Bio-based solution-cast blend films based on polylactic acid and polyhydroxybutyrate: Influence of pyromellitic dianhydride as chain extender on the morphology, dispersibility, and crystallinity

Bio-based solution-case blend films are a particular class of materials used in various fields such as coatings and their use is taking big steps in view of their eco-friendly nature. Blend of biopolymers can bring about complementary properties for replacing the petroleum-based polymer with renewable ones to minimize the environmental damaging. In this work, bio-based solution-case blend films based on PLA and PHB are prepared and characterized. The thermal, crystallinity and morphology of the cast films are studied as well. Bio-based blends of polyhydroxybutyrate and polylactic acid (PHB/PLA) films were prepared via solvent-cast method and PDMA was utilized as chain extender. FTIR, DSC, WARD and SEM analyses were performed for evaluating the properties under the influence of PDMA. A fall in glass transition temperature was observed upon increasing PDMA content which exhibited good correlation with Fox Equation. PMDA due to the ring opening substitution from carbonyl group coupled to both polymers, hence, affected the crystallinity. Addition of PDMA exhibited gigantic effect on the crystallization behavior/rate of samples. Due to this behavior, film properties can be adjusted by altering the PMDA content. The results of this work can be applied in developing bio-coatings based on blends of other types of biopolymers.