Isothermal crystallization kinetics of pure and surface-modified silica/high-density polyethylene nanocomposites

The isothermal crystallization kinetics of high-density polyethylene (HDPE) nanocomposites containing 0, 0.5, 0.75, and 2 wt% of pure and surface-modified silica were evaluated at three crystallization temperatures (Tc) of 120 degrees C, 121 degrees C, and 122 degrees C using differential scanning calorimetry (DSC) and applying Avrami, Tobin, and Malkin equations. According to Hoffman-Weeks theory, the values of the equilibrium melting point (Tm degrees$$ {T}_{\mathrm{m}}<^>{{}<^>{\circ}} $$) of the nanocomposites decreased with increasing nanoparticle content and were higher in the samples containing AMS nanoparticles, owing to the larger crystal. The results of all three models offered the same trend according to which the change in the crystallization temperature influenced the nucleation mechanism and the crystallization rate. It was found that a greater number of spherulites can be formed via increasing Tc from 120 degrees C to 122 degrees C which also decreased the crystallization rate of the nanocomposites. At the crystallization temperature of 122 degrees C, the lowest melting temperature was recorded for the samples, attributed to the formation of more crystals with a lower thickness. Moreover, in HDPE/AMS nanocomposites, the crystallization rate was higher than that of HDPE/PSN, ascribed to the positive effect of surface modification on nanoparticles.HighlightsIncreased polymer/particle compatibility and isothermal crystallization.Evaluating the nucleation and crystallization using different models.The impact of isothermal crystallization temperature on crystallinity.Variation of equilibrium melting point with the nanoparticle content. The addition of compatible/un-compatible silica nanoparticles to high-density polyethylene considerably affects the isothermal crystallization process, based on how nanoparticles interact with the surrounding matrix and/or other particles. It was found that the content and dispersion quality of different types of nanoparticles may substantially alter the structure of formed crystals, crystallinity degree and melting point of the samples.image

Automated summary

This study evaluated the isothermal crystallization kinetics of high-density polyethylene (HDPE) nanocomposites containing different weight percentages of pure and surface-modified silica nanoparticles. The results showed that the crystallization temperature influenced the nucleation mechanism and the crystallization rate. The addition of compatible/un-compatible silica nanoparticles significantly affected the isothermal crystallization process, and surface modification had a positive effect on the crystallization rate of the nanoparticles.