Fiber orientation and fiber attrition of glass fiber-reinforced thermoplastics

Mechanical properties of thermoplastic and thermosetting polymers are improved when they are reinforced with fibers. Fibers will increase the strength, stiffness and impact resistance. These materials can easily be processed using conventional processing techniques such as injection and compression molding, as well as extrusion. However, fiber damage or attrition will shorten the length of the reinforcing fibers during processing. Shorter fibers will diminish the mechanical effectiveness of the composite, and in some cases will result in properties that are inferior to the un-reinforced polymer’s properties. Fiber damage during processing can be attributed to at least the following mechanisms:

  • Melting
  • Deformation of the Polymer Melt
  • Fiber-Fiber Interactions
  • Fiber-Equipment Interactions

Within this study, analytical and numerical models are developed and used to assess the significance of each individual mechanism. In addition, controlled experimental set-ups are built to study the various mechanisms and for model verification. Results from this study will lead to a full understanding of fiber attrition during processing. This will aid the process engineer to design a process, i.e. mixing devices, screw geometry, gates, or charge locations, that will lead to fiber composites with ideal fiber length distributions.