TTL763 TECHNICAL TEXTILES PRESENTED BY: PUNEET KUMAR SINGH 2010TTE3664

COMPOSITES - INTRODUCTION Composite materials are those that are formed by the combination of two or more materials to achieve properties that are superior to those of its constituents. Composites could be Natural Synthetic. Bamboo is a very good example of efficient Natural Composite. The components are cellulose and lignin, as in all other wood, however bamboo is hollow. This results in a very light yet stiff structure. Centuries ago people used to use combination of mud and straw that forms a composite; to make their home, which is stronger than either the mud or the straw by itself

Composites are combinations of two materials in which one of the material is called the reinforcing phase, is in the form of fibers, sheets, or particles, and is embedded in the other material called the matrix phase. Typically, reinforcing materials are strong with low densities while the matrix is usually a ductile or tough material. If the composite is designed and fabricated correctly, it combines the strength of the reinforcement with the toughness of the matrix to achieve a combination of desirable properties not available in any single conventional material. COMPOSITE STRENGTH DEPENDS ON FOLLOWING FACTORS: Inherent fiber strength, Fiber length, Number of flaws Fiber shape The bonding of the fiber (equally stress distribution) Voids Moisture (coupling agents)

It was only in 1893, though that Edward D. Libby, the founder of Libby Glass Company, Toledo, Ohio, made filaments that could be woven into fabric. The basis of textile grade glass fibers is silica, SiO 2. In its pure form it exists as a polymer, (SiO 2 ) n. Other components are aluminum oxide, boron oxide, magnesium oxide, calcium oxide, sodium and potassium oxide. Glass Fiber Composites “ A material having reinforcing phase as glass fiber in sheet, mat or in any other form embedded in a matrix phase (other than glass).” Many types of resins are used to give a wide range of chemical, mechanical, and thermal properties. Polyester & Epoxy resins are used in most of the reinforced plastics Glass Fiber

Properties High strength High modulus (50-90 GPa) High stiffness Non-flammable Resistant to heat Good chemical resistance Relatively insensitive to moisture Good electrical insulation Able to maintain strength properties over a wide range of conditions

Advantages of Composites Higher Specific Strength (strength-to-weight ratio) Design Flexibility Durability Corrosion Resistance Low Relative Investment Disadvantages of Composites Composites are Heterogeneous Composites are relatively anisotropic

MANUFACTURING PROCESSES OF COMPOSITES Composite materials have succeeded remarkably in their relatively short history. But for continued growth, especially in structural uses, certain obstacles must be overcome. A major one is the tendency of designers to rely on traditional materials such as steel and aluminum unless composites can be produced at lower cost. Cost concerns have led to several changes in the composites industry. There is a general movement toward the use of less expensive fibers. For example, graphite and aramid fibers have largely supplanted the more costly boron in advanced– fiber composites. As important as savings on materials may be, the real key to cutting composite costs lies in the area of processing.

The processing of fiber reinforced laminates can be divided into two main steps:  Lay–up  Curing Curing is the drying and hardening (or polymerization) of the resin matrix of a finished composite. This may be done unaided or by applying heat and/or pressure. Lay–up basically is the process of arranging fiber–reinforced layers (laminae) in a laminate and shaping the laminate to make the part desired. (The term lay–up is also used to refer to the laminate itself before curing.) Unless prepregs are used, lay–up includes the actual creation of laminae by applying resins to fiber reinforcements.

Laminate lay–up operations fall into three main groups: A. Winding and laying operations B. Molding operations C. Continuous lamination Continuous lamination is relatively unimportant compared with quality parameters as not good as wrt other two processes. In this process, layers of fabric or mat are passed through a resin dip and brought together between cellophane covering sheets. Laminate thickness and resin content are controlled by squeegee rolls. The lay–up is passed through a heat zone to cure the resin.

B. Molding Operations Molding operations are used in making a large number of common composite products. There are two types of processes: A. Open–mold (1) Hand lay–up (2) Spray–up (3) Vacuum–bag molding (4) Continuous pultrusion and pulforming. B. Closed–mold (1) Matched–die molding (2) Injection molding

1. Hand Lay-up Hand lay–up, or contact molding, is the oldest and simplest way of making fiberglass–resin composites. Applications are standard wind turbine blades, boats, etc.)

2. Spray-up In Spray–up process, chopped fibers and resins are sprayed simultaneously into or onto the mold. Applications are lightly loaded structural panels, e.g. caravan bodies, truck fairings, bathtubes, small boats, etc.

Pulforming is similar to pultrusion in many ways. However, pultrusion is capable only of making straight products that have the same volume all along their lengths. Pulformed products, on the other hand, can be either straight or curved, with changing shapes and volumes. A typical pulformed product is a curved reinforced plastic car spring. (shown in figure.)

Prepregs Prepreg and prepreg layup “prepreg” - partially cured mixture of fiber and resin  Unidirectional prepreg tape with paper backing wound on spools Cut and stacked Curing conditions  Typical temperature and pressure in autoclave is C, 100 psi

Manufacturing - Layups compression molding vacuum bagging

Technoeconomics Of Glass Composites Major manufacturers which dominate glass composites production in world are Owens Corning, Saertex, PPG, Vetrotex Certainteed, Sangobain and Johns Manville. And the manufacturers in India are Kush Synthetics, Saertex and Kemrock Industries etc. The North American market is 60% of the total world market. In the United States, about 3 billion pounds of composite products are manufactured each year. There are approximately 2000 composites manufacturing plants and materials suppliers across the U.S. which,employ more than 150,000 people. About 65% of all composites produced use glass fiber and polyester or vinyl ester resin. The remaining 35% are produced with advanced materials, such as carbon or aramid fiber. Data Year 2000

Applications Areas where composites are widely used. Automotive Industry Aerospace Industry Other Transport Engineering applications Defense Industry Plastic Industry Sports ware Construction Industry Electronics Corrosion resistant applications Other Manufacturing Industries

Composites Application In Aircraft External Body Structure

Corrosion Resistance

Construction Materials Applications Ceilings Flooring – Cushioned Vinyl Carpet Tiles Roofing Gypsum Wall Board Insulation Facers Wall Covering High-performance glass fabric laminates Glass Mat composites

Engineered Paving Mat These mat delays reflective cracking, forms a nearly impermeable moisture barrier when applied with asphalt and does not shrink or melt like competitive products. Have extended life Lowers the cost of ownership. Mat is also millable and recyclable at the end of the pavement life. The product provides a continuous, non deforming water-resistant barrier. High temperature stability upto 495°F is a cornerstone feature of these engineered paving mat. Pavement overlays that do not include these will typically show reflective cracks within several months to a year. These have low elongation and good tensile strength

Electrical Laminates Electronic printed circuit boards laminates offers a major market. It offers better dimensional stability than phenolic paper base laminates and lower processing costs than circuit boards reinforced with woven glass fabric. These are available in various weights and widths to suit all the manufacturing processes and are compatible with epoxy resin systems. High consistency, superior fiber distribution and surface smoothness. Glass Composites in bath tubs

Glass Composites In Wind Energy Harnessing ULTRAMODERN GLASS COMPOSITES have been introduced to Reduce weight of blades by up to 18 percent while keeping length constant Increase blade length by up to 6 percent Improve blade stiffness by up to 20 percent Decrease blade thickness by up to 6 percent to increase aerodynamic efficiency Reduce total blade weight by up to 5 percent to ease the load on the turbine and tower, and enabling turbines to operate at lower wind speeds

Use Of Glass Composite In Advanced Automobiles High Speed Racing Cars Super Bus Sports Utility Vehicles World cup stadium made of glass composites

THANKS