HIPS has the dimensional stability of general purpose polystyrene (GPPS) with better impact strength and rigidity.
The relative density of HIPS is 1.04~1.06 and the thermal deformation temperature is 70~84℃. The HIPS tensile strength is about 15~30MPa and the elongation is 35~60%. It increases with the decrease of temperature and the increase of strain rate, somewhat like a rubber toughening system. HIPS behaves somewhat like a viscoelastic solid and can creep when exposed to constant tensile stress. Creep decreases with increasing molecular weight and generally increases with increasing rubber content. The creep behavior of HIPS is strongly dependent on the average molecular weight (MW). The bending strength is 29.4~50 MPa, the impact strength is 0.09~0.16N/M, the Vicat softening point is 84~100℃, and the melt index is 2~9g/10min. The heat resistance of HIPS components depends on their shape, production conditions, heat source type and heating duration, and is also affected by the HIPS grade.