Polycarbonate (PC) has been widely utilized for many applications such as electric appliances, automotive parts, LED lighting and medical equipment due to its transparency, excellent impact resistance and dimension stability. However, the processing window of PC is generally inferior to other plastics and sometimes causes insufficient appearance like flow marks and weld lines.
In this study, PC/polycarbonate oligomer (PC-O) blend, which has equivalent viscosity-average molecular weight (Mv) to general PC, was prepared, then the effects of PC-O addition to PC on thermal and rheological properties, flowability and appearance property were investigated. It was suggested that addition of PC-O promoted more movement of polymer chain at awidetempera ture range as the result of Tg and rheological properties. Bar flow length of PC/PC-O blend, was larger than that of general PC which has equivalent Mv, especially thin wall molding condition. V notch roughness of weld specimen which was molded by PC/PC-O blend also diminished effectively at a wide range of mold temperature. It is estimated that the thickness of the solidified layer of PC/PC-O blend along the mold surface is thinner than that of general PC while conducting injection molding due to addition of PC-O, therefore PC/PC-O blend has better flowability and finally shows less V notch roughness. These results also suggest that improvement of surface appearance would be highly possible by utilizing PC-O.

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