Morphology and viscoelastic properties of UV cured-polyurethane acrylate/silicon carbide nanocomposites

Abstract

The viscoelastic properties of semi-conductive UV cured urethane acrylate/silicon carbide nanocomposites (UV-PUA/SiC) containing 0.1, 0.3, 0.6, 1, 3, and 5% (wt) of SiC are studied. Scanning electron microscopy (SEM) was employed to examine the state of the spatial distribution of SiC particles in the matrix. In conjunction with the electron microscopy technique, dynamic mechanical thermal analysis (DMTA) was employed as an indirect tool for the microstructure characterization and evaluation of the network heterogeneity and cross-link density of the nanocomposites. The influence of SiC nanoparticles on the storage modulus, loss modulus, cross-link density, glass transition temperature, and activation energy for glass transition of the UV-PUA matrix are investigated. The effect of SiC content on the network structures and degree of curing of the nanocomposites was evaluated by William-Landel-Ferry (WLF) constants. The breadth of the glass transition in the tanδ curve and shape parameter (β) in the Kolrausch-Williams-Watts (KWW) equation were used to investigate the network heterogeneity of the samples. All these referred parameters increased with SiC nanoparticles loading up to 0.6% (wt). In contrast, upon introducing SiC at higher concentrations, the viscoelastic properties of the nanocomposites reduced significantly. SEM analysis was used to evaluate the DMTA results regarding the dispersion state of the nanoparticles in the matrix.