A novel and facile nanoclay aerogel masterbatch toward exfoliated polymer-clay nanocomposites through a melt-mixing process

Abstract

This research employed a novel and facile approach called nanoclay aerogel masterbatch.. This innovative technique was conducted by attaching the clay layers directly onto a mobile polymer, for example, polyethylene glycol (PEG), in order to modify the clay layer through PEG-clay intercalation and PEG-hydrogen bonding. This state was maintained with a small amount of the anionic polymer hydrogel, for example, kappa-carrageenan (KC), and turning it into a highly porous and fragile structure by freeze-drying, thus a so-called nanoclay aerogel masterbatch. The facile nanoclay aerogel masterbatch was able to be attained even at high clay loadings (55–67 wt.% of the inorganic clay content) with constant PEG and KC loadings. The interlayer spacing enlargement of the nanoclay galleries was around 17 Å with the typical lamellar morphology like a house of cards structure. The density values were within 0.108–0.122 g·cm−3. The thermal stabilities were up to 270°C, revealing better thermal stability for melt mixing with the commodity plastics at a high melting temperature. The flowability and processability were certified by the melt flow index (MFI) results. The highest nanoclay loading capacity (67 wt.%) of the achieved nanoclay aerogel masterbatch was selected to prepare PS-clay nanocomposites via a melt-mixing process. The comparative nanocomposites were produced by using organoclay. The results of the X-ray diffraction (XRD) and transmission electron microscopy (TEM) exhibited that the exfoliated morphologies were obtained at all clay contents (1–3 wt.%); however, the intercalated structure was gained by using organoclay. The outstanding transparency and brightness were remarked from the specimens prepared by using the nanoclay aerogel masterbatch. The brownish specimens were observed by using organoclay. The significant improvements of tensile properties, glass transition temperature (Tg), and thermal stability were noticed from the nanocomposites prepared using the nanoclay aerogel masterbatch.