Fundamental study of mutual separation of waste prastic using critical surface tension.

以湿润剂强化伽马浮选分离废塑料为研究对象，进行了基础研究。研究中使用了含有几种商品润湿剂的聚氯乙烯和聚酯平板。根据测定的表面张力g和接触角q，绘制了不同浓度的润湿剂溶液的Zismann曲线，将Zismann曲线外推到q=1，计算出PVT和PET的临界表面张力分别为38.7mN/m和39.5mN/m。两种样品的临界表面张力均为-45mN/m，表现出更强的亲水性。单宁酸对其溶液在聚氯乙烯上的接触角的转化率远小于蒸馏水。用化学分析方法测定了PVA和单宁酸的吸附性能，并在润湿剂存在下对PVC和PET进行了伽玛浮选。在回复率与条件溶液表面张力的关系中，还得到了临界表面张力，即各样品的回复率将急剧下降的点。在伽马浮选中，除样品本身的表面性质外，取决于润湿剂的气泡行为也会影响回收率。

The basic research was aimed at separation of waste plastics through gamma flotation enhanced with wetting agents. Plates of PVC and PET with several commercial wetting agents were used in the investigation. Zismann plot was drawn for solution of each wetting agent with a series of concentration, based on measured surface tension g and contact angle q on PVC or PET.Critical surface tension of PVC and PET was calculated by extrapolating the curve of Zismann plot to q =1. Resulting values for critical surface tension were 38.7mN/m forPVTand39.5mN/m for PET.When PVA solution was used. the two samples yielded similar result for critical surface tension as -45 mN/m, showing more hydrophillic property. Tannic acid was found to convert contact angle of the its solution on PVC much smaller than that of distilled water. Adsorption of PVA and tannic acid was also experimentally measured by chemical analysis.Gamma flotation was performed for PVC and PET in the presence of wetting agents. Critical surface tension was also attained as a point which recovery of each samples would fall drastically in the relation between recovery and surface tension of the conditioned solution. In gamma flotation behavior of bubbles dependent on wetting agents would also affect recovery, apart from surface property of the samples themselves.