Department of Civil and Environmental Engineering, Faculty of Engineering, National University of Singapore, Singapore 117576, Singapore.
Department of Chemistry, Amirkabir University of Technology, Tehran 15875-4413, Iran.
Molecules. 2021 Mar 13;26(6):1597. doi: 10.3390/molecules26061597.
The incorporation of nanofillers such as graphene into polymers has shown significant improvements in mechanical characteristics, thermal stability, and conductivity of resulting polymeric nanocomposites. To this aim, the influence of incorporation of graphene nanosheets into ultra-high molecular weight polyethylene (UHMWPE) on the thermal behavior and degradation kinetics of UHMWPE/graphene nanocomposites was investigated. Scanning electron microscopy (SEM) analysis revealed that graphene nanosheets were uniformly spread throughout the UHMWPE's molecular chains. X-Ray Diffraction (XRD) data posited that the morphology of dispersed graphene sheets in UHMWPE was exfoliated. Non-isothermal differential scanning calorimetry (DSC) studies identified a more pronounced increase in melting temperatures and latent heat of fusions in nanocomposites compared to UHMWPE at lower concentrations of graphene. Thermogravimetric analysis (TGA) and derivative thermogravimetric (DTG) revealed that UHMWPE's thermal stability has been improved via incorporating graphene nanosheets. Further, degradation kinetics of neat polymer and nanocomposites have been modeled using equations such as Friedman, Ozawa-Flynn-Wall (OFW), Kissinger, and Augis and Bennett's. The "Model-Fitting Method" showed that the auto-catalytic nth-order mechanism provided a highly consistent and appropriate fit to describe the degradation mechanism of UHMWPE and its graphene nanocomposites. In addition, the calculated activation energy (E) of thermal degradation was enhanced by an increase in graphene concentration up to 2.1 wt.%, followed by a decrease in higher graphene content.
将纳米填料（如石墨烯）掺入聚合物中，已显示出对所得聚合物纳米复合材料的机械性能、热稳定性和导电性的显著改善。为此，研究了将石墨烯纳米片掺入超高分子量聚乙烯（UHMWPE）中对 UHMWPE/石墨烯纳米复合材料热行为和降解动力学的影响。扫描电子显微镜（SEM）分析表明，石墨烯纳米片均匀地分布在 UHMWPE 的分子链中。X 射线衍射（XRD）数据表明，分散在 UHMWPE 中的石墨烯片的形态为剥离型。非等温热重分析（DSC）研究表明，与 UHMWPE 相比，在较低浓度的石墨烯时，纳米复合材料的熔融温度和熔融潜热明显升高。热重分析（TGA）和导数热重（DTG）表明，通过掺入石墨烯纳米片提高了 UHMWPE 的热稳定性。此外，使用 Friedman、Ozawa-Flynn-Wall（OFW）、Kissinger 和 Augis 和 Bennett 等方程对纯聚合物和纳米复合材料的降解动力学进行了建模。“模型拟合方法”表明，自催化 n 级机制提供了高度一致和合适的拟合，以描述 UHMWPE 及其石墨烯纳米复合材料的降解机制。此外，随着石墨烯浓度的增加，热降解的计算活化能（E）增加到 2.1wt.%，随后在更高的石墨烯含量下降低。
