A comparative study of thermal and morphological properties of polyhydroxybutyrate/bentonite clay and polyhydroxybutyrate/organically modified nanoclay composites

Abstract

Bacterial biopolymers are polymeric materials that are produced by microorganisms. Due to its inherent brittleness and slow crystallization rate, it has limited industrial applications. Polyhydroxybutyrate (PHB) composites have been created to tackle these problems by combining non‐modified clay and organically modified nanoclay. In this study, 3 wt % of two different kinds of clays were incorporated to PHB through melt mixing method to prepare composites of PHB/bentonite Clay (BC) and PHB/organically modified nanoclay (Cloisite 30B (C30B)). The characteristics of PHB and its composites were investigated to study their thermal, rheological, morphological, surface properties and biodegradability. The study showed that the incorporation of C30B and BC into the PHB matrix improved the crystallization temperature to 97.30 and 96.82°C respectively as compared to the crystallization temperature of the PHB matrix as 88.79°C. The increased result of storage modulus (G') and loss modulus (G") in its rheological analysis confirmed that there was proper melt intercalation in case of both PHB/C30B and PHB/BC composite. The morphological characteristics results provide less coagulation and good clay distribution over the polymer matrix which leads to improved contact angle of 66.60° and 68.15° in case of PHB/BC and PHB/C30B respectively. Further both the composites and PHB film showed biodegradation characteristics. In the realm of nanocomposite films for various applications, where the cost is the major consideration, the PHB/BC composite films are promising economical solution in place of high cost PHB/C30B nanocomposite films.Highlights The BC/PHB and C30B/PHB composite films were developed using a micro‐compounder. Each films having a thickness 0.6 mm was extruded using a die. Uniform dispersion of clay is characterized from SEM. PHB with clay, boosted complex viscosity, storage, and loss modulus. PHB decomposes readily in compost, as do PHB/C30B and PHB/BC composites.