Small Angle X-Ray Scattering of Segmented Block Copolyetheresters during Stretching

摘要

The scattering behaviour of polyetherester thermoplastic elastomers based on polybutylene terephthalate as hard segments and polyethylene glycol (Mn= 1000) as soft segments in a ratio 49/51 wt. is studied under stress. Drawn (#x3BB; = 5) bristles are annealed with fixed ends in order to create a standard initial structure. Samples with structure destroyed by additional drawing as well as with structure regenerated by solid-state reactions or chemical crosslinking are prepared. The data from small-angle x-ray scattering (SAXS) taken under or without stress are evaluated using Stribeck's method and the sizes of crystalline (d1) and amorphous (d2) regions are directly obtained. A constant value ofd1#x224A; 50 #xC5; is found for all samples except for the chemically crosslinked one, for whichd1changes at deformations higher than 80 due to axial displacement of the crystallites. The size of the amorphous regionsd2measured under stress (#x3F5; 30-50) rises slightly and reversibly followed by a drop similarly to the measurements without stress, thus indicating that the observed changes in theL-value are due to changes in the amorphous regions only. Further, in the chemically crosslinked sample a reversible axial displacement of the crystallites is observed in the range #x3F5; = 100-200, suggesting a complete elimination of the interfibrillar contacts as well as stretching and relaxation of intrafibrillar tie molecules.