Synthesis of pectin from orange peel and innovation of biodegradable polyhydroxyalkanoate film for packaging application

In this work, polyhydroxyalkanoate (PHA) reinforced with silane-treated pectin from orange peel is used to create and characterize biodegradable composite films. The mechanical, thermal, surface, and microstructural characteristics of the composites were assessed. As the pectin content increased, mechanical tests revealed notable gains in hardness, tensile strength, and rip strength. Due to ideal filler dispersion and robust interfacial bonding, specimen MP2, which included 3 vol% silane-treated pectin, demonstrated the best mechanical performance with a tensile strength of 141 MPa, tear strength of 112 MPa, and hardness of 80 Shore-D. Thermal conductivity improved progressively with filler addition, with specimen MP3 with 5 vol% pectin, achieving the highest value of 0.65 W/mK due to the formation of dense, thermally conductive pathways. Water contact angle measurements revealed enhanced hydrophilicity, with MP3 displaying the lowest angle of 68°, indicating superior surface polarity and potential for improved compostability. Thermogravimetric analysis (TGA) confirmed that MP3 also exhibited the greatest thermal stability with 98% mass retention and a peak decomposition temperature of 401 °C, attributed to a more continuous thermally resistant filler network. SEM analysis validated these findings by showing uniform filler dispersion and strong interfacial adhesion in MP2, while MP3 exhibited slight filler agglomeration but still maintained enhanced thermal and surface characteristics. The results highlight the potential of silane-treated pectin as a sustainable reinforcement agent for improving the functional performance of PHA films in packaging applications.