Thermotropic side-chain liquid crystalline polymer (SLCP) and corresponding side-chain liquid crystalline ionomer (SLCI) containing sulfonate acid were used in the blends of polypropylene (PP) and polybutylene terephthalate (PBT) by melt-mixing respectively, and thermal behavior, morphological, and mechanical properties of two series of blends were investigated by differential scanning calorimetry, Fourier transforms infrared spectroscopy (FTIR), scanning electron microscopy, and tensile measurement. Compared with the immiscible phase behavior of PP/PBT/ SLCP blends, SLCI containing sulfonate acid groups act as a physical compatibilizer along the interface and compatibilize PP/PBT blends. FTIR analyses identify specific intermolecular interaction between sulfonate acid groups and PBT, and then result in stronger interfacial adhesion between these phases and much finer dispersion of minor PBT phase in PP matrix. The mechanical property of the blend containing 4.0 wt % SLCI was better than that of the other blends.
Side-chain liquid crystalline ionomers containing M 1 (4-allyoxybenzoyloxy-4 0 -amylbenzoyloxy biphenyl) as mesogenic units and M 2 (4-undecylenicoxy-4 0 -phenylazobenzene sulfonic acid) as ionic units were synthesized by graft copolymerization. Their liquid crystalline properties were characterized by differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction measurements. The results showed that introduction of nonmesogenic ionic units into polymeric structure could cause additional reduction of the clearing point of the ionomers, compared with the corresponding nonion polymers. When the content of ionic units increased to 8.5%, the ionic clusters and mesogens in the ionomers may be dispersed each other to form multiple blocks, but the introduction of ionic groups in LCIs did not change their mesogenic type.
ABSTRACT:The liquid-crystalline (LC) monomer 4-allyoxybenzoyloxy-4Ј-buthylbenzoyloxy-p-phenyl (M 1 ), whose LC phase appeared at lower temperatures, from 137 to 227°C, and the modified mesogenic monomer 4-allyoxybenzoyloxy-4Ј-methyloxybenzoyloxy-p-biphenyl (M 2 ), whose LC phase appeared at higher temperatures, from 185 to 312°C, were prepared. A series of side-chain LC polysiloxanes containing M 1 and M 2 were prepared by graft copolymerization. Their LC properties were characterized by differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy, and X-ray diffraction. The results show that the introduction of the modified mesogenic monomer M 2 into the polymeric structure caused an additional increase in the clearing point (isotropic transition temperature) of the corresponding polysiloxanes, compared with unmodified polysiloxanes, but did not significantly affect the glass-transition temperature. Moreover, the modified polysiloxanes exhibited nematic phases as the unmodified polymer did.
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