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POLYMERIZATION
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MONOMER
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| Single repeating unit of a large molecule or polymer is called a “monomer”. | |||
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POLYMER
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| A high molecular mass compound, which consist of repeating units, is called “polymer”. | |||
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POLYMERIZATION
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| A self-addition reaction in which a number of simple molecules (monomers) are joined to form a very large molecule is called polymerization. | |||
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| A chemical reaction in which monomers are converted into polymer is called polymerization. | |||
| For example: | |||
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n(C2H4)
(-CH2-CH2-CH2-) or (-CH2-CH2-)n |
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| monomer
polymer (ethylene) (polyethene) |
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TYPES
OF POLYMERIZATION
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| There
are two types of polymerization. Addition polymerization. Condensation polymerization. |
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| For latest information , free computer courses and high impact notes visit : www.citycollegiate.com | |||
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ADDITION
POLYMERIZATION
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| When
a number of monomers undergo self-combination, resulting substance has a
molecular mass many times larger than the monomer, the type of polymerization
is known as “ Addition polymerization”. The empirical formula of addition polymer and the monomer is same. These reactions are catalyzed by peroxides or acids. Generally these reactions required a pressure of 100 atmosphere at 200oC. Examples: polyethylene, polypropylene, P.V.C(Poly Vinyl Chloride), teflone. |
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CONDENSATION
POLYMERIZATION
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| Condensation
polymers are formed by the combination of monomers with the elimination
of simple molecules such as H2O or CH3OH. There are two types of Condensation polymers: 1. Polyester. 2. Polyamide. |
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| Examples: Nylon, terylene, Bakelite. | |||
| What
is Bakelite? Bakelite is a condensation polymer of phenol and formaldehyde. Bakelite is widely used for making molded products. |
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| For latest information , free computer courses and high impact notes visit : www.citycollegiate.com | |||
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VITAL
FORCE THEORY
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In old days, it was believed that organic compounds could be produced only
by living matte. It was also assumed that living matter possess a mysterious
or vital force which converts it into organic compounds and only living
matter can produce organic compounds. FAILURE OF VITAL FORCE THEORY: Vital force theory has failed now because a number of organic compounds can be prepared by inorganic or non-living stuff. FREDRICK WHOLER, a German chemist was the first person who, in 1828 prepared an organic substance UREA by using inorganic substance Ammonium Cyanate by boiling with water. |
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KOCN
+ NH4Cl
KCl + NH4OCN NH4OCN
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CATENATION
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Carbon has ability to form bonds successively to other C-atoms to form chains
of varying lengths, structures and shapes. This property of carbon is called
"Catenation". Catenation is responsible for the variety and a
large number of organic compounds. Due to catenation carbon forms long chains, branched chains, rings, ring and chain structured compounds. |
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