Polyetherketone powder/epoxy blends with low viscosity and high mechanical properties

The difficult forming process and construction caused by high viscosity has been the main problem restricting the application of high-performance thermoplastic/epoxy blends. In this contribution, low viscous polyetherketone (PEK)/diglycidyl ether of bisphenol A epoxy resin (DGEBA) blends were prepared by mixing the ultrafine PEK powder and DGEBA monomer at ambient temperature. Rheological behaviour shows that complex viscosity of the undissolved blends containing 20 wt% PEK powder is two orders of magnitude lower than that of the dissolved one. Interestingly, diffusion and phase separation of PEK powder in the undissolved PEK/DGEBA/2-methylimidazole/dicyandiamide (M-DICY) blends are affected by the curing processes. Phase-inverted morphology was observed after curing at 120°C/1h + 160°C/0.5 h for the undissolved 20 wt% PEK/DGEBA/M-DICY blends which also exhibited outstanding tensile strength and lap shear strength both at 298 and 77 K. We believe this work should provide a new insight into the preparation of advanced thermoplastic/epoxy blends.

Nanomechanical Properties of a Bicomponent Epoxy Resin via Blending with Polyaryletherketone

In order to investigate the nanomechanical behaviors and nanotribological properties of bicomponent epoxy resin (BE) blends, which were filled with thermoplastic polyaryletherketone (PAEK) powders, nanoindentation and nanoscratch tests were performed. The brittle fractured morphologies of bicomponent epoxy resin blends were studied. The microhardness and elastic modules of the materials were measured using the nanoindentation technology. The hardness, elastic modulus, and other mechanical properties of materials on a nanoscale were determined. Nanoindentation and scratch experiments showed that the indentation response is dominated by plastic deformation. The microhardness is the lowest as the content of PAEK powders is increased to 30 parts per hundred parts of resin (phr), while that of the neat bicomponent epoxy resin specimen is the highest. Furthermore, the pristine bicomponent epoxy resin (BE) exhibited better load-carrying and indentation recovery capacity than the other three samples. The nanoscratch results indicate that the frictional coefficient of the BE/PAEK-30 blend is the lowest, and while that of the pristine bicomponent epoxy resin is the highest, with better scratch/wear resistance.

Phase separation behavior of poly(methyl methacrylate)/poly(styrene-co-maleic anhydride) in the presence of hollow silica nanotubes

The phase separation behavior of poly(methyl methacrylate) (PMMA)/poly(styrene-co-maleic anhydride) (SMA) blends with and without one-dimensional hollow silica nanotubes (HSNTs) was investigated using time-resolved small-angle laser light scattering. During isothermal annealing over a range of 100 °C above the glass transition temperature, the Arrhenius equation is applicable to describe the temperature dependence of phase separation behavior at the early and late stages of spinodal decomposition (SD) for unfilled and filled PMMA/SMA systems. The mechanical barrier effect of HSNTs on the macromolecular chain diffusion of the blend matrix may retard the concentration fluctuation at the early stage and slow down the domain coarsening at the late stage of SD phase separation for the blend matrix to result in the decrease of apparent diffusion coefficient D app, the postponement of the relaxation time and the decline of temperature sensitivity for the phase separation rate.