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

Danke, Varun; Gupta, Gaurav; Huth, Heiko; Schawe, Jürgen E. K.; Beiner, Mario

Thermochimica Acta, 2019, vol 677pp. 162-168



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 ????? 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.

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