Glass fibre is a completely natural material, ecologically clean and harmless to human health. Glass fibre is obtained from sand by melting together with other raw materials in a glass melting furnace at a high temperature of around 1500 ° C to 1700 ° C. It also has added binders to give the materials better strength and water tightness.
The special evaluations of fibreglass give it many unique properties: good tensile and compressive strength, high temperature and humidity resistance, non-flammable, resistance to chemical and biological effects, relatively low density. It is a material that can be twisted, woven, wound, braided, bent, and processed like any other fibre.
E-glass fibres are the most common type of glass fibres used in composites today because of their low cost and good strength, high electrical properties and good heat resistance. However, their impact resistance is relatively poor. For critical applications where more strength is required, S-Glass offers higher heat resistance and about 1/3 more tensile strength compared to E-glass and at a higher cost.
Carbon fibre is produced by the controlled oxidation, carbonization at temperature between 2000 ° C to 3500 ° C and graphitization of carbon rich organic precursors which are already in fibre form. Properties such as density and elastic modulus are determined by the degree of carbonisation employed and carbon fibre reinforcements are now available to meet a wide range of strength and stiffness requirements. Composites made using high modulus, uni-directional carbon fibre can exceed the modulus of steel.
Carbon fibre in general has high tensile strength and modulus, high fatigue strength, and high thermal conductivity. The strength and stiffness of carbon fibers are higher than glass and aramid fibres.
They are used in military application, sporting goods, automobile and aerospace industries where high strength to weight ratio of carbon fibre is required.
Aramid fibre is man-made organic polymer such as aromatic polyamide produced by spinning a solid fibre from a liquid chemical blend. They have much better mechanical properties than steel and glass fibres on an equal weight basis. Aramid fibres are inherently heat and flame resistant. Aramid also has very high modulus because of which they have high impact resistance. This is the reason because of which they are extensively used in ballistic applications.
Strength of laminate depends upon the position of individual strands of fibre in a mat or roving.
High percentage of fiberglass in a particular direction increases the tensile and compressive strength in that particular direction. There are three basic arrangements namely: Unidirectional (Continuous strand roving, Unidirectional mat), bidirectional (Woven roving, Woven fabric) and multidirectional (Chopped strands, Chopped strand mat, Tri axial fabric)