<\/span><\/h2>\nA polymer<\/strong> is a large molecule (macromolecule) made up of repeating units called monomers<\/strong>, linked together by covalent bonds<\/strong> in long chains. The word “polymer” comes from the Greek words “poly”<\/em> (many) and “meros”<\/em> (parts).<\/p>\n<\/span>\u00a0Classification of Polymers<\/span><\/h2>\nPolymers can be classified in several ways:<\/p>\n
<\/span>1. Based on Origin<\/strong><\/span><\/h3>\n\n- \n
Natural Polymers<\/strong>: Found in nature (e.g., cellulose, proteins, DNA, silk, rubber).<\/p>\n<\/li>\n- \n
Synthetic Polymers<\/strong>: Man-made (e.g., polyethylene, polystyrene, nylon, PVC).<\/p>\n<\/li>\n<\/ul>\n<\/span>2. Based on Polymerization Reaction<\/strong><\/span><\/h3>\n\n- \n
Addition Polymers<\/strong>: Formed by joining monomers without loss of atoms (e.g., polyethylene).<\/p>\n<\/li>\n- \n
Condensation Polymers<\/strong>: Formed by the elimination of small molecules like water (e.g., nylon, polyester).<\/p>\n<\/li>\n<\/ul>\n<\/span>3. Based on Structure<\/strong><\/span><\/h3>\n\n- \n
Linear Polymers<\/strong>: Long straight chains (e.g., HDPE).<\/p>\n<\/li>\n- \n
Branched Polymers<\/strong>: Side chains attached to the main chain (e.g., LDPE).<\/p>\n<\/li>\n- \n
Cross-linked Polymers<\/strong>: Chains connected by covalent bonds (e.g., vulcanized rubber).<\/p>\n<\/li>\n<\/ul>\n<\/span>4. Based on Thermal Behavior<\/strong><\/span><\/h3>\n\n- \n
Thermoplastics<\/strong>: Soften when heated and can be reshaped (e.g., polypropylene, PET).<\/p>\n<\/li>\n- \n
Thermosets<\/strong>: Harden permanently after being heated (e.g., epoxy, Bakelite).<\/p>\n<\/li>\n- \n
Elastomers<\/strong>: Rubber-like materials with high elasticity (e.g., natural rubber, silicone rubber).<\/p>\n<\/li>\n<\/ul>\n<\/span>\u00a0Polymerization: How Polymers Are Made<\/span><\/h2>\nPolymers are synthesized through a process called polymerization<\/strong>, where monomers are chemically bonded into a chain.<\/p>\n<\/span>Types of Polymerization:<\/span><\/h3>\n\n- \n
Addition Polymerization<\/strong>:<\/p>\n\n- \n
Monomers add to each other without any by-product.<\/p>\n<\/li>\n
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Example: Ethylene \u2192 Polyethylene<\/p>\n<\/li>\n<\/ul>\n<\/li>\n
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Condensation Polymerization<\/strong>:<\/p>\n\n- \n
Involves the elimination of small molecules like water or methanol.<\/p>\n<\/li>\n
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Example: Terephthalic acid + Ethylene glycol \u2192 PET (polyester)<\/p>\n<\/li>\n<\/ul>\n<\/li>\n
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Copolymerization<\/strong>:<\/p>\n