Ongaro Greta, Pontefisso Alessandro, Zeni Elena, Lanero Francesco, Famengo Alessia, Zorzi Federico, Zaccariotto Mirco, Galvanetto Ugo, Fiorentin Pietro, Gobbo Renato, Bertani Roberta, Sgarbossa Paolo
Department of Structural and Geotechnical Engineering, Sapienza University of Rome, v. A. Gramsci 53, 00197 Rome, Italy.
Department of Management and Engineering, University of Padova, Stradella San Nicola 3, 36100 Vicenza, Italy.
Polymers (Basel). 2023 Mar 15;15(6):1456. doi: 10.3390/polym15061456.
Two nanomicas of similar composition, containing muscovite and quartz, but with different particle size distributions, have been used to prepare transparent epoxy nanocomposites. Their homogeneous dispersion, due to the nano-size, was achieved even without being organically modified, and no aggregation of the nanoparticles was observed, thus maximizing the specific interface between matrix and nanofiller. No exfoliation or intercalation has been observed by XRD, despite the significant dispersion of the filler in the matrix which produced nanocomposites with a loss in transparency in the visible domain of less than 10% in the presence of 1% wt and 3% wt of mica fillers. The presence of micas does not affect the thermal behavior of the nanocomposites, which remains similar to that of the neat epoxy resin. The mechanical characterization of the epoxy resin composites revealed an increased Young's modulus, whereas tensile strength was reduced. A peridynamics-based representative volume element approach has been implemented to estimate the effective Young's modulus of the nanomodified materials. The results obtained through this homogenization procedure have been used as input for the analysis of the nanocomposite fracture toughness, which has been carried out by a classical continuum mechanics-peridynamics coupling approach. Comparison with the experimental data confirms the capability of the peridynamics-based strategies to properly model the effective Young's modulus and fracture toughness of epoxy-resin nanocomposites. Finally, the new mica-based composites exhibit high values of volume resistivity, thus being excellent candidates as insulating materials.
两种成分相似、含有白云母和石英但粒径分布不同的纳米云母已被用于制备透明环氧纳米复合材料。由于其纳米尺寸，即使未经有机改性也能实现均匀分散，且未观察到纳米颗粒的聚集，从而使基体与纳米填料之间的特定界面最大化。尽管在1%重量和3%重量的云母填料存在下，填料在基体中显著分散，导致纳米复合材料在可见光范围内透明度损失小于10%，但XRD未观察到剥离或插层现象。云母的存在不影响纳米复合材料的热行为，其热行为与纯环氧树脂相似。环氧树脂复合材料的力学表征显示杨氏模量增加，而拉伸强度降低。已采用基于近场动力学的代表性体积单元方法来估计纳米改性材料的有效杨氏模量。通过这种均匀化程序获得的结果已用作分析纳米复合材料断裂韧性的输入，该分析通过经典的连续介质力学-近场动力学耦合方法进行。与实验数据的比较证实了基于近场动力学的策略能够正确模拟环氧树脂纳米复合材料的有效杨氏模量和断裂韧性。最后，新型云母基复合材料表现出高体积电阻率值，因此是优异的绝缘材料候选者。
