Study On Toughening And Modification Of Polycarbonate With Styrenic Thermoplastic Rubber

Polycarbonate (PC) has many distinct properties. However, PC has some characteristics that limit its use in many applications; for instance, it exhibits poor solvent resistance, poor processability and notch sensitivity. In this paper, we selected some kinds of Styrenic Thermoplastic Rubber (TPS: SEP, SEBS, SEPS and SEEPS) with different structures to blend with PC and PC/PP. The influence of adding TPS on the properties, such as mechanic properties, processability and Environmental Stress Cracking Resistance (ESCR), of PC/TPS and PC/PP/TPS was studied. The structure and morphology of the blends were explored by SEM and DSC.Pure PC has excellent mechanical properties. The notched Izod impact strength of the thin (3.2mm) samples is above 800J/m, but the notched Izod impact strength of the thick (6.4mm) samples is very low (less then 200J/m). The addition of the small amount of SEPS and SEEPS to PC can bring about a notable improvement of notched Izod impact strength of the thick PC samples; the samples were not broken in the test, and the blends also have the excellent mechanical properties of PC. At the same time, the processability and ESCR of the blends were greatly improved. SEM observations of fractured surface of thick samples show that the addition of TPS makes greatly changes of morphology of blends, and the samples broke from brittleness to toughness.Blends of PC with Polypropylene (PP) can obviously reduce the cost; improve the solvent resistance, processability and notch sensitivity of PC. But because PP and PC are immiscible, which makes PC/PP lost the excellent mechanical properties of PC. In this paper, we used TPS to blend with PC/PP.