Long and continuous fiber thermoplastic composites are taking center stage in industry research and applications.
Research and innovations in thermoplastic composites today are centered primarily on long fiber reinforced thermoplastics (LFRTs) and continuous fiber reinforced thermoplastics (CFRTs). Market studies on ReportLinker project a global 8.5 percent compound annual growth rate (CAGR) between 2017 and 2021 for LFRTs and a 9.5 percent CAGR for CFRTs from 2017 to 2022. Short fiber thermoplastics, by contrast, can expect a CAGR of only 4.5 percent through 2021.
LRFTs are available as pellets and used primarily in injection and compression molding, while CFRTs are found in unidirectional (UD) tapes and used for woven sheets, filament winding and pultrusion. Despite the differences in form, these thermoplastic materials share many desirable characteristics.
“The use of continuous fiber thermoplastics is based on three essential qualities: They can reduce the weight [of parts] versus traditional materials such as wood, thermosets or metal without compromising structural strength, they have enhanced physical properties such as stiffness and they are recyclable,” says Kelly Wessner, global marketing director, PolyOne Advanced Composites.
Long and continuous fiber thermoplastics increase manufacturing efficiencies because they are easier to use than traditional materials and can streamline processing. In addition, they have greater flexibility to handle complex design geometries compared to metal or thermoset continuous fiber materials. “Because they can be post-formed [remelted], thermoplastics can be used in multi-material processes such as panels incorporating a PET [foam] honeycomb core or injection overmolding of tapes and laminates for localized reinforcements,” Wessner adds.
Unlike thermoset parts, which must be joined with mechanical fasteners or adhesively bonded, thermoplastic components can be welded together. That eliminates the weight and cost of fasteners, which is a major advantage in the automotive and aerospace industries. “In the airline industry, for every pound that the airline can take out, it’s a $1,000 a year cost savings,” notes Jason Lyons, manager of Arkema’s Kepstan® polyetherketoneketone (PEKK) business.
But barriers to widespread adoption of thermoplastic composites remain. For one thing, they’re not as well known or understood as thermosets. “Thermosets have been entrenched in the composite and manufacturing worlds for a longer time, so it takes a different mindset to adopt some of the thermoplastic processing techniques and to fully realize the positive return on investment,” says Mark Aubart, scientific director at Arkema. “Companies that are willing to implement these innovative technologies can see the longer view and will reap the benefits.”