Effects of alkali treatment of fibers on the processing and the mechanical properties of jute-vinylester composites

EXEQUIEL S. RODRIGUEZ; ANALÍA VÁZQUEZ

Buenos Aires, Argentina

Conferencia; 3st CONFERENCE ON SCIENCE AND TECHNOLOGY OF COMPOSITE MATERIALS, COMAT 2005; 2005

Universidad Nacional de Mar del Plata - Universidad de Perugia

In this work, natural fiber composites were obtained by vacuum infusion using non- treated and alkali-treated jute fabrics. The effect of the treatment on the mechanical properties of the fibers, the processing conditions and the mechanical properties of the composites was studied. Chemical treatment of natural fibers is a widely spread technique used to improve fiber/matrix adhesion and therefore mechanical properties of thermosetting composites. But, in spite of the large number of published results in chemical treatment of natural fiber, there are very few works in which its influence on the whole obtaining process (raw material, processing and final product) is analyzed. The fibers were treated with NaOH (   6% w/v) during 4 hours at room temperature. After washing and drying, single filament tests were performed. It was observed an important drop in the tensile modulus and tensile strength, attributable to the extraction of lignin during the chemical treatment. The lack of lignin reduces the adhesion among the elementary fibers that constitute the technical fibers, reducing its ability to support load. In reference to the processing conditions, an increment in the injection time was observed for the alkali-treated fabric. The treatment is thought to decreases the fabric permeability by separating the technical fibers, which produce an increment in exposed area and therefore in the flux resistance. The flexural and impact properties of the composites were also determined. A decrease of about a 20% was observed for the alkali-treated jute composites. SEM micrographs showed good fiber-matrix adhesion in both types of composites, but the mechanical damage of the alkali-treated jute fibers was evident. Hence, a strong chemical treatment did not improve the mechanical properties of the composite materials, but the results were more homogeneous.