Browsing by Author "Menard, KP"

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    Morphology and thermal properties of two polymethacrylates modified by a polymer liquid crystal
    (WILEY-BLACKWELL, 2004) Brostow, W; Gargallo, L; Hormazabal, A; Jaklewicz, M; Menard, KP; Opazo, A; Radic, D
    We have studied blends of a polymer liquid crystal (PLC) with poly(cyclohexylethyl methacrylate) (PCHEMA) or poly(cyclohexylpropyl methacrylate) (PCHPMA). The PLC is PET/0.6PHB where PET = poly(ethylene terephthalate), PHB = p-hydroxybenzoic acid and 0.6 is the mole fraction of the latter in the copolymer. The microstructure was studied by scanning electron microscopy (SEM). PCHEMA + PLC (20 wt% of the latter, blend E) has a fine texture with LC islands evenly distributed in the matrix and good adhesion between the phases resulting from their partial miscibility. The PCHPMA + PLC (20 wt% of the latter, blend P) shows only limited compatibility. The SEM results are confirmed by values of the glass transition temperatures T-g determined via thermal mechanical analysis. The T-g value of the blend E is shifted towards the T-g of PLC; T-g of blend P is practically equal to that of PCHPMA. The linear isobaric expansivity alpha(L) values for both blends are lower than the respective values for pure PCHPMA and PCHEMA. Thermal stabilities of the blends determined by thermogravimetry are also better than those of pure polymethacrylates. The temperature of 50% weight degradation for blend E is higher than that for pure PCHEMA by more-than 60K (C) 2004 Society of Chemical Industry.