Nanostructure, dynamics, and mechanical properties of nanocomposites based on polyurethane-poly (2-hydroxyethyl methacrylate) semi-interpenetrating polymer network with ultra-low MWCNT contents

Nanocomposites based on polyurethane-poly(2-hydroxyethyl methacrylate) semi-interpenetrating polymer network (PU-PHEMA semi-IPN) doped with 0.01, 0.05, 0.1, or 0.25 wt% of non-functionalized multi-walled carbon nanotubes (MWCNTs) were synthesized. Their nanostructure was studied by small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) techniques, and their dynamics and properties were characterized over the temperature range from -100 degrees C to 180 degrees C using dynamic mechanical analysis (DMA) and laser-interferometric creep rate spectroscopy (CRS). It was shown that ultra-low MWCNT contents (0.01%-0.1%) substantially modified matrix nanostructure due to the influence of nanofiller on the processes of micro-phase separation and mixing of matrix components, the changes in the molecular packing density, and good dispersion of MWCNTs. The structural changes were somewhat smaller at 0.25% nanotubes where tendency to formation of their aggregates was observed. Accordingly, the strong changes in dynamic behavior, elastic properties and creep resistance in the studied materials were caused by ultra-low MWCNT additives. The strong effect of extraordinary broadening of the PHEMA relaxation peak in the nanocomposites and, simultaneously, the strongly improved creep resistance over the 80 degrees C-160 degrees C temperature range (at 0.1% MWCNTs) were shown that is of importance for the application of these nanocomposites as perspective damping materials. POLYM. COMPOS., 39:263-273, 2018. (c) 2016 Society of Plastics Engineers