2003 Progress Report: High Strength Degradable Plastics From Starch and Poly(lactic acid)

EPA Grant Number: R829479C012
Subproject: this is subproject number 012 , established and managed by the Center Director under grant R829479
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: The Consortium for Plant Biotechnology Research, Inc., Environmental Research and Technology Transfer Program
Center Director: Schumacher, Dorin
Title: High Strength Degradable Plastics From Starch and Poly(lactic acid)
Investigators: Sun, Susan Xiuzhi , Seib, Paul
Institution: Kansas State University
EPA Project Officer: Lasat, Mitch
Project Period: July 1, 2002 through June 30, 2004
Project Period Covered by this Report: July 1, 2002 through June 30, 2003
RFA: The Consortium for Plant Biotechnology Research, Inc., Environmental Research and Technology Transfer Program (2001) RFA Text |  Recipients Lists
Research Category: Targeted Research , Hazardous Waste/Remediation

Objective:

The goal of this research project is to develop affordable, durable, and degradable bioplastics from starch and poly(lactic acid) (PLA). The specific objectives are to: (1) identify plasticizers that can enhance the flowability (processibility) of starch and PLA blends, while retaining strength and improving flexibility of the blends; and (2) determine degradability of the starch/PLA/methylenediphenyl diisocyanate (MDI) blends.

Progress Summary:

High-strength bioplastics from starch and PLA have been obtained by using coupling reagents. MDI is the most effective coupling reagent to improve the interfacial strength between starch and PLA, as well as the tensile strength. The amounts of MDI and the PLA/starch ratios were optimized. A 0.5 wt percent MDI gave the PLA/starch (55/45) 66.7 MPa tensile strength, which is higher than that without MDI (36 MPa), and even higher than raw PLA of 62.1 MPa, even though the flexibility was retained as raw PLA. Moreover, poly(vinyl alcohol) (PVOH), a readily available biodegradable material, has the ability to enhance compatibility and improve mechanical properties of PLA/starch blends. At proportions greater than 30 percent, low molecular weight PVOH (Mw 6,000) forms a continuous phase with starch.

The mechanical and physical performances of various plasticizers were studied, and better plasticizers were identified. Various concentrations of plasticizers with PLA/starch were used, and the temperature, rotor-speed, and processing time were varied. Three groups of plasticizers were used: (1) water; (2) a low molecular-weight, nontoxic citrate ester; and (3) a high-molecular weight, polymeric plasticizer. The mechanical, thermal, and water absorption properties were determined. Water is a ready-to-use plasticizer, completely miscible with starch. The tensile strength of water plasticized blends was reduced, but with no significant increase in elongation. The most apparent disadvantage of water as a plasticizer was the easy thermal loss during processing, as determined by the dynamic mechanical analyzer and isothermal treatment at a certain high temperature. As a plasticizer, citrate ester significantly reduced the glass transition temperature of blends, thereby improving the elongation at break. Although citrate ester was an effective plasticizer, there was thermal loss during processing and isothermal treatment. Fifteen percent citrate gave the PLA/starch (55/45 wt) blend 130-percent elongation, and a 10 MPa tensile strength. The elongation was dramatically improved compared to 2.7 percent elongation of PLA/starch at the same ratio, even though tensile strength was lower than the 30 MPa without citrate. Both water and citrate ester as plasticizers for PLA/starch blends gave the blends unstable mechanical and physical properties in the long term. The presence of water or citrate esters as plasticizers, however, reduced the efficiency of coupling reagents. The polymeric plasticizer also significantly reduced the glass-transition temperature of the blends, and improved elongation at break. Ten percent of the polymeric plasticizer gave the blend 20 MPa tensile strength and 24 percent elongation, which was much better than citrate ester in this concentration. The polymeric plasticizer was able to maintain the ductile material at a certain tensile strength. A noticeable merit of using polymeric plasticizer with the PLA/starch blend was that no plasticizer was thermally lost during processing, and isothermal treatment gave the blends a stable mechanical property. Both citrate ester and polymeric plasticizers improved the blends’ elongation by percolation.

We also investigated starch as a nucleation agent on PLA crystallization behavior. Starch effectively increased the crystallization rate of PLA, even at a concentration of 1 percent. The crystallization rate increased slightly as the starch content in the blend increased. The addition of starch into the PLA did not significantly affect tensile strength, but slightly improved elongation when added at a relatively low concentration (less than 10 percent).

Future Activities:

The optimization of formulas for a large variety of applications, including foam, film, and rigid molding articles, will be determined. Biodegradability studies will be conducted.


Journal Articles on this Report : 4 Displayed | Download in RIS Format

Other subproject views: All 19 publications 12 publications in selected types All 11 journal articles
Other center views: All 211 publications 48 publications in selected types All 44 journal articles
Type Citation Sub Project Document Sources
Journal Article Ke TY, Sun XZ. Melting behavior and crystallization kinetics of starch and poly(lactic acid) composites. Journal of Applied Polymer Science 2003;89(5):1203-1210. R829479 (2006)
R829479C012 (2003)
R829479C012 (Final)
  • Abstract: Wiley-Abstract
    Exit
  • Journal Article Ke TY, Sun XZS. Thermal and mechanical properties of poly(lactic acid)/starch/methylenediphenyl diisocyanate blending with triethyl citrate. Journal of Applied Polymer Science 2003;88(13):2947-2955. R829479 (2006)
    R829479C012 (2003)
    R829479C012 (Final)
  • Abstract: Wiley InterScience
    Exit
  • Journal Article Ke TY, Sun SXZ, Seib P. Blending of poly(lactic acid) and starches containing varying amylose content. Journal of Applied Polymer Science 2003;89(13):3639-3646. R829479 (2006)
    R829479C012 (2003)
    R829479C012 (Final)
  • Abstract: Wiley-Abstract
    Exit
  • Journal Article Zhang J-F, Sun XZ. Mechanical properties and crystallization behavior of poly(lactic acid) blended with dendritic hyperbranched polymer. Polymer International 2004;53(6):716-722. R829479 (2006)
    R829479C012 (2003)
    R829479C012 (Final)
  • Abstract: Wiley-Abstract
    Exit
  • Supplemental Keywords:

    bioplastics, biopolymers, starch, poly(lactic acid), plasticization, mechanical property, foam, extrusion, biodegradation, water absorption, thermal property, plasticizer., Scientific Discipline, TREATMENT/CONTROL, Sustainable Industry/Business, Genetics, Geochemistry, Technology, New/Innovative technologies, Environmental Engineering, Agricultural Engineering, polylactic acid, bioengineering, biodegradable plastics, plant genes, biotechnology, plant biotechnology, novel plastics

    Relevant Websites:

    http://www.oznet.ksu.edu/dp_grsi/sun Exit
    http://www.cpbr.org Exit

    Progress and Final Reports:

    Original Abstract
  • Final Report

  • Main Center Abstract and Reports:

    R829479    The Consortium for Plant Biotechnology Research, Inc., Environmental Research and Technology Transfer Program

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R829479C001 Plant Genes and Agrobacterium T-DNA Integration
    R829479C002 Designing Promoters for Precision Targeting of Gene Expression
    R829479C003 aka R829479C011 Biological Effects of Epoxy Fatty Acids
    R829479C004 Negative Sense Viral Vectors for Improved Expression of Foreign Genes in Insects and Plants
    R829479C005 Development of Novel Plastics From Agricultural Oils
    R829479C006 Conversion of Paper Sludge to Ethanol
    R829479C007 Enhanced Production of Biodegradable Plastics in Plants
    R829479C008 Engineering Design of Stable Immobilized Enzymes for the Hydrolysis and Transesterification of Triglycerides
    R829479C009 Discovery and Evaluation of SNP Variation in Resistance-Gene Analogs and Other Candidate Genes in Cotton
    R829479C010 Woody Biomass Crops for Bioremediating Hydrocarbons and Metals
    R829479C011 Biological Effects of Epoxy Fatty Acids
    R829479C012 High Strength Degradable Plastics From Starch and Poly(lactic acid)
    R829479C013 Development of Herbicide-Tolerant Energy and Biomass Crops
    R829479C014 Identification of Receptors of Bacillus Thuringiensis Toxins in Midguts of the European Corn Borer
    R829479C015 Coordinated Expression of Multiple Anti-Pest Proteins
    R829479C016 A Novel Fermentation Process for Butyric Acid and Butanol Production from Plant Biomass
    R829479C017 Molecular Improvement of an Environmentally Friendly Turfgrass
    R829479C018 Woody Biomass Crops for Bioremediating Hydrocarbons and Metals. II.
    R829479C019 Transgenic Plants for Bioremediation of Atrazine and Related Herbicides
    R829479C020 Root Exudate Biostimulation for Polyaromatic Hydrocarbon Phytoremediation
    R829479C021 Phytoremediation of Heavy Metal Contamination by Metallohistins, a New Class of Plant Metal-Binding Proteins
    R829479C022 Development of Herbicide-Tolerant Energy and Biomass Crops
    R829479C023 A Novel Fermentation Process for Butyric Acid and Butanol Production from Plant Biomass
    R829479C024 Development of Vectors for the Stoichiometric Accumulation of Multiple Proteins in Transgenic Crops
    R829479C025 Chemical Induction of Disease Resistance in Trees
    R829479C026 Development of Herbicide-Tolerant Hardwoods
    R829479C027 Environmentally Superior Soybean Genome Development
    R829479C028 Development of Efficient Methods for the Genetic Transformation of Willow and Cottonwood for Increased Remediation of Pollutants
    R829479C029 Development of Tightly Regulated Ecdysone Receptor-Based Gene Switches for Use in Agriculture
    R829479C030 Engineered Plant Virus Proteins for Biotechnology