Polyurethane triblock copolymers were synthesized by reacting 4,4-methylenebis(phenyl isocyanate) (MDI)-endcapped poly(tetramethylene oxide) (PTMO) with mono-amine-amide (MMA) units. Four different MMA units were used, i.e. no-amide (6m), mono-amide (6B), di-amide (6T6m) and tri-amide (6T6B), based on hexylamine (6m), 1,6-hexamethylenediamine (6), terephthalic acid (T), and benzoic acid (B). The PTMO had a molecular weight of 2000 g/mol. Thermal and thermo-mechanical properties were studied by means of differential scanning calorimetry and dynamic mechanical analysis, respectively. The structure of the carbonyl bond was explored by infra-red analysis and the elastic behavior of the materials by compression set experiments. The triblock polyurethanes with mono-disperse, hard end-segments displayed low molecular weights (3200-3800 g/mol). The crystallinity of the MDI urethane-urea group was found to depend on the structure of the amide. Increasing the number of amide bonds in the mono-disperse hard segment increased the modulus and the hard segment melting temperature, and decreased the compression set values. The low temperature properties were hardly affected by the amide length
|Journal||Polymer engineering and science|
|Publication status||Published - 2008|
Araichimani, A., Baack, K. K. J., & Gaymans, R. J. (2008). Polyurethaan triblock copolymers with mono-disperse hard segments. Influence of the hard segment length on thermal and thermomechanical properties. Polymer engineering and science, 48(6), 1222-1230.