STABILITY OF JUNCTIONS OF 3-DIMENSIONAL S TRUCTURE IN RADIATION-GRAFTED COPOLYMERS OF POLYETHYLENE WITH ACRYLIC-ACID

Polyethylene films radiation-grafted with acrylic acid were studied by means of thermomechanical analysis in a wide range of temperatures an d pressures. The three-dimensional structure of the films was found to be labile as evidenced by disappearance of the rubbery region in ther momechanical curves at a certain critical pressure. The magnitude of c ritical pressure was shown to correspond to the yield point of die mat erial at temperatures above the melting point of PE. The junctions of the three-dimensional structure were concluded to be associated not wi th covalent carbon-carbon bonds, but with intermolecular bonds between the macromolecules of PE and particles of the microphase of the graft ed copolymer.