MECHANICAL PERFORMANCE OF NOVEL POLYISOBUTYLENE-BASED ELASTOMERIC POLYURETHANES BEFORE AND AFTER HYDROLYSIS

Abstract

ABSTRACT The mechanical performance of thermoplastic elastomeric polyurethanes (PUs) before and after hydrolysis is investigated. These new PUs were prepared with a new asymmetric polyisobutylene-diol (PIB-diol), without the use of solvents, and with short reaction times. The PUs were made with dicyclohexylmethane 4,4′-diisocyanate and 1,4-butanediol in the hard segments and poly(hexamethylene carbonate) (PC)-diol and polyisobutylene (PIB)-diol in the soft segments. The functionality of PIB-diol was verified by mass spectrometry. Optimum solventless synthesis conditions and performance were found with a mixture of 50/50 PIB-diol/PC-diol (28.9 wt% PIB in the PU). This PU had 26.03 ± 1.19 MPa tensile strength with 286.92 ± 12.17% elongation before and 16.22 ± 0.65 with 301.17 ± 15.08% elongation after American Society for Testing and Materials (ASTM) hydrolytic stability testing. Importantly, after the hydrolytic stability testing, the stress–strain plot of this PIB–PU was similar to that of the control PC–PU. The PU with 70/30 PIB-diol/PC-diol (41.2 wt% PIB in the PU) performed slightly better but needed solvent during synthesis because of the high viscosity of the mixtures.