Abstract

The effect of thermal oxidation on the crystalline phase of polypropylene in composites with single-walled carbon nanotubes has been studied. The composites are synthesized in propylene bulk using a homogeneous catalytic system rac-Me₂Si(2-Me-4PhInd)₂ZrCl₂, activated by methylaluminoxane. The effect of thermal oxidation on thermophysical characteristics (the heat of melting and the melting temperature) measured by DSC and changes occurring in the polymer investigated by IR spectroscopy is studied. Changes in the structure of PP during thermo-oxidative degradation are studied by DSC at 140 and 170°С, that is, before and after melting of the samples. It is shown that the oxidized PP in the composites possesses a higher degree of crystallinity and a more perfect structure than the pure PP. At 170°С the effect of thermo-oxidative stabilization is observed only at low filling degrees (up to 3 wt %), in agreement with the TGA data. An analysis of IR spectra demonstrates that the presence of nanotubes in PP‑based composites during oxidation slows down the formation of oxygen-containing groups in the polymer. The conclusion is made that carbon nanotubes inhibit the thermal oxidation of polypropylene in the composites.

中文翻译：

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氧化温度对单壁碳纳米管复合材料中聚丙烯晶相的影响

摘要

研究了热氧化对单壁碳纳米管复合材料中聚丙烯晶相的影响。该复合材料是使用均相催化系统rac -Me ₂ Si(2-Me-​​4PhInd) ₂ ZrCl _{2在丙烯本体中合成的}，由甲基铝氧烷活化。研究了热氧化对 DSC 测量的热物理特性（熔化热和熔化温度）的影响以及通过红外光谱研究聚合物中发生的变化。通过 DSC 在 140 和 170°С（即样品熔化之前和之后）研究了热氧化降解过程中 PP 结构的变化。结果表明，复合材料中的氧化PP比纯PP具有更高的结晶度和更完美的结构。在 170°С 下，仅在低填充度（最高 3 wt%）下观察到热氧化稳定效果，与 TGA 数据一致。红外光谱分析表明，氧化过程中聚丙烯基复合材料中纳米管的存在减缓了聚合物中含氧基团的形成。结论是碳纳米管抑制了复合材料中聚丙烯的热氧化。