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聚四氟乙烯在高温受热条件下发生解聚,并件有单体C_2F_4的析出,单体继续发生化学反应。本文用激波管实验方法研究了半径为10μm和70μm聚四氟乙烯粉粒在温度为1400K至3300K,时间为500μs条件下解聚机理和表面解聚速率常数的测定,给出了解聚速率常数ω_s=1.6exp(-18400/RT)克·厘米~(-2)·秒~(-1)这一结果与Steg与Lew的理论结果相比,表现激活能小了一半,而在这一温度范围内,绝对速率小四至五个量级。分析了这两个结果的差异,指出对于高温、大样品、短时间尺度来说,扩散阻滞和逆向解聚起了重要作用。
Polytetrafluoroethylene under high temperature heating conditions depolymerization, and the monomer C 2 F 4 precipitation, the monomer continues to occur chemical reaction. In this paper, the experimental study of shock tube with a radius of 10μm and 70μm polytetrafluoroethylene powder at a temperature of 1400K to 3300K, the time of 500μs under the conditions of the disaggregation mechanism and the surface of the rate of disaggregation was measured, the rate of disaggregation was given ω_s = 1.6exp (-18400 / RT) g · cm -2 (sec -1) This result shows that the activation energy is half as small as the theoretical results of Steg and Lew, and at this temperature Range, the absolute rate of small four to five orders of magnitude. The differences between these two results are analyzed, pointing out that diffusion retardation and reverse depolymerization play an important role in high temperature, large samples and short time scales.