TYPES OF PLASTIC There are 2 types of plastic that is: a) Thermoplastics - A polymer that softens ans melts gradually when heated and it can be reshaped when still warm. b) Thermosets - A polymer that cant be reshaped after manufacture
Thermoplastics polyethylene, polypropylene, polystyrene & polyvinyl chloride (PVC) most common thermoplastics Any object made from thermoplastic can be remolded into a new shape. Thermoplastics creep considerably more than thermosets, particularly at higher temperature Can be used for light structural properties
Polystyrene has specific gravity of 1.05 It tensile strength is low, less than 48.5 MPa Modulus of Elasticity is low has good water resistance and dimensional stability and inexpensive (cheap) But it possesses poor heat resistance, limited weather resistance. It is brittle and lacks toughness
Pure polystyrene that is crystal clear used for storage container and cups. Polystyrene and expanded polystyrene used in tiles, packaging, containers, foams and housewares. Foamed polystyrene used in poured-in- place concrete wall systems & as insulation boards for foundation walls, masonry and wood walls and roofing.
Polyvinyl Chloride (PVC) Specific gravity about 1.39 Its made from monomer, vinyl chloride Tensile strength low nearly like polystyrene Its an excellent insulator Used in raincoats and shower curtains Extensively used in floor tiles, electric cables, flexible sheeting, hoses, pipes, expansion joint filler,,moldings, luggage, decorative wall coverings,
Multi-Lock Industrial Warehouse Floor Tile Made Using PVC
Polyethylene Specific gravity of 0.92 Tensile strength very low, less than 13.8 Mpa Modulus of Elasticity is very low Its tough, weather-resisting plastic & durable Has excellent electrical properties Has favorable chemical resistance
Its common application is as polyethylene bags Polyethylene used in manufacture of films, sheets, pipings, tanks, foams, electrical conduit and moldings. Polyethylene films & sheets used as dampproof courses, membranes & curing membranes
Polypropylene Has low specific gravity like polyethylene Low modulus of elasticity lightest material of all thermoplastics Has a higher softening point and shinier Good heat resistance but degrades under exposure to sunlight Has good abrasion resistance and hardness Used for pipes, sheets, geomembranes
Acrylics Crystal clear in natural form has good weather resistance and ease of forming Tensile strength higher than other thermoplastic material Used in light fittings, skylights, screen doors, paints and adhesives
Thermosets Most popular thermosets are unsaturated polyester, epoxides, phenol-formaldehyde and polyurethane. Polyester used in manufacture of fiberglass product and composite materials Phenol-formaldehyde used in lavatory seats, electrical fittings and equipment decorative laminates.
Advantages Of Plastic It has high damping capacity ( ability to absorb part of the vibrational energy) that makes it suitable in application where vibration is encountered. Excellent water resistant. - It have low water-absorption properties making suitable as impervious membrane layers that could prevent movement of water. Application in foundation, water supply installation, for concrete curing
Its lower prices have contributed to the universal application of plastic. Low cost Plastics have a favorable strength / weight ratio. It has low density (less than half of the concrete and 1/7 steel) Since plastic is light, it present ease in handling, transportation, storage and assembly. Most plastics are generally maintenance free and have good corrosion resistance
Thermal insulation of plastic is higher than other material. - used extensively as wall & ceiling insulation in both cast-in-place (as foamed insulation) and precast constructions (as rigid insulation) Plastics can be molded to any shape and pattern. Plastic products come in variety of colors & textures. - Manufactured plastics have good surface finish and may not require maintenance. - Its availability in many color & texture makes it commonly used for floor, wall tiles & countertops. Plastics can be manufactured with consistent quality.
Disadvantages Of Plastic It has low stiffness and strength which make it can be used for load bearing construction - It is subject to creep, that is the increase in deformation, under load, with time - Rate of creep of plastic higher than concrete - Creep deformation increases with stress level - Therefore, plastics become dimensionally unstable under load.
Plastics are combustible/flammable material. Plastics emits toxic gases such as carbon monoxide during burning. Plastics may emit dense smoke, thereby making escape more difficult. - Shouldnt be used in exits areas of building such as around stairways and corridors Expensive and subject to uncertainties arising for the oil price fluctuations. Acoustical insulation of plastic is poor.
Modified Plastic Addition substances can be added to the plastic during manufacturing process to improve the properties of the plastic. Plasticizers to soften the plastic & make it easier for shaping. Antioxidants prevent degradation by light and heat. Colorants give color to plastic Fibers to improve strength of thermoplastic & thermosets
Fiber Reinforced Plastic For application requiring very high tensile strength Fibers added not only increase stiffness & strength but also reduce shrinkage, improve abrasion resistance & provide dimensional stability to plastic resin. This is a light weight, high strength & corrosion resistance material. In civil engineering application for pedestrian bridges, bridge repair and as prestressing tendons.
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