R. Vinayagamoorthy

Owing to the increase in demand on bio-degradable materials, the present researches focus on the development of materials with full degradability. This research is intended to develop a bio-resin–based composite from senegalia catechu gum for light load automotive applications. The bio-resin obtained from the plant is processed with commercial polyester in order to make it as a functional resin for composite preparation. The synthesized resin is made in the form of structural materials by adding jute reinforcements in varying proportions. An extensive study on the various characters in comparison with the synthetic resin–based composites has been done which includes mechanical strengths analysis and thermal characters investigation. It is revealed that the bio-resin–based composites are good against tensile, flexural and impact loads as compared to that of the synthetic resin composites. In addition, it has been witnessed that the material with 40% weight of jute fabric is apt for offering highest resistance against tensile, flexural and impact loads. Micro-structural investigations proved that the bio-resin–based composites are superior in reducing the flaws and enhancing the bonding of resin with fibres as compared to that of the synthetic resin-based composites. Further, the thermal characterization showed that the bio-resin–based composites have high thermal stability as compared to the synthetic composites, and hence, a positive sign is obtained for bio-resin–based composites in both mechanical and thermal characters.

The use of natural fibres as composite reinforcements is inevitable in view of developing a sustainable environment. When a natural fibre is extracted from a plant or ground or animal, they are prone to contain impurities and other unwanted substances. By removing these unwanted substances and by enhancing the strengths of the fibres, the reinforcements become predominant to carry the loads in a composite material and thus help the composite to acquire major mechanical properties. Hence, pretreatment methods are adopted for green fibres and it includes a series of chemical treatment, drying, heating in a furnace, and so on. These treatments help to enhance the surface roughness of the fibre, and thus, it increases the bonding strength with the surrounding matrix. The present study gives a clear picture of various pretreatment methods made in different research and their effect on the properties of the composite materials.

Polymer-based materials are mainly intended for structural applications in industries. Due to their competitive properties, they are used as a replacement for wood and other conventional materials. During their manufacture, fibres are reinforced into the polymer resin in different shapes as required. Among several available reinforcements, glass fibre in many researches showed the best in mechanical characters, ability to get reinforced in the matrix and handling ability. In contrast, bio-reinforcements from various natural sources are also used as an alternative and they provide an equal performance like the man-made reinforcements. When both the artificial fibre and natural fibre are used in a composite material, the composite attains the iconic characters of each reinforcement; thus, the material as a whole shows excellent characteristics. This chapter provides a clear picture on characterization of composites with glass reinforcement in sandwich form, and also shows various trends like the elevation or decline in their strengths, their possible reasons and the potential ways for elevating the characters of the composite.

The present research has been made to investigate the characteristics of a new composite material made up of limestone as particle reinforcement. New composites are made by taking limestone particles in five different sizes and jute as woven reinforcement in polypropylene matrix. Mechanical characteristics of the composites that include strengths against tension, compression, flexural, impact and hardness are evaluated and a comparative investigation is made among the composites. The effect of particle size on the properties is analysed and found that the composite with medium particle size bears the highest strength in all aspects. In addition, microscopic image analysis is carried out to investigate the distribution of particles, bonding capacity and other morphologies. The results showed that limestone will be apt particle reinforcement and its presence enhances all the characteristics of the composite.

Fiber reinforced composites are majorly used as structural components in industries and also as a replacement for wood. Fiber reinforced composites are manufactured by reinforcing fibers in the polymeric matrix in appropriate shapes. At the inception, man-made fibers like carbon, glass, and kevlar are used as reinforcements and are proven to be the best in respect to the properties, reinforcing ability and usability. On the other hand, natural fibers like jute, sisal, flax, hemp, vetiver, etc., are nowadays widely used as reinforcements and they are on par with the behavior of artificial fibers. Research studies also confirm that when both man-made and natural reinforcements are used in hybrid form, the composite properties are improved to a greater extent. Under this combination, the composite material gains all the superior properties of individual fibers and when the composite is subjected to different loading, each fiber offers its own maximum resistance. Hence, the composite would be superior in all the properties. The present article gives a detailed insight on the various issues related to synthesis, mechanical characterization and machining of natural fiber reinforced hybrid composites.

The research on polymeric composites is always in the stage of enhancing the properties. Several researches have been explored in recent decades to investigate the behaviour of both man-made fibre and bio-fibre-reinforced composites. In all these works, an artificial polymeric resin has been utilized as the matrix and it has been revealed that though they provide competent properties, the composites are partially degradable. To enhance the degradability to the fullest extent, both the reinforcements and the matrix must be biodegradable and this could be achieved only if both are derived from natural sources. During the synthesis of a bio-resin, a series of treatments must be followed to make it in to a usable form. The present work addresses a comprehensive survey about various bio-resins, their applications, various synthesis methods followed and the challenges faced during incorporation of reinforcement during composite formulation. The work also gives a clear picture on the challenges faced during characterization of green resin-based composites.