This study investigates deformation of a thermotropic liquid crystalline polymer (TLCP) in different die geometries. Blends of a TLCP with a thermoplastic elastomer of EPDM were made in a twin-screw extruder. Morphological observation of the extruded blends demonstrates the complimentary effect of shear in the die exit on dispersed phase deformation and fibril formation. Shear strain can affect fibril formation for a relatively large dispersed phase in the region close to the die wall. However, the main role of shearing is in breaking up the larger particles and initial polydomain structure. A strong elongational deformation on the blended melt after the die exit is required, and fine microfibrils normally observed in in situ compos ites were not easily formed by shear deformation only in the die.
Miscibility and Mechanical Properties of Poly(ether imide)/Liquid Crystalline Poly(ester imide) BlendsAs a part of continuous study to search for the high performance in situ composite, this study examines the miscibility of liquid crystalline poly(ester imide) (PEsI) with poly(ether imide) (PEI) and its effect on the mechanical properties and the morphology of the blends of these polymers. Liquid crystalline polymers (LCPs) were synthesized from trimellitic anhydride and α,ω-diaminoalkane with 8, 10, 12 methylene groups. Thermal condensation of these diacids with 4,4'-diacetoxybiphenyl yielded the corresponding imides of thermotropic homopolyesters. Optical polarized micrographs show that the synthesized poly(ester imides) have the smectic structure. Partial miscibility was observed from the shift of the glass transition temperature determined by differential scanning calorimetry. Increasing concentration of the liquid crystalline PEsI in the PEI/PEsI blends shifted the glass transition temperature of the PEI phase to a lower temperature. Mechanical properties of the PEI/PEsI blends were changed with the number of methylene units in PEsI. Morphologies of the partially miscible system were found to be quite different from those of an immiscible system. Strong adhesion between the matrix (PEI) and dispersed phase (LCP) was observed, but fine fibril formation was not possible due to the absence of smectic-nematic transition.
ABSTRACT:The chain-end sulfonation of a,w-dilithiopolystyrene prepared by lithium naphthalenide as a difunctional initiator using 1,3-propanesultone was studied by the characterization methodologies such as acid/base titration, colorimetric method using methylene blue, two-phase titration with Hyamine 1622, size exclusion chromatographic analysis infrared, and 1 H NMR spectroscopic analysis. The reactivity modification of a,w-dilithiopolystyrene through the end-capping with 1,1-diphenylethylene prior to the sulfoalkylation in benzene-tetrahydrofuran (THF) ( 10: 1, v /v) at 25°C with excess 1,3-propanesultone is suggested as a useful method for the preparation of the corresponding dilithium a,w-disulfonated polystyrene in relatively high yield based on the results from the acid/base titration (>85%).
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