MOLECULAR-MASS DISTRIBUTION CHANGES DURING PROCESSING OF POLY(ETHYLENE-TEREPHTHALATE)

Poly(ethylene terephthalate) in the form of granules and, after proces sing, in the form of filaments, has been fractionated according to mol ecular mass by the column dissolution method in phenol-n-heptane as a solvent-nonsolvent system. Stepwise solvent and temperature gradients were used. The molecular mass distributions were determined and the di stribution functions were approximated by the theoretical Tung's two p arameter function. The change in the distribution parameters show that the degradation of poly(ethylene terephthalate) occurs during process ing, e.g. during melting and extrusion, or during the extension or the rmofixation of the spun fibres.