Abstract. This paper deals with plastic-wood composites based on low density polyethylene (LDPE) and olive husk flour (OHF). The problem of incompatibility between the hydrophilic wood filler and the LDPE hydrophobic matrix was treated by two methods: a chemical modification of the olive husk flour with maleic anhydride to esterify the free hydroxyl groups of the wood components and the use of a compatibilizer agent, i. e. an ethylene-butyl acrylate-glycidyl methacrylate (EBAGMA) terpolymer. The changes in the structure, the morphology, and the properties resulting from these treatments were followed by various techniques, especially FTIR spectroscopy, scanning electron microscopy (SEM), tensile measurements and water absorption. The experimental results indicated that both methods, i.e. the chemical treatment of the olive husk flour with maleic anhydride and the inclusion of EBAGMA terpolymer, improved the interactions between the two composite components and promoted better dispersion of the filler in the matrix. Moreover, ultimate tensile properties were also increased. However, the use of EBAGMA terpolymer as compatibilizer produced better enhancement of the properties of LDPE/OHF composites compared to those treated with maleic anhydride.

Mechanical property changes, thermal stability, and water absorption capacity of poly(vinyl chloride) (PVC)/sisal fiber composites were assessed with respect to the effect of maleic anhydride chemical treatments of the sisal fiber, for five different sisal fiber contents, varying from 0 to 30% by weight in the composite. The composites prepared with the untreated sisal exhibited higher tensile modulus and hardness than the unloaded resin, while elongation and tensile strength were reduced. The deterioration in the mechanical properties of PVC blended with sisal fiber is attributed to the presence of moisture, interfacial defects at the fiber and polymer interface, and fiber dispersion in the PVC matrix. The amount of absorbed water is a function of the amount of fiber in the composite (F0 ¼ 0 phr, F5 ¼ 0.77 phr, and F20 ¼ 4.83 phr). The comparison of the results of characterization of F5, F20, and F30 formulations prepared with the untreated fibers and the treated ones showed a reduction in absorbed water after the chemical treatment of fiber with maleic anhydride (F0 ¼ 0 phr, F5 ¼ 0.28 phr, and F20 ¼ 2.99 phr), thus improving the mechanical properties of composites prepared with the treated sisal.

International audienceThe main objective of this research was to investigate the effect on the thermal and mechanical properties of the addition of two different compatibilizing agents, malefic anhydride-grafted polyethylene (PE) [synthesized in a solution state (MAPE) and commercial (XA255)], to olive husk flour, high-density polyethylene (HDPE) composites. The composites contain 30 wt % of olive husk flour and a variable proportion of compatibilizer (3, 5, and 7 wt %). The grafting reaction was followed by Fourier transform infrared, and the grafting degree was evaluated by means of titration. The effect of grafting on the thermal properties of MAPE was observed by ATG/DTG. The mechanical and thermal properties of the composite were investigated. A morphological study of the composite reveals that there is a positive effect of compatibilizing agent on interfacial bonding

2Chaire de recherche du Canada sur la valorisation, la caract erisation et la transformation du bois, Universit e du Qu ebec en Abitibi-T emiscamingue, Rouyn-Noranda, Qu ebec, Canada J9X 5E4 Wood flour (WF)-filled composites based on a polypropylene (PP)/recycled polyethylene terephthalate (r-PET) matrix were prepared using two-step extrusion. Maleic anhydride grafted polypropylene (MAPP) was added to improve the compatibility between polymer matrices and WF. The effects of filler and MAPP compatibilization on the water absorption, mechanical properties, and morphological features of PP/r-PET/WF composites were investigated. The addition of MAPP significantly improved mechanical properties such as tensile strength, flexural strength, tensile modulus, and flexural modulus compared with uncompatibilized composites, but decreased elongation at break. Scanning electron microscopic images of fracture surface specimens revealed better interfacial interaction between WF and polymer matrix for MAPP-compatibilized PP/r-PET/WF composites. MAPP-compatibilized PP/r-PET/ WF composites also showed reduced water absorption due to improved interfacial bonding, which limited the amount of absorbable water molecules. These results indicated that MAPP acts as an effective compatibilizer in PP/r-PET/WF composites. POLYM. COMPOS., 38:1749-1755, FIG. 8. Chemical reactions between (a) cellulosic fillers and MAPP [42], (b) r-PET and MAPP [43].

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The objective of the investigation described in this work was to study the reprocessing effects on the alfa fiber reinforced polyvinylchloride composites with and without maleic anhydride-grafted polyvinyl chloride used as compatibilizer. The material was characterized after each extrusion using tensile tests, scanning electron microscopy (SEM), dynamic mechanical, and thermal analysis. Results indicated that generally after four cycles, the recycled composites had considerably higher modulus as compared with the original composites, which were attributed to changes in physical and chemical properties of the composites induced by the recycling process. This effect was enhanced for the compatibilized samples. Increase of the modulus strength of the poly(vinyl chloride) (PVC) matrix is detected due to the molecular chain cross-linking resulting from degradation. In addition, it was found that the reprocessing cycles increase in glass transition temperature of PVC and PVC/alfa composites.

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