Location: Plant Polymer Research2022 Annual Report
The goal of this research project is to use a wide range of technological approaches in the utilization of agricultural byproducts and feedstocks to improve functionalities of protein/carbohydrate particles for applications including, polymer seals, battery, pesticide, food ingredients, cellulose products, elastomer, and water treatment. Over the next five years, we will focus on the following objectives: Objective 1: Enable commercial production of new products based on functionalized particles for polymer seals and energy storage applications. Objective 2: Enable commercial production of new products based on the microencapsulation of environmentally-friendly pesticides and bioactive food ingredients. Objective 3: Enable commercial production of value-added products of micro/nano-sized celluloses and hemicelluloses from various agricultural wastes. Objective 4: Enable commercial processes to produce biochar products for elastomer composites and water treatment applications.
This research aims to enable biobased particle technologies that produce functional particles using renewable agricultural byproducts and feedstocks. The characteristics of these functional particles include size, shape, aggregate structure, and surface functionalities. These particles can be further modified to function as reinforcements in polymer matrices, multifunctional coatings for battery separator membranes, as controlled-release materials delivering food ingredients and chemicals and as cosmetic ingredients, and filtering media for water purification. The outcome of this research will contribute to the utilization of vast amounts of byproducts generated by the food industries, and benefit climate change by reducing greenhouse gases, all of which will promote a sustainable global bio-economy. Our previous research on biobased particles has produced composites with useful mechanical properties. Further development will advance polymer seals and energy storage applications. Our ‘masterbatch process’ will be applied to develop multifunctional coatings on battery separator membrane for ion conduction and short circuit prevention. Encapsulated products will be developed to extend active time of natural pesticides and to stabilize bioactive food ingredients. We will also develop nano-size hemicellulose/cellulosic materials for composite and cosmetic applications. Sustainable biochar from agricultural byproducts will be developed as an effective water filtration media for agricultural run-off and potable water. We will also improve biochar to become a more effective rubber filler. Upon the completion of this project plan, all technologies developed will be transferred to respective industries.
For the manufacture of rubber composites, various types of fillers are incorporated into rubber. Among many types of fillers, hydrophilic (dispersible in water) fillers have an advantage over others as they can readily form chemical bonds with other component materials. Previously, it was reported that the rubber composites (seals) reinforced with soy protein particles (hydrophilic filler) have less swelling in oil, and the mechanical strength does not decrease significantly as the temperature is increased when compared with carbon black reinforced rubber. As a continuation of this research under Objective 1, ARS researchers in Peoria, Illinois investigated the effect of the different manufacturing processes on mechanical properties and thermal degradation of the final products. The rubber composites reinforced with soy protein particles and carbon black were processed using two different methods: casting (a manufacturing process in which products are fabricated in the mold) and freeze-drying. This research revealed that rubber composites prepared by casting showed desirable mechanical properties due to the greater interactions between component materials in the reinforced rubber. Encapsulation is an emerging technology that can be used for the controlled release of pesticides or for the prevention of degradation of bio-active food ingredients. Our laboratory has been systematically analyzing one of the encapsulation techniques (that is, induction of emulsion formation followed by wrapping the formed droplets with protein molecules) to find optimal conditions for the process. As a result, two environment-friendly pesticides could be encapsulated into protein nanocapsules at the highest possible encapsulation efficiency. In the current work under Objective 2, ARS researchers in Peoria, Illinois, successfully encapsulated a bioactive food ingredient, alpha-tocopherol (a form of vitamin E), into corn protein nanocapsules with some modifications of the previously defined process. As the same procedure is expected to be applicable to many other bioactive food ingredients including water-insoluble vitamins and polyphenols, more experiments for the encapsulation of these ingredients are in progress. Additional research under Objective 2 enhanced the encapsulation process using ethanol. Our current encapsulation process can be used as long as the materials to be encapsulated are soluble in 90% aqueous ethanol. Since this requirement limits the usage of the process, a protocol that employs pure ethanol was developed. Given that pure ethanol dissolves many water-insoluble food ingredients, the newly developed encapsulation procedure is expected to be applicable to a much broader range of materials. The efficacy of this new process is shown to be promising, but its performance needs to be further verified by the actual production of nanocapsules that are loaded with active food ingredients. Many agricultural residues such as sorghum stover have little economic value other than for mulching back into the soil or for burning as fuel. Sorghum stover contains several fibers such as hemicellulose, cellulose, and lignin. Cellulose is the most abundant organic polymer on earth and has been used as digestible fibers in food products and as the major constituent of paper, paperboard, and card stock for many years. However, cellulose particles are usually very large and are not soluble in water unless their sizes are reduced to the nanometer scale. Under Objective 3, significant progress was achieved by ARS researchers in Peoria, Illinois in developing and optimizing a method for the preparation of nano-cellulose from sorghum stover. The variables for the cellulose extraction include pH (acidity/basicity), temperature, and heating time. The product of these efforts provided nano-cellulose with a diameter of 10-30 nm (1 nm = 1/1,000,000 millimeter). The purity of the sorghum stover-based nanocellulose and the physical/mechanical properties of the films/gels prepared using nano-cellulose are being investigated. Car and truck tires may have up to 30% carbon black. There is a need to make rubber composites for the tire industry that replace carbon black filler (fossil fuel based) with biochar (from renewable biomass) in a way that will not provide an inferior tire. This improves sustainability of the tire industry by using biomaterials as filler instead of petroleum products. Under Objective 4, significant progress was achieved by ARS researchers in Peoria, Illinois, in developing two methods to modify the surface of biochar in order to enhance its interactions with rubber for automotive tire applications. Both methods are being tested on high carbon-content biochar that has been silica milled to increase surface area to assess if biochar can replace carbon black more effectively as a reinforcing filler.
1. Improved rubber composites using soy protein particles. A composite material is a combination of multiple components with different physical and chemical properties. Conventionally, carbon black has been used as a filler to reinforce rubber. Agricultural fillers in principle can be used to reinforce rubber, however, they typically do not provide sufficient benefits to offset the increased cost. To address this, ARS researchers in Peoria, Illinois, prepared rubber composites by using soy protein particles as the agricultural filler. The resulting rubber composites underwent less swelling when exposed to oil and temperature induced mechanical strength loss was reduced versus carbon black. The outcome of this research is expected to encourage rubber industries to use agricultural fillers and foster the market for soybean crop and soy protein, creating new economic opportunities for farmers and rural communities.
2. Encapsulated bio-active food ingredients into protein nano capsules that can aid in reducing the risk of chronic diseases. The most abundant and biologically active form of vitamin E is alpha-tocopherol (TOC). It is a water-insoluble antioxidant and can reduce the risk of many chronic diseases associated with oxidative stress, such as cancer, cardiovascular disease, and neurological and endocrinological disorders. However, TOC is biologically unstable when exposed to environmental factors such as light, temperature, and air (oxygen). To improve the stability of this type of bioactive compound, ARS researchers in Peoria, Illinois, have developed a procedure to encapsulate TOC into zein (corn protein) nanocapsules (the diameter of these particles is ~1/10,000 of a millimeter). The developed encapsulation process uses edible ingredients, and its encapsulation efficiency is higher than 90%, thus markedly improving the stability of the active ingredient. This new process should be applicable to the encapsulation of many other bio-active food ingredients that are not miscible in water. This technology provides a viable route to provide unstable valued ingredients to the consumer in an inexpensive and robust fashion and to utilize zein as a valuable corn product, benefiting farmers, food producers, and the ultimate consumer.
3. Developed value-added nano-cellulose from sorghum stover expanding its commercial uses. Sorghum stover is considered an agricultural waste that has little economic value. It contains several fibers such as hemicellulose, cellulose, and lignin. Cellulose, which has been used for many years in food and non-food applications (as digestible fibers in food products and as the major constituent of paper, paperboard, and card stock), is the most abundant organic polymer on earth. However, one of the drawbacks slowing the rate of cellulose penetration into the water soluble/dispersible products markets is that cellulose particles are too large to process in water. If the particle size of cellulose is reduced to the nanometer scale (1 nm = 1/1,000,000 millimeter), these particles can be dispersed into water and form gel-like suspensions which have unique properties that significantly expand it’s beyond those highlighted earlier. These applications would include automobile panels, paints, and 3D printing. Unfortunately, little research has been conducted in using agricultural waste sorghum stover for isolating cellulose and producing sorghum nano-cellulose. ARS researchers in Peoria, Illinois, have developed a relatively simple method to prepare cellulose from sorghum stover. After treating the sorghum cellulose in a fashion often seen in the paper industry, the material was subjected to high temperature (200 F) with extremely high mixing (high pressure homogenization). This resulted in the long sorghum cellulosic fibers to be reduced mechanically to provide nano-sized cellulose. The nano-sized cellulose will broaden the use of cellulose from sorghum, a climate resilient crop, and benefit consumers by providing a new route for delivering high value biobased products.
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