The rheological and morphological properties of the nanoclay-filled LDPE/PHB blends using LDPE-g-MAH as compatibilizer were determined. SEM data showed that the morphology was more sensitive to organoclay incorporation, compared to inclusion of the compatibilizer. Moreover, the results of image analysis and rheological studies indicated that nanoclay was located in the PHB phase after migrating from the LDPE phase, due to the thermodynamic and viscosity effects. The data obtained also showed that the stabilization mechanisms of PHB and LDPE matrix nanocomposites is due to coalescence prevention (due to the physical barrier) and alteration in the viscosity ratio of the phases, respectively. The obvious, pseudo-solid-like behavior over a wide range of frequencies in the PHB/LDPE/nanoclay systems demonstrated that the strong interaction between PHB/LDPE and nanoclay restricted the relaxation process of polymer chains. Therefore, PHB/LDPE/nanoclay was associated with a greater melt strength, which is essential for its favorable processability and applications. POLYM. COM-POS., 40:4125-4134, 2019.

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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.