Extensional Viscosity of Elastomers and Thermoplastic Elastomers

The strain hardening of random copolymer elastomer melts is being investigated as a function of composition, strain rate and temperature. Sensitivity to detailed experimental procedures with two different instruments -- the RME and the rotary EVF fixture on the ARES-- has been investigated specifically for elastomers in this project.

Extrusion and extensional flow of thermoplastic elastomers

Thermoplastic vulcanizates (TPVs) investigated here consist of micron-sized, crosslinked EPDM rubber particles dispersed at high volume fractions in a 0.8 MFR polypropylene matrix with a high-temperature paraffinic oil. The morphology and rheology of these suspensions is complicated by the presence of oil in both phases. One area of interest is in understanding the evolution of two-phase morphology with slip flow and boundary lubrication during extrusion of TPVs. Another is to develop procedures for using profile dies in estimating strain averaged extensional viscosity of TPV melts at higher strain rates.

Fabrication of Large Diffractive Optical Element Solar Concentrator Panels by Extrusion

The low density of optically clear thermoplastics compared to inorganic glass makes them the materials of choice for making large area diffractive lenses with very low mass per unit area or areal density to be used as solar concentrators in space applications. Smaller optical components have been produced on a large scale by injection molding thermoplastic polymers; however optical elements in the present application will cover areas of up to 50 square meters. Hence the goal of this project is to achieve tight tolerances on thickness profiles over large areas of diffractive optical elements produced with an extrusion line from optical grade thermoplastic.

Polymer nanocomposites and foams with nanoparticles

The goal of the project is to develop new cost-effective thermoplastic elastomer nanocomposite foam with a semi-crystalline polymer matrix such as polypropylene. Improving the melt strength of the polymer is essential for this task. Recent work by Pathak and Jayaraman (2007) shows evidence of improvements in melt strength of linear polypropylene by incorporation of anisotropic nanoparticles. Optimum foaming process conditions will be developed for both extrusion and injection molding of polymers and blends reinforced with nanofibers and nanolayers to control the cell size distribution in the foamed product.

Processing of Particulate Polymer Composites Below the Melting Point

The goal of the proposed project is to gain a scientific understanding of microstructure development in processing polymer composites below the melting point Tm. The filler/matrix interaction when processing below Tm is being examined in various flow fields.

Reviewed Journal Publications

Kumar,S.; Pathak,T.; Jayaraman,K. "Processing of Polypropylene-Clay Nanocomposites with Silanes"

Kolli, V.G.; Jayaraman, K.; Ellul, M.D. "Slip Flow of PP-EPDM Thermoplastic Vulcanizate Melts in Capillary Dies"

Patham, B.; Papworth, P; Jayaraman, K; Shu, C; Wolkowicz, M., "Flow marks in Injection Molding of Polypropylene and Ethylene-Propylene Elastomer Blends: Analysis of Morphology and Rheology," J. Appl. Polym. Sci., 96 (2), 423-434, (2005)

Patham, B. and Jayaraman, K., "Creep Recovery of Random Ethylene-Octene Copolymer Melts with Varying Comonomer Content," J. Rheol., 49 (5),989-999, (2005)

Jayaraman, K; Kolli, VG; Kang, S-Y; Kumar S; Ellul, MD, "Shear Flow Behavior and Oil Distribution between Phases in Thermoplastic Vulcanizates," J. Appl. Polym. Sci., 93 (1), 113-121 (2004)

Mishra, S. and Jayaraman, K., "Asymmetric Flows in Planar Symmetric Channels with Large Aspect Ratio," Int. J. Numer. Meth. Fluids 38 (10), 945-962 (2002)

Marchant, D. and Jayaraman, K., "Strategies for Optimizing Polypropylene-Clay Nanocomposite Structure," Ind. Eng. Chem. Res. 41 (25), 6402-6408 (2002)

Satyadev, C.N.; Jayaraman, K.; Petty, C.A.; Losure, N.S., "Stability of Polymerizing Liquid Flow in Porous Media," Polymer Reaction Engineering 8 (2), 167-197 (2000)

Asthana, H. and Jayaraman, K., "Rheology of Reactively Compatibilized Polymer Blends with Varying Extent of Interfacial Reaction," Macromolecules 32 (10), 3412-3419 (1999)

Books, Chapters, Monographs

Jayaraman, K. and Kumar, S., "Polypropylene Layered Silicate Nanocomposites," Chapter 4 in Review Volume: Polymer Nanocomposites ed. Mai, Y.W.and Yu, Z.Z., Woodhead Publishing, 2006

Conference Proceedings

Mills, J.E.; Jayaraman,K; Patham, B.; Dong, D.S.; Wolkowicz, M. "Strain Hardening vs. Temperature in Uniaxial Extensional Flow of Random Copolymer Melts" 15th International Congress on Rheology, p. 357-359 (2008)

Pathak, T.J.; Jayaraman, K. "Extensional Melt Flow of Polypropylene-Layered Silicate Nanocomposites" Keynote Lecture in Symposium on Nanostructured Materials at the 24th International Polymer Processing Society Meeting, Salerno, Italy (2008)

Mills, J.E.; Jayaraman, K.; Kolli, V.G.; Ellul, M.D. "Extensional Flow Behavior of PP-EPDM Thermoplastic Vulcanizate Melts" Symposium on Elastomers and Elastomer Processing at the 24th International Polymer Processing Society Meeting, Salerno, Italy (2008)

Shipley, K.S.; Jayaraman, K; Nichols, K.L.; Mazor, M.F. "Morphology Development with Tensile Strain in Glass Flake Filled Polypropylene" Society of Plastics Engineers ANTEC Proceedings, Milwaukee, WI (2008)

Chaudhary, A.; Jayaraman, K. "Foaming Polypropylene with Nanoclays," Society of Plastics Engineers ANTEC Proceedings, Milwaukee, WI (2008)

Kolli, V.G.; Jayaraman, K.; Ellul, M.D. "Extrusion of Oil Extended Thermoplastic Vulcanizates," Society of Plastics Engineers ANTEC Tech Papers: Boston, MA, 51, (2005).

Kolli, V.G., Jayaraman, K. and Ellul, M.D., "Interpretation of Flow Curves from Semi-Hyperboloidal Dies," Society of Plastics Engineers ANTEC Tech Papers: Boston, MA, 51, (2005).

Patham, B; and Jayaraman, K "Nonlinear Elongational Viscosity of Ethylene-Octene Copolymers with Varying Content," in Proc. XIVth Int. Congr. on Rheology, Seoul, Polymer Melts Symposium, paper no. 28, 2004.

Kumar, S. and K. Jayaraman, "Process induced orientation of nanolayers in polyolefin nanocomposites," Society of Plastics Engineers ANTEC Tech. Papers, Chicago, Vol. 50, 2004.

Kumar, S. Jayaraman, K. "Structure of PP nanocomposites with edge silated layered silicates," in Proc. Society of Plastics Engineers Automotive TPO Conference, Dearborn, Materials Development, 2004.

Kolli, V.G.; Jayaraman, K.; Ellul, M.D. "Extrusion of oil extended thermoplastic vulcanizates," in Polymer Processing Society International Meeting PPS-20, Akron, Ohio, Rubber Performance Keynote Paper (no. 340), 2004.

Marchant, D.; Jayaraman, K. "Effectiveness of PP-g-MA compatibilizers for nanolayer dispersion in PP: bound vs. free anhydride," Society of Plastics Engineers Tech. Papers 49, (2003).

Kumar, S.; Jayaraman, K. "Performance of PP/Clay nanocomposites with edge functionalized clay," Proceedings of 3rd Annual Society of Plastics Engineers Automotive Composites Conference, (2003).

Marchant, D.; Kumar, S.; Jayaraman, K. "Compatibilizers for PP/Clay and TPO/Clay nanocomposites," Proceedings of Society of Plastics Engineers Automotive TPO Global Conference, 95-107, (2003).

Chaneske, J.; Jayaraman, K.; Norman, D.; Robertson, R., "Effects of Preform Architecture on Racetracking in Liquid Molding," Proceedings of 45th International SAMPE Symposium, Long Beach CA, 954-966, (2000)