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In the structural applications, the composite material employs a significant contribution in various industrial applications. In this paper, the experimental nonlinear viscoelastic behavior, tensile and flexural strength properties are analyzed in aloevera /hemp/flax natural fiber sandwich laminate composites (NSLC) with the addition of barium sulfate filler. The dynamic mechanical properties such as storage modulus (E′), loss modulus (E″) and damping factor (Tan δ) are analyzed using dynamic mechanical analyzer as a function of temperature and frequency. The homogeneity, crosslink between the fiber and the matrix of the natural fiber sandwich laminate composite samples are analyzed by a cole-cole plot and complex modulus models. The improvement in flexural strength is observed in the NSLC4 sample (138.34 N/mm2), but the addition of barium sulfate affects the tensile strength (28.8 N/mm2). From the dynamic mechanical analyzer, it is observed that the storage modulus (E′) at the glassy region in the NSLC2 sample is 19.9% whereas in the NSLC4 sample it is 15.57%. Further, the addition of barium sulfate filler enhances the loss modulus (E″) by 28% in NSLC4 sample. The NSLC4 sample shows the better homogeneity in the cole-cole plot and high crosslink between the fiber and the matrix is observed from the complex modulus.

Adding different reinforcements to the polymer composite is gaining more importance in the manufacturing industries because of their variation in mechanical properties. To satisfy modern industrial requirements, the mono-fiber polymer composites are substituted by hybrid composites in civil and automotive applications. The present work is to develop and investigate the hybrid composite behavior reinforced with AISI 304 (500 µm) wire mesh and jute fiber with epoxy LY556 resin. To analyze the mechanical properties of hybrid composites, two different orientations (45° and 90°) of wire mesh are selected and stacked with jute fiber by hand lay-up method. The wire mesh composite or hybrid composite is subjected to mechanical characterization like tensile, flexural, impact, and interlaminar. Subsequently, the viscoelastic behavior of the wire mesh composite is observed in terms of storage modulus (E′), loss modulus (E″), and damping factor (tan δ) by the dynamic mechanical analyzer (DMS 6100). The fractured surface microstructure of the wire mesh composite is analyzed by scanning electron microscope. The 45° oriented wire mesh composite sample shows better mechanical properties in ultimate tensile strength (20.55 MPa), flexural strength (0.145 kN), percentage of elongation (2.83%), and interlaminar strength (0.120 kN). At the transition region, the peak energy absorption of 0.622 is observed in the 90° oriented wire mesh composite sample at 0.5 Hz frequency.

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In this current investigation, alkali and Trimethoxymethylsilane treated custom made (irregular type) basket woven fabric at different weight percentages (0, 25, 35 and 45 wt.% and named as Pure epoxy, 25 FE, 35 FE, and 45 FE respectively) were reinforced with epoxy resin to develop flax/epoxy composites and tested for mechanical, dynamic mechanical, and sound absorption properties as per ASTM standards. Mechanical results revealed that, amongst the composites, 45 FE showed highest tensile strength, flexural strength, Impact strength and Shore D hardness of 91.07 MPa, 109.5 MPa, 295.65 J m−1, and 85.23 respectively, whereas ILSS property did not shows much appreciable progress even at high fiber loadings. Dynamic mechanical analysis (DMA) tests were conducted for five different frequencies (0.5, 1, 2, 5, and 10 Hz) at varying temperature and properties such as storage modulus (E′), loss modulus (E″), and damping (tanδ curve) were evaluated. DMA properties of the composites have found to be improved after reinforced with the treated flax fabric. Effectiveness coefficient (C) confirms that 45FE composites exhibited better strong fiber-matrix interface and shows good agreement with cole-cole plot analysis. Sound absorption performance of the composites were determined in terms of sound absorption coefficient (SAC) using Impedance tube system for the frequency range 0–6400 Hz. Results indicated that flax-epoxy composites exhibit better sound absorption properties at medium and higher frequency levels. SEM analysis was carried out to understand the cause of failure in mechanically fractured composites. Moreover, morphologies of the fibers were also studied by XRD technique.