MECHANICAL-BEHAVIOR OF POLYPROPYLENE COMPOSITES CONTAINING FINE MINERAL FILLER - EFFECT OF FILLER SURFACE-TREATMENT

The inclusion of mineral fillers in thermoplastics improves some mecha nical properties but reduces others, such as impact strength. However, the use of ultrafine fillers limits this degradation. The influence o f two surface treatments on the mechanical propel ties of polypropylen e/ultrafine-kaolin composites was studied. In the first treatment, ste aric acid was used on dry powder, and the second was a cationic treatm ent with quaternary ammonium in suspension. An improvement in the impa ct strength was found when the second agent was used. This can be expl ained from both macroscopic and microscopic points of view. We observe a better particle dispersion in the matrix and thermal analysis indic ates that the crystalline structure of these materials is finer. In ad dition, tensile tests carried out on matrix/agent blends show that a s oft interface around each particle could act as a shock absorber durin g an impact test. (C) 1998 Published by Elsevier Science Ltd. All righ ts reserved.