Polycarbonate (PC) is an important engineering plastic. It offers excellent transparency, toughness, thermal stability and dimensional stability. These properties are utilised in safety-critical applications, such as helmets, visors, lighting and aircraft and ballistic glazing. Its superior moulding characteristics and incredible impact strength make it the go-to material for many automotive, consumer electronic and small appliance housings, too.

The compatibility of PC with other plastics is utilised in alloys (blends), which combine the benefits of the mixed polymers to better fit the performance and productivity requirements of the application. PC is combined with acrylonitrile butadiene styrene (PC/ABS), which is an upgrade on ABS but less expensive than pure PC. It is combined with acrylonitrile styrene acrylate (PC/ASA) for enhanced resistance to weathering and UV light, ensuring colour retention over time. And it is combined with polyester – polyethylene terephthalate (PC/PET) and polybutadiene terephthalate (PC/PBT) – to produce a material with enhanced chemical resistance.

In the past, PC was commonly used in drinks bottles, babies bottles and other food contact applications. Its transparency and impact properties make it a tough and lightweight alternative to glass. However, the downside of PC is its chemistry: it is most commonly formed with the reaction of bisphenol A (produced through the condensation of phenol with acetone under acidic conditions) with carbonyl chloride. Bisphenol A (BPA) has been at the centre of numerous studies, because it poses a risk to people and the environment (it is an endocrine disruptor and oestrogen-mimicker). The concern is that small amounts of the chemicals present in food packaging materials migrate into the contents. The US Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA) consider BPA to be safe at current levels occurring in foods. In other words, they currently approve the use of PC in food containers and packaging (BPA is found in the epoxy-based coatings used to line the inside of metal cans as well as PC). Whether it is dangerous or not, public opinion resulted in a shift away from PC in applications where a ‘safer’ alternative existed.