Structure and properties of talc-filled polypropylene: Effect of phosphate coating

Talc surface treatment was carried out using a series of phosphate coating levels. The coated talc was characterized using quantitative diffuse reflectance FTIR analysis, which revealed a saturation of surface coverage at around 6 wt % phosphate. Coated and uncoated talc had a nucleation effect; and the degree of crystallinity of composites increased initially, then gradually decreased with increasing phosphate coating level. The talc dispersion was improved as coating level increased; however, the platelet alignment was reduced. The addition of 0.5 wt % phosphate to talc resulted in a maximum increase in tensile strength and a significant drop in flexural modulus. Improvement of falling weight impact properties of the composites were achieved at high coating levels. (C) 1996 John Wiley & Sons, Inc.