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.

Dynamic vulcanization of a soft grade of thermoplastic natural rubber (TPNR) was carried out using several concentrations of Hexamethylene N, N 0 bis (tert-butyl peroxy carbamate) (HBTP). The blends were melt mixed in a Brabender plasticorder. The effectiveness of dynamic vulcanization was investigated using the Brabender plastograms, swelling index measurements, rheological behavior by means of a capillary rheometer, dynamic mechanical properties, and tensile testing. It was found that varying the HBTP concentration had a great influence on the rheological behavior as well as the dynamic and tensile properties of the material. The increase of HBTP dosage resulted in an increase of the extent of crosslinking and caused an increase of the elastic modulus and a reduction of the loss modulus. The ultimate tensile strength and elongation at break also increased with increasing HBTP loading. The rheograms indicated that the blends exhibit a pseudoplastic behavior.

Recycled polyethylene terephthalate (PET) fiber has been used as reinforcing filler for unsaturated polyester resin (UPR) in order to obtain UPR/PET fiber composites. Different loadings of PET fibers (5-18 phr-parts per hundred parts of resin) of different average lengths (2-3 to 20 mm) were added to the UPR. The mechanical properties of the UPR/PET fiber composites increased up to 8 phr PET fiber loading with a length lower than 5 mm, because of the high affinity between the UPR and the PET fiber surface and the good dispersion of the fiber into the matrix. However, higher PET fiber loading caused a decrease in the mechanical properties of the composites because of the agglomeration of the fibers. The UPR/PET fiber composites presented higher storage moduli than the UPR, and an increase of the glass transition temperature in the composites reinforced with 5-8 phr of short PET fiber was found; further, higher degree of crosslinking was reached. The addition of 5-8 phr PET fiber of short length improved the thermal stability of the composites and the post-curing was produced at higher temperature with much reduced enthalpy.

Poly(ethylene terephthalate) (PET) is the most widely used plastic in beverages packaging. It is also the most recycled plastic in the world. It is estimated that 6 million tons of PET are recycled (rPET) each year worldwide. Recycling of this material by melt processing has been the subject of many studies, in order to limit the degradation processes that lead to a significant decrease in the molecular weight (viscosity). Two key points are highlighted: The former is the presence of impurities like adhesive, glue and Poly Vinyl Chlo ride etc. The latter is the presence of water. These were therefore the main factors of the degradation of rPET. The impurities can be eliminated by a selective recovery and the moisture by a suitable drying combined with the addition of chain extenders namely Caprolactam (CAP) and/or Trimellitic anhydride (TMA). This com bination has proved to be very promising since extruded mixtures (rPET/TMA or CAP) have quite acceptable rheological properties especially in terms of intrinsic viscosity, dynamic viscosity and melt flow index (MFI) at low concentration of chain extender. Rheological and FTIR analysis showed that the degradation of rPET becomes more significant from the second extrusion cycle. Finally, DSC analysis showed that T g were not affected by extrusion cycle number; However, cold crystallization temperature T cc2 were significantly affected by heat treatment. The DSC analysis showed also that from the 2nd extrusion cycle, a conversion of heating crystallization temperature (T c ) which appeared during the first heating (1st scan) to a melting temperature (T m1 ) that appeared during the second heating (3rd scan) occurred due to the change of the decomposition mechanism environment (from oxygen environment to that of nitrogen).

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