| dc.description |
Preparation and characterization of pure metal soaps and investigation of their effects on poly(vinyl chloride) (PVC) dehydrochlorination were the objectives of the present study. Magnesium stearate (MgSt(2)), cobalt stearate (CoSt(2)), and copper stearate (CuSt(2)) were prepared by a precipitation method. An aqueous sodium stearate (NaSt) solution was mixed at 500 rpm with respective metal salt solutions at 75 degrees C. The precipitates that formed were collected by filtration, washed with water, and ultimately dried at 105 degrees C under reduced pressure. Lamellar crystals that melted on heating were obtained. Solid-liquid phase transitions were observed by optical microscopy at 160 degrees C, 159 degrees C, and 117 degrees C for MgSt(2), CoSt(2), and CuSt(2), respectively. However, the melting points of MgSt(2), CoSt(2), and CuSt(2) were determined as 115 degrees C, 159 degrees C, and 111 degrees C, respectively, by analysis by differential scanning calorimetry. The onset temperature of the mass loss was the lowest at 255 degrees C for CuSt(2) and the lowest activation energy for thermal decomposition was 18 kJ/mol for CuSt(2). CoSt(2) was effective in extending the induction time of PVC dehydrochlorination at both 140 degrees C and 160 degrees C. The activation energy calculated from stability time decreased from 175 kJ/mol for a blank PVC sample to 114, 105, and 107 kJ/mol for MgSt(2), CoSt(2), and CuSt(2)-containing PVC samples, respectively. All three metal soaps accelerated the dehydrochlorination of PVC. (C) 2014 Society of Plastics Engineers |
|