Thermal and phase behavior of polyurethane based on chain extender, 2,2-bis-[4-(2-hydroxyethoxy)phenyl]propane

Abstract

A series of polyurethanes based on Poly(oxytetramethylene)glycol (PTMG), 4,4′-diphenylmethane diisocyanate (MDI) and 2,2-bis-[4-(2-hydroxyethoxy)phenyl]propane (BHPP) was synthesized by two-step solution polymerization varying PTMG soft segment length and hard segment content. Thermal and dynamic mechanical properties were studied by DSC and DMA. Solubility and interactions were calculated and quantitative assessment based on the shift of glass transition temperature and heat capacity change at glass transition was used to predict the extent of phase separation. DSC and DMA results showed that Tg shifted to higher temperature with increasing hard segment content and decreasing soft segment molecular weight, indicating partial phase mixing between hard and soft segment.