Browsing by Author "Chiou, YP"

Now showing 1 - 2 of 2

In situ compatibility of polystyrene and liquid crystalline polymer blends
(1996-12-01)
Chiou, YP
;
Chang, DY
;
Chang, FC
;
應用化學系
;
Department of Applied Chemistry
The styrene-glycidyl methacrylate (SG) copolymer can be used to compatibilize the immiscible and incompatible blends between polystyrene (PS) and liquid crystalline polymer (LCP) copolyester. The epoxy functional groups present in the SG copolymer can react with the carboxylic and/or the hydroxyl terminal groups of the LCP at interface to form the SG-g-LCP copolymer during melt processing. This in situ-formed graft copolymer tends to reside along the interface to reduce the interfacial tension in the melt state and to increase the interphase adhesion in the solid state. However, the compatibilized PS/LCP blends reduce the number of LCP fibrils formed and have a tendency to form droplet LCP domains. The overall mechanical properties, stiffness and toughness of the blends improved after compatibilization, but the extent of the improvement is not very significant. It appears that the gain from the adhesion enhancement is more than offset by the loss due to the reduction in LCP fibril formation. The ethyl triphenylsphosponium bromide catalyst can further improve the compatibility of the blends by increasing the rate of the graft reaction. Copyright (C) 1996 Elsevier Science Ltd.
In situ compatibilized polypropylene/liquid crystalline polymer blends
(1996-09-01)
Chiou, YP
;
Chiou, KC
;
Chang, FC
;
應用化學系
;
Department of Applied Chemistry
Ethylene-glycidyl methacrylate copolymer (EGMA) has been investigated as a reactive compatibilizer for the immiscible and incompatible blends of polypropylene (PP) and a liquid crystalline polymer (LCP). The epoxy functional groups of the EGMA copolymer can react with the carboxylic acid and/or hydroxyl end-groups of the liquid comptalline copolyester. The in situ-formed EGMA-g-LCP copolymer tends to reside along the interface of the PP-LCP and reduces the interfacial tension during melt processing. The compatibilized PP/LCP blends show finer disperse LCP domains and tend to shift the LCP fibrous structure near the skin region of the uncompatibilized blends into the droplet domains. The PP crystallinity in the compatibilized PP/LCP blends is lower than that of the corresponding uncompatibilized blends due to interference in the PP crystallization by the in situ-formed EGMA-g-LCP copolymers. The lower PP crystallinity of the compatibilized blends is reflected in a substantial reduction in stiffness (in terms of the tensile modulus). However, the improved adhesion of the compatibilized blends results in an improvement in the toughness (in terms of the tensile elongation and impact strength). Copyright (C) 1996 Elsevier Science Ltd.