D. D. Deshpande

Cast polyurethanes: effect of chain extenders on thermal, mechanical, and dynamic mechanical properties

Abstract Effects of various diol chain extenders on thermal, mechanical, and viscoelastic properties of polyurethanes are discussed. Elastomers were prepared by using polyester (polyethylene-co-propylene adipate), toluene-2,4-diisocyanate, and α,ω-aliphatic diols. The properties imparted by the extenders are explained on the basis of the number of methylene carbons in the extenders. Butanediol-extended polymer showed superior properties, which are ascribed to regularity in the backbone chain of the polymer and ease of formation of hydrogen bonds.

Reinforcement in Polybutadiene by Metal Oxides

Abstract The effects of chemical characteristics of metal oxide fillers on mechanical and dynamic mechanical properties of polybutadiene are investigated.

Dielectric and Viscoelastic Behavior of Poly-(n-Butyl Methacrylate) Containing Cholesteric Compounds

Abstract Dielectric and dynamic mechanical behavior of poly(n-butyl methacrylate) (PBMA) containing small concentrations of cholesteryl chloride (ChCl), cholesteryl caprylate (ChCp), and cholesteryl laurate (ChL) have been studied in the temperature range -20 to 80°C. Tan αmax (dielectric and mechanical) in all systems containing an additive shifts to lower temperature compared to that in pure PBMA. In the glassy region, the dynamic storage modulus E′ for all the PBMA plus additive systems is higher than that for pure PBMA. This behavior is similar to the β-peak suppression and the increase in tensile strength of poly(vinyl chloride) on addition of a small concentration of plasticizer. Using the WLF equation with C1 and C2 obtained from the data on pure PBMA, the reference temperature To for PBMA plus additive systems are determined for the best fit of the experimental points to the WLF curve and are in agreement with measured glass-transition temperatures. With respect to To of pure PBMA, the To of PBMA ...