TWI Frequently asked question
by Roger Wise
Generally, recycling will involve passing a thermoplastic polymer through an extruder which will melt and convert it into pellets for reuse. The extrusion process will typically involve some reduction in the average molecular weight of the polymer because some polymer chains will be broken by the action of the extruder. This means that the mechanical properties of the recycled polymer will be inferior, to some extent, to those of the pre-recycled material. This degradation will not affect the weldability of the polymer.
Studies carried out by TWI and automotive battery producer Cookson Technology confirmed that it is possible to weld (in these cases, ultrasonic and hot plate welding were used) recycled plastics provided that the recyclate is clean and free from contamination prior to injection moulding and post-moulding operations such as welding.
Related information
Who supplies recycled plastics?
