Foluke Salgado de Assis

Characterization of Banana Fibers Functional Groups by Infrared Spectroscopy

A number of methods are available for characterization of the structural, physical, and chemical properties of natural fibers. Various methods are used for fiber identification like microscopic analysis, solubility, heating and burning technique density, staining etc. End-use property characterization methods often involve use of laboratory techniques which are adapted to simulate actual application as composite reinforcement. One of the techniques used on this kind of studies is the infrared spectroscopy. In fact, Fourier Transform Infrared (FTIR) spectroscopy is a valuable tool in the determination of functional groups actively interacting within a fiber. In this work, the banana fiber was evaluated by FTIR to reveal these functional groups and compare to similar works on other different types of banana fibers.

Izod Impact Tests in Polyester Matrix Composites Reinforced with Malva Fibers

Polymer matrix composites have been applied in components such as helmets and shielding for which toughness is a major requirement. A natural fiber presents interfacial characteristics with polymeric matrices that favor a high impact energy absorption by the composite structure. The objective of this work was then to assess the Izod impact resistance of polymeric composites reinforced with different amounts, up to 30% in volume, of a promising high strength natural fiber, the banana fiber. The results showed a remarkable increase in the notch toughness with the amount of incorporated banana fibers. This can be attributed to a preferential debonding of the fiber/matrix interface, which contributes to an elevated absorbed energy.

Fique Fabric: A Promising Reinforcement for Polymer Composites

A relatively unknown natural fiber extracted from the leaves of the fique plant, native of the South American Andes, has recently shown potential as reinforcement of polymer composites for engineering applications. Preliminary investigations indicated a promising substitute for synthetic fibers, competing with other well-known natural fibers. The fabric made from fique fibers have not yet been investigated as possible composite reinforcement. Therefore, in the present work a more thorough characterization of fique fabric as a reinforcement of composites with a polyester matrix was performed. Thermal mechanical properties of fique fabric composites were determined by dynamic mechanical analysis (DMA). The ballistic performance of plain woven fique fabric-reinforced polyester matrix composites was investigated as a second layer in a multilayered armor system (MAS). The results revealed a sensible improvement in thermal dynamic mechanical behavior. Both viscoelastic stiffness and glass transition temperature were increased with the amount of incorporated fique fabric. In terms of ballistic results, the fique fabric composites present a performance similar to that of the much stronger KevlarTM as an MAS second layer with the same thickness. A cost analysis indicated that armor vests with fique fabric composites as an MAS second layer would be 13 times less expensive than a similar creation made with Kevlar™.

Tensile and Impact Properties of Two Fiber Configurations for Curaua Reinforced Composites

Natural fibers have been extensively investigated in the past decades, due to their good properties, lightweight, low cost and renewable nature. From the ananas erectifolius plant, high strength and high modulus curaua fibers can be obtained. Their remarkable properties make them adequate to several high performance applications. In the present work, tensile and impact properties of two fiber configurations for curaua reinforced composites were investigated: a non-woven fiber fabric (NWFF) and high percentage continuous and aligned fiber (HPCAF) composites, using epoxy and polyester as polymeric matrix, respectively. The results showed that the fabric configuration does not effectively reinforce the polymer on tensile load, in spite of promoting significant improvement on the impact properties of the composite. The latter configuration results in both high strength and tough composites, however, its ability to resist to impacts depends on the direction of load.

Photoacoustic Thermal Characterization of Banana Fibers

Natural fibers are attracting the interest of engineering sectors owing to specific advantages such as lightweight and lower cost as well as for their inherent condition of being renewable, biodegradable, recyclable and neutral with respect to CO2 emission. In particular, the fiber extracted from the malva plant stem is nowadays recognized as one of the strongest lignocellulosic fibers. However, the thermal properties of the malva fibers have yet not been fully investigated. The present work had as its objective to investigate, by photoacoustic spectroscopy and photothermal techniques the thermal properties of diffusivity, specific heat capacity and conductivity of a pressed malva fibers sample. The results revealed that these fibers showed a superior thermal insulation capacity.

Performance of Plain Woven Jute Fabric-Reinforced Polyester Matrix Composite in Multilayered Ballistic System

The ballistic performance of plain woven jute fabric-reinforced polyester matrix composites was investigated as the second layer in a multilayered armor system (MAS). Volume fractions of jute fabric, up to 30 vol %, were mixed with orthophthalic polyester to fabricate laminate composites. Ballistic tests were conducted using high velocity 7.62 mm ammunition. The depth of penetration caused by the bullet in a block of clay witness, simulating a human body, was used to evaluate the MAS ballistic performance according to the international standard. The fractured materials after tests were analyzed by scanning electron microscopy (SEM). The results indicated that jute fabric composites present a performance similar to that of the much stronger Kevlar™, which is an aramid fabric laminate, as MAS second layer with the same thickness. The mechanism of this similar ballistic behavior as well as the comparative advantages of the jute fabric composites over the Kevlar™ are discussed.

PROPRIEDADES DE TRAÇÃO DE COMPÓSITOS DE EPOXY REFORÇADOS COM ALTOS VOLUMES DE FIBRAS DE JUTA

Natural fibers are increasingly being employed as a reinforcing phase in composites with polymeric matrix materials is that they have ecological and economical advantages when compared to synthetic fibers. They are renewable raw materials, are biodegradable and use less energy for their production. Tensile properties of composites of polymer hue were evaluated epoxy reinforced with high volume corresponding to 40% and 50% by volume of continuous, aligned fibers of jute. The tests were performed on an Instron Universal Machine. The tensile strength showed a steady increase with the addition of phase jute fibers in the matrix.

Charpy Toughness Behavior of Jute Fabric Reinforced Polyester Matrix Composites

The fique fiber is an important natural fiber, originally from Colombia where it is used for sacks and crafts while its plant is used to contain slopes. However, few studies were realized with the fiber obtained from the fique plant leaf, its mechanical properties are superior in many aspects in comparison to some other lignocellulosic fibers. This work investigated the toughness behavior of polyester matrix composites reinforced with up to 30% in volume of a fabric made of fique fiber by means of Charpy impact tests. It was found that the addition of fique fabric results in a marked increase in the absorbed energy by the composites. Macroscopic observation of the post-impact specimens and SEM fracture analysis showed that transversal rupture through the fique fabric interface with the polyester matrix is the main mechanism for the remarkable toughness of these composites.

Izod Impact Tests in Polyester Matrix Composites Reinforced with Fique Fabric

Jute fibers are among the lignocellulosic fibers with greater potential for use as fabric reinforcing polymer composites. This study evaluated the impact resistance of this type of composite. Specimens were made with up to 30% in volume of jute fabric in an Izod normalized mold. The jute fabric was embedded with polyester resin and cured at room temperature for 24 h. The specimens were tested in Izod impact pendulum and the fracture surfaces were examined by scanning electron microscopy (SEM). The impact resistance of composites increased linearly with the relative amount of jute fabric reinforcing the composite. This performance was associated with the difficulty of rupture imposed by the jute fabric as well as the type of cracks resulting from the interaction jute fiber/polyester matrix that corroborate the energy absorption at the impact test.

Curaua Non-woven Fabric Composite for Ceramic Multilayered Armors: A Lightweight, Natural, and Low Cost Alternative for KevlarTM

Advanced ceramics have been extensively applied for ballistic protection, when high levels of protection and low weight are demanded. However, their spalling characteristics require the suitable backing materials to collect the fragments generated on the impact. Synthetic fiber laminates, as KevlarTM and DyneemaTM, are currently the most used solutions despite of their high cost and non-sustainable conditions. Therefore, several materials are being studied to replace the synthetic fiber laminates as second layer, including natural fiber composites, which are light, low cost and sustainable materials. Among these, Amazon curaua fiber composites are promising, due to its known high strength and high modulus. In the present work, novel curaua non-woven fabrics polymer composites have been investigated as part of the ceramic armor system. Ballistic tests were performed following NIJ 0101.06 armor standard. The results showed that these composites are promising alternatives to the synthetic fiber laminates as ceramic backing materials.