Comparison of the properties of segmented copolyetheresteramids with commercial segmented copolymers

The thermal (using differential scanning calorimetry), dynamic mechanical (using a dynamic mechanical analyzer), and mechanical properties of segmented copolyetheresteramides with aramid units of uniform length (TT) and poly(tetramethylene oxide) (PTMO) segments were compared to those of commercial segmented copolyetheresters (PBT-PTMO) and thermoplastic polyurethanes. The hard segments in T.T-containing polymers were found to crystallize almost completely, unlike the hard segments of Arnitel and Desmopan. Consequently, the glass-transition temperature of T.T-containing polymers is lower and the melting temperature higher than those of Arnitel and Desmopan. Furthermore, the rubbery plateau of the T.T-containing polymers is temperature independent, making the service temperature range wider. In T.T-containing polymers a lower concentration of hard segment is needed to obtain dimensionally stable polymers with a high melting temperature. No melt phasing occurs during polymerization and therefore long PTMO segments can be used, producing very soft and elastic materials. The polymers crystallize faster than do commercial materials. The elasticity of the T.T-containing polymers is comparable to the elasticity of Desmopan and better than that of Arnitel. T.T-(PTMO1000/DMT) copolymers are transparent and the solvent resistance is high.