THE EFFECT OF SHEAR CONTROLLED ORIENTATION IN INJECTION-MOLDING ON THE MECHANICAL-PROPERTIES OF AN ALIPHATIC POLYKETONE

This article relates to an investigation of injection moulding a new c ommercial polymer, an aliphatic polyketone (PK). A terpolymer and a 30 % glass-filled grade were used as study materials together with an iso tactic polypropylene that was used as a basis for comparison. Both con ventional injection moulding and shear-controlled orientation injectio n moulding (SCORIM) were employed in processing. Tensile testing was c arried out at 80 degrees C as well as at room temperature. Polarized l ight microscopy and wide-angle x-ray diffraction were used in the char acterization of the mouldings. An increase of up to 30% in Young's mod ulus and 35% in ultimate tensile strength, and a 70-90% increase in st rain at peak were gained for the terpolymer (PK) at room temperature, as a result of SCORIM processing. A substantial improvement at 80 degr ees C was also recorded for unfilled SCORIM PK mouldings, and is attri buted to the pronounced molecular alignment that was induced in SCORIM mouldings, as shown by Debye patterns. It is notable that the SCORIM mouldings of PK exhibit a greater tensile strength at 80 degrees C tha n the SCORIM mouldings of isotactic polypropylene at 23 degrees C. (C) 1997 John Wiley & Sons, Inc.