Epoxy Composites Co-reinforced By Dimensionally Different Nanophases

The rapid development of aerospace, submarine, and weaponry industries raises anurgent need for lightweight materials with good comprehensive performance. Epoxynanocomposites hold great promise for meeting this need. They not only retain such epoxymerits as light total weight and high chemical resistance, but also obtain impressivelyenhanced mechanical, thermal, and barrier properties due to the incorporation ofnanoparticles. However, most epoxy nanocomposites now available only containnanoparticles of the same dimensionality. Although these nanocomposites can improve insome properties, the improvement is frequently accompanied by decrease in some otherproperties. So far, this compromise is still a problem that defies solution. In this study, anew strategy was presented to solve this problem that multiple dimensionally differentnanoparticles were co-incorporated into epoxy matrix. Through experimental andtheoretical exploration, the intended purpose was achieved.In this study, nanocomposites reinforced by nanoparticles of single dimensionalitywere prepared by separately incorporating zero-dimensional nanoSiO₂andtwo-dimensional montmorillonite (MMT) into epoxy resin, termedepoxy/zero-dimensional nanoSiO₂nanocomposite and epoxy resin/two-dimensional MMTnanocomposite, respectively. Nanocomposites reinforced by nanoparticles of two differentdimensionalities were prepared by co-incorporating zero-dimensional nanoSiO₂andtwo-dimensional MMT into epoxy resin, termed epoxy/zero-dimensionalnanoSiO₂/two-dimensional MMT nanocomposite. Thermogravimetric analysis (TGA),differential scanning calorimetry (DSC), mechanical property tests, X-ray diffraction(XRD), scanning electronic microscopy (SEM), and transmission electronic microscopy(TEM) were used to study the properties and structures of the nanocomposites, as well asexplore their enhancing mechanism. The results are as follows:The zero-dimensional nanoSiO₂reinforced epoxy/zero-dimensional nanoSiO₂nanocomposites exhibited enhancement in mechanical properties but decrease in thermalstability, when compared with pure epoxy.The two-dimensional MMT reinforced epoxy/two-dimensional MMTnanocomposites displayed improved thermal decomposition temperature, flexuralperformance, and impact performance, but showed declined glass transition temperatureand tensile strength in comparison with pure epoxy.As to the epoxy/zero-dimensional nanoSiO₂/two-dimensional MMT nanocomposites,co-reinforced by zero-dimensional nanoSiO₂and two-dimensional MMT, they obtainedgreatly improved thermal stability and mechanical properties compared with pure epoxy. Both thermal stability and mechanical properties of the epoxy/zero-dimensionalnanoSiO₂/two-dimensional MMT nanocomposites, which are reinforced by multipledimensionally different nanoparticles, were comprehensively and considerably higher thanthose of the epoxy/zero-dimensional nanoSiO₂nanocomposites andepoxy/two-dimensional MMT nanocomposites, which are reinforced by dimensionallysingle nanoparticles.Corresponding to the above performance variations, the three kinds of epoxynanocomposites showed significant differences in microstructure. In theepoxy/zero-dimensional nanoSiO₂nanocomposites, zero-dimensional nanoSiO₂particleswere unevenly distributed in the matrix, with some enriching regions present. In theepoxy/two-dimensional MMT nanocomposites, the two-dimensional MMT retainedlayered structure, forming typical intercalated nanocomposites. In theepoxy/zero-dimensional nanoSiO₂/two-dimensional MMT nanocomposites, thezero-dimensional nanoSiO₂particles were evenly distributed, and the MMT lost itslayered structure and was disassembled into individual nano-plateletts. Thezero-dimensional nanoSiO₂particles and the MMT nano-plateletts dispersed in the epoxymatrix in an interlacing manner and formed a new structure.The reasons for the considerable and comprehensive improvement in materialperformance, generated by co-reinforcement with nanoparticles of multiple dimensionalies,were investigated; the corresponding changes in material microstructure were alsoexplored. Through theoretical calculation, it was elucidated that the performanceimprovement is due to the distinctive microstructure of the epoxy/zero-dimensionalnanoSiO₂/two-dimensional MMT nanocomposites, and that this distinctive microstructureis derived from the interaction between the dimensionally different nanoparticles.The experimental and theoretical calculation results indicate that co-incorporation ofproper, dimensionally different nanoparticles into epoxy matrix is a successful way toprepare new comprehensive and high performance epoxy nanocomposites. Furthermore,this study provides a new path to comprehensive and high performance nanocompositedevelopment in the future.