If short fibers are added in a polymer matrix, after mixing during extrusion, these short fibers are aligned automatically along the direction of extrusion. What changes in the extrusion process can be made so that the fibers are randomly oriented and not along the direction of extrusion?
It is virtually impossible. Even the melt itself is oriented, the anisometric fillers (as short fiber) will necessarily orient too. The degree of orientation will depend on the shear rate, viscosity of the melt, the L/D ratio of the fiber. The orientation will not be uniform along the cross section. If you use the pellets for injection molding, you will again get orientation which will be different at various points of the product. Certain simulation programs can predict the general features of filler orientation. If you want to avoid orientation you should use isometric fillers - but in this case you will less reinforcement.
- Badges
- Science topic
- Similar topics
- Engineering
- Materials Engineering