Characterization of Bio‐Based Phenolic Plasticizer Extracted From Rambutan Fruit Shell Waste: A Sustainable Alternative to Synthetic Plasticizers for Green Polymer Applications

ABSTRACT The development of eco‐friendly plasticizer is driving the interest of many scientists due to its environmentally benign nature. This study investigated the extraction and characteristics of bio‐based phenolic compounds from underutilized rambutan shell waste (RSW) as potential plasticizers. A surfactant‐assisted alkali‐acid treatment was used to extract the plasticizer (RSWP), which was then selectively oxidized and dried to produce a solid plasticizer. FTIR revealed the presence of functional groups such as hydroxyl, ester, and aromatic moieties, which are critical for plasticization. XRD analysis indicated a crystalline‐phase composition with a crystallinity index of 78.91%, suggesting possible compatibility with semicrystalline biopolymers. TGA and DSC tests showed superior thermal stability, with a peak degradation temperature of 302.97°C and a high residual char content of 48%. SEM and EDX tests revealed heterogeneous morphology as well as high carbon (42%) and sodium (30.8%) content, which may enhance hydrophilicity. Particle size analysis indicated considerable polydispersity, with an average particle size of 1.249 μm. An AFM investigation indicated anisotropic nanoscale roughness, with a larger peak‐to‐valley height in the horizontal scan (0.098 nm) than in the vertical (0.070 nm). The RSWP performed better than plasticizer systems in terms of heat endurance and surface smoothness, suggesting that it could be used as an environmentally friendly packaging alternative.