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
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
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
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.
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.
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.
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:
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
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.
- Thermoplastic starch-polyester reactive blends
- Soy protein/oil-polyester reactive blends
- Starch esters and starch derivatives as biodegradable thermoplastics.
- Manufacture (see
Reactive Extrusion Processing
), characterization, applications, and biodegradability (see
) are being studied.
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.
LCA is a holistic environmental & energy audit (accounting procedure)
that focuses on the entire life cycle of the product.
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.
- From raw material acquisiton to final product disposition
- Not based on a single manufacturing step or environmental emission
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
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
- Provide an inclusive overview of impacts
- Serve as a powerful tool for planning and forecasting financial and
- Be actively employed to identify potential areas of concern and minimize
cost and risk.
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.
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.
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.
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.