%0 Journal Article
%T Thermal aging of HTPB/IPDI-based polyurethane as a function of NCO/OH ratio
%A Villar
%A Luciene Dias
%A Cicaglioni
%A Thiago
%A Diniz
%A Milton Faria
%A Takahashi
%A Marta Ferreira Koyama
%A Rezende
%A Luis Cl¨¢udio
%J Materials Research
%D 2011
%I ABM, ABC, ABPol, SBCC, SBCr, SBMM, SBPMat
%R 10.1590/S1516-14392011005000063
%X thermal aging of hydroxy-terminated polybutadiene/isophorone diisocyanate (htpb/ipdi)-based polyurethane was studied as a function of nco/oh ratio (1.0 and 0.85). samples were aged in air ovens at 50, 60, 65, and 70 oc for periods of time from 1 to 34 weeks. changes in chemical (swelling testing and ft-ir spectroscopy) and mechanical (tension testing and hardness) properties were evaluated throughout the aging assays. correlation between equilibrium swelling ratio and elastic modulus, coupled with changes in ft-ir spectra, indicated oxidative cross-linking as the dominant mechanism for both molar ratios investigated. however, determination of arrhenius activation energy resulted in values of (82 ¡À 10) kj.mol-1 and (156 ¡À 30) kj.mol-1 for 1.0 and 0.85 nco/oh ratios, respectively, thus revealing faster oxidative degradation kinetics for higher urethane linkage networks.
%K aging
%K htpb
%K polyurethane.
%U http://www.scielo.br/scielo.php?script=sci_abstract&pid=S1516-14392011000300015&lng=en&nrm=iso&tlng=en