To prepare fully biodegradable materials, variable concentrations of luffa fiber (LF) namely 1, 3, and 5 phr, were incorporated into a poly(lactic acid) (PLA) matrix. To counteract the poor adhesion of the LF to PLA, a compatibilizer which is maleic anhydride‐grafted poly(lactic acid) has been incorporated and the properties of the composites with and without compatibilizer noted, respectively, PLA/LF and PLA/PLA‐g‐maleic anhydride (MA)/LF, were compared. The final torque of PLA/LF was found to decrease with the LF content contrary to that of PLA/PLA‐g‐MA/LF composite which was seen to increase as a result of the interfacial reaction occurring between maleic anhydride groups of the compatibilizer and the hydroxyls of LF. This outcome has been evidenced from the Fourier transform infrared spectroscopy which pointed out the disappearance of the vibration band owing to the anhydride groups of the compatibilizer from the spectra of the PLA/PLA‐g‐MA/LF composite and the better impregnation of LF by the matrix as it has been observed from scanning electron microscopy. Subsequently, the Izod impact strength of the compatibilized composites was seen to increase, especially for 1 phr of LF, whereas the water uptake aptitude was considerably reduced. Also, PLA phase into the composites exhibited lower thermal stability and glass transition temperature compared to pristine PLA.

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In this study, physical and electrostatic interactions existing between poly(lactic acid) (PLA) and poly(ethylene terephthalate) (PET) fiber were proved as a promising strategy for preparing novel lightweight PLA/PET fiber composites, without the need of adding compatibilizer or carrying out chemical/physical treatments to the fiber. The impact resistance of the PLA/PET fiber composites increased notably by adding up to 1.5 phr PET fibers thanks to the better dispersion of PET fibers and good polymer-fiber adhesion caused by the creation of hydrogen bonds between the surface hydroxyl and carbonyl groups on both polymers. However, the composites with 2-3 phr PET fibers were brittle due to PET fibers aggregation. The glass transition temperature of PLA increased moderately due to the good matrix/filler interfacial adhesion via hydrogen bond interactions, and its crystallinity showed a trivial variation contrary to the crystallites size, this decreased noticeably because of the fibers inhibiting effect. Finally, an increased thermal stability of the PLA/PET fiber composites was demonstrated.