Structural, thermo-mechanical and morphological properties of composites made with poly(lactic acid) and poly(ethylene terephthalate) fibers without compatibilizer

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, increased thermal stability of the PLA/PET fiber composites was demonstrated.