废旧PVC塑料制备PVC沥青的研究

Study on Preparing PVC-Dased-Pitch from Wasted PVC Plastics

以废旧聚氯乙烯(PVC)塑料为原料,采用两阶段恒温法制备PVC沥青,通过正交实验,确定制备PVC沥青的最优条件.采用热重分析、红外光谱分析和软化点分析等测定结果,初步分析PVC沥青的形成机理.研究结果表明,对于所选择的废旧PVC塑料,第一恒温阶段主要是通过热解脱除氯化氢阶段,该阶段的最佳温度为270℃,最佳恒温保持时间为150 min,在此条件下废旧PVC塑料的HCl脱除率可高达95%.在第二恒温阶段中,脱HCl后的PVC中C=C烯烃链段结构被破坏,经氧化、交联、重整,重新形成脂肪族、芳香族类物质.该阶段的最佳温度为410℃、保持时间以120 min为宜.

Wasted polyvinychlorid （PVC） plastics was used as raw materials, PVC based pitch was prepared by two phase＇s isothermal method; using orthogonal experiments, the pptimum preparation conditions were investigated. Thermogravimetry （TG）, Fourier transform infrared （FTIR） arid soften point measurement were used to discuss the mechanism of reforming PVC into pitch. The results showed that dehydrochlorination of the wasted PVC predominantly taken place in the first thermal treatment stage. Under the optimum conditions as of 270℃ and 150 rain of retention time, the dehydrochlorination ratio is as high as 95 %. In the second thermal treatment process, dehydrochlorided PVC is preoxidated in air, the structure of C=C is destroyed, cross-linked , and reformed into alicyclic and/or aromatic compounds. The optimum conditions for the second process are： 410℃ of temperature with 120 min of retention time,