Film preparation by melt- or compression-process using poly(vinyl chloride) powder swollen with dimethylformamide

摘要

A melt-process was used to prepare high molecular weight Poly(vinyl chloride) (PVC) films without the use of a conventional plasticizer and heat stabilizer. Rigid PVC powder was swollen with dimethylformamide containing 4∼10 vol% water to reduce its melting temperature. The swollen powder was pressed at a relatively low temperature of 75∼125 °C to form a film shape, and then washed and dried. The visible light transmittance, X-ray diffraction, density and the tensile properties of the resulting films were examined to estimate the success or failure of film formation. The films could be produced by not only the melt-process but also a compression-process using the rigid, highly swollen PVC powder. The resulting films had no voids, which are generally observed in PVC products formed by a solution process. The minimum temperature for these processes decreased with decreasing water content in the mixture: The minimum temperatures according to the water content in the mixture to produce faultless films through the melt-process were 4 %–105 °C, 6 %–115 °C, 8 and 10 %–125 °C, while those through the compression process were 4 %–95 °C, 6 and 8 %–105 °C, 10 %–115 °C.