J.-C. Quantin

Granulometric Characterization of Short Fiberglass in Reinforced Polypropylene. Relation to Processing Conditions and Mechanical Properties

Abstract In most cases, for reinforced thermoplastics, a knowledge of average filler length is not enough information. The entire granulometric filler distribution needs to be known, if structure is to be correlated with properties. We have developed a technique of granulometric determination based on image analysis to analyse rapidly the evolution of the granulometry of short fiberglass. Once images in grey levels from polarized light microscopy have been acquired, each selected fiber on the frame is individualized and labelled before measurement and data treatment. For the fiber, the size factor chosen is the length, or the maximum Feret diameter. With this tool, we have been able to study more precisely the evolution of the fiber length distribution during processing with a polypropylene matrix. Finally, we elucidate the dependence of mechanical properties such as impact and tensile strengths on glass filler size.

Determination of the microtexture of reinforced thermoplastics by image analysis

Abstract The mechanical properties of reinforced thermoplastics depend on such characteristics of the filler as granulometry, orientation and dispersion. These different microtextural parameters were determined by using a single tool: image analysis, which was coupled with optical and electron microscopies. The different materials tested were based on short-glass-fibre-reinforced polypropylene obtained by extrusion and injection steps. For the different samples analysed, the processing conditions and the filler concentration were constant, and variability was due to the different average lengths of the filler incorporated in the matrix. The different filler parameters were determined with particular emphasis on the techniques of dispersion characterisation. The techniques developed in this study were based on image analysis. They enabled us to estimate filler-size distribution and development of the three-dimensional orientation inside the material and between different samples. The development of the filler dispersion was also made apparent. In addition, the relationships obtained between the different microtextural parameters were investigated. The general conclusion is that image analysis is very suitable for characterisation of this kind of material.