Whether the fibers are long or short, incorporating glass or carbon reinforcements into thermoplastic matrices addresses the same fundamental objective—improving the mechanical and structural performance of polymers. These two primary methods of reinforcing injection molding thermoplastics differ in a number of ways, ranging from how they are combined with the polymer matrix to the level of performance they provide. End-use applications are another area where one form of fiber may be more appropriate than the other, but for molders, the main difference between short and long fiber is how aggressively they can be processed.
In Part 1 of this series, we address long-fiber processing fundamentals and best practices, including practical tips and guidance on maintaining fiber length and deriving maximum advantages for demanding end applications. For Part 2, we will provide the same information for short-fiber materials.
Mold Simulation Collection (Part 2)
This collection of popular articles on mold flow simulation from Plastics Technology and MoldMaking Technology includes:
Preservation, Not Perfection
The primary goal in processing long-fiber reinforced thermoplastics is to preserve fiber length, which is critical to optimizing properties like strength and toughness. Fiber breakage negatively impacts polymer composite performance and may ultimately cancel out the benefits of using long fiber in the first place. Fiber breakage can be caused by careless handling, problematic tooling and part design, or the use of processing equipment or settings that have not been optimized.