what is the plastics and rubbers.pptx

plastics

1. CONSTRUCTION & MATERIALS- PLASTICS & RUBBERS

2. WHAT ARE PLASTICS? Plastic is usually considered to be an amorphous or crystalline polymer which is hard and brittle at ordinary temperatures. It is a material that contains as an essential ingredient, an organic substance of a large molecular weight, is solid in its finished state. Plastics are organic materials, just like wood, paper or wool. The raw materials used to produce plastics are natural products such as cellulose, coal, natural gas, salt and, of course, crude oil. Two main processes are used to produce plastics - polymerisation and polycondensation - and they both require specific catalysts. COMPOSITION OF PLASTICS: Organic polymers + Carbon + Oxygen + Nitrogen + Sulphur = Plastic Where organic polymers may include Chalk, Starch, Ivory dust , Wood floor ,Zinc oxide

3. CLASSIFICATION OF PLASTICS: THERMOPLASTICS THERMOSETTING PLASTICS

4. THERMOPLASTICS: A thermoplastic material is one which can be softened and molded on heating. They are elastic and flexible above a certain glass transition temperature. They can be recycled. Example: Nylon ,it was the first commercial polymer to be made as a substitute for silk for making parachutes, vehicle tires, garments, fabrics, footwear ,etc. PROPERTIES: It may melt before passing to a gaseous state. Allow plastic deformation when it is heated. They are brittle and glossy. They are soluble in certain solvents. Swell in the presence of certain solvents. Good resistance to creep. TYPES OF THERMOPLASTICS: Polythene/polyethylene Polypropylene Polyvinyl chloride (PVC) Polymethyl methacrylate ( perspex ) Acrylonitrile butadiene styrene

5. THERMOSETTING PLASTICS: Thermosetting resins do not become softy on heating & they never melt once set. Example: Bakelite, polyester resin, vulcanized rubber, epoxy resin. PROPERTIES: These are soluble in alcohol and certain organic solvents, when they are in thermo-plastic stage. This property is utilized for making paints and varnishes from these plastics. These are durable, strong and hard. They are available in a variety of beautiful colours . They are mainly used in engineering application of plastics. TYPES OF THERMOSETTING PLASTIC: Phenol formaldehyde Urea formaldehyde Melamine formaldehyde Polyurethane Silicon resin

6. RUBBER Rubber  is a material, which can stretch and shrink. It is a  polymer . It can be produced from natural sources (e.g. natural rubber) or can be synthesized on an industrial scale. Many things are made from rubber, like gloves, tires, plugs, and masks. TYPES OF RUBBER: Natural rubber – A yellowish, amorphous, elastic material obtained from the latex of various tropical plants, especially the rubber tree. Synthetic rubber - A material with the mechanical property that it can undergo elastic deformation under stress and still return to its previous size without permanent deformation.

7. Rubbers Synthetic Rubbers Natural Rubbers Isoprene Rubbers (IR) Nitrile Rubbers (NBR) Styrene - Butadiene Rubbers (SBR) Butadiene Rubbers (BR) Polychloroprene (CR) Neoprene Rubber (NR) Butyl Rubber (BR)

8. Video on what is a plastics https:// youtu.be/Wza4LH_qt1M?si=ppu_SeUx5hDpARxx

9. Conclusion Thermoplastics can be melted and reshaped over and over. Thermosetting plastics harden permanently and can't be reshaped. Rubber is stretchy and used in lots of products. Fiberglass is strong and light, used to make things stronger, like boats and car parts. Each material is used for different things because of its unique properties.