For some applications, two different materials with differing properties are used together. Co-extrusion may be carried out to produce the component. Each material requires an individual extruder which feeds into a special co-extrusion die where the melts can be combined as required. Multi-layer pipes and sheets can be produced, which enables recyclate materials to be sandwiched between virgin material outer layers if required. Multi-layer technologies are not limited to extrusion, it is also possible to create multi-layers using injection moulding, blow moulding and film blowing.
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