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Polymorphic states and phase transitions in a comb-like polymer having a rigid polyester backbone and flexible side chains

: Danke, V.; Gupta, G.; Huth, H.; Schawe, J.E.K.; Beiner, M.


Thermochimica acta 677 (2019), pp.162-168
ISSN: 0040-6031
Journal Article
Fraunhofer IMWS ()

Structure formation in an alkoxylated polyester having rigid backbone and flexible side chains composed of 10 alkyl carbons per side chain is studied using X-ray diffraction, conventional DSC and flash DSC techniques. Two crystalline states-modification B and modification A are observed with their occurrence depending on the thermal treatment. Additionally, a liquid crystalline phase is also detected above the melting temperature of modification A. While modification B is the thermodynamically preferred phase at low temperatures consisting of crystalline side chains, modification A is observed on heating above 120 °C and shows a disordered packing of the side chains. Rapid cooling using Fast Differential Scanning Calorimetry (FDSC) yields a liquid crystalline state wherein a long range ordered layered morphology exists, however, the π − π stacking of the backbones is absent. The molecular orientation of backbones under the influence of shear fields as well as on a glass fiber surface is also studied. Both modifications A and B show backbone orientation along the shear fields in an extruded sample while a preferential edge-on orientation is inferred on the glass fiber surface.