CHARACTERIZATION OF THERMOTROPIC BLOCK COPOLYETHERESTERS BY X-RAY-DIFFRACTION AND DSC

The block copolyetheresters with hard segments of poly(alkylene-p,p'-b ibenzoate) and soft segments of poly(tetramethylene ether) have been i nvestigated by two x-ray diffraction techniques and differential scann ing calorimetry (DSC). The results from the counter diffractometry tec hnique indicate the effect of composition on the diffraction peaks and relative crystallinity of the block copolyetheresters. The results fr om the photographic technique not only show the presence of the diffra ction peaks qualitatively, but also indicate the layer spacings relati ng to the smectic phase for certain block copolyetheresters. The succe ssive DSC heating curve after cooling from the isotropic (I) state to a temperature below the I-S (smectic) transition but well above the S- K (crystalline) transition indicates the nature of the S-I transition for some block copolyetheresters. The S-I transition peak overlaps wit h the K-S transition peak, or is even replaced by a K-I transition pea k. Thus it is difficult to distinguish between the K-S, S-I transition s and a K-I transition in second-run DSC heating curves for the block copolyetheresters.