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प्रश्न
What is the role of benzoyl peroxide in addition polymerisation of alkenes? Explain its mode of action with the help of an example.
उत्तर
Role of benzoyl peroxide is to generate free radicals. A variety of alkenes or dienes and their derivatives are polymerised in the presence of a free radical generating initiator (catalyst) like benzoyl peroxide, acetyl peroxide, tert-butyl peroxide, etc. For example, the polymerisation of ethene to polythene consists of heating or exposing to light a mixture of ethane with a small amount of benzoyl peroxide initiator. The process starts with the addition of phenyl free radical formed by the peroxide to the ethane double bond thus generating a new and larger free radical. This step is called chain initiating step.
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संबंधित प्रश्न
Write the free radical mechanism for the polymerisation of ethene.
Why should the monomers used in addition polymerisation through free radical pathway be very pure?
Match the polymers given in Column I with their chemical names given in Column II.
| Column I | Column II |
| (i) Nylon 6 | (a) Polyvinyl chloride |
| (ii) PVC | (b) Polyacrylonitrile |
| (iii) Acrilan | (c) Polycaprolactum |
| (iv) Natural rubber | (d) Low-density polythene |
| (v) LDP | (e) cis-polyisoprene |
Match the polymers given in Column I with the preferred mode of polymerisation followed by their monomers.
| Column I | Column II |
| (i) Nylon-6,6 | (a) Free radical polymerisation |
| (ii) PVC | (b) Ziegler-Natta polymerisation or coordination polymerisation |
| (iii) HDP | (c) Anionic polymerisation |
| (d) Condensation polymerisation |
Assertion: Polytetrafluoroethene is used in making non-stick cookwares.
Reason: Fluorine has highest electronegativity.
Low density polythene and high density polythene, both are polymers of ethene but there is marked difference in their properties. Explain.
Which one of the following can be used as monomer in a polymerisation reaction?
Which one of the following polymers are prepared by addition polymerisation?
\[\ce{X + C + Cl2 ->[High temperature][of about 1000 K] Y + CO}\];
\[\ce{Y + 2H2O -> Z + 2HCl}\]
Compound Y is found in polymeric chain structure and is an electron-deficient Molecule. Y must be:
Which of the following statements about low density polythene is false?
