The 2010s were a transformative decade for composites as the industry’s focus shifted from production of small, non-structural parts made with woven fabrics to larger, structural parts made with unidirectional reinforcements. The impetus for change came from the automotive and aerospace industries. They appreciated composite materials’ unique properties – especially their light weight – and wanted to incorporate more composites into their products. But there was a stumbling block to widespread adoption; the speed of thermoset composite production wasn’t up to large-scale applications.
“They said, ‘We need to have fast manufacturing solutions,’ and that’s where thermoplastic composites come in,” says Sebastiaan Wijskamp, technical director of the ThermoPlastic Composites Research Center (TPRC) in The Netherlands. Founded 10 years ago, TPRC is a consortium of industrial and academic members whose goal is to enable a wider use of thermoplastic composites by eliminating technological barriers.
One reason for the high speed of thermoplastic composite production is its use of unidirectional tape and automated fiber placement (AFP) equipment. “You can build up a large piece, kind of like using a 3D printer, but with carbon reinforced tapes,” says Wijskamp. “If you do that well, you shouldn’t have to do an autoclave step to melt and consolidate the part under pressure. If we can stop that autoclaving step, we should be able to make big parts in a very short time.”
There are several other benefits, too. Using AFP, manufacturers can tailor parts by placing unidirectional fibers to reinforce areas that need strength and eliminating unnecessary material where it’s not required for structure. In addition, thermoplastic composite parts can be quickly joined together through processes like fusion bonding or heat welding, speeding manufacture and enabling faster repair of composite components.
Another benefit to thermoplastic composites is their recyclability. Production scraps and no-longer-needed parts can be kept out of landfills and reused. “The nice thing is that you only have to shred the composite pieces and melt them,” says Wijskamp. “There is no pyrolysis or burning of the matrix or any chemical process involved. So it’s an energy efficient and very clean way of recycling.”
The development of new materials and equipment for thermoplastic composites is one indicator of the market’s growing interest in them. One example is the VICTREX™ AE250 product family, which includes polyaryletherketones (PAEK) and carbon-fiber based unidirectional tapes that enable faster manufacturing of thermoplastic composites while reducing their weight.
“Developing a new polymer is a big investment, and polymer manufacturers don’t usually undertake such an action before they see market potential,” says Wijskamp. “You also see it with machine builders. Ten to 15 years ago there were only some very dedicated, small companies building machines for thermoplastic composite processing. Now you see all major machine builders going into this market.”