Influence of blend composition on mechanical properties of ASA/SAN binary blends

In this study, acrylonitrile-styrene-acrylic/styrene-acrylonitrile copolymer (ASA/SAN) binary blends with different compositions were prepared by mixing ASA and SAN by melt blending. Properties of the binary blends were studied by dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC), fourier transform infrared spectra (FTIR), heat distortion temperature (HDT), melt flow rate (MFR), mechanical properties and scanning electron microscopy (SEM), respectively. Since a grafted SAN shell is contained in ASA's core shell structure, it is considered to have a good compatibility with SAN, and the results confirmed it. The binary blends showed a single glass transition temperature (Tg) according to DSC and DMTA measurements. Only weak interactions between the characteristic groups were obtained in FTIR spectrum. No obvious phase separation observed in SEM photographs indicated good compatibility between ASA and SAN. With respect to mechanical properties, impact strength and elongation at break of ASA/SAN blends decreased significantly with the SAN content but tensile strength, flexural strength and modulus increased. In addition, the incorporation of SAN enhanced the heat resistance and processability of the blend system.