Abstract and subjects
A polyester polyurethane, was subjected to humid and dry aging conditions at 70
°C with 75% and 0% relative humidity, respectively. Differences in molecular weight and quasi-static tensile strength between humid- and dry-aged samples are attributed to hydrolysis of the humid-aged polymers. A phase-separation study was performed on selected samples from the aging matrix. Polymer samples were subjected to 110
°C for 10
min, by mixing the polyester (soft) and the polyurethane (hard) domains, then rapidly cooled to room temperature, initiating the phase-separation process. Uniaxial tension, dynamic shear and infrared spectra of these samples were measured as a function of time providing insight into the effects of hydrolytic degradation and the relationship of mechanical and molecular-level properties. An Avrami-type analysis shows two distinct processes whose characteristics vary as a function of increased hydrolysis.
LA-UR 04-6447.