The Future of Materials
Composite material systems are rapidly evolving to increase the performance of existing systems – notably higher strength carbon and glass fibers – as well as to develop new material systems, such as resins that can function in high-temperature environments. Innovation in material formats is co-evolving with the increased utilization of automation and out-of-autoclave (OoA) processes.
Automation requires materials with tight tolerances and low variability to produce parts with minimal intervention during the manufacturing process and thereby realize the full promise of in-service performance benefits. OoA processing is gaining traction in numerous industries due to dramatic reductions in void volume fractions that approach those of parts processed by autoclave. Thermoplastic composites are increasingly deployed for potential decreased cycle times and increased recyclability.
The choice of materials used in composites manufacturing is primarily driven by industry requirements and government investments and regulations. Industrial requirements for materials focus foremost on cost reductions enabled by lowered raw materials costs, as well as attractive processing parameters, such as short cycle times, low processing temperatures and zero scrap rates. Government investments in composites manufacturing should aim to increase sustainability via recycling efforts and bio-derived material sourcing and to substantially reduce the embodied energy.
Domestic government regulations are currently directed at limiting styrene and other organic vapor emissions. The FIBERS team anticipates that manufacturers will eventually be responsible for costs associated with end-of-life solutions for many of their composite parts. Such a responsibility provides the incentive to develop and use sustainable material formulations that accommodate recycling (or remaking) as opposed to sending to landfills.
Materials challenges for today’s composites industry revolve around cost, cycle time, processing bottlenecks, standardization, reduced variability, sustainability and protection of corporate intellectual property and trade secrets. The cost of materials, particularly carbon fiber and epoxy resins, are prohibitively high for widespread use in market segments such as wind power and automotive. Processing cycle times are a consequence of resin viscosities that define fill time, the length of time required to reach and hold cure temperatures, and lot variability.
Lot variability forces users to always bias to the most extreme condition – to design for the worst-case scenario, which errs on the side of a long cure time. These issues invite negative comparisons when referenced to steel or aluminum within the automotive industry. The integration of feedback control can help reduce the negatives of lot variability.
Two-thirds of survey respondents prioritize the development of new resin materials, with the primary aim to reduce process time and decrease part cost. These new materials, however, often require costly certifications of both material systems and processes that are a barrier to even large industry members. While industrial participants expressed conceptual interest in material recyclability and sustainable practices, few economic options are presently available. Therefore, many companies cannot make a business case for significant investment.