The plastic waste problem has recently attracted unprecedented attention globally. To reduce the adverse eff ects on environments, biodegradable polymers have been studied to solve the problems. Poly(ε-caprolactone) (PCL) is one of the common biodegradable plastics used on its own or blended with natural polymers because of its excellent properties after blending. However, PCL and natural polymers are difficult to blend due to the polymers’ properties. Grafted polymerization of maleic anhydride and dibenzoyl peroxide (DBPO) with PCL is one of the improvements used for blending immiscible polymers. In this study, we first focused on the effects of three factors (stirring time, maleic anhydride (MA) amount and benzoyl peroxide amount) on the grafting ratio with a maximum value of 4.16% when applying 3.000 g MA and 1.120 g DBPO to 3.375 g PCL with a stirring time of 18 h. After that, the grafting condition was studied based on the kinetic thermal decomposition and activation energy by the Coats–Redfern method. The optimal fitting model was confirmed by the determination coefficient of nearly 1 to explain the contracting volume mechanism of synthesized PCL-g-MA. Consequently, grafted MA hydrophilically augmented PCL as the reduced contact angle of water suggests, facilitating the creation of a plastic–biomaterial composite.

Plastic waste is a global issue because it causes overflowing landfills and pollution, leading to environmental concerns. To address this crisis, materials that can be decomposed in the natural environment are introduced to replace conventional plastics. Poly‐ε‐caprolactone (PCL) is a commonly used plastic that can degrade in natural environments. However, owing to its hydrophobicity, its natural decomposition rate is low. In this study, PCL is modified with maleic anhydride (MA) (PCL‐g‐MA) to increase hydrophilicity and amorphous region for faster decomposition. To assess the hydrolysis in seawater, lipase hydrolysis is performed to compare the decomposition of PCL‐g‐MA and PCL. Consequently, in a Pseudomonas lipase‐containing PBS solution, it takes 72 and 120 h for complete hydrolyze of PCL‐g‐MA and PCL, respectively. MA grafted onto PCL increases the amorphous region, where lipase can easily diffuse into PCL‐g‐MA. Morphological (FESEM and POM images), thermal (TGA and DSC), and structural (FTIR, XRD, and XPS) analyzes support the hydrolysis reaction. The mechanisms proposed in this study confirm that lipase hydrolysis starts in the amorphous regions and then transfers to the crystal regions. This hydrolysis progress is expected to facilitate the creation of eco‐friendly low‐cost PCL‐g‐MA composites with high‐rate hydrolysis, such as bio‐plastics and bio‐fibers.