Polyester films modified by chemical compositions and physical treatment studied by X-ray diffraction methods

We prepared a series of polyester films containing a large amount of amorphous phase, but differing in molecular mass as well as in volume and WAXS crystallinities. We used commercial granulates of PET and PBT as well as PET copolymer with lactic acid (by K. Grzebieniak, Institute of Chemical Fibres, Lodz, Poland). The films were obtained by hot pressing under modified conditions, and submitted afterwards to thermal treatment followed by irradiation with heavy ions. The films were characterised using standard WAXS diffraction, density measurements & molecular mass analysis, and examined by means of the radial distribution function (RDF). On the basis of different solutions of G(r) and P(r) functions obtained for the particular films, it can be stated that the atomic ordering in the amorphous PBT phase was better developed as compared to that in the amorphous phases in PET and PET-lactic acid films. No small-distance ordering (apart from that connected to the benzene rings) can be deduced in the case of the totally amorphous PET film. Annealing the PET and PBT films led to a development of the atomic ordering in the amorphous phase, accompanied by an increase in the molecular mass of polymer and in crystallinity. No modifications of the coordination number connected to irradiation were noticed in the amorphous phase of PET and PBT films, despite the recorded decrease in crystallinity and the decrease in the mean molecular mass. However the development of such ordering was discovered in the case of PET-lactic acid films. On the basis of the present data, it can be deduced that irradiation with heavy ions did not influence the benzene rings in polyesters.