The effects of PHB-g-MA types on the mechanical, thermal, morphological, structural, and rheological properties of polyhydroxybutyrate biopolymers

Abstract

This study investigates the grafting of polyhydroxybutyrate (PHB) chains with maleic anhydride (MA) in concentrations ranging from 5 % to 10 % by weight. This process was conducted during microwave treatment and using a reactive extruder, employing benzoyl peroxide (BPO) as the initiator. The impact of these methods on PHB's overall properties was thoroughly investigated. In the study, PHB–g–MA was incorporated into neat PHB via the extrusion process at a 5 % loading rate. Notably, the mechanical properties exhibited an increase in the presence of PHB–g–MA, likely due to morphological improvements in the neat PHB, as indicated by morphological characterization. X-ray diffraction results indicated crystallinity percentages increase with the addition of MA. Differential scanning calorimetry revealed minimal variation in melting and crystallization temperatures when PHB–g–MA was included. Both storage and loss moduli were enhanced by the incorporation of PHB–g–MA, and the blends exhibited consistent tan delta values. Regarding rheological properties, the storage and loss moduli of PHB blends containing PHB–g–MA blends were observed to rise with rising frequency values. Based on these results, the microwave process was identified as the most effective method for grafting.