Note for Production Technology - PT By Vishal Shinde

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Manufacturing Process - I UNIT –III Plastic Processing Prepared By Prof. Shinde Vishal Vasant Assistant Professor Dept. of Mechanical Engg. NDMVP’S Karmaveer Baburao Thakare College of Engg. Nashik Contact No- 8928461713 E mail:- nilvasant22@gmail.com 28/07/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK

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Introduction • Term “polymer”: greek poli (many) + meros (unit) = many units • Polymers are a large class of materials consisting of many small molecules (called monomers) that can be linked together to form long chains, thus they are known as macromolecules (term introduced by H. Staudinger in 1920’s). • A typical polymer may include tens thousands of monomers. Because of their large size, polymers are classified as macromolecules. • Polymers occur naturally in the form of proteins, cellulose(plants), starch(food) and natural rubber. • Engineering polymers, however, are usually synthetic polymers. 28/07/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK

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• A plastic material is any of a wide range of synthetic or semi-synthetic organic solids that are mouldable. • Plastics are typically organic polymers of high molecular mass, but they often contain other substances. • They are usually synthetic, most commonly derived from petrochemicals, but many are partially natural. • POLYMERIZATION: The simplest substances consisting of one primary chemical are known as the monomers or monoliths. They are to be combined or synthesized to form polymers by the process known as the polymerization. 28/07/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK

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Properties of plastics • Less brittle than glass ,hence can be made transparent and smooth. • Corrosion resistance. • Low electrical and thermal conductivity, insulator. • Easily formed into complex shapes, can be formed, casted and joined. • Wide choice of appearance, colors and transparencies. • Light weight but posses good strength and rigidity. • Low moisture absorption. • Heat resistance. 28/07/2016 PROF.V.V.SHINDE NDMVP'S KBTCOE NASHIK