TEMPERATURE-DEPENDENCE OF DEFORMATION VS STRENGTH PROPERTIES OF RADIATION-CROSS-LINKED POLYETHYLENE

We have studied the deformation vs. strength properties of radiation-crosslinked low-density polyethylene, irradiated by gamma-irradiation up to doses from 5.0.10(4) to 1.0.10(6) Gy. We present the elongation diagrams taken at temperatures below and above the melting point of the polymer. We have obtained the dependences of the breaking stress and the pre-break elongation of the polymer on the irradiation doses and the testing temperature. Based on the kinetic lifetime equation, we calculated the values of the activation energy for mechanical fracture and the structure-sensitive coefficient gamma. We show that in the crystalline state the strength of radiation-crosslinked polyethylene is determined by the chemical interactions along the chain of polymer macromolecules; and in molten polyethylene, by the crosslinks between the macromolecules.