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首页> 外文期刊>Polymer Degradation and Stability >Thermal stability and fire retardant performance of photo-oxidized nanocomposites of polypropylene-graft-maleic anhydride/clay
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Thermal stability and fire retardant performance of photo-oxidized nanocomposites of polypropylene-graft-maleic anhydride/clay

机译：聚丙烯接枝马来酸酐/粘土光氧化纳米复合材料的热稳定性和阻燃性能

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Polypropylene-graft-maleic anhydride (PPgMA)/montmorillonite nanocomposites have been prepared using direct melt intercalation techniques (extrusion and injection molding). Characterization of the nanocomposites, performed with X-ray diffraction and transmission electronic microscope techniques, suggested an importance of the mode of preparation and the type of organic modification that was used in the montmorillonite on the dispersability of clay in the polymer matrix. Injected mold nanocomposites were generally exfoliated in opposite to extruded samples that presented different structures (exfoliated, immiscible). Thermal degradation and fire behaviour of the corresponding nanocomposites displayed an improvement in comparison to pure PPgMA; this improvement was more important for injected mold specimen than for the extruded ones. It was ascribed to the presence of clay layers which act as diffusion barriers and reduced the mass loss; results that got the support of Limiting Oxygen Index measurements. A deterioration of these properties was observed on UV-irradiated nanocomposites. This was ascribed to the generation of weak points issue from the photo-oxidation reactions that take place mainly on the sample surface as shown in the oxidation profile. The oxygen starvation and reduced radical mobility, due to the presence of clay platelets, are blamed to be responsible for this oxidation profile. On the other hand, pure PPgMA showed an outstanding improvement of the fire behaviour with ageing time. Improvement that was attributed to cross-linking reactions which create a compact structure that is less inclined to volatilize.
机译：聚丙烯接枝马来酸酐（PPgMA）/蒙脱土纳米复合材料已使用直接熔融插层技术（挤出和注塑）制备。用X射线衍射和透射电子显微镜技术对纳米复合材料进行表征，表明了蒙脱石中制备方式和有机改性类型对粘土在聚合物基体中的分散性的重要性。注射的模具纳米复合材料通常与呈现不同结构（剥离，不混溶）的挤压样品相反地剥离。与纯PPgMA相比，相应纳米复合材料的热降解和着火行为显示出改善。与注塑成型的样品相比，这种改进对注模样品更为重要。这归因于粘土层的存在，它们充当了扩散的屏障并减少了质量损失。结果得到了极限氧指数测量的支持。在紫外线辐射的纳米复合材料上观察到这些性能的下降。这归因于主要发生在样品表面的光氧化反应所产生的弱点，如氧化曲线所示。归因于粘土薄片的存在，缺氧和自由基迁移率降低是造成这种氧化现象的原因。另一方面，纯PPgMA表现出随老化时间的着火性能的显着改善。归因于交联反应的改进，该交联反应产生了不易挥发的紧凑结构。

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