Small‐ and intermediate‐angle neutron scattering from amorphous and semicrystalline polyethylene terephthalate

Abstract

Abstract Small‐ and intermediate‐angle (0.006 < Q < 0.25 Å) neutron scattering experiments have been performed on polyethylene terephthalate (PET). Amorphous and semicrystalline samples with deuterated PET molecular weights of 24,200 and 40,500 were prepared. The average value of R /M determined in the small‐angle region for the amorphous samples is 0.406, in close agreement with the experimental θ‐solvent (0.398–0.420) and theoretical (0.394) values for unperturbed dimensions. The intermediate‐angle results for the amorphous sample are consistent with the random coil prediction to Q = 0.08 Å, but beyond this Q value there is some deviation from Gaussian behavior. The semicrystalline samples show a decrease in the radius of gyration as measured in the small‐angle region and an increase in intensity (when compared to the amorphous data) in the intermediate‐angle region, especially for the low‐molecular‐weight material. These results suggest that crystallization in PET is accompanied by greater molecular reorganization than has previously been observed in most bulk polymers.