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Effects of hydrolysis-induced molecular weight changes on the phase separation of a polyester polyurethane |
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| Authors: | Darla Graff Thompson Jill C Osborn Jon R Schoonover |
| Institution: | a Dynamic Experimentation Division, MS C920, Los Alamos National Laboratory, Los Alamos, NM 87545, USA b Materials Science and Technology Division, MS E549, Los Alamos National Laboratory, Los Alamos, NM 87545, USA c Theoretical Division, MS B214, Los Alamos National Laboratory, Los Alamos, NM 87545, USA |
| Abstract: | 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. |
| Keywords: | Estane Polyester polyurethane Vibrational spectroscopy Hydrolysis Molecular weight |
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