Rheology of short glass fiber‐reinforced thermoplastics and its application to injection molding. II. The effect of material parameters

The effect of fiber concentration, fiber length, and temperature on the shear viscosity and die swell of several short glass fiber‐filled thermoplastics has been determined. In addition, a study of the injection molding behavior of these materials has been performed. At low shear rates, viscosity increases appreciably with both fiber length and fiber concentration, but at high shear rates the effect is much less pronounced. A qualitative explanation is proposed for these effects in terms of the fiber orientation studies reported in Part I of this paper (1). The die swell is an important parameter in determining the method of mold filling of these materials, and depends strongly on fiber length.