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United States Department of Agriculture

Agricultural Research Service

Research Project: Viscoelastic Properties and Polymer Composite Applications of Nano-Materials Derived from Agricultural Byproducts and Feedstocks

Location: Plant Polymer Research

2013 Annual Report


1a.Objectives (from AD-416):
Objective 1: Develop commercially viable polymer composites that contain soy- and cereal derived nanoparticle aggregates. Objective 2: Develop commercially viable polymer composites that contain carbonized agricultural byproducts and feedstocks as filler substitutes for carbon black. Objective 3: Develop new commercially viable biobased nanoparticles by copolymerization of biopolymer and biodegradable synthetic polymers.


1b.Approach (from AD-416):
This plan seeks to develop methods of producing nanoparticle aggregates from soybean, cereal grains, and biochar for polymer composite applications. The research includes developing economically viable methods using mechanical shear and chemically-induced rearrangements of proteins and carbohydrates to form nanoparticle aggregates and modifying their surface with both chemical and physical methods. The proposed experimental approaches will establish scientific working principles of bio-based nanocomposites by investigating size and shape of nanoparticle aggregates and their surface properties that can influence the properties of polymer composites. The proposed experiments will also investigate the mixing and flow behaviors of nanoparticles in polymer composites, and develop commercially viable processing technologies for these composites. The result will then be transferred to composite developers of various applications.


3.Progress Report:
Developing renewable agricultural based particulates for a variety of industrial elastomeric applications will contribute to the development of a healthy environmental friendly and sustainable business. Particles being evaluated in various systems include protein/carbohydrate aggregates, protein/biomass carbon materials, various biochars, and coated protein nanoparticles.

Two composite rubber systems were investigated where renewable materials were used as the reinforcing material. Thermal/shear reduced aggregates and thermal/shear/impact reduced particulates were used in producing natural rubber composites with improved properties. Novel methods were developed to produce the reinforcing agents. The impact of incorporating various amounts of these agents on physical properties was determined. Modulus increased between 5 and 10 x relative to control. These results suggest that these compositions would deliver value in a variety of molded plastic/rubber objects such as rubber flooring.

The impact that production method has on the quality of biochar has been investigated. Two production methods were utilized to produce biochar from corn stover or wheat straw. One method used an atmospherically-controlled oven to carry out pyrolysis (heating without oxygen) while the other used micro-gasification in an open-atmosphere oven. This later method produced biochar by utilizing primary and secondary air chambers to physically separate where the combustion of gases occurred from where the feedstock fuel underwent thermal conversion. Although the pyrolysis method produced biochar that had higher carbon content and lower ash content than the micro-gasification method, it remains to be seen whether or not the pyrolysis method actually has more commercial potential, mainly because cost and scale-up issues strongly favor the micro-gasification method of production. Improving the carbon yield and ash content of biochars produced utilizing this method is the near term focus of this research.

Nanoparticles produced from copolymers of cereal protein and acrylamide have been produced that can be used as fillers for rubber composites or as an agents that change the surface wetting properties of glass or plastics. As a surface modifying agent, these nanoparticles dramatically and instantly changed the wetting properties of transparent materials without noticeably changing the transparency. An in-depth study was performed for the characterization of these nanoparticles. An optimum production process was developed with the product fully characterized (a patent application was filed). The performance of the produced nanoparticles as a surface-modifying agent was evaluated in the field. A rubber composite was produced by using heat-treated starch as filler. The produced composites showed improved mechanical properties, increased tensile strength and modulus, without losing translucency. As expected, the dominant factors that influence the physical properties of the composite are particle size and the particle compatibility with the bulk material.


4.Accomplishments
1. Modified protein/carbohydrate and protein/biomass carbon. Polymers often have deficient physical properties that can be improved through the incorporation of reinforcing particles. These reinforcing particles are often petroleum based carbon black. Particulates made from renewable materials may be useful for polymer reinforcement to improve the environmental sustainability of the process. ARS, Plant Polymer Research Unit scientists at the National Center for Agricultural Utilization Research in Peoria, Illinois, have produced elastic biocomposites using soy protein/carbohydrate and protein/carbon particles as agents to deliver natural rubber composites having increased mechanical strength. Practically useful strength was achieved with the incorporation of either of these particles. These results demonstrate that valued plastic/rubber products, such as tiling, mats, and tires can be produced using a renewable material content and reducing the amount of petroleum derived carbon black.

2. Biochar production methods. Carbon black is a useful material in reinforcing rubber and plastics. Biochar is a type of carbon black produced from renewable materials. Ash, composed of metal oxides, is an undesirable component of biochar that dilutes the positive effects of the carbon present in biochar. ARS Plant Polymer Research Unit scientists at the National Center for Agricultural Utilization Research in Peoria, Illinois, compared biochar generated from corn stover and wheat straw feedstocks, using two different production methods. The first method employed a sealed oven, and the second method used an open-air flame system. The sealed oven method of biochar production provided biochar with 50% less ash than the open-air flame system. However, the open-air flame system may have better economies of scale. Through an improved understanding of the impact of processing conditions on biochar properties, biochar can be tailor made for discreet products such as removing unwanted compounds from industrial products such as pharmaceuticals or other chemicals.


Review Publications
Jong, L. 2013. Characterization of soy protein nanoparticles prepared by high shear microfluidization. Journal of Dispersion Science and Technology. 34(4):469-475.

Kim, S., Biswas, A., Singh, M., Peterson, S.C., Liu, S.X. 2012. Thermal dissolution of maize starches in aqueous medium. Journal of Cereal Science. 56(3):720-725.

Peterson, S.C., Appell, M.D., Jackson, M.A., Boateng, A.A. 2012. Comparing corn stover and switchgrass biochar: characterization and sorption properties. Canadian Journal of Agricultural Science. 5(1):1-8.

Kim, S., Evans, K.O., Biswas, A. 2013. Production of BSA-poly(ethyl cyanoacrylate) nanoparticles as a coating material that improves wetting property. Colloids and Surfaces B: Biointerfaces. 107(1):68-75.

Jong, L. 2013. Reinforcement effect of biomass carbon and protein in elastic biocomposites. Polymer Composites. 34(5):697-706.

Peterson, S.C. 2012. Utilization of low-ash biochar to partially replace carbon black in SBR composites. Journal of Elastomers and Plastics. 45(5):487-497.

Last Modified: 11/25/2014
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