Practical Tips for Molding Long Fiber Reinforced Polymers
Processing long fiber reinforced thermoplastics
The primary goal of processing long-fiber-reinforced thermoplastics is to maintain fiber length, which is critical for optimizing strength and toughness. Fiber breakage can have a negative impact on the properties of the polymer composite and may ultimately negate the benefits of using glass fibre threads. Improper handling and faulty tooling and component design, or the use of unoptimized processing equipment or setups, can lead to fiber breakage.
Unlike chopped fiber reinforced plastics, long fiber reinforced materials are usually made by pultrusion. The process involves stretching glass roving impregnated with thermoplastic resin through a special impregnation die (so that the resin can wrap around and bond the fibers), and then cut the extruded strands into pellets, the fibers in the pellets are typically 12mm The long, full-length features unidirectional fiber reinforcement, and this length is critical for enabling the polymer to efficiently transfer stress to stronger fibers.
When these pellets are used for injection molding, the long fibers are aligned and tightly wound to form an internal skeleton that provides strength and toughness. Compared to short-fiber filled materials, composites reinforced with long fibers, whether fibreglass fibres or carbon fibers, provide higher strength-to-weight ratios, impact toughness, longer cyclic fatigue life, and wider heat resistance and better dimensional stability.
These durable materials offer structural performance comparable to metal, yet are lighter than metal, and are able to take advantage of the processing efficiency benefits of injection molding. 1k carbon fiber cloth is particularly valuable as a metal replacement because they are 70% lighter than steel and lighter than steel. Aluminum is 40% lighter, so long-fiber-reinforced composites can be used to manufacture demanding components in automotive, sporting goods, aerospace, consumer goods and industrial equipment. Typical base resins include polyamide (PA or nylon), polypropylene (PP), rigid thermoplastic polyurethane (ETPU), and high temperature resins such as polyetheretherketone (PEEK), polyphthalamide (PPA), and polyamide. Ether imide (PEI) etc. While any thermoplastic can be reinforced with fibers, only some offer higher performance because they are better reinforced. More precisely, semi-crystalline resins are better reinforced by fibers than amorphous resins, which means that their stiffness and strength are increased even more.