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

Performance of jute non-woven mat reinforced polyester matrix composite in multilayered armor

This paper presents results obtained through ballistic tests on multilayered armor system (MAS) using polyester composite reinforced with jute non-woven mat as second layer. Following international standard tests are carried out with ammunition 7.62 × 51 mm, with a velocity above of 800 m/s. The MAS is composed of a front layer with hexagonal ceramic tile (alumina doped with 4 wt% of niobia), the second layer of polyester matrix composite reinforced with 30 vol% of jute non-woven mat and the third layer an aluminum alloy plate. The utilization of polymeric composites reinforced with natural fibers to replace the aramid fabric (Kevlar™) is of interest because their performances are similar in the armor system but the composite is less expensive. Scanning electron microscopy analyses show that the polyester/jute non-woven mat composite captured ceramic fragments through mechanic incrustation. Moreover the replacement of aramid fabric for polyester matrix composites reinforced with jute non-woven mat provides weight reduction of the MAS by 5.4% and a cost reduction of 474%. Keywords: Jute non-woven, Polyester composite, Multilayered armor, Ballistic performance, Economical advantag

Charpy impact tenacity of epoxy matrix composites reinforced with aligned jute fibers

Natural fiber reinforced polymer matrix composites are gaining attention as engineering materials for advanced applications, including components of high performance ballistic armors. This requires superior mechanical properties, such as tenacity. Composites reinforced with jute fiber are currently being investigated as possible advanced engineering materials. Therefore, the objective of the present work was to evaluate the impact resistance of epoxy matrix composites reinforced with up to 30 vol% of continuous and aligned jute fibers. This evaluation was performed by measuring the Charpy absorbed impact energy of standard ASTM notched specimens. The results indicated a significant increase in the absorbed impact energy with the volume fraction of jute fibers. The microstructural mechanism related to this performance was revealed by scanning electron microscopy analysis. Keywords: Jute fiber, Epoxy composites, Charpy, Impact tes

Alkaline Treatment Investigation for Sedge Fibers (<i>Cyperus malaccensis</i>): A Promising Enhancement

Natural fibers have some advantages in comparison to synthetic fibers, especially because they are more environmentally friendly. For this reason, using them as a reinforcement for polymeric matrices is growing exponentially. However, they present the disadvantage of having the hydrophilic nature, which strongly reduces the interface interaction. Sedge fibers have been investigated when reinforcing an epoxy matrix in terms of ballistic properties and mechanical performance. Aiming to enhance the fiber−matrix interface, an alkali treatment was proposed. The group conditions were divided into three NaOH concentrations (3%, 5%, and 10%), as well as the three periods of immersion (24, 48, and 72 h). Therefore, nine different conditions were investigated in terms of their thermal behaviors, chemical structures, physical structures, and morphological aspects. Based on TGA curves, it could be noticed that treatments related to 3% NaOH for 24 h and 48 h exhibited better thermal stability properties. For the time of 48 h, better thermal stability with for a decay of the thermal DSC curve was shown for all treatment conditions. The FTIR spectra has shown a reduction of waxes for higher NaOH concentrations. The XRD diffractogram exhibited an increase in the crystallinity index only for 5% NaOH and an immersion time of 48 h. The morphological aspects of fibers treated with 5% and 10% of NaOH have shown that the treatments have damaged the fiber, which highlighted the crystallinity index reductions

Carnauba leaf fibers: correlation among diametrical variation, physical and mechanical properties

The variability of properties presented by natural lignocellulosic fibers (NLFs) is an important issue to highlight, since such inconsistencies in their characteristics put them at a disadvantage when comparing them to synthetic materials. It is important to point out that the application of methodologies that make it possible to predict the behavior of NLFs in the face of mechanical stress is essential for the use of these materials in engineering applications. For this, the present study proposes to evaluate the influence of the carnauba fibers (Copernicia prunifera) morphology in the properties presented by these materials. Optical microscopy (OM) was applied to determine the cross-section and diametrical variation of the fibers, enabling the evaluation of density by Archimedes method according to the mean diameter of the fibers. The mechanical properties were evaluated by tensile testing and the data were acquired by Weibull analysis. The morphological aspects of the longitudinal and cross-sections of the fibers were evaluated with scanning electron microscopy (SEM). The fibers had an average density of 1.13 ± 0.22 g/cm3, with diameter intervals ranging from 0.31 to 1.21 mm. The fibers have reasonable mechanical properties, with an average tensile strength of 64.7 ± 40.9 MPa, Young's modulus of 1.37 ± 0.80 GPa and elongation of 5.59 ± 1.60%. The SEM micrographs highlighted the defects present on the outer surface of the fiber as well as in the cross-section. There was a high potential for the use of carnauba fibers in the manufacture of polymer matrix composites

Relevance of Dynamic Strain Aging under Quasi-Static Tension on AISI 304 Stainless Steel

<div><p>The interval of existence of dynamic strain aging (DSA) in AISI type 304 austenitic stainless steel subjected to quasi-static tension tests, under strain rates from 3.5 x 10-2 to 3.5 x 10-4 s-1, in the temperature range from 25 to 800ºC was investigated. It was found that DSA occurs in the range extending from around 200 to 700ºC. Plastic instabilities associated with serrations, Portevin-Chatelier effect, allowed activation energies to be calculated and a possible mechanism of dislocation interaction with interstitial carbon atoms to be proposed. Significant increase in the ultimate strength, uniform elongation and work hardening demonstrate that DSA is a relevant phenomenon, which improves the high temperature mechanical properties of 304 steel.</p></div

Dynamic mechanical and thermal mechanical analysis of Cyperus malaccensis sedge fiber reinforced GO-incorporated epoxy nanocomposites: a short communication

The sedge fiber extracted from the Cyperus malaccensis (CM) plant has recently been found as a promising reinforcement of polymer composites. Incorporation of 30 vol.% CM sedge fibers improved the impact resistance and tensile elastic modulus of epoxy composites with only slight differences in their thermogravimetric parameters. However, dynamic mechanical viscoelastic behavior is still needed to complete these composites characterization for possible engineering applications. This complementary research work extends the previous study to dynamic mechanical analysis (DMA) and thermal mechanical analysis (TMA) for GO-incorporated epoxy matrix nanocomposites incorporated with 30 vol.% of CM sedge fibers. In comparison to basic epoxy (control sample) the damping factor (tan δ), as the ratio between DMA loss and storage moduli, is significantly increased from 0.45 to 0.75 for 30 vol.% CM fiber composite. TMA findings disclosed only slight variations in the glass transition temperature (119–124 °C) as well as in the thermal expansion coefficient (168 x 10–6 to 220 x 10–6/°C). These DMA and TMA results confirms the promising CM sedge fiber reinforcing effect on GO-incorporated epoxy nanocomposites and its mechanical/thermal viscoelastic contribution