Technical Paper
Aspect of High Shear Rheology Applied to a Technical Part
1998-02-23
980720
Engineering plastics, such as polybutylene terephthalate (PBT) with high levels of short glass fibers exhibit unusual flow behavior during injection molding which may affect the final properties of moulded pieces. Through short-shots experiments it is obvious that jetting during cavity filling was systematically associated with highly filled materials, while neat polymers fill cavities through the simple laminar flow. Jetting phenomenon was related with very low, if any, post-extrusion swelling of highly filled materials. In order to study the high shear rheological properties of engineering plastics, in conditions similar to industrial processing, an injection capillary rheometer was developed and fixed on an injection machine. In that case, pressure, shear rate, material plastification and injection are representative of the processing. For comparison, standard laboratory rheometer was performed.