Graphene-polymer nanocomposites have attracted considerable attention due to their unique properties, such as high thermal conductivity (~3000 W mK-1), mechanical stiffness (~ 1 TPa) and electronic transport properties. Relatively, the thermal performance of graphene-polymer composites has not been well investigated. The major technical challenge is to understand the interfacial thermal transport between graphene nanofiller and polymer matrix at small material length scale. To this end, we conducted molecular dynamics simulations to investigate the thermal transport in graphene-polyethylene nanocomposite. The influence of functionalization with hydrocarbon chains on the interfacial thermal conductivity was studied, taking into account of the effects of model size and thermal conductivity of graphene. The results are considered to contribute to development of new graphene-polymer nanocomposites with tailored thermal properties.
Adequate amount of graphene oxide (GO) was firstly prepared by oxidation of graphite and GO/epoxy nanocomposites were subsequently prepared by typical solution mixing technique. X-ray diffraction (XRD) pattern, X-ray photoelectron (XPS), Raman and Fourier transform infrared (FTIR) spectroscopy indicated the successful preparation of GO. Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) images of the graphite oxide showed that they consist of a large amount of graphene oxide platelets with a curled morphology containing of a thin wrinkled sheet like structure. AFM image of the exfoliated GO signified that the average thickness of GO sheets is ~1.0 nm which is very similar to GO monolayer. Mechanical properties of as prepared GO/epoxy nanocomposites were investigated. Significant improvements in both Young’s modulus and tensile strength were observed for the nanocomposites at very low level of GO loading. The Young’s modulus of the nanocomposites containing 0.5 wt% GO was 1.72 GPa, which was 35 % higher than that of the pure epoxy resin (1.28 GPa). The effective reinforcement of the GO based epoxy nanocomposites can be attributed to the good dispersion and the strong interfacial interactions between the GO sheets and the epoxy resin matrices.
A key step towards the commercialization of microstructured polymer optical fibers is the ability to cleave and splice
them. The cleaving of polymer optical fiber (whether by cutting or fracture) depends upon the mechanical properties of
the material. These in turn depend on the conditions under which the fiber is drawn from the preform. The relationship
between fiber draw conditions, mechanical properties of the drawn fiber and the ability to cut the heated fiber with a hot
razor blade has been investigated for PMMA fibers of varying hole structure. Differential scanning calorimetry measurements
indicate that the type of PMMA used exhibits two 'relaxations' with inflexion points at 115±3oC and 80±2oC
respectively, independent of draw conditions. The first of these is in the range expected for the α-relaxation. The origin
of the second is unknown. Dynamic mechanical analysis of fiber samples indicates that the temperature dependence of
the elastic and loss moduli of the fiber vary significantly with draw conditions. The end-face produced by cutting with a
razor blade also varies with draw conditions. Fiber drawn under high tension splinters during cutting and fiber drawn
under low tension undergoes ductile deformation and fracture. However for intermediate draw conditions the fiber can
be cleanly cut with a razor blade at a temperature of 80±10oC.