Adaptation of alternative and novel materials in place of traditional metals and alloys is getting higher attention in all domains of life. Tailored or customized fiber reinforced composite materials offer multiple advantages such as lighter systems with adequate strength, cost-effectiveness, and easier handling during fabrication and service time. In this review paper, attempts are made to comprehensively look into property improvement, fabrication, and characterization followed by researchers for natural fiber reinforced, natural fiber-synthetic fiber reinforced and hybrid natural fibers reinforced polymer-based composites. Composites having natural fibers as reinforcements had improved sound absorption and vibration damping properties. A combination of natural and synthetic fiber was found to be ideal for obtaining improved mechanical properties.

The structural components made of polymer composites in aviation, automobile, and marine applications are subjected to various environmental conditions throughout their design service life. Furthermore, the examination of the effect of various ageing environments on moisture absorption and mechanical behaviour is essential to protect the structures from premature and catastrophic failures. This study evaluates the influence of three different ageing conditions, namely, ambient (25°C), sub-zero (−10°C), and humid (40°C and 60% relative humidity) on the mechanical properties of hybrid interply basalt-aramid/epoxy composites. The compression molding process was adopted to fabricate the specimens and the specimens were aged in a distilled water environment for a period of 180 days. The aged specimens were subjected to static and dynamic mechanical tests viz. tensile, flexural (3-point bending), short-beam shear (SBS), and Charpy impact tests to study the behaviour, and then results were compared with the unaged specimens. Fourier Transform Infrared Spectroscopy (FTIR) was also performed to analyze the chemical changes within the composites due to the ageing process. It was witnessed that moisture absorption rate increases with - increase in ageing period and attains a state of saturation between 1.8% and 5.44% depending on the ageing conditions. Investigations revealed that moisture absorption has an unfavourable effect on the mechanical performance of the composites. The retention of mechanical strengths of aged composites is in the order of Unaged > Sub-zero > Humid > Ambient. Fractured tensile specimens were analyzed for microscopic observation using Scanning Electron Microscope (SEM) to study the damage morphology. Matrix decomposition, matrix cracks, and interfacial debonding were the major failure modes observed in aged composites.

Fibre-reinforced polymer (FRP) composites are gaining more attention for civil, automobile, aircraft and marine applications due to their excellent properties. The present work investigated the effect of ageing on mechanical properties of the autoclave-cured quasi-isotropic carbon/epoxy prepreg composites. The specimens were aged at artificial seawater under ambient, sub-zero (− 15 °C), and humid conditions (70% RH. and 40 °C) for 12 months. The tensile, flexural and impact properties were determined at regular intervals. The gravimetric study revealed that moisture absorption behaviour depended on the medium and duration of ageing condition. The moisture absorption for the quasi-isotropic carbon/epoxy composite specimens followed a non-fickian distribution. The moisture absorption of the carbon/epoxy composite laminate specimens showed an adverse effect on their mechanical properties. The moisture absorption results revealed that composite specimens aged under ambient condition absorbed more moisture compared with sub-zero and humid conditions. It was evident from the results that there was a 36.06% reduction in tensile properties of the composite specimens aged under ambient condition in comparison with pristine specimens. In contrast, the flexural properties were affected largely at sub-zero condition, and the impact properties were largely degraded at humid condition. The failure surface morphology revealed that matrix cracking and inner fibre debonding were the major causes of degradation in mechanical properties. Graphical abstract

In the pursuit of sustainable materials, natural fibers are gaining attention because of their renewable nature and low environmental impact. However, their application in composites has been hindered by their hydrophilicity and non-homogeneity in the properties. To address these issues, chemical treatments such as Sodium Hydroxide and Potassium Permanganate have been utilized. This study explored the impact of chemical treatments on Bamboo fibers and their subsequent influence on the vibration and acoustic properties of Carbon/Bamboo fiber-reinforced hybrid composites. This study investigates the vibration damping and acoustic characteristics of hybrid composites, considering the synergistic advantages of Bamboo’s natural damping properties and Carbon fiber’s mechanical strength. The damping factor of Sodium Hydroxide treated Bamboo fiber reinforced hybrid composites is 34.55% higher than that of untreated Bamboo fiber reinforced hybrid composites. It is also 11.95% higher than that of Potassium Permanganate treated Bamboo fiber reinforced hybrid composites. The flexural modulus of untreated Bamboo fiber reinforced hybrid composites was 164.36% and 157.77% higher than that of Sodium Hydroxide treated and Potassium Permanganate treated Bamboo fiber reinforced hybrid composites, respectively. The effect of chemical treatment on the fiber properties were analysed using the FTIR spectrum. Acoustic characterization revealed that untreated Bamboo fiber composites have higher sound absorption coefficients at lower frequencies, whereas Sodium Hydroxide-treated composites have higher sound absorption coefficients at medium and high frequencies. The results indicated that chemical treatment enhanced fiber-matrix adhesion, reduced stiffness, and influenced the damping and acoustic performance of the hybrid composites.