Dynamic properties and structure of polypropylene composites reinforced glass fibre
Renata Sobczak*, Zygmunt Nitkiewicz*, Józef Koszkul** *Politechnika Częstochowska, Instytut Inżynierii Materiałowej, al. Armii Krajowej 19, 42-200 Częstochowa **Politechnika Częstochowska, Katedra Przetwórstwa Tworzyw Sztucznych i Zarządzania Produkcją, al. Armii Krajowej 19c, 42-200 Częstochowa
Annals 4 No. 12, 2004 pages 369-373
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abstract The effect of glass fibre content on dynamical properties of polypropylene composites has been examined. Within the confines of the work the annealing influence on the properties has also been determined. Polypropylene and its composites filled with 30 and 50% of glass fibre have been tested. The investigation of dynamical properties of composites matrix has been made in order to compare. Figure 1 shows the storage modulus (E’) and loss modulus coefficient (tgδ) measured by DMA at 10 and 20 Hz as a function of temperature for composites: PP+30% glass fibre (Fig. 1a) and PP+50% glass fibre (Fig. 1b). The glass transition the most evident for polypropylene. In case of polypropylene composites range of glass transition is less evident, in particular for composite polypropylene with 30 and 50% glass fibre content. It was found, that increase in of glass fibre content in the composites decrease value of tgδ. The influence of heat-treatment (soaking) shows the bigger values of the storage modulus E’. Optical microphotographs of thin polypropylene and composite specimens (~10 μm) were taken by using a Polam - 113 polaryzing light microscope. In the composites (Fig. 3), the PP spherulites are not well defined and their size decreases which could be attributed to restictions created by the glass fibres on the development of a spherulitic structure. SEM microphotographs of different magnifications are shown in Figure 4: the composites PP+50% GF (Fig. 4a) and PP+50% GF after soaking (Fig. 4a). Spherulit structure occurs in polypropylene as well as in its composites. SEM microphotographs provide evidence of good filler dispersion in the matrix, effective wetting of fibres by the matrix and strong interfacial adhesion between the components. Key words: composite, polypropylene matrix, glass fibre, dynamic properties, spherulitic structure