Modeling of Fiber Dispersion for Long Fiber-reinforced Thermoplastics

As some industries have become more dependent on discontinuous fiber-reinforce polymers (FRP), there has been an effort to improve the manufacturing process of said parts. To improve this process, it is important to fully understand the process by which fibers disperse as fiber dispersion will have a direct impact on a part’s strength and durability. This makes it important to have a model which can predict fiber dispersion with given parameters.

Figure 1. Fiber dispersion and breakage in plastication unit

Much of the work done to investigate and model the effects of processing on fiber orientation and fiber damage focuses on the effect of flow fields upon the suspension of individual fibers. Comparatively, little work has been done focusing on the transition of fiber bundles to a suspension of individual fibers. As illustrated in Figure 1, when processing long fiber-reinforced thermoplastics, the region with the highest fiber breakage coincides with the transition from the heterogeneous mix of polymer and fiber bundles to a suspension of individual fibers. This fact motivates us to investigate the kinematics of fiber dispersion in LFT pellets.

Topics studied under the fiber dispersion project include:

  • The effect of fiber bundle morphology on dispersion
  • Single Pellet dispersion under shear flow (Figure 2)
  • Multi-Pellet dispersion under shear flow
  • Multi-Pellet breakup in single screw channel (Figure 3)
  • Modeling of fiber dispersion in single screw channel

Figure 2. Single pellet dispersion under simple shear flow

Figure 3. Multi-pellet breakup in single screw channel