Thermally stable low‐density polyethylene/polyhydroxybutyrate pairs: Synergy between organomodified nanoclay and LDPE‐g‐MAH

Abstract

Nanocomposites of low‐density polyethylene/polyhydroxybutyrate (LDPE/PHB) containing organomodified montmorillonite (OMMT) and/or LDPE grafted maleic anhydride (LDPE‐g‐MAH) were prepared with a wide range of composition ratios using a vertical co‐rotating twin‐screw microCompounder. To infer the effect of OMMT and LDPE‐g‐MAH on the thermal stability of prepared nanocomposites, all samples were characterized by thermogravimetric analysis while changing clay and compatibilizer contents. Accordingly, two commonly used kinetic models (Coats–Redfern and Horowitz–Metzger) were employed to correlate the thermal stability of the samples with kinetic parameters, including activation energy and pre‐exponential factor. Furthermore, morphological features of LDPE/PHB in the presence or absence of OMMT and LDPE‐g‐MAH were studied using scanning electron microscopy, transmission electron microscopy, and wide‐angle X‐ray diffraction analysis. It was found that for a specific OMMT composition ratio (1 wt %), the thermal stability is enhanced due to an exfoliated structure. However, for samples containing more organoclay (>=3 wt %), the thermal stability was reduced showing the competition between the barrier effect of organoclay platelets and the catalyzing effect of ammonium salts. Moreover, when using LDPE‐g‐MAH as compatibilizer, it acted as a good coupling agent in all compositions in LDPE major phase systems in contrast to PHB major phase samples. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45922.

Microstructure effects on the rheology of nanoclay‐filled PHB/LDPE blends

“…We have previously demonstrated the effects of organoclay Cloisite 10A on PHB thermal degradation kinetics [14] and also PHB crystallization kinetics in PHB/LDPE/clay nanocomposites [24]. In the present work, rheological measurements were utilized as the powerful tools for studying nanoclay dispersion level and localization within a multicomponent PHB/LDPE/compatibilizer/clay system.…”

“…Blending is a successful and cheap method to overcome such processing difficulties [12]. To improve its thermal stability, the effects of organoclays and other additives on PHB thermal degradation kinetics have been extensively reported, and some interesting results have been obtained [9,13,14]. Aiming at controlling brittleness, PHB crystallization kinetics have been studied, and the effects of blending with other polymers and organoclay incorporation have been well documented [15,16].…”