The kinetics of suspended emulsion polymerization of methyl methacrylate (MMA), in which water acted as the dispersed phase and the mixture of NMA and cyclohexane as the continuous phase, was investigated. It showed t...The kinetics of suspended emulsion polymerization of methyl methacrylate (MMA), in which water acted as the dispersed phase and the mixture of NMA and cyclohexane as the continuous phase, was investigated. It showed that the initial polymerization rate (R-p0) and steady-state polymerization rate (R-p) were proportional to the mass ratio between water and oil phase, and increased as the polymerization temperature, the potassium persulphate concentration ([I]) and the Tween20 emulsifier concentration ([S]) increased. The relationships between the polymerization rate and [I] and [S] were obtained as follows: R-p0 proportional to [I](0.73)[S](0.32) and R-p proportional to [I](0.71)[S](0.23). The above exponents were close to those obtained from normal MMA emulsion polymerization. It also showed that the average molecular weight of the resulting poly(methyl methacrylate) decreased as the polymerization temperature, [I] and [S] increased. Thus, MMA suspended emulsion polymerization could be considered as a combination of many miniature emulsion polymerizations proceeding in water drops and obeyed the classical kinetics of MMA emulsion polymerization.展开更多
Car headlight plastic as a kind of evidence often can be seen in traffic accidents and some other cases.We tested 20 brands of car headlight plastic using gel chromatography.The data were processed using the Statistic...Car headlight plastic as a kind of evidence often can be seen in traffic accidents and some other cases.We tested 20 brands of car headlight plastic using gel chromatography.The data were processed using the Statistical Package for the Social Sciences(SPSS)one‑way analysis of variance(ANOVA)and the discrimination rate was 97.14%.This indicated that we could discriminate between different headlights by the molecular weight of their headlight plastic.Gel permeation chromatography is an effective method of discriminating between headlights,particularly in the case of a traffic accident.展开更多
基金This work was supported by the National Natural Science Foundation of China (No. 29906009).
文摘The kinetics of suspended emulsion polymerization of methyl methacrylate (MMA), in which water acted as the dispersed phase and the mixture of NMA and cyclohexane as the continuous phase, was investigated. It showed that the initial polymerization rate (R-p0) and steady-state polymerization rate (R-p) were proportional to the mass ratio between water and oil phase, and increased as the polymerization temperature, the potassium persulphate concentration ([I]) and the Tween20 emulsifier concentration ([S]) increased. The relationships between the polymerization rate and [I] and [S] were obtained as follows: R-p0 proportional to [I](0.73)[S](0.32) and R-p proportional to [I](0.71)[S](0.23). The above exponents were close to those obtained from normal MMA emulsion polymerization. It also showed that the average molecular weight of the resulting poly(methyl methacrylate) decreased as the polymerization temperature, [I] and [S] increased. Thus, MMA suspended emulsion polymerization could be considered as a combination of many miniature emulsion polymerizations proceeding in water drops and obeyed the classical kinetics of MMA emulsion polymerization.
文摘Car headlight plastic as a kind of evidence often can be seen in traffic accidents and some other cases.We tested 20 brands of car headlight plastic using gel chromatography.The data were processed using the Statistical Package for the Social Sciences(SPSS)one‑way analysis of variance(ANOVA)and the discrimination rate was 97.14%.This indicated that we could discriminate between different headlights by the molecular weight of their headlight plastic.Gel permeation chromatography is an effective method of discriminating between headlights,particularly in the case of a traffic accident.
