Fiber reinforced composites are used in many applications where metals have been commonly used because of their high specific mechanical properties. Most high strength fibers and resins used in these ‘Advanced Composites’ are based on petroleum feedstock, a non-renewable resource that is expected to be almost non-existent 50-60 years from now. With double digit growth in production and use of composites in the past couple of decades, their disposal problem has become difficult and expensive. Because composites are made combining two dissimilar materials they cannot be recycled or reused easily. While only a small fraction of the composite waste is incinerated to obtain energy or crushed into powder for use as low grade filler, most of the composites, after their intended life, end up in landfills. Major part of our research is directed towards creating fully sustainable and environment-friendly ‘green’ resins and composites using yearly renewable plant-based fibers and polymers that are mostly carbon neutral. At the end of their life green composites can be easily composted creating organic soil for growing more plants. Current versions of green composites based on modified plant proteins and starches developed in my research group are not only suitable for use in packaging, housing or transportation panels, furniture, board sports and secondary structural applications, but the high strength Advanced Green Composites made using liquid crystalline cellulose fibers and soy protein based resins have toughness comparable to aramid fiber based composites. These advanced green composites may be used as primary structural elements or for ballistic applications.
Second part of our research in composites involves Advanced Composites made using high strength fibers such as graphite, aramids and ultra-high molecular weight polyethylene (UHMWPE) that are used in a wide range of applications from aerospace to sports gear and from automobile body parts to civil structures. Critical mechanical properties of composites such as toughness and longitudinal and transverse strength are controlled by fiber/resin interfacial bonding. My research group is involved in modifying fiber surface topography and chemistry to control their interfacial (adhesion) with different resins. We have used many techniques including plasmas, pulsed excimer laser, high power ion beam, solvent treatments and their combinations to obtain desired chemical groups on the fiber surface and modify surface roughness to control the fiber/resin interfacial bonding. We are also working to control resin and fiber/resin interfacial properties using nanoparticles and nanofibrils in resin or fiber surfaces.
Our research in nanofibers involves creating new nanofibers such as bacterial cellulose (BC) using food and agricultural waste and green nanofibers from plant and other proteins and starches for high efficiency filters that can catch dust, bacteria as well as air borne viruses. The BC nanofibers can be used for applications including composites and medical.
Current research projects:
- Development of fully biodegradable, environment-friendly ‘green’ composites and nanocomposites using plant based fibers and resins
- Surface modification of high strength fibers to control their adhesion to various resins including nanophase epoxies
- Development of bacterial cellulose and high strength composites
- Development of 'green' nanofibers for high efficiency filters
- Development of 'green' seed coatings