The hydrostatic extrusion and die‐drawing of glass‐fiber‐reinforced polyoxymethylene

The solid-phase forming of glass-fiber-reinforced poly-oxymethylene has been investigated using the techniques of hydrostatic extrusion and die-drawing. Although considerable orientation of the glass fibers and the polymer matrix occurs in both processes, there are very appreciable differences between the stiffnesses of the glass-filled products in the two cases. For hydrostatic extrusion, the moduli of the glass-filled products are significantly higher than those of the unfilled products. In die-drawing, however, the absence of hydrostatic pressure allows debonding of the fibers from the matrix to occur, accompanied by extensive void formation. The fibers are, consequently, no longer effective as a reinforcing phase, the moduli of the glass-filled products being no higher than those of the unfilled products.