埃洛石对硬质PVC材料的阻燃抑烟作用研究

Study on the Flame Retardant and Smoke Suppressive Effects of Halloysite on Rigid PVC Nanocomposites

摘要:

硬质PVC材料具有优异的物理机械性能、阻燃性能和烟雾释放性能，同时又可满足汽车轻量化需求，因此在汽车领域中得到广泛应用。虽然PVC材料具有先天的阻燃特性，但在燃烧过程中释放的烟雾较大，应尽可能降低其燃烧条件下的发烟性能。因此，研究硬质PVC的燃烧性能十分必要。采用熔融共混方法，分别制备了硬质PVC、硬质PVC/超细碳酸钙、硬质PVC/埃洛石纳米复合材料，并对他们的结构和性能进行了研究。结果表明，相较于普通的硬质PVC和硬质PVC/超细碳酸钙体系，硬质PVC/埃洛石纳米复合材料中的埃洛石纳米颗粒实现了纳米级分散，并在物理机械性能方面表现出良好的均衡性，其弯曲模量提高25%、弯曲强度提高6%、拉伸强度提高5%、冲击性能提高5%。此外，由于埃洛石具有中空管状结构及较高的比表面积，因而能有效吸收PVC分解第一阶段产生的自由基和HCl气体，提高材料的热稳定性。热失重分析和锥形量热仪的燃烧特性测试结果表明，相较于普通的硬质PVC和硬质PVC/超细碳酸钙材料，硬质PVC/埃洛石纳米复合材料的最大热失重温度提高了约9 ℃，热释放速率降低49%、点燃时间延长10 s、总生烟量减少40%及成碳层更加完整坚固。埃洛石在阻燃和抑烟方面具有优异的性能，5 份埃洛石纳米材料的引入，解决了硬质PVC材料在汽车轻量化过程中机械性能与阻燃性能间的矛盾，为天然一维纳米材料埃洛石在PVC阻燃抑烟改性中的应用奠定了基础。

Abstract:

When rigid PVC is widely used in the lightweight requirements of automobiles， it is crucial to consider not only the physical and mechanical properties but also the flame retardancy and smoke release characteristics of the system. This study used the melt blending method to prepare rigid PVC， rigid PVC/calcium carbonate， and rigid PVC/halloysite nanocomposites， and investigated their structure and properties. The results showed that compared to ordinary rigid PVC and rigid PVC/ calcium carbonate systems， the introduction of 5 phr halloysite nanomaterials resulted in nanoscale dispersion within the PVC matrix， as observed through SEM. This dispersion led to a balanced enhancement in physical and mechanical properties： bending modulus increased by 25%， bending strength by 6%， tensile strength by 5%， and impact performance by 5%. Additionally， the high specific surface area and hollow tubular structure of halloysite effectively absorbed free radicals and HCl gas generated during the initial stage of PVC decomposition， improving the thermal stability of PVC material. Thermogravimetric analysis indicated an increase in the maximum decomposition temperature by approximately 9 ℃. Specifically， the combustion characteristics tests using a cone calorimeter demonstrated that the heat release rate of the rigid PVC/halloysite nanocomposite decreased by 49%， ignition time was extended by 10 seconds， total smoke generation decreased by 40%， and carbon formation was more complete and sturdy. Halloysite exhibitedexcellent performance in flame retardancy and smoke suppression. This work effectively addresses the conflict between mechanical properties and flame retardancy in rigid PVC materials for automotive lightweighting applications by introducing 5 phr halloysite nanomaterials， laying the foundation for the application of natural one-dimensional nanomaterials like halloysite in PVC flame retardant and smoke suppression modifications.