Effects of clay type, clay/compatibiliser content and matrix viscosity on the mechanical properties of polypropylene/organoclay nanocomposites

Polypropylene (PP)/organoclay nanocomposites (PPNC) were prepared using a twice direct compounding method in a twin screw extrusion process. Three grades of PP with different melt viscosities and three types of organomodified montmorillonite (MMT) clay with varied interlayer spacings were investigated in the presence of maleated PP (MAPP) as the compatibiliser. In order to understand these materials' effects on the mechanical properties, Taguchi design of experiments (DoE) method was employed and preferred combinations of factors to enhance each of tensile, flexural and impact properties of nanocomposites were determined using Pareto analysis of variance (ANOVA). It is concluded that PP grade has the most significant effect on the overall improvements of mechanical properties and as somewhat expected, PP with the lowest viscosity shows the best performance. In addition, clay content is detected as the second significant factor to enhance the tensile and flexural properties. However, clay type and MAPP content are two non-significant factors found in this study except that MAPP content has greater influence on the impact properties of nanocomposites. (C) 2008 Elsevier Ltd. All rights reserved.