REACTIVE EXTRUSION PROCESSING& EXTRUSION POLYMERIZATION

Extruders can function as continuous stirred tank reactors (CSTR’s) for polymerizations, polymer modifications, and reactive blending of polymers. It eliminates the use of solvent and can be integrated with compounding operations (addition of fillers, additives etc.) to provide the final resin product in one step operation.

Bulk polymerizations in extruders of cyclic ester monomers, particularly lactones, using coordination catalysts are being studied. e-caprolactone has been polymerized to high molecular weight poly (e-caprolactone) and the synthesis of a family of copolymers with polycaprolactone, polylactic acid, and other polyesters are being studied.

Maleation of polyolefins (polypropylene and polyethylene) polyesters ( like polycaprolactone, polylactic acid) and copolyesters in twin screw extruders have been studied and detailed work including process modeling is underway.

Using maleic anhydride functionalized synthetic polymers, preparation of starch/cellulose - synthetic polymer alloys are being studied. In-situ grafting reaction between the hydroxyl group on the natural polymer backbone and the anhydride functionality on the synthetic polymer results in a graft copolymer that functions as the compatibilizing agent.

Biodegradable starch foam products using extrusion processing.
We have developed technology to manufacture starch foam products having the resilience and compressibility of foam polystyrene, using water as the plasticizer and blowing agent. The foam noodles are being commercialized through one of our companies (KTM Industries/KidTech Tools) as an arts & crafts material and for toy applications. Visit the web site www.wetnset.com for details).

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In this project we are developing process engineering know how to make a portfolio of foam products with control of cell structure, and die shapes. Other blowing agents, and thermoplastic starch is to be evaluated.

BIOBASED THERMOPLASTIC & THERMOSET COMPOSITES

Design and engineering of biofiber-polypropylene composite resins with properties comparable to that of mineral filled and some glass fiber reinforced PP composites have been achieved. Biofibers like wood, sisal, kenaf are being studied. Biofibers, natural lignocellulosics, have an outstanding potential as a reinforcement in thermoplastics. Our studies deals with the preparation of biofiber composites by reactive extrusion processing in which good interfacial adhesion is generated by a combination of fiber modification and matrix modification methods. PP matrix was modified by reacting with maleic anhydride and subsequently bonded to the surface of the modified lignocellulosic component, in-situ. The fiber surface was modified by reacting it with a silane in a simple and quick aqueous reaction system, similar to that employed for glass fibers. The modified fibers are then extruded with the modified polymer matrix to form the compatibilized composite. The various reactions between the lignocellulosic fiber/filler and modified polymer chains, improved the interfacial adhesion significantly as opposed to simple mixing of the two components, since new covalent bonds between the fiber surface and matrix are created in the former case. These composite blends were then injection molded for mechanical characterization. Typical mechanical tests on strength, toughness and Izod impact energy were performed and the results showed good impact and tensile strengths.

Soybean Thermoset Composites
This project involves the design and engineering of a biofiber reinforced natural soybean based thermoset composite. A new thermoset matrix will be synthesized based exclusively on soybean feedstocks. Soybeans is one of the most important crops of Michigan, and finding new, industrial, value-added uses for soybeans has been made a priority critical need for the Michigan farmer. The soybean oil is chemically modified with suitable functional groups (hooks) that will react with each other and create a three dimensional crosslinked thermoset composite matrix. Biocomposites will be fabricated by impregnating selected biofibers with the functionally modified soybean prepolymer and cured by compression molding using process parameters developed from thermal cure studies of the chemically soybean oils.

BIODEGRADABLE PLASTICS

New environmental regulations, societal concerns, and a growing environmental awareness throughout the world have triggered the search for new products and processes that are compatible with the environment. Thus, new products have to be designed and engineered from cradle to grave incorporating a holistic "life cycle thinking" approach. The impact of raw material resources used in the manufacture of a product and the ultimate fate (disposal) of the product when it enters the waste stream have to be factored into the design of the product. The use of annually renewable resources and the biodegradability or recyclability of the product are becoming important design criteria. This has opened up new market opportunities for developing biodegradable products.
Currently, most products are designed with limited consideration of its ultimate disposability. Of particular concern are plastics used in single-use disposable packaging. Designing these materials to be biodegradable and ensuring that they end up in an appropriate disposal system is environmentally and ecologically sound. For example, by composting our biodegradable plastic and paper waste along with other "organic" compostable materials like yard, food, and agricultural wastes, we can generate much-needed carbon-rich compost (humic material). Compost amended soil has beneficial effects by increasing soil organic carbon, increasing water and nutrient retention, reducing chemical inputs, and suppressing plant disease. Composting infrastructures, so important for the use and disposal of biodegradable plastics, are growing in the U.S. and are in part being regulatory driven on the state level.
The following biodegradable polymer resins are under extensive investigation:

Engineering and Design of Natural-Synthetic Polymer Composite Systems

New approaches to tailor-made cellulose/starch/lignin-synthetic polymer graft copolymers with precise control over molecular weight, degree of substitution, backbone-graft linkage, and the overall grafting process are being studied. Cross-linked graft copolymers with exactly defined polymer chain segments between crosslink points have been prepared. The graft copolymers exhibit a two-phase morphology and can function effectively as compatibilizers/interfacial agents to alloy cellulosic and lignocellulosic materials with synthetic polymers. This approach opens up new opportunities for economically combining lignocellulosic materials with plastics to engineer new materials with unique balance of properties targeted for precise end-use applications. Structure-property relationship, morphological studies, processability and potential applications of such binary and ternary blend systems are under intense study. Some exciting applications are in the preparation of biodegradable plastics for packaging applications -- See Biodegradable Plastics

Biodegradation and Composting Studies

Biodegradation studies on plastics and other biodegradable polymers using National (ASTM) and International (ISO) Standards protocols are under study. Basic mechanisms for biodegradation are being elucidated and a structure-biodegradability relationship is being developed.

Fundamental studies and field trials are being conducted on composting selective waste streams, which includes the new biodegradable materials, and plastics to quality, humic-rich compost. Effect of process parameters and reactor configurations on the composting process, microbial populations developed during composting, and the characteristics of the resultant compost are being evaluated.

Life Cycle Assessment (LCA)

LCA is a holistic environmental & energy audit (accounting procedure) that focuses on the entire life cycle of the product.
  1. From raw material acquisiton to final product disposition
  2. Not based on a single manufacturing step or environmental emission
LCA evaluates environmental burdens associated with a product, process, or activity by identifying and quantifying energy and materials used and wastes released to the environment; to assess the impact of those energy and material uses and releases to the environment; and to identify and evaluate opportunities to affect environmental improvements.Issues associated with designing, manufacturing, maintaining and disposing of systems while adhering to environmental laws, budgetary constraints and minimizing risks are addressed. Special emphasis is given to evaluation of potential hazardous materials during the early stages of system concept. The methodology and process developed are transferable to the commercial sector.

The methodology and process developed by us provide a practical, pragmatic structure for evaluating the Life Cycle, performing Cost/Benefit and Risk/Benefit analyses of a system. Applied prior to initialization of a project they can:

  1. Provide an inclusive overview of impacts
  2. Serve as a powerful tool for planning and forecasting financial and resource requirements
  3. Be actively employed to identify potential areas of concern and minimize cost and risk.
Have experience in LCA for meeting a product's environmental stewardship.  Published papers in the area including a student thesis entitled "Investigation of Hierarchical Classification for Life Cycle Analyses.  A member of ISO (International Standard Organization) - SAGE (Strategic Advisory Group on the Environment) LCA sub-group. U.S. Technical Expert to ISO TC-207 on Environmental management -- Life Cycle Analysis and Environmental Labeling subcommittees.  

Environmentally Compatible Materials

Biodegradable plastics, Biodegradable polymers, plastic environmental effect, plastic non-hazardous solid waste management, paper coatings, moisture barrier material. Research on design and engineering of new biodegradable materials that are thermoplastic, yet break down under appropriate environmental conditions just like its organic (lignocellulosic) counterpart.  Major end-uses are in moisture and grease barrier paper coatings, and disposable single-use packaging, cutlery, and non-wovens.

Plastics Recycling & Polymer Matrix Composites

Polymer recycling, polymer modification chemistry, polymer blends, polymer alloying, reactive polymer, compatibilizing agent, Fiber reinforced composite.

Design and engineering of biofiber-polypropylene composites with properties comparable to that of glass fiber reinforced PP composites and can be recycled unlike its glass fiber analog.  Expertise in reactive extrusion processing, including polymer modification such as maleation and sulfonation.  Experience in carrying out polymer modifications in the extruder to enhance compatibility with other polymers.  Have done a lot of work on blending and alloying of natural - synthetic polymers, including detailed morphological characterization using electron microscopy (SEM, TEM, and confocal microscopy).  Compatibilization of the blends done by generating the graft copolymer (compatibilizing agent) in-situ in the extruder.  Used these concepts to utilize recycled/reclaimed thermoplastics in engineering higher-value composite materials.

Natural Polymers

Amylose, amylopectin, cellulose, cellophane, cellulose acetate, cellulose ester, cellulosic polymer, cellulosic resin.

Have worked extensively on cellulosic graft copolymers, and blends & alloys of cellulose acetate with synthetic and natural polymers, including biofiber-based composites.  Recently edited a book on "Emerging Technologies for Materials and Chemicals from Biomass", and contributed two chapters to the book.  National Technical Program Chairperson for the American Chemical Society's Cellulose, Paper & Textile Division.

Composting

Plastic biodegradation, plastic degradation, plastic solid waste management.

The mere production of biodegradable materials does not ensure market, environmental, or regulatory acceptance of these products.  The ultimate disposability of these materials and the environmental benefits that accrue from the use and disposal of these materials, as opposed to today's non-biodegradable synthetic based materials are currently being demonstrated with the support of an industrial consortium, and the U.S. Government. Both fundamental studies and field trials on composting selective waste streams, which includes the new biodegradable materials, and plastics to quality, humic-rich compost is underway.  The project will establish the potential benefits of applying such quality compost on agricultural land in terms of sustainable agriculture concepts, and recycling waste to useful products.


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