-plasticizers. Although percolated SP thread network structure could be formed in the blend when SP was processed as a plastic during compounding, the PLA/SPC blends still exhibited lower tensile properties than neat PLA. We introduced a creative dual compatibilization method in which poly(2-ethyl-2-oxazoline) (PEOX) was first used during the compounding step because it was water compatible and resulted in fine dispersion of SPC, and a co-compatibilizer, polymeric methane diphenyl diisocyante (pMDI), was applied in the subsequent processing step, e.g., injection molding or extrusion for products. This dual compatibilization yielded PLA/SPC blends having strength higher than that of neat PLA. Water and glycerol are often used together as co-plasticizers in SP plastics. However, their influences on plasticization and morphology were never clarified in the literature. Our study illustrated that water is indispensible for SP to behave like a plastic and is the best plasticizer for SP. In blending SPC with other thermoplastic polymers, both water and glycerol promoted plastic deformation of SPC during mixing, but the former was much more effective than the latter which required higher shear stress at the same concentration. We further demonstrated that glycerol tended to result in phase coarsening in the blends. Our study demonstrated that plasticization and shear stress interplayed in determining the morphological structure of the blends.
Publications
- 1. Bo Liu; Long Jiang; Jinwen Zhang. 2010. Study of effects of processing aids on Properties of Poly(lactic acid)/Soy Protein Blends, Journal of Polymer and the Environment, DOI 10.1007/s10924-010-0274-0
- 2. Feng Chen; Jinwen Zhang. 2010. Effect of plasticization and shear stress on phase structure development and properties of soy protein blends, ACS Applied Materials and Interfaces, 11, 3324-3332.
- 3. Luis Bastarrachea; Sumeet Dhawan; Shyam S. Sablani; Jae-Hyung Mah; Dong-Hyun Kang; Jinwen Zhang; Juming Tang. 2010. Biodegradable poly(butylene adipate-co-terephthalate) films incorporated with nisin: characterization and effectiveness against Listeria innocua, Journal of Food Science, 75(4), E215-E224.
- 4. Hongzhi Liu; Feng Chen; Bo Liu; Gregory Estep; Jinwen Zhang. 2010. Super toughened poly(lactic acid) ternary blends by simultaneous dynamic vulcanization and interfacial compatibilization, Macromolecules, 43, 6058-6066.
- 5. Bo Liu; Long Jiang; Hongzhi Liu; Jinwen Zhang. 2010. Synergetic compatibilizing effect of dual compatibilizers on poly(lactic acid)/soy protein concentrate blends, Industrial & Engineering Chemistry Research, 49, 6399-6406.
- 6. Feng Chen; Jinwen Zhang. 2010. In-situ Poly(butylene adipate-co-terephthalate)/Soy Protein Concentrate Composites: Effects of Compatibilization and Composition on Properties, Polymer, 51, 1812 - 1819.
- 7. Bo Liu; Long Jiang; Hongzhi Liu; Lili Sun; Jinwen Zhang. 2010. Different effects of water and glycerol on Morphology and Properties of Poly(lactic acid)/Soy Protein Concentrate Blends, Macromolecular Materials and Engineering, 295, 123-129.
- 8. Long Jiang; Feng Chen; Jun Qian; Jijun Huang; Jinwen Zhang. 2010. Reinforcing and Toughening effects of bamboo pulp fiber on poly(3-hydroxybutyrate-co-3-hydroxyvalerate) composites, Industrial & Engineering Chemistry Research, 49, 572-577.
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: For the past year, we have conducted further investigation on processing technology and application development of biopolyesters. Specifically, we have advanced the investigation in the following aspect of the materials technology; (1) reinforcing and toughening of biopolyesters; (2) novel processing techniques for soy protein (SP) blends; (3) microcellular foaming of the polyester blends and composite; and, (4) reinforcement via in-situ fibrillation. Three oral presentations of the results were given at: (1) International Symposium on Polymers and the Environment: Emerging Technology and Science & the 2009 BioEnvironmental Polymer Society Annual Meeting; (2) 238th ACS annual meeting; and, (3) 2009 Genes to Products: Agricultural Plant, Microbe & Biobased product Research, United States Agriculture Department, respectively. PARTICIPANTS: Dr. Jinwen Zhang (PI) oversees the project and directly advises his graduate students and postdoc, all of whom participate in different aspects of the project. Dr. Long Jiang advises graduate students, and characterizes the polymer blends. Dr. Xiaoqing Liu mainly undertakes the chemical modification of PLA, PHAs for compatibilizer application. Miss Feng Chen, PhD student in Washington State University's Materials Science Program, studies soy protein blends. Mr. Bo liu, PhD student in the Materials Science Program, mainly undertakes the study of foaming processing technology. TARGET AUDIENCES: U.S. corn growers will be the immediate beneficiaries of the investigation by finding new applications of PLA and PHAs in a market dominated by petroleum-based plastics, because both polymers are corn starch-based. The general public will benefit from the results, because PLA and PHAs are environmentally friendly: both are biodegradable and compostable. In addition, the findings from this project will advance the bioplastics knowledge base and stimulate future developments within the biobased plastic materials industry. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
We found that bamboo pulp fiber (BPF) not only reinforced but also toughened poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). This result is in contrast to most other short fiber reinforced biocomposites which demonstrate reduced strain-at-break. The unique toughening effect of BPF was caused by the similar yield strain but much higher strain-at-break of BPF with respect to that of PHBV. This finding could provide important guidance in design and materials selection of biocomposites with both reinforced and toughened properties. We have introduced a novel manufacturing technique for soy protein blends by processing SP as plastic rather as filler with other thermoplastic polymers. By processing SP as plastic, the morphological structure of the blends can be significantly manipulated, thereby altering the properties of the blends. A percolated fine SP thread network structure was formed in the blend and in certain conditions even continuous blends were obtained. We also found that using water and glycerol together as plasticizers for SPC during blending actually resulted in opposite effects. This finding is significant because, currently, it is common practice to use glycerol in SP plastics and blends. We also studied the microcellular foaming technology of SP blends, and developed a comprehensive understanding of the processing. In another study, we demonstrated that the in-situ flow induced micro-fibrillation of PLA in poly(lactic acid) PLA/starch blends greatly reinforced the blends.
Publications
- 1. Honghua Wang, Xiaoqing Liu, Jinwen Zhang, Ming Xian. Synthesis of Rosin-based Flexible Anhydride Type Curing Agents and Properties of the Cured Epoxy, Polymer International 2009,58, 1435-1441.
- 2. Long Jiang, Bo Liu, Jinwen Zhang. Properties of Poly(lactic acid)/Poly(butylene adipate-co-terephthalate)/Nanoparticle Ternary Composites, Industrial & Engineering Chemistry Research 2009, 48 (16), 7594-7602.
- 3. Feng Chen, Jinwen Zhang. A new approach for morphology control of poly(butylene adipate-co-terephthalate) and soy protein blends, Polymer 2009, 50, 3770-3777.
- 4. Xiaoqing Liu, Wenbo Xin, Jinwen Zhang. Rosin-based acid anhydrides as alternatives to petrochemical curing agents, Green Chemistry 2009, 11, 1018-1025.
- 5. Long Jiang, Bo Liu, Jinwen Zhang. Novel high strength thermoplastic starch reinforced by in-situ poly(lactic acid) fibrillation, Macromolecular Materials and Engineering 2009, 294, 301-305.
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: For the past year, the investigation was focused on the manufacturing and properties of several biobased polyester/natural fiber composites. Approaches and mechanisms for improved mechanical, thermal mechanical properties are being studied. This study also provides important guidelines and references for the forming of these composites. The natural fibers used in this study included wood flour, nano cellulose whisker, sugar beet pulp and bamboo fibers. The biobased polyesters used were poly(lactic acid), poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate). All three are cornstarch-based polymers. The effects of fiber length, size, L/D ratio and compatibilization on the morphology and properties of the composites were studied. Mechanisms of reinforcing and toughening were investigated. One oral presentation of the results was given at the "International Symposium on Polymers and the Environment: Emerging Technology and Science & the 2008 BioEnvironmental Polymer Society Annual Meeting," Nashua, NH, October 7 - 10, 2008. PARTICIPANTS: Dr. Jinwen Zhang (PI), oversees the whole project, directly advises his graduate students and postodc who participate in different parts of the whole project. Dr. Zhang sometimes also physically conducts some of the experiments. Dr. Long Jiang assists Dr. Zhang on project planning, analyzes results, and also helps Dr. Zhang in supervising the students. Miss Feng Chen of WSU, PhD student in Materials Science Program, is partially involved in the project. Mr. Bo liu, PhD student in Materials Science Program,, is partially involved in the project. TARGET AUDIENCES: U.S. corn growers will be the immediate beneficiaries of the investigation by finding new applications of PLA and PHAs in a market dominated by petroleum-based plastics, because both polymers are corn starch-based. The general public will benefit from the results, because PLA and PHAs are environmentally friendly: both are biodegradable and compostable. In addition, the findings from this project will advance the bioplastics knowledge base and stimulate future developments within the biobased plastic materials industry. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
In the study of PHBV/bamboo pulp fiber composite, the crystallization ability, tensile strength and modulus, flexural strength and modulus were increased substantially by the addition of bamboo fiber. Tensile and flexural elongations were also increased moderately at low fiber content (<20%). Adding boron nitride (BN) was found to increase the overall properties of the neat polymer and the composites due to the refined crystalline structure. Maleic anhydride grafted PHBV improved polymer/fiber adhesion and hence resulted in increased strength and modulus. However, the toughness of the composites was reduced with improved adhesion because of the hindrance to fiber pullout. In our sugar beet pulp (SBP)/PLA composites, we successfully prepared composites with high fiber content, which demonstrated high levels of mechanical and physical properties that had not been achieved by other groups. By utilizing the porous structure of the SBP and improving the interfacial adhesion, we were able to retain 89 and 83% of the high neat PLA strength at 30 and 50% SBP, respectively. The composites displayed excellent water resistance. We also made significant progresses in other natural fiber biocomposites.
Publications
- 1. Feng Chen, Linshu Liu, Peter H. Cooke, Kevin B. Hicks, Jinwen Zhang. 2008. Performance Enhancement of Poly(lactic acid) and Sugar Beet Pulp Composites by Improving Interfacial Adhesion and Penetration, Ind. Eng. Chem. Res. 2008, 47, 8667 - 8675.
- 2. Long Jiang, Erving Morelius, Jinwen Zhang, James Holbery, Michael Wolcott. 2008. Study of the Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV)/Cellulose Nanowhisker Composites Prepared by Solution Casting and Melt Processing, Journal of Composite Materials. 42, 2629 - 2645.
- 3. Long Jiang, Jijun Huang, Jun Qian, Feng Chen, Jinwen Zhang, Michael P. Wolcott, Yawei Zhu. 2008. Study of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/Bamboo Pulp Fiber Composites: Effects of Nucleation Agent and Compatibilizer, J. Polym. Environ. 16, 83 - 93.
- 4.Performance enhancement of poly(lactic acid) and sugar beet pulp composites by improving interfacial adhesion and penetration, Feng Chen, Jinwen Zhang, International Symposium on Polymers and the Environment: Emerging Technology and Science, BioEnvironmental Polymer Society, Nashua, NH, Oct. 7 - 10, 2008 (Abstract).
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: For the past 12 months, processing and application development of biopolyesters (PLA and PHAs) was further investigated in several aspects. We studied the effects of processing methods on mechanical and physical properties of wood/PHA composites, including injection molding and extrusion. Reinforcing and toughening mechanisms of PLA using rigid inorganic filler were further elucidated. Effect of bamboo fiber induced crystallization of PHBV on mechanical properties and effects of the added nucleating agent on the fiber induced crystallization and mechanical properties of the composites were investigated. Reinforcing of PHBV with cellulose nanowhisker was also investigated. The research results from this project were presented at professional conferences. Three invited oral presentations were given at: 1. ACS symposium on "Polymers from Renewable Resources", 234th ACS National Meeting, Boston, Aug, 19-23, 2007; 2. 9th International Conference on Wood & Biofiber Plastic
Composites, Madison, WI, May 21-23, 2007; and 3. The symposium, "Biomedical/Biorelated Materials", at the AAAS Pacific Division conference & ACS Northwest regional meeting, Boise, ID, June 1-21, 2007. A general oral presentation was given at: The "International Symposium on Polymers and the Environment: Emerging Technology and Science & the 2007 BioEnvironmental Polymer Society Annual Meeting", Vancouver, WA, October 17-20, 2007. An invited seminar was given at the USDA Eastern Regional Research Center, Wyndmoor, PA, May xx, 2007.
PARTICIPANTS: Dr. Jinwen Zhang (PI), oversees the project, directly advises his graduate students and postodc who participate in different parts of the project. Dr. Zhang sometimes physically conducts some of the experiments as well. Dr. Long Jiang assists Dr. Zhang on project planning, analyzes results, and also helps Dr. Zhang in supervising the students. Mr. Scott Anderson, MS student in Material Science and Engineering, is partially involved in the wood/PHA composite processing and characterization. Miss Feng Chen of WSU, PhD student in Materials Science Program, is partially involved in the project. Mr. Bo liu, PhD student in Materials Science Program, is partially involved in the project.
TARGET AUDIENCES: U.S. corn will be the immediate beneficiaries of the investigation by finding new applications of PLA and PHAs in a market dominated by petroleum-based plastics, because both polymers are corn starch-based. The general public will benefit from the results, because PLA and PHAs are environmentally friendly: both are biodegradable and compostable. In addition, the findings from this project will advance the bioplastics knowledge base and stimulate future developments within the biobased plastic materials industry.
Impacts
Fiber induced crystallization of polymer has been studied by many others. However, its role in mechanical properties of the composites is still not clear. For the first time, we demonstrated that by adding a nucleating agent to the bamboo/PHBV composite, the overall properties of the neat polymer and the composites were improved due to refined crystalline structures. The added nucleating agent basically minimized the fiber induced crystallization. Part of the results on bamboo fiber reinforced PHBV has been submitted for publication. We first elucidated the toughening mechanisms PLA nanocomposites with organo- clay and nano-sized CaCO3. While CaCO3 causes massive crazing which toughens the PLA, organo-clay at low concentration allows large shear yielding. This finding should be considered very important, because it will provide significant information in future design of PLA nanocomposites. Part of the results from this research has been published in a recent issue of
Polymer journal.
Publications
- Qian, J.; Zhu, L.; Zhang, J.; Whitehouse, R. 2007. Comparison of different nucleation agents on crystallization of poly(3-hydroxybutyrate-co-3-hydroxyvalerate), J. polym. Sci. part B: phys. 45, 1564 - 1577.
- Jiang, L.; Wolcott, M.P.; Zhang, J.; Englund, K. 2007. Flexural properties of surface reinforced wood plastic deck board, Polym. Eng. Sci. 47, 281-288.
- Zhang, J.; Jiang, L.; Wolcott, M.P. 2007. Comparison of nano-sized calcium carbonate and organoclay polylactide (PLA) nanocomposites: toughening and reinforcing effects, Polymer Preprints.
- Jiang, L.; Zhang, J.; Wolcott, M.P. 2007. Comparison of polylactide/nano-sized calcium carbonate and polylactide/montmorillonite composites: Reinforcing effects and toughening mechanisms, Polymer 48, 7632 -7644.
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Progress 01/01/06 to 12/31/06
Outputs
During the past 12 months, development of biopolyesters (PLA and PHAs) was further investigated in several aspects including nucleating and crystallization, toughening and toughening mechanism, and natural fiber reinforcement. In the literature, the nucleating effects of talc, nanoclay, -cyclodextrin, lignin and other inorganic and organic chemicals have been studied for PHB and PHBV crystallization. However, the nucleating effects of these chemicals are significantly inferior to that of boron nitride which is the current nucleating agent in commercial PHB and PHBVs. In this research, a series of organic and inorganic chemicals was screened to identify potential alternatives to boron nitride, including saccharin, thymine, melamine, abeitic acid, thiocyanuric acid, and nano-sized CaCO3. The results suggested that thymine showed the most similar nucleating effect to boron nitride. Melamine also demonstrated a significant nucleating effect but not as good as
thymine. Comparison of crystallization kinetics of PHB and PHBVs using boron nitride, thymine and melamine were further studied. Toughening of PLA and PHBV using poly(butylene adipate-co-terephthalate) (PBAT) was studied. The micromechanical deformation process and toughening mechanism of PLA/PBAT blends were revealed by the change of morphological structures. It was concluded that the debonding induced shear yielding process was responsible for the significant toughening effect. To our knowledge, this study is the first to reveal the toughening mechanism of biopolyesters based on experimental evidence. Further investigation is underway to identify the effects of compatibilization, rubber particle size, and interparticle distance. PLA nanocomposites with nano-sized CaCO3 and nanoclay were studied and compared. At relatively low concentrations of nanoclay (<5 wt%), both reinforcing and toughening can be achieved. Nano-sized CaCO3 increased the ductility of PLA but not its strength.
Different micromechanical deformation processes were involved in these two nanocomposites. Reinforcing PHBV using bamboo pulp fiber was also conducted. In contrast to many natural fiber/PHBV composites which show little or no increase in strength and often decreased toughness, adding bamboo pulp fiber results in an increase in both strength and toughness. Co-continuous PLA/soy protein bends were successfully prepared and the properties were studied, representing significant progress in the development of bioplastics. While blending soy protein with thermoplastic PLA directly overcomes the problems of low flowability and low moisture resistance of soy protein-based plastics, it also aids the cost effectiveness for biopolyester products through blending PLA with natural polymers.
Impacts
In general, the outcomes from all the on-going investigations will contribute to the viability of alternatives to petrochemical plastics. Improving the toughness of biopolyesters is crucial for their broad application in replacing petrochemical plastics. Reinforcement with nanofillers and natural fibers leads to the attainment of high performance biopolyester biopolastics. Blending biopolyesters with natural polymers also aims to lower production cost.
Publications
- Jiang, L.; Lam, Y.C.; Tam, K.C.;Li, D.T.; Zhang, J. 2006. The influence of fatty acid coating on rheological and mechanical properties of thermoplastic polyurethane (TPU)/nano-sized precipitated calcium carbonate (NPCC) composites, Polm. Bulletin, 57, 575 - 586.
- Zhang, J.; Jiang, L.; Zhu, Z. Jane, J.; Mungara, P. 2006. Morphology and properties of soy protein and polylactide blends, Biomacromolecules, 7, 1551 - 1561.
- Zhang, J.; Jiang, L. 2006. Development of soy protein and polylactide blends: processing, toughening, morphology, and properties, Polym. Matr.: Sci. Eng., 95, 611 - 612.
- Jiang, L.; Zhang, J.; Wolcott, M.P. 2006. Toughening poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with poly(butylene adipate-co-terephthalate) (PBAT), Polym. Matr.: Sci. Eng., 95, 1037 - 1038.
- Zhang, J.; Jun, Q. 2006. Biocomposites of bamboo pulp fiber and poly(3-hydroxybutyrate-co-3-hydroxyvalerate): Performance enhancement, Forest Product Society 60th International Convention Abstract, p48.
- Zhang, J.; Jiang, L.; Qian, J.; Wolcott, M.P. 2006. Toughening and reinforcing of polylactide by poly(butylene adipate-co-terephthalate) and inorganic nanofiller, International Degradable Plastics Symposium: Status of Biobased and Synthetic Polymer Technology, Chicago, IL, June 14 - 17, 2006 (Abstract#20).
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Progress 01/01/05 to 12/31/05
Outputs
For the past 12 months, several aspects of the natural fiber reinforced PHA composites have been studied, including crystallization of PHAs and transcrystallization of the PHAs in the composites, effect of fiber pre-treatments, effect of compatibilizers, foamability, and toughening. Because of the induced crystallization by natural fibers, PHB and PHBV containing 8% HV in the composites can crystallize at a reasonable rate without using a nucleating agent. However, a nucleating agent is needed for PHBV containing 12%HV, and a high mold temperature is required for the injection molding process. Treating fibers with titanate-type coupling agents did not result in improvement of interfacial adhesion between fiber and PHBVs, while maleic anhydride grafted PHBVs show obvious positive effects. Foam extrusion and foam injection molding were also attempted, but the resulting foams tended to have large voids due to low melt strength and viscosity. The composites were brittle,
and adding a rubbery polymer increased the impact strength. The mechanical properties of samples made by extrusion and injection molding were compared. The results suggest that these two processing methods yielded products with comparable mechanical properties, with injection molded samples showing slightly high values. The better performance of products from injection molding might be attributed to the higher degree of orientation of woodfibers and polymer molecules. Preliminary work on the morphologies of the composites was conducted. It was found that wood fibers were well dispersed in the polymer matrix in most cases, irrespective of whether the surface was treated or not treated. Fiber pull-out was also identified in all composites. These results suggest insufficient interfacial adhesion for the resulting composites. On the other hand, SEM reveals MA-PHBV resulted in a better wetting of the fiber surface, compared with the untreated fiber or Lica (titanate) treated fiber, as less
fiber pull-out was shown in the former. Similarly, untreated fiber looks better wetted than Lica treated fiber. These results are consistent with mechanical testing. More morphological characterization is underway. Further investigations on the approaches for the interfacial adhesion and melt strength improvements will be conducted.
Impacts
This research aims to manufacture plastic materials by utilizing biopolymers and abundant natural fibers. The technology developed from this project will directly benefit plant growers and biopolymer manufacturers. Developing products based on renewable resources reduces the nation's reliance on foreign oil and contributes to environmental protection.
Publications
- Jiang, L.; Wolcott, M.P.; Zhang, J. 2006. Study of biodegradable polylactide/poly(butylene adipate-co-terephthalate) blends, BioMacromol. 7: 199 - 207.
- W. Gacitua, A. Ballerini, J. Zhang 2005. Polymer nanocomposites: Synthetic and natural fibers a review, Madera. Ciencia y Tecnologia, 7(3): 159 - 178.
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Progress 01/01/04 to 12/31/04
Outputs
Most PHAs, such as PHB and PHBV, have quite low melt strength. The melt strength is further decreased by adding natural fiber in the system, and this makes it difficult for PHAs to retain the cell expansion during the foaming process. In addition, thermal degradation of PHAs starts in the vicinity to their melting points. Reduced processing temperature is beneficial to both the improvement of melt strength and reduction of thermal degradation. Due to the characteristic slow crystallization rate, it was found that the PHBV supercool melt retained its fluidity for a considerable long period. A reverse temperature process was adopted in which PHA was melted in the beginning zones of the extruder, and then the melt temperature was gradually decreased downstream to the temperature below its melting point. Thermal degradation was reduced greatly, and melt strength was increased significantly. Other measures, such as molecule branching (or cross-linking) and blending, will
also be evaluated for melt rheology improvement. The foaming process optimization will be studied.
Impacts
The development of the microcellular foam technology for natural fiber reinforced biopolymesters will result in the cost effective and energy efficient production of biopolyester products, which aim to compete with fossil carbon based products both in performance and economics. Several fundamental problems in the preparation of microcellular foam of PHAs and biocomposites will be solved. Prototypes of extruded foam and injection molded foam products of PHAs and biocomposites will be obtained at the completion of the project, and they will guide the commercialization of these products in future.
Publications
- J. Zhang, S. McCarthy, R. Whitehouse. "Reverse temperature processing of Biopol and the improvement on its properties", J. Appl. Polym. Sci., 94,483-491(2004).
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