天然石膏的改性

Modification of nature gypsum

为了改善石膏与树脂的相容性,以硬脂酸为改性剂对天然石膏进行表面湿法改性,考察石膏表面改性中改性剂用量、温度、时间及pH值等因素对活化指数的影响。结果表明:硬脂酸用量6%、温度60℃、时间40min、pH7条件下获得的改性石膏的活化指数达100%.通过红外光谱分析表明,改性剂与石膏表面形成化学吸附.对天然石膏改性前后的接触角、相容性分析,发现改性天然石膏的表面接触角由35.64°增加到87.47°,改性石膏与液体石蜡的相容性良好.改性石膏填充聚甲基丙烯酸甲酯树脂表明,改性天然石膏/聚甲基丙烯酸甲酯树脂复合材料的透过率高于天然石膏/聚甲基丙烯酸甲酯树脂复合材料.

To improve the compatibility of gypsum and resin ,the surface modification of natural gypsum by stearic acid was investigated .The effects of parameters of the surface modification of natural gypsum including dosage of reagents ,temperature ,time and pH on activation index were discussed .The results show that the activation index of modified gypsum reaches 100% as the stearic acid dosage of 6% ,the temperature of 60℃ ,the time of 40min and pH of 7 .The Fourier Transform Infrared demonstrates that chemical adsorption is formed between natural gypsum and stearic acid .The contact angel of gyp-sum increases from 35 .64° to 87 .47° and the compatibility between gypsum and atoleine gets much bet-ter after modification .The transparence of modificated gypsum/methyl methacrylate polymer compos-ites is better than that of untreated gypsum/methyl methacrylate polymer composites .