Statement of Research Interests

My research interests encompass several areas of Plastics Engineering and Processing. My research is directed towards understanding the interrelationships between product properties and process parameters in order to develop models that can be used to predict these relationships. To this end several research topics have been or are being investigated.

One area that I am currently investigating is the formation of polymer nanocomposites via reactive extrusion processes. This is a collaborative research between me and Professor Charles Beatty from the Materials Science and Engineering Department of University of Florida. In this collaborative research we are investigating a novel reactive extrusion route to produce self-reinforcing nanocomposites, involving reactive chemistry that enhances the bonding between dispersed liquid crystalline phase and a thermoplastic matrix. We are also investigating the properties of composites so produced. The self-reinforcing nano-composite thermoplastics could produce a series of families of nano-composites with wide-ranging properties – which we can’t fully envision at this time.

Within the subject of polymer nanocomposites, I am investigating the toughening mechanisms in polymer-layered silicate nanocomposites, using both experimental and analytical methods. The primary objective of this project is to investigate the principles underlying the toughening mechanisms of the so-called hybrid organic-inorganic nanocomposites, and to formulate more precise criteria for the selection and modification of these nanocomoposites that might result in the optimization of their impact properties without sacrificing the tensile properties. The nanocomoposites in this context refer to polymeric materials containing layered silicates like montmorillonite, hectorite, and saponite, dispersed as a reinforcing phase in an engineering polymer matrix. We are also investigating methodologies to achieve good dispersion of the nanoparticles in the matrix polymer (See Bhaskar and Narh, under Publications).

In another area, within the theme of polymer nanocomposites, we are investigating the manufacture and nanomechanics of polymer nanocomposites based on carbon nanotubes (CNTS). In particular, we are addressing the issue of dispersion and alignment of carbon nanotubes in the polymeric matrix, and the creation of adequate interface between CNTS and the matrix for proper transfer of load to the fibers.

In the immediate past, I have investigated the phenomenon of thermal contact resistance (TCR) at a plastic-metal interface due to an imperfect contact between thermoplastics and metal surfaces, as might arise in injection molding. While TCR at metal-metal and metal-hard surface interfaces have been investigated extensively, TCR at metal-plastic interface has not been studied in any detail. The research activities in this Ph.D. project focused on three issues: a) developing a novel methodology for determining thermal conductivity for polymers, and thermal contact resistance (TCR) at a plastic-metal interface during polymer processing, b) studying the effect of injection molding process parameters on TCR and c) developing a heat transfer model that incorporates TCR at a moving (contracting) interface (See Sridhar and Narh, under Publications).

In another area, I have investigated the influence of stress-induced crystallization kinetics in injection molding. My primary objective in this work was to use flow-induced crystallization data firstly to improve the prediction of injection-molding parameters for semi-crystalline polymers, and, secondly, to predict the final microstructure, such as crystallinity and orientation, of the injection-molded part. As the mechanical property of the final product is largely affected by its microstructure, an accurate prediction of the latter is of great interest to the plastics industry. The study involves developing a stress-induced crystallization model that can be used to predict the flow behavior of semi-crystalline polymers in injection molding processes. Algorithms for computer simulation of stress-induced crystallization of semi-crystalline polymers are developed (See Guo and Narh, under Publications).

I have also investigated self-reinforcing composites based on liquid crystalline polymers (LCPs) as reinforcing species. In this project, both experimental and analytical studies were carried out in order to develop a composite model to predict the properties of the self-reinforcing composites containing LCPs, to investigate the effect of compounding methods, processing parameters, and concentration of LCPs on the rheological and mechanical properties of the self-reinforcing composites, and to design, analyze and manufacture prototype parts from these blends (See Li and Narh, under Publications).