High-loading effect of surface-modified inorganic particles in polymer materials

Abstract

Recently fine-particle technology has been extending its application not only to existing multiphase metals, paint and coatings, but also to other wider industrial fields (such as polymers, ceramics, etc.). In the polymer industries, inorganic particles (mica, talc, calcium carbonate, etc.) are combined to polymer materials in order to improve the stiffness and thermal stability, but the lack of affinity at the interface between particles and the polymer matrix causes a reduction of the mechanical properties and increases the melt viscosity of the composites. Various surface modifications of inorganic particles have therefore been undertaken in order to improve the affinity of the interface between both phases [1-7]. The ceramics industry requires new technology developments such as (a) the evaluation of surface modification for ceramic powders and their sintering performance and (b) high-loading of ceramic powders for the preparation of injection-moulding material for ceramic products [8, 9]. As mentioned above, fineparticle loading technology, evaluation of the particle surface modification, interactive particle-particle forces and the role of the particle-polymer interface are becoming an important technology which is essential for the development and design of composite materials. Based on the above considerations, the high-loading method of inorganic particles in a polymer matrix has been tried and the relationship between particle properties (particle size, size distribution and surface modification) and the properties of particle-filled polymer (the flux rate of the composites and maximum particle loading rate) was investigated in this study. Isotactic polypropylene (PP; Showalomer SA710 from Showa Denko Co. Ltd, [r/] = 1.78 dl g ~ in tetralin at 135°C) was used as the polymer base resin. Calcium carbonate (CaCO3, density 2.7 g cm-3; Bifoku Funka Co. Ltd) and aluminium oxide (A1203, density 4.0 g cm 3; Showa Keikinzoku Co. Ltd) were used as particles as shown in Table I. The surface modifiers for TABLE I Particle properties of CaCO 3 and AI203 Mean particle Surface area a*-value size 0zm) (m2g 1)