PVC搪塑粉的热降解特征及其动力学研究

摘要

Pyrolysis gas chromatography/mass spectrometry is used to analyze the pyrolysis products of PVC slush powder. Combined with thermal gravimetric analysis, the thermal degradation characteristics are studied. The effects of heating rate, atmosphere and slush molding on the process are discussed, and with X-ray fluorescence spectrum, the degradation kinetics is also analyzed. The results indicate that the degradation process of PVC slush powder can be divided into three stages, the first stage is caused by dehydrochlorination of PVC and evaporation of plasticizer. The interaction between PVC and plasticizer makes the process more complicated. Heating rate and atmosphere affects greatly the powder pyrolysis. The stability of the polymer-based skins is improved because plasticizer can act as a protection coating of the PVC macromolecules. The study on the kinetics at the first stage reveals that the activation energy and reaction order are smaller in nitrogen than in oxygen-containing atmosphere.%粉末搪塑表皮被广泛应用在各种中高档汽车仪表板上。为了优化设计搪塑粉、提高热加工性能从而促进高档汽车国产化，本文首先利用热重分析和裂解气相色谱/质谱实验探讨搪塑粉的热降解失重特征，分析升温速率、实验气氛和搪塑加工对其热降解行为的影响，继而结合X射线荧光光谱实验对其热降解动力学进行研究。结果表明：搪塑粉的热降解过程可分为3个阶段，PVC和增塑剂的相互作用使其热降解过程更加复杂；随升温速率的增加，热降解失重曲线向高温区偏移；搪塑粉在有氧气氛中更易发生热降解，失重率较大；与搪塑粉相比，搪塑表皮的热稳定性能得到一定程度的提升；第1热降解阶段氮气条件下的热降解活化能和反应级数较小。