Irradiation-induced transformation of macromolecular structure and mechanisms of mechano-chemical microdestruction in amorphous-crystalline polymers

The microreliefs of the fractured surfaces of non-irradiated low density po lyethylene (LDPE) and gamma irradiated high density polyethylene (HDPE) "BU LEN" are similar, but are obtained due to different microdestruction mechan isms determined by different interaction mechanisms of the macromolecular c hains. The LDPE is characterized by low degree of co-operation of the suble vels of the superstructural molecular organization, high branching and high density entanglements of the macromolecular chains which are uniformly dis tributed in the amorphous regions and in the intercrystalline amorphous reg ions. The surface structures in the gamma irradiated HDPE represent areas w ith homogeneous distribution of the radiation-induced chemical crosslinking density nu(ch) which form lattices build up of macromolecular networks and are distributed predominantly in the intercrystalline amorphous regions. O btaining such superstructural molecular organization in the irradiated poly mer depends strongly on the state and structural organization of the initia l non-irradiated polymer.