DSC investigations of the surface layer of an aged
polypropylene/wood composite (in English)
Polimery 2011, No 5, 401
DSC investigations of composite material taken from the surface of the molded pieces formed with the injection molding method have been carried out in order to evaluate changes caused by ageing processes. Composites were prepared from polypropylene (PP) filled with wood flour in the amount of 50 wt. %. Moldings were aged for four years in atmospheric conditions or laboratory conditions under UV radiation for 100, 200 and 300 hours, respectively. Essential ageing changes have been noticed on the surface of the samples exposed to the atmospheric conditions on the basis of DSC curves recorded during the second heating. PP crystallites are much less organized and melt in temperature lower by over 25 °C than PP crystallites in the non-aged composite. On the other hand, the crystallites considerably different in terms of organization degree and melting temperature may occur side by side in composite aged with UV irradiation. There have been observed on the DSC endothermic curves of such samples even up to three melting areas of crystallites differing in macromolecules organization.
Key words: polypropylene, wood flour, composite, natural ageing, accelerated ageing