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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Paper discusses the possibility of incorporation of date seed waste as fillers (DSF) into starch-g-PP matrices compared to kenaf fibers (KF with two  lengths) based composites. Three starch-g-PP matrices (G906PF, G906PJ and G720PJ) were studied in parallel to a fully PP one. The investigated composites loaded to 20 wt.%, showed differences in performance related, principally, to loading type (DSF, KF) and matrix used. Results showed an  improvement of tensile and impact stress at break as well as Shore D hardness of starch-g-PP composites reinforced with date seed fillers (DSF) or kenaf  fibers (KF). Further, tensile, storage and loss moduli increased also with loading. Vicat softening point of either KF or DSF/starch-g-PP composites was  greater with higher values for KF composites. However, thermal stability of starch-g-PP composites was better when DSF was used.