DIACETYLENE-CONTAINING POLYMERS .6. EFFECT OF ELECTRON-BEAM ON MECHANICAL-PROPERTIES OF POLY(OCTA-3,5-DIYNYLENE SEBACATE) AND POLY(HEXA-2,4-DIYNYLENE SEBACATE)

The mechanical properties and their dependence on electron beam irradiation were studied for high molecular weight diacetylene-containing thermoplastics: poly(octa-3,5-diynylene sebactate) and poly(hexa-2,4-diynylene sebacate). The tensile strength of the polymers goes through a maximum reaching 330 MPa (with irradiation dose of 0.2 Mrad) for the former and 129 MPa (1 Mrad) for the latter in the case of oriented samples. Further irradiation of the samples leads to decrease in tensile strength, an increase in Young's moduli and decrease in the strain at break. FT-IR spectroscopy of the samples showed that even at 15 Mrad, when tensile strength drops by several times, compared to unirradiated samples, irradiated samples still contain many unreacted diacetylenic groups. Data from thermal mechanical analysis showed that irradiation by 1 Mrad already leads to loss of the thermoplastic properties of material due to polydiacetylene network formation.