Compatibilization of natural fibres as reinforcement of polymeric matrices

Abstract

Natural fibers have become a valuable resource in the composite industry; however, their use is limited due to their low compatibility with traditional polymeric matrices. That low compatibility promotes low mechanical strength in the composite material. In order to avoid this, it is necessary to treat the reinforcement material or the matrix before the composite manufacturing. This paper presents the results of a research aimed to study the effect of two compatibilization techniques applied to natural fibers, on the mechanical properties of the composite. The analyzed techniques were sodium hydroxide (NaOH) baths acting as coupling agent, as well as treatments using a dry etching plasma (physical sputtering). Natural fibers employed in this research were obtained from Guadua angustifolia bamboo culms, and the manufacturing of the composite was accomplished using a manual moulding technique and a polyester matrix. Results revealed that treatments using sodium hydroxide decrease the fibers' tensile strength, while the dry etching plasma treatments do not appear to affect their tensile strength. Moreover, both compatibilization techniques improve guaduapolyester composites' strength. It is believed that this increment is the result of the increase in the bonding strength between composite's phases.

Recycling of Nonwoven Waste Resulting from the Manufacturing Process of Hemp Fiber-Reinforced Recycled Polypropylene Composites for Upholstered Furniture Products

“…The problem associated with natural fiber-reinforced polypropylene composites is a low compatibility between hydrophilic fibers and the hydrophobic matrix, which leads to poor adhesion at the matrix-fiber interface and therefore to poor mechanical properties of the composite materials. In order to overcome this disadvantage, the properties of the reinforcing fibers can be modified by physical modification techniques, such as corona, plasma, and alkali treatments, or by chemical modification techniques, such as esterificationbased treatments (acetylation, propionylation, or benzylation), graft polymerization, use of silane coupling agents, and treatment using isocyanates [62,63]. The polypropylene matrix can also be modified by grafting maleic anhydride (MAPP), glycidyl methacrylate, and trimethylolpropane triacrylate or by surface peroxidation with heterofunctional polyperoxides [64][65][66][67][68][69][70].…”