Synthesis and properties of new polyurethane elastomers:
Two series of poly(ester urethane) (PUR) elastomers, containing poly(ε-caprolactone) diol of Mn=2000 as soft segments were synthesized. In each series the same diisocyanate in hard segment, i.e., 1,6-hexamethylenediisocyanate was used in the same content. The PUR polymers were prepared in two-step polymerization in the absence of a catalyst; the molar ratio of OHpolyol/NCO/OHchain extender was 1/2/1. The chain extenders were 1,4-cyclohexane diol, 1,4-bis(hydroxymethyl)cyclohexane diol, glycerin or castor oil. The structures of all polymers were determined by FTIR, the physico-chemical and thermal properties were determined by differential scanning calorimetry and by thermogravimetry and additionally tensile properties were analyzed. Poly(ester urethane)s with 1,4-cyclohexane diol exhibited higher tensile strength (up to 16MPa vs 13MPa) and elongation at break (up to ~780% vs. 600%) in comparison with the corresponding poly(ester urethane)s based on 1,4-bis(hydroxymethyl)cyclohexane diol. A decrease in the chain length between crosslinking points was accompanied by an increase in thermal stability. Tensile strength can be attributed to a relatively dense crosslinking network and strong intermolecular hydrogen bonding.
Synthesis and properties of new polyurethane elastomers: influence of hard segment structure (in English)