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United States Department of Agriculture

Agricultural Research Service

Research Project: VISCOELASTIC PROPERTIES OF BIO-BASED ELASTOMERIC COMPOSITES

Location: Plant Polymer Research

2007 Annual Report


1a.Objectives (from AD-416)
Develop improved rubber composites and their applications by using bio-based fillers. The research product of this work will aid in generating new markets for agricultural materials, and alleviate the problem of surplus agricultural commodities. This work will also aid in reducing our dependence on petroleum by substituting bio-based fillers from renewable resources for petroleum-based fillers (carbon black).


1b.Approach (from AD-416)
This proposal seeks to develop various economically viable bio-based fillers for rubber composite applications, and their optimum use and processing technology in rubber applications. The proposed experimental approach will investigate factors that can influence the properties of rubber composites such as filler size, filler structure, filler-filler interactions, and filler-rubber interactions. The result will then be used to identify commercially viable bio-fillers and to optimize the composite properties. The proposed experiments will also investigate the mixing and flow behaviors of bio-filler reinforced rubber composites, and develop a commercially viable processing technology for these composites.


3.Progress Report
It is known that the reduction of filler size can contribute to the increase of rubber reinforcement effect. During this reporting period, the size reduction of soy protein aggregate was studied. A near nano-sized soy protein isolate (SPI) were obtained by a hydrolysis and separation process. Particle sizes of the swollen nanoparticles in water were determined by light scattering and showed a narrow size distribution. Nanocomposites were formed by mixing SPI particles with carboxylated styrene-butadiene (SB) particles in the aqueous phase, followed by freeze-drying and compression-molding. Compared with unreinforced SB matrix, SPI/SB nanocomposites exhibited a significant increase in their modulus. Near nano-sized SPI particles were also found to increase the elasticity of nanocomposites by forming a more elastic particle-matrix network.

In addition to soy products that were used as reinforcements in rubber composites, other cost-effective bio-fillers were also studied. The use of wheat flour and its components as reinforcements is currently under investigation. During this reporting period, the effect of gluten content and starch swelling on the viscoelastic properties of polymer composites reinforced by wheat flour was determined. The use of wheat flour as a biomaterial filler for rubber composites was studied, and the effects of gluten content and starch swelling on the final composite modulus were measured. The reinforcement effect of the wheat flour was directly increased by the gluten content. The swelling of the starch within the wheat flour was controlled through the cook temperature of the wheat flour, and it was found that by increasing the swelling of the starch the reinforcement properties of wheat flour as a biomaterial filler were also increased directly.

In order to develop a process for these biobased rubber composites, flow properties of natural rubber/defatted soy flour composites were studied. Previously, defatted soy flour (DSF) in a styrene-butadiene matrix has been shown to have a significant reinforcement effect. In this study, the objective is to investigate the flow properties of composites in natural rubber to understand their processing characteristics. Composites with various loadings of DSF and carbon black (CB) were prepared by freeze drying and compression molding. A capillary rheometer was used to measure the viscosity of the composites at various temperatures and shear rates. Rubber and composites are non-ideal fluids, and CB filled composites had higher viscosities than DSF composites. The viscosity of DSF filled composites was also less temperature dependent than that of natural rubber matrix.


4.Accomplishments
(1) The reinforcement effect of hydrolyzed soy protein isolate in rubber composites:

In order to improve the rubber reinforcement by biobased fillers, a method to change filler size has to be developed. A near nano-sized soy protein isolate (SPI) was obtained by a hydrolysis and separation process. Particle sizes of the swollen nanoparticles in water were determined by light scattering and showed a narrow size distribution. Nanocomposites were formed by mixing SPI and SB particles homogeneously. Compared with unreinforced SB matrix, SPI/SB nanocomposites exhibited a significant increase in their modulus. Near nano-sized SPI particles increased the elasticity of nanocomposites by forming a more elastic particle-matrix network. This work will impact the technology of biobased nanocomposites. The accomplishment falls under National Program 306, Quality and Utilization of Agricultural Products, Component 2 – New Processes, New Uses, and Value-added Foods and Biobased Products. The research addresses Problem area 2a – New Product Technology.

(2) Determine the effect of gluten content and starch swelling on the viscoelastic properties of polymer composites reinforced by wheat flour:

In order to investigate the use of wheat flour as a biomaterial filler for rubber composites, the effects of gluten content and starch swelling on the final composite modulus were measured. The reinforcement effect of the wheat flour was directly increased by the gluten content. The swelling of the starch within the wheat flour was controlled through the cook temperature of the wheat flour, and it was found that by increasing the swelling of the starch the reinforcement properties of wheat flour as a biomaterial filler were also increased directly. This work will impact the technology of biobased composites. These accomplishments fall under National Program 306, Quality and Utilization of Agricultural Products, Component 2 – New Processes, New Uses, and Value-added Foods and Biobased Products. The research addresses Problem area 2a – New Product Technology.


5.Significant Activities that Support Special Target Populations
None.


6.Technology Transfer

Number of new CRADAs and MTAs1
Number of non-peer reviewed presentations and proceedings6

Review Publications
Jong, L. 2007. Effect of soy spent flakes and carbon black co-filler in rubber composites. Composites Part A Applied Science and Manufacturing. 38(2):252-264.

Selling, G.W., Lawton Jr, J.W., Bean, S., Dunlap, C.A., Sessa, D.J., Willett, J.L., Byars, J.A. 2005. Rheological studies utilizing various lots of zein in N, N-dimethylformamide solutions. Journal of Agricultural and Food Chemistry. 2:40.

Peterson, S.C., Eller, F.J., Fanta, G.F., Felker, F.C., Shogren, R.L. 2007. Effects of critical fluid lipid extraction on the gelatinization and retrogradation of normal dent cornstarch. Carbohydrate Polymers. 67(3):390-397.

Last Modified: 7/28/2014
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