Dynamic mechanical properties of supported polymers. I. Application of the torsional braid technique to the study of glass transition temperatures

摘要

AbstractAn analysis of the parameters involved in torsional braid measurements is given. It is found that the amount of polymer on the braid controls the level of rigidity modulus attained by the composite specimen, but does not affect the measured glass transition temperature of the polymer. Treating the torsional braid system as a fabric braid filled polymer system, an empirical relation is given relating the measured modulus,G, to the modulus of the unfilled polymer,G0, and the volume fractions of voids, φvand support φs. This equation takes the form,documentclass{article}pagestyle{empty}begin{document}$$ G/G_0 {rm } = {rm 1 } + {rm (}k_s phi _s {rm } + {rm }k_v phi _v )/1 - (S_s ^prime phi _s + S_v ^prime phi _v )^2 $$end{document}whereks,kv,Ss′, andSv′ are constants. This equation is evaluated for the polystyrene–cotton thread system. The effect of braid length on the measured modulus is di