Improvement in the heat resistance of poly(vinyl chloride) profile with styrenic polymers

The styrenic polymers poly(α-methylstyrene-acrylonitrile) (α-MSAN) and poly(acrylonitrile-butadiene-styrene) (ABS) and (three types) were used to improve the heat resistance of poly(vinyl chloride) (PVC). The glass transition temperature (T_g) and miscibility were analyzed by dynamic mechanical thermal analysis (DMTA). Effects of composition on heat distortion temperature (HDT) were investigated with the different styrenic polymers. Other physical properties such as mechanical properties and melt flow rate (MFR) were also determined. Morphology was observed by scanning electron microscopy (SEM) in order to support the mechanical property results. The PVC was miscible with α-MSAN but partially miscible with the ABS series, and α-MSAN was much more effective in enhancing the T_g and HDT of rigid PVC than the ABS series as for mechanical properties, the addition of α-MSAN could improve the tensile strength, bending strength, and bending modulus but decrease the impact strength of the materials compared with the addition of the ABS series. Improvement in processability was observed in the MFR results with the addition of the styrenic polymers. On the basis of all the properties, the formulation with an α-MSAN content of 30 phr (parts per hundred parts of resin) was superior for heat-resistant PVC profile. The HDT of PVC could be increased from 76.9°C to 85.4°C (measured under the maximum bending stress of 0.45 MPa) and combined with good mechanical properties and processability by the addition of 30 phr of α-MSAN. Also, a heat-resistant PVC profile was successfully fabricated. J. VINYL ADDIT. TECHNOL., 2011.