Optimization five: comingled fibrous materials
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Section outline
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One of the drawbacks of traditional composite laminate manufacturing is the extended cycle times required to properly cure a thermoset resin. These lengthy processes often impede productivity and increase costs in industrial applications. To address this, new materials known as comingled fibers have been developed to decrease processing time significantly. In comingled fibers, a carbon fiber tow incorporates additional thermoplastic matrix materials directly into its fiber structure. This innovation not only enhances manufacturing efficiency but also offers new possibilities for composite material applications.
These comingled materials can be stitched using techniques similar to those applied in other tailored fiber placement composite materials. The advantage of using comingled fibers lies in their ability to be rapidly thermocycled in heated presses, which dramatically reduces the cycle processing time. Traditional thermoset composite materials, when processed using resin transfer molding, can require curing times ranging from 30 minutes to as long as 40 hours to properly set and cure a single piece. In contrast, comingled fibers streamline this process, offering substantial time savings and operational efficiencies.
Tailored fiber placement of comingled materials enables the concurrent placement of both the reinforcing fiber and the matrix material within the same preform. As the preform is heated, the thermoplastic matrix material melts and is distributed seamlessly into the carbon fiber, ensuring proper wetting and adhesion. This method eliminates the need for additional resins, which not only reduces material costs but also minimizes the potential for voids and defects in the final composite. Moreover, the desired fiber-to-volume fraction is established during the comingling step, enhancing the uniformity and consistency of the composite material across different production batches.
Finally, these comingled fiber composites represent a step towards more sustainable carbon fiber composites due to their ability to be re-melted and reformed into new shapes at the end of their lifecycle. This reusability aligns with modern sustainability goals by reducing waste and promoting the recycling of composite materials, thereby contributing to a more circular economy.
Further Reading & Resources