Habibur rahman high polymer

Habibur rahman high polymer

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  High Polymer Habib 20121107042 ACCE Definitions:: • Polymer:a long chain molecule made up of many small identical units. • Monomer: the smallest repeating unit of a polymer (propene in polypropylene).
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   Properties ofPolymer::
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  Types of Polymers
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  Addition polymerisation
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   Step-growth polymers,also called condensation polymers ,are made by combining two molecules by removing a small molecule.
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  Example: Condensation Reactions
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  Nylon is actuallya “copolymer” because is it made from two monomers. Polyester is a another copolymer. Polyester is made from the two monomers, terephthalic acid and ethylene glycol. This makes a popular plastic called PETE, which is short for Polyethylene Terephthalate. The synthesis is also called a dehydration reaction because of water elimination .  Random Copolymer::
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   Alternate Copolymer:: Block Copolymer When small groups of monomers are attached to each other in alternating fashion, the product is called a block copolymer.  Graft Copolymer:: When ‘sections’ of one type of polymer is attached or ‘grafted’ to the main chain of another polymer.  Terpolymer:: When three types of ‘mers’ polymerized together, it is known as a terpolymer. Acrylonitrile Butadiene Styrene (ABS) is a terpolymer of Acrylic, Butadiene rubber, and Styrene.
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   Branching:: During thepolymerization process, reactions can also happen off of the side of the main chain. These side-chains are known as branching.  Branch Polymer::
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   Homopolymer::  MolecularWeight Molecular weight is the sum of the atomic weights of the atoms that make up the molecule. Carbon has an atomic weight of 12.011 grams/mole. 12 is close enough for what we’re doing A mole is 6.0221415×1023 atoms or molecules This is known as Avogadro's number.  Molecular Weight There are two types of molecular weight average: The first is the Number Average Molecular Weight ( ) The second is the Weight Average Molecular Weight ( )
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   Properties Increasing themolecular weight of the material increases many of the properties of the material by increasing the entanglement of the molecules. A higher molecular weight: Increases the chemical resistance - to a point -It takes more damage to the main chains of the molecules before it will affect the strength of the material -The big loophole to this is if you have a chemical that is very similar to the chemical makeup of the main chain, it will dissolve it much more easily  Properties A higher molecular weight: Increases how far the material can stretch before rupturing (ductility) -The higher degree of entanglement allows the material to be pulled further before the chains break