A Characterization Study of Morphology and Properties of Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) / Aloe Vera Fibers Biocomposites: Effect of Fiber Surface Treatments

The depletion of petroleum resources and the environmental concerns during the last decade, led both academia and industry to look for a new class of ecofriendly materials with improved functional properties. In this regard, the biodegradable composites, also called "green composites" have been paid increasing attention by researchers worldwide. Among all the biodegradable polymers, polyhydroxyalcanoates (PHA) are considered as the potential candidates to replace the petroleum-based polymers. On the other hand, cellulose-based fibers which have many advantages including low cost, good biodegradability and thermal insulation can be used as reinforcement in polymer composites. However, to ensure good adhesion between lignocellulosic fibers and the matrix, the fibersurface is modified using chemical (alkaline, silane, acetylation, benzoylation, acrylation, permanganate, peroxide or isocyanate treatment) or physical treatments (corona or plasma treatment) prior to processing. Therefore, the objective of the paper was to investigate the effect of various surface treatments of Aloe Vera fibers (AVF) used as reinforcement in poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) biocomposites. Indeed, various fiber treatments were carried out involving alkaline, organosilanes and combined alkaline/organosilanes. PHBHHx/AVF biocomposites samples were prepared by melt compounding at loading ratio of 20 wt% selected as an optimal composition. The results showed that the biocomposite PHBHHx/ combined alkaline/organosilanes treated AVF exhibits a finer and homogeneous surface morphology indicating a good fiber/matrix interfacial adhesion. Accordingly, the rheological properties (complex viscosity and storage modulus) were increased and the water uptake was reduced. This study highlights the effectiveness of combined alkaline/organo-silanes treatment of AVF over alkaline and organo-silanes and their applications in PHBHHx biocomposites as an interesting source of cellulosic reinforcing materials.