This study aimed to assess the effect of hybridization on thermomechanical properties and water absorption of composite materials, by introducing sisal fiber tissue into the material. To that end, two composite material plates were manufactured, the first with five layers of E-glass reinforcement mat and the second with three layers of E-glass fiber interspersed with two layers of sisal fibers, both used as an orthophthalic polyester resin matrix. The material was then submitted to tensile, three-point bending and water absorption tests. It was observed that hybridization causes a change in both the final strength and stiffness of the material.

The use of composites in manufacturing equipment and products is taking a very important space in the industry in general. Moreover these materials have unique characteristics when analyzed separately from constituents who are part of them. However it is know that cares must be taken in their manufacture, as the use of appropriate process and the composition of each element, in addition to adherence fiber / matrix, which is a major factor in obtaining of the final mechanical strength of the product. One should also take into account whether the composites are environmentally friendly. For this reason, in this work, a composite partially ecological was made, using as reinforcement, a sisal woven and, as matrix, the polyester resin. Seeking to improve the adherence fiber / matrix, a treatment in sisal woven was performed with aqueous solution of sodium hydroxide (NaOH) at a concentration of 3%. The composite subjected to this treatment presented, in bending test, a better mechanical performance, with an increase of 27% in the flexion strength and of 54% in maximum strain, but there was a reduction of about 15% in its flexural modulus.

The aim of this study was to analyze the effect of hybridization on impact and residual strength in composites as well as the types of damage caused by the impacts, quantifying the delaminated area of the test specimens. Two 11-layer composite laminates were developed, one with bidirectional glass fiber woven and the other a hybrid with three layers of bidirectional aramid fiber substituting the outer layers and the middle layer of the glass fiber. The materials revealed that the hybrid laminate obtained greater impact strength withstanding one impact of 76 J, albeit with an increase in the damaged area of between 64 and 85 cm2, resulting in a decline in mechanical properties along nearly the entire test specimen. This contrasts with what occurred in the glass fiber laminates, which recovered over 80% of their mechanical properties for a distance of 35 mm from the edge of the impactor. Moreover, it demonstrated that the variation in residual strength can be represented by an equation and that there is a relation between the damage area and the residual properties of the glass fiber material.

RESUMONo setor industrial, materiais que apresentem bom desempenho mecânico atrelado com uma vida útil elevada e a uma boa relação custo/benefício vem a cada dia sendo mais procurado, diante disso, os materiais compósitos, dentre eles os compósitos poliméricos fibrosos estão a cada dia sendo mais utilizados, pois estes desempenham determinadas funções que os materiais convencionais não conseguem desempenhar. No entanto, em se tratando dos compósitos poliméricos é importante que se saiba de fato qual o comportamento que este material tem quando está em situações adversas como em contanto com os fluidos de processo ou até mesmo com calor. Desta forma, o objetivo dessa pesquisa foi desenvolver um compósito utilizando uma matriz polimérica de resina poliéster com reforço fibroso de manta de vidro-E, onde este foi imerso em água do mar por um período de 1460 dias. Os corpos de prova (CP's) foram submetidos ao ensaio de tração uniaxial, buscando determinar resistência e módulo de tração. Feito isso, realizou-se um comparativo das propriedades mecânicas para todas as condições de ensaio como estado seco e água do mar. Além disso, foi caracterizada a fratura final dos CP's para a condição de imersão. Ao término dos ensaios observou-se perda nas propriedades mecânicas para a condição de ensaio de tração após o período de imersão, porém esta perda não invalida o seu uso uma vez considerando estes parâmetros durante a elaboração do projeto estrutural. PALAVRAS-CHAVE:Compósitos Poliméricos; Degradação Mecânica; Água do Mar; Propriedades Mecânicas. Analysis of Mechanical Properties of PRFV Composite when Immersed inSeawater for Extended Time. ABSTRACTIn the industrial sector, materials that present good mechanical performance linked to a high useful life and at a good cost / benefit comes every day being more sought, in front of this, the composite materials, among them the fibrous polymeric composites are every day being more requested, because they perform certain functions that conventional materials cannot perform. However, when it comes to polymer composites, it is important to know the behavior of this material when it is in adverse situations, such as in process fluids or even heat. In this way, the objective of this research was to develop a composite using a polymer matrix of polyester resin with fibrous reinforcement of E-glass, where it was immersed in sea water for a period of 1460 days. The specimens (CPs) were submitted to the uniaxial tensile test, seeking to determine strength and tensile modulus. After this, a comparative of mechanical properties was performed for all the test conditions as dry state and sea water. In addition, the final fracture of the CPs was characterized for the immersion condition. At the end of the tests, loss of mechanical properties was noticed for the tensile test condition after the immersion period, but this loss does not invalidate its use once considering these parameters during the structural project elaboration.