Supermolecular structure and thermal properties 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 3 No. 8, 2003 pages 343-348
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abstract The effect of glass fibre content on degree of crystallinity and thermal properties of polypropylene composites has been examined. The polypropylene and its composites filled with 30 and 50% of the glass fibre have been tested. The study has been carried out by means of the differential scanning calorymetry (DSC) and the thermal microscopy. The thermal analysis measurements were performed using a DSC 200 PC Phox by Netzsch. The samples of about 10 mg were heated to 200oC at then held for 4 min in order to eliminate any thermal history in the material. Then the samples were cooled to the crystalliza- tion temperature Tc. The experiments were carried out in nitrogen atmosphere and the scans were obtained at 10oC ⋅ min−1. After crystallization, the samples were heated to the melting point of the matrix composites. The melting temperatures Tm and the degree of crystallinity of the composites were obtained from the maximum and the area of the endothermic peaks. The DSC thermograms are shown in Figures 1-2. Thermal parameters such as: melting temperature Tm, crystallization temperture Tc, heat of fusion ΔH and the degree of crystallinity of the studied samples are reported in Table 1. The morphology of the polymer matrix was studied by using an optical polaryzing microscopy with Mettler Toledo FP82HT automatic stage thermal control. The PP spherulitic growth was observed by taking photomicrographs. Figures 3 and 4 show the morphology of polypropylene and polypropylene with the glass fibre composites. The degree of crystallinity of the composites decrease as fibre content increases which is indicating that the glass fibres doesn’t as act as nucleant agents. In the composites, the PP spherulites are not well defined and their size decreases which could be attributed to restrictions created by the glass fibres on the development of a spherulitic structure. Key words: polypropylene composites reinforced glass fibre, degree of crystallinity, melting temperature, crystallization temperture