Polycarbonate (PC) is an amorphous engineering plastic with a glass transition temperature of 150°C. In its natural form this material provides a unique combination of rigidity, hardness and strength at temperatures up to 135°C to 140°C, plus excellent dimensional stability.
The mechanical properties of all thermoplastics deteriorate when exposed to high temperatures. Compared with most engineering thermoplastics, PC has superior resistance to thermal ageing, as illustrated by the permissible temperature during continuous use, which may be as high as 125°C. Brief exposure to higher temperatures is limited principally by the glass transition temperature of the material. The maximum permissible temperature is approximately 140°C.
PC absorbs only approximately 0.15% moisture at 23°C/50% RH and 0.35% when saturated in water at 23°C. However, PC may not be used in humid environments where the temperature exceeds 70°C, because hydrolysis will cause a significant deterioration of the mechanical properties, and impact resistance in particular.
The chemical resistance of PC is limited and certain chemicals cause cracks through environmental stresses or will dissolve the polymer. PC is not resistant to aromatic hydrocarbons, phenols, ketones, ethers, petrol, alkalis and most oxidising substances and acids. It is also poorly resistant to water and salt solutions, whereas its resistance to alcohol is good.
PC possesses reasonable UV stability; for better performance in this field it is necessary to use UV-stabilised qualities.