Melt blends of ?SAN with a phenoxy

Abstract

Melt blends of poly(α-methyl styrene-co-acrylonitrile) (αSAN) with a phenoxy were prepared using a Brabender Plasticorder. Morphological, thermal, rheological, and mechanical properties of the blends were studied. DSC (differential scanning calorimetry) measurements showed two T g (glass transition temperature) of the blends. T g of αSAN decreased by 5 to 7°C, whereas that of phenoxy increased slightly. Melt viscosity measured using an RDS (Rheometrics dynamic spectrometer) showed a small negative and relatively large positive deviation in aSAN- and phenoxy-rich blends, respectively. Transverse views of SEM (scanning electron microscopy) micrographs of the fractured surfaces again showed two phases, regardless of composition. Traces of full-out upon fracture were seen in αSAN-rich but not in phenoxy-rich blends, indicating stronger interfacial adhesion in phenoxy-rich blends. Longitudinal views of the SEM micrographs showed highly elongated structure of disperse phases (30 to 70% of phenoxy), especially when phenoxy forms dispersed phase, resulting in finer and well developed phenoxy fibrils. Tensile modulus and strengths showed a negative deviation in αSAN and positive deviation (strength) or additivity (modulus) in phenoxy-rich blends.