Consolidation of Composites by Using Coextruded Tape Technology

8 Consolidation of Composites by Using Coextruded Tape Technology 

This coextruded tape may then be highly drawn to achieve the required mechanical properties, and subsequently consolidated by processes similar to the hot compaction processes described by Ward and Hine [33]. Alcock et al. describe that one of the main advantages of using the coextruded precursor material was that the processing temperature window can be as large as the difference between the melting temperature of the matrix skin layer and the relaxation temperature of the 

Additionally, the coextruded skin layer present on these precursor tapes was identified by Deng et al. as a potential medium for carrying additives such as carbon nanofillers [170]. While earlier studies showed that the tape cores could be made electrically conductive by the addition of carbon nanofiUers [171, 172], the ability to contain the nanofillers exclusively within the coextruded lower melting temperature skin layer allows the use of thermal annealing to cause reaggregation of the nanofillers, leading to a further increase in electrical conductivity. 

Following commercialisation of the concept of using coextruded tape technology to create self-reinforced polymer composites based on PP by Lankhorst Pure Composites (The Netherlands) as the product PURE, the mechanical properties were also assessed by Abraham et al. [173] and Banik et al. [174, 175]. A very similar concept for creating self-reinforced polymer composites was also presented by Kim et al. [176], although this time using commercially available coextruded 

PP tapes, which comprised a highly oriented PP homopolymer core coated with a thin PP copolymer skin layer. As in the coextruded tape systems reported by Peijs [5], this PP copolymer skin layer has a lower melting temperature than the PP homopolymer core. 

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