Polypropylene (PP) is more durable and more temperature-resistant than polyethylene. Polypropylene density is one of the lowest (approx. 0.9 g/cm3) of all plastics. The maximum polypropylene usage temperature is 120-140°C. All polypropylene products can be sterilized repeatedly by vapour or boiling as this does not influence their shape or mechanical features. PP surpasses PE by its heat resistance features, but it is less cold-resistant and becomes brittle at -5°C. Thus, PP manufacturers add special additives to increase its resistance to low temperatures.