Effect Of Annealing And Temperature On The Morphological Structure Of Polymers

Abstract

During heat treatment of a semicrystalline polymer, various alterations of the morphological structure can occur. Two special cases are treated in more detail: the irreversible thickening of the polymer crystals during annealing and the reversible premelting effects occurring during heating of a well annealed sample. With regard to the thickening process, two mechanisms have to be taken into account: melting and recrystallization on the one hand and refolding in the solid state due to the high mobility of the chain molecules on the other. Which type of process predominates depends on crystallization conditions, heating rate and molecular weight. The changes in the morphological structure due to premelting can be analysed by x-ray small angle scattering studies. It is shown that the decrease of crystallinity within the so-called melting range is due to an increase of the thickness of the disordered surface layer. © 1972, Walter de Gruyter. All rights reserved.