SYNTHESIS AND CHARACTERIZATION OF NEW BIOPLASTICS FROM THE THERMAL POLYMERIZATION OF AGRICULTURAL OILS

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: NRI COMPETITIVE GRANT
• Reporting Frequency: Annual
• Accession No.: 0193689
• Grant No.: 2003-35504-12874
• Proposal No.: 2002-01557
• Project Start Date: Nov 1, 2002
• Project End Date: Oct 31, 2005
• Grant Year: 2003
• Program Code: [71.2]- (N/A)

Recipient Organization
IOWA STATE UNIVERSITY
2229 Lincoln Way
AMES,IA 50011

Performing Department
CHEMISTRY

Non Technical Summary
The plastics industry is the fastest growing industry in the United States. It currently produces over 60 billion pounds of plastics a year. The vast majority of these materials are derived from petroleum. There is a tremendous need for new materials with properties comparable to or better than those of current materials that might be prepared from renewable natural resources, such as agricultural materials. The Larock and Sheares groups are presently developing novel materials ranging from rubbers to elastomers to tough, hard plastics from natural oils, like soy, corn, peanut and linseed oils, and readily available compounds already used in the plastics industry. The research should increase the value of these crops as raw materials for manufacturing various products and conserve renewable petroleum resources. The specific goal is to enhance the profitability of American agriculture by developing exciting new agricultural oil-based plastics and composites possessing tremendous industrial potential. In the three-year period of the project, the research will focus on the study of these new materials to determine the best processes for producing them. In addition, a variety of oil-based plastics and composites will be developed and a thorough examination of their thermal, mechanical, physical and chemical properties conducted. We anticipate that the research will not only address the conservation of nonrenewable resources, but will also provide promising new materials with economic, energy and environmental benefits to the entire U.S.

Animal Health Component

30%

Research Effort Categories

Basic

70%

Applied

30%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
511	1510	2000	25%
511	1820	2000	25%
511	1855	2000	50%

Knowledge Area
511 - New and Improved Non-Food Products and Processes;

Subject Of Investigation
1510 - Corn; 1820 - Soybean; 1855 - Tung;

Field Of Science
2000 - Chemistry;

Keywords

composites

oils

polymerization

plastics

synthesis

characterization

chemical properties

heat

corn

soybeans

engineering

process development

performance evaluation

structural properties

formulations

technology transfer

peanuts

linseed oil

manufacturing

mechanical properties

physical properties

Goals / Objectives
The objectives are (1) to optimize the reaction conditions, procedures and processes for the thermal polymerization of a variety of agricultural oils and comonomers, producing useful materials ranging from plastics to composites; (2) to determine the thermophysical and mechanical properties of the polymers and composites; (3)to correlate the structures of the oils, reaction formulations and processing techniques utilized with the resulting properties, including damping and shape memory properties; (4) to compare the properties with commercial polymers using standard techniques in order to determine where these new polymers may find commercial utility; (5) to transfer the project results to appropriate audiences through presentations at local, national and international conferences, journal publications and presentations to industrial parties with the intent of eventually transferring the technology to industrial partners.

Project Methods
Given our initial success on the thermal polymerization of tung oil, styrene and/or divinylbenzene, we plan to utilize this system for our initial oil studies and then expand the findings with this oil to a number of other agricultural oils. We will first determine the optimal procedures for obtaining fully-cured polymer products. This will include an investigation of the effect of oxygen uptake on the gelation and vitrification processes of these particular systems. Upon establishing the time-temperature-transformation (TTT) cure diagrams, we will determine the effect of the stoichiometry, curing time and temperature on the structure and yield of the resulting polymers. The microstructures of the resulting polymers will be characterized by a number of spectroscopic techniques including proton nuclear magnetic resonance, carbon nuclear magnetic resonance, solid state magic angle spinning carbon 13 NMR and Fourier transformed infrared spectroscopies. The yields will be determined after Soxhlet extraction. Once the optimal cure conditions are established, a series of fully-cured tung oil polymeric materials will be prepared for testing of their thermophysical and mechanical properties. To better understand the properties of these new bioplastics and to create a structure/property correlation, a variety of tung oil polymers will be prepared by varying the ratio of the tung oil to styrene and/or divinylbenzene. The thermal properties of the resulting polymers will be examined by thermogravimetric analysis to determine the temperatures at which these materials decompose. The tensile, flexural and compressive mechanical properties, together with impact toughness and hardness, will be determined by employing standard tests (ASTM). Dynamic mechanical measurements will provide useful data in understanding the viscoelastic behavior and in-depth insights into the relationship between structure, morphology and possible applications of the polymers. Although the above research does not employ any catalysts or additives, metallic catalysts, such as calcium, cobalt and zirconium compounds have proven to be effective in accelerating the thermal polymerization process and lowering the activation temperatures of the thermal polymerization of some agricultural oils. To make our study complete, similar metallic compounds will be tested in the thermal polymerization of tung oil-styrene-divinylbenzene systems. Finally, to fabricate composite materials, a variety of reinforcing fillers will be employed, including inorganic reinforcements, such as glass fiber, conductive carbon black, carbon fiber, silicon gel, and the bio-absorbable P-glasses, as well as natural reinforcements, such as wood fibers, linen fibers, soy proteins, etc. In most cases, compression molding, a very simple, convenient and economic processing technique will be utilized. Through thermal and mechanical property characterization, we will gain a thorough understanding of how the properties of the composite materials vary as we change the composition of the polymer matrix.

Progress 11/01/02 to 10/31/05

Outputs
A variety of exciting new polymers have been prepared by the copolymerization of natural oils by thermal, free radical and cationic processes. Materials ranging from rubbers to tough, rigid plastics have been prepared by the thermal copolymerization of tung oil, styrene (ST) and divinylbenzene (DVB) with variations in the stoichiometry, oxygen uptake, peroxides, and metallic catalysts used. Gelation occurs at >140 C, and fully-cured thermosets are obtained at 160 C. These thermosets contain ~90-100% crosslinked materials, are light yellow and transparent, possess glass transition temperatures of -2 - 116 C, crosslink densities of 1,000 - 25,000 mol/m3, coefficients of linear thermal expansion of 23,000 - 44,000 per C, compressive moduli of 0.02-1.12 GPa, and compressive strengths of 8-144 MPa. They are thermally stable below 300 C, and exhibit major thermal degradation at 493-506 C. Novel opaque, white polymers ranging from rubbers to tough, rigid plastics have been prepared by the thermal polymerization of conjugated linseed oil, ST, and DVB. Gelation occurs at >120 C, and fully cured thermosets are obtained at 160 C. These thermosets contain ~35-85% crosslinked materials composed of a soft rubbery phase with a glass transition temperature of -50 C and a hard brittle plastic phase with a glass transition temperature of 70-120 C. They possess crosslink densities of 1,500-24,000 mol/m3, compressive Youngs moduli of 12-438 MPa, compressive strengths of 2-27 MPa, are thermally stable below 350 C, and exhibit a major thermal degradation at ~500 C. Adding Co, Zr and Ca catalysts to the conjugated linseed oil, ST, and DVB provides ~64-77% crosslinked materials. The insoluble fraction increases with increasing Co concentration, reaching a maximum for the Co-Zr mixture and a minimum for the Co-Ca mixture. These materials are composed of a soft rubbery phase with a glass transition temperature of -50 C and a hard brittle plastic phase with a glass transition temperature of 70-120 C. These polymers possess crosslink densities of 6,300-9,100 mol/m3 and compressive strengths of 2.0-26.6 MPa, are thermally stable below 300 C, and exhibit major thermal degradation at ~500 C. New thermosets have been prepared by the free radical copolymerization of conjugated linseed and low saturation soy oils, plus acrylonitrile (AN) and DVB or dicyclopentadiene (DCP). The clear yellow soy oil-DCP samples have slightly better damping properties than the DVB samples. These thermosets are transparent and exhibit good mechanical and damping properties, and thermal stability. Finally, thermosets ranging from tough and ductile to soft rubbers have been prepared by the cationic copolymerization of regular and conjugated soy oils plus DCP. The gelation time are 4-991 minutes at 110 C. These copolymers consist of a crosslinked soy oil-DCP network plasticized by less crosslinked copolymers and unreacted oil. The bulk copolymers have glass transition temperatures of -22.6 - 56.6 C, tan delta values of 0.7 to 1.2, and are thermally stable below 200 C.

Impacts
The thermal, free radical and cationic copolymerization of tung, linseed, and soy oils provides a wide range of industrially-promising, new biopolymers with excellent thermal and mechanical properties. We have provided the first examples of useful bioplastics from the simple thermal and free radical copolymerization of natural oils. like linseed, tung and soy oils, with simple comonomers, like styrene (ST) and acrylonitrile (AN). These thermosets possess excellent thermal and mechanical properties, plus very promising damping properties. We have also found a very good, cheap replacement for the expensive crosslinking agent DVB. DCP provides excellent crosslinking in the free radical copolymerization of conjugated soy oil and a range of exciting new rubbers and hard plastics have been prepared by the cationic copolymerization of regular and conjugated soy oils with DCP. The resulting glossy brown materials have excellent thermal, mechanical and damping properties. With the increasing price and scarcity of petroleum, there is tremendous interest in developing new biobased materials. All of the new bioplastics developed on this project appear very promising as replacements for petroleum-based plastics. They also possess value-added properties, like excellent damping of sound and vibration and shape memory properties. In fact, Ashland Specialty Chemical and Goodyear Tire and Rubber are presently working with us to attempt to commercialize these novel materials.

Publications

• Li, F.; Larock, R. C., Synthesis, Structure and Properties of New Tung Oil-Styrene-Divinylbenzene Copolymers Prepared by Thermal Polymerization, Biomacromolecules, 2003, 4, 1018-1025.
• Li, F.; Larock, R. C., Synthesis, Properties and Potential Applications of Novel Thermosetting Biopolymers from Soybean and Other Natural Oils, CRC Press, book chapter, 2005.
• Andjelkovic, D. D.; Li, F.; Larock, R. C., Novel Polymeric Materials from Soybean Oils-Synthesis, Properties and Potential Applications, Feedstocks for the Future: Renewables for the Production of Chemicals and Materials, ACS, 2005, pp. 67-81.
• Kundu, P. P.; Larock, R. C., Novel Conjugated Linseed Oil-Styrene-Divinylbenzene Copolymers Prepared by Thermal Polymerization. I. Effect of Monomer Concentration on the Structure and Properties, Biomacromolecules 2005, 6, 797-806.
• Andjelkovic, D. D., Larock, R. C. Novel Rubbers from the Cationic Copolymerization of Soybean Oil, PMSE Preprint 2005, 93, 882-883.
• Henna, P.; Larock, R. C. Biobased Thermosets from the Free Radical Polymerization of Conjugated Linseed Oil, PMSE Preprint 2005, 93, 768-769.
• Valverde, M.; Larock, R. C. Conjugated Low Saturation Soybean Oil Thermosets: Free Radical Copolymerization with DCP and DVB, PMSE Preprint 2005, 93, 766-767.
• Andjelkovic, D. D.; Valverde, M.; Henna, P.; Li, F.; Larock, R. C. Novel Thermosets Prepared by Cationic Copolymerication of Various Vegetable Oils - Synthesis and Their Structure-Property Relationships, Polymer 2005, 46, 9674-9685.
• Andjelkovic, D. D.; Larock, R. C. Novel Rubbers from Cationic Copolymerization of Soybean Oils and Dicyclopentadiene. I. Synthesis and Characterization, Biomacromolecules 2006, 7, 927-936.
• Andjelkovic, D. D.; Larock, R. C. Mechanical Properties of Novel Rubbers from the Cationic Copolymerization of Soybean Oil and Dicyclopentadiene, PMSE Preprint 2006.