Why polycarbonate? Just a comparison:

Polycarbonat (PC)

Chemical-physical properties

Polycarbonates are highly shock and scratch resistant plastics being marked by extraordinarily high weather resistance and long longevity. They do not embrittle and keep their shock and scratch resistant properties far beyond a broad temperature range without requiring considerable volumes of additives. They are water-resistant, resistant to many mineral acids and aqueous solutions of neutral salts and oxidizing agents. Also some covalent organic solvents such as hydrocarbons and many oils and greases do not affect polycarbonates. Polycarbonate can be sterilised at a temperature of 120°C.

Ecological aspects and safety aspects to be taken into account:

Polycarbonates are completely harmless in physio-logical terms and are widely used in medical engineering. They may show self-extinguishing properties, in case of fire, no further substances were detected apart from the usual low-temperature products being formed in each organic compound in case of fire. Polycarbonates are eligible for eco-abels: Blue Angel (certification), TCO, Nordic Swan, EU Flower require, among other things, that the plastics used are free of any carcinogenic and mutagenic substance, or the fire proofing packages have to be free of bromine, chlorine and antimony. Polycarbonates are halogen-free according to
DIN 0472.


Chemical – physical properties

PVC is a very hard and brittle synthetic material the hardness and brittleness of which increase at lower temperatures. PVC is highly weather-resistant and can practically not be degraded biologically. Pure PVC is, however, chemically unstable. All kinds of PVC have to be stabilised to a great extent by using antioxidisers, UV-stabilizers or thermal stabilisers. PVC is very hard and brittle. Adding softening agents increases elasticity, the addition of chlorinated polyethylene increases impact strength. By adding softening agents, however, PVC looses its self-extinguishing properties. PVC shows only very low thermal stability.

Ecological and safety aspects to be taken into account:

Softening agents in PVC tend to diffuse so that some embrittlement is noticed after a certain period of use. In physiological terms, the used softening agents are partially be classified as being problematic. The same applies to the stabilisers being used to a considerable extent. The German Federal Environmental Agency says in this regard: Especially children are being exposed to some risk. The commonly used softening agents phthalates are considered to be highly harmful since they have an impact on the hormonal balance of the human-being and impair reproduction and development.“
Independent of this fact, PVC may cause considerable problems in case of fire since it decomposes by more than 50% of weight in pure hydrochloric acid steam under heat by considerable formation of soot particles. This steam partially reacts with the other low-temperature products in the soot, and the fumes and the soot that are emitted include poly-condensed aromatics such as benzo(a)pyrene, pyrene, chrysene being highly toxic and carcinogen.