The material recycling of plastics exhibits many advantages as compared to other kinds of similar processes. These require lower costs and offer possibilities to apply conventional techniques and commonly used processing equipment like injection moulding presses and extruders. Thus, material recycling is widely utilised in the reuse of waste generated during the industrial processing of plastics.
In recent years, the researchers have become more and more interested in the recycling of the PC and ABS blends. However, during reprocessing of a polymer, its degradation caused by shear stress, heat, oxygen, and catalyst residues occurs. Therefore, the authors undertook the studies, described in this article, to investigate the effect of multiple injection moulding on Polycarbonate (PC).
Polycarbonates are linear polyesters of carbonic acid and diols, containing carbonate units. For practical applications, mostly aromatic polycarbonates are used. They are produced by polycondensation of bisphenol A and phosgene and are commonly called polycarbonate (PC). PC is a polymer of superior mechanical (including high impact strength), thermal (including very low thermal expansion in a wide temperature range), electrical, and optical properties. Therefore, it is considered as a constructional material, used in important applications such as airplane cockpits, bullet-proof windows, astronaut helmets, medical equipment, and construction parts, as well as in electrical and electronic engineering.
PC can be processed using methods such as injection moulding, extrusion, and vacuum forming. It is well known that the degradation of PC may be regarded as the sum of all physical and chemical effects occurring during its degradation in manufacturing processes, ageing during product life and degradation during recycling. The changes in physical properties of PC during series of subsequent recycling cycles are still not very well understood.
This article is a sum-up of a technical study carried out to investigate the influence of multiple (up to 6 times) injection moulding of polycarbonate (PC) on certain properties of the obtained moulded pieces. The investigated samples were obtained through industrial injection moulding and it was observed that the largest changes in some of the examined properties of polycarbonate occured during the first injection moulding.