MELT BLENDS OF POLY(METHYL METHACRYLATE) WITH A PHENOXY

Melt blends of poly(methyl methacrylate) (PMMA) with a phenoxy (polyhy droxy ether of bisphenol A) have been prepared over the complete compo sition range using a single-screw extruder. Injection-moulded specimen s of the blends were transparent, and differential scanning calorimetr y and rheological measurements gave a single glass transition temperat ure (T-g), indicating miscibility of the blends. The plot of measured T-g versus composition showed negative deviation from additivity, exce pt for the 10/90 (PMMA/phenoxy) blend which showed a positive one. Fou rier transform infra-red spectroscopy showed that the maximum peak aro und 3400 cm(-1) moved towards a higher frequency in the blends, sugges ting that intercomponent hydrogen bonding exists. Tensile properties ( modulus, strength and elongation at break) of the blends showed a nega tive deviation for PMMA-rich compositions, and a positive deviation or followed simple additivity in phenoxy-rich blends. The blends were al so miscible in the melt state, and a viscosity rise over log additivit y in phenoxy-rich compositions strongly suggested chemical reactions b etween the ester groups of PMMA and hydroxy groups of the phenoxy poly mer in these compositions.