Location: Bioproducts Research2012 Annual Report
1a. Objectives (from AD-416):
Objective 1: Develop novel commercially viable composite materials from agricultural residues and industrial crops. a. Develop novel commercially viable fiber-reinforced composite materials. b. Develop novel commercially viable composite materials for agricultural applications and consumer goods. Objective 2: Develop novel technology to enable the commercial production of nanofibers from biopolymers. Objective 3: Develop commercially viable biobased polymers and polymer blends with improved functionality. Objective 4: Develop technologies to enable the commercial production of non-fuel commodity bioproducts from agricultural and biorefinery feedstocks and byproducts.
1b. Approach (from AD-416):
Novel commercially viable composite materials will be developed from agricultural fibers and binders. Fiber composites with superior strength and flexibility will be made by uniformly distributing agricultural fibers in matrices using and array of dispersants. Matrix materials will include biopolymers and inorganic binders. Fiber reinforced composites will also be made using micro and nanofibers made from biopolymers. Composite materials with liquid activated clumping properties will be made using agricultural binders with high molecular weight and strong hydrophilic properties. Composite materials that function as control-release devices will be developed both for controlling important agricultural pests and for providing plant nutrition and protection. The devices will utilize biodegradable, natural polymers and beneficial soil microbes. In addition to composite materials, micro and nanofibers and/or nanoparticles will be made from biopolymers using a solution blow spinning technology recently developed. Biopolymer solutions will be used to make an array of micro and nanofibers with active agents that provide functionality for applications for medical products and personal hygiene items. Nanoparticles from starch and/or cellulose will be produced by chemical and mechanical means. The materials will be used to make nanocomposites with improved strength and modulus. Low molecular weight polyesters will be made based on di and triols/diacids that can plasticize polylactic acid (PLA) or polyhydroxyalkanoates (PHA). PLA and PHA polymers containing the plasticizers will be tested for strength and stability by recording mechanical properties. Green pathways for making styrene and terephthalic acid will be explored along with other WRRC cooperators. The Bioproducts Group’s main focus in this collaborative effort will be to assist in characterizing the mechanical and physical properties of the biopolymers and partnering with industry to facilitate scale-up. Non-fuel commodity bioproducts from crop residues, fish waste and wheat gluten will be made. Cellulose fiber will be extracted from crop residues and processed into bioproducts including agricultural mulches and tessellated fiber board. Bioproducts from fish waste will include gelatin polymers for biomedical applications such as tissue scaffolding. Nanofibers from fish gelatin or blends of fish gelatin and other polymers will be made by electrospinning. Processing parameters will be optimized and fiber properties will be characterized using microscopy and analytical methods. Antibiotics will be incorporated into the fibers and films. The antimicrobial effectiveness of fibers will be compared to films as to their effectiveness against different bacteria using an overlay inhibition technique. Work on wheat gluten bioproducts will also be performed with the goal of developing natural protein polymers from vital wheat gluten that can be chemically modified to impart greater ability to absorb water.
3. Progress Report:
Significant progress has been made on all aspects of the Project Plan. Fiber composite materials were developed as directed (under objective 1); specifically cellulose nanofibers were isolated from cassava bagasse and interspersed in a thermoplastic starch matrix to improve their properties, This research, in collaboration with Embrapa scientists, expanded the international marketability of these ag-derived composites. The composite materials had improved properties compared with controlled samples, making them more cost-effective for BCE's CRADA partner. In Objective 2 of the Project Plan, BCE scientists focused on the development of nanofiber technology whereby a solution blow spinning (SBS) process for making nanofibers was developed jointly with EMBRAPA researchers, and a patent application was filed. Further work was done to optimize SBS of poly (lactic acid) (PLA) polymer solutions. An application was identified in water sensors where a thin film of SBS fibers improved the sensitivity and performance of disposable sensors. In composite research, PLA and fiber composites have been developed for making injection molded eating utensils. The composite materials are less expensive than PLA yet have adequate functional properties. In other biopolymer work, a partially biobased plasticizer for food packaging applications was developed. It is currently being tested by a large food company to reduce “noisy” biobased packages. The plasticizer is a block-copolymer of d-lactide and a polyester. The plasticizer improves polymer flexibility and also increases the heat-distortion temperature of PLA and PLA blends. In short, these improvements will help increase the functionality and commercial applications of PLA. In other fiber work, research is ongoing to improve the torrefaction process to be able to process agricultural waste into a biocoal. A mobile processing system is being manufactured to enable processing at the site of waste generation. As part of objective 4, wheat proteins have been chemically modified to make natural polymer-based superabsorbent polymers. The wheat proteins are modified with phosphoric acid resulting in a modified polymer that absorbs up to eighty-eight times its weight in water. In collaboration with Italian scientist several chemical and processing strategies were successively developed to compatibilize blends of biopolymers and synthetic polymers that are otherwise incompatible.
1. Improved properties for commercial-grade bioplastics. The market penetration of the commercial biopolymer, poly(lactic acid), PLA, which is derived from fermenting corn-based sugars, has been limited by its mechanical properties -- the plastic has a relatively low softening point and it is considered too brittle for all applications. BCE scientists, along with a research partner, have developed additives, termed plasticizers and heat stabilizers, that improve the market applicability of PLA. These additives are based on a block-copolymer of d-lactide and/or a polyester. Specifically, the plasticizer improves the flexiblity of poly(lactic acid) and can also raise the heat distortion temperature to over 150 C. This new material could be used for hot drinks, soups, microwaveable food packaging and even be used in dishwasher-safe utensils.
2. Improved plates, bowls and single-use utensils. Single use items, such as plates, bowls, forks and knives, derived from agricultural fibers have been commercialized in the U.S., but the pulp sources are often cheaper overseas. ARS scientists in Albany, California, and their research partner have focused on creating fiber composites from economically-viable biomass sources readily available in the Western States. Pulp from straw, rice hulls, artichoke fibers, and wood fibrils were mixed with poly(lactic acid) (PLA) and optimized for injection molded food service products. The heat resistance of these injection molded fiber-filled composites was improved by heat-treating after extrusion whereby the effect of annealing time, annealing temperature (100°C or 80°C), fiber content (0% to 40%), and fiber type improved the crystallinity and heat resistance of the PLA composites. These stronger and cheaper single-use items have already been introduced to a CRADA partner to investigate their commercialization.
3. Improved blow-spinning process for creating nano-scale structures. The promise of nanotechnology to add value to agricultural applications in biosensors, "smart" packaging, and improved composite materials has been hampered by the inability to scale up nano-scale materials in cost-effective processes. ARS scientists in Albany, California, have developed a new process solution blow spinning to produce nanofibers, that is much cheaper than the industry standard, electrospinning, and can also be more readily scaled-up. The specific advantages of nano-scale blow spinning vs. elecrospinning are the following: a higher fiber production rate, an ability to scale-up production using commercially-available, inexpensive components, the ability to blow nano-structured materials onto surfaces without consideration of their electrical charge, its relative portability and the savings in that no high-voltage equipment are required. A patent has been filed with ARS researchers in Albany, California, looking forward to working with potential partners in an array of areas to commercialize this new nanotechnology.
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