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प्रश्न
Low density polythene and high density polythene, both are polymers of ethene but there is marked difference in their properties. Explain.
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उत्तर
| LDP | HDP |
| 1. It is obtained by the polymerisation of ethene under high pressure of 1000 to 2000 atmospheres at a temperature of 350 K to 570 K in the presence of traces of dioxygen or a peroxide initiator (catalyst). | 1. It is formed when addition polymerisation of ethene takes place in a hydrocarbon solvent in the presence of a catalyst such as triethylaluminium and titanium tetrachloride (Ziegler-Natta catalyst) at a temperature of 333 K to 343 K and under a pressure of 6-7 atmospheres. |
| 2. (LDP) is obtained through the free radical addition and H-atom abstraction. It has highly branched structure. | 2. (HDP) thus produced, consists of linear molecules as shown below and has a high density due to close packing. |
| 3. Low-density polythene is chemically inert and tough but flexible and a poor conductor of electricity. | 3. It is also chemically inert and more tough and hard. |
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संबंधित प्रश्न
What is the role of t-butyl peroxide in the polymerization of ethene?
Which of the following is a natural polymer ? Buna-S, Proteins, PVC
Write the free radical mechanism for the polymerisation of ethene.
Out of chain growth polymerisation and step growth polymerisation, in which type will you place the following.
What is the role of benzoyl peroxide in addition polymerisation of alkenes? Explain its mode of action with the help of an example.
Match the polymer of column I with correct monomer of column II.
| Column I | Column II |
| (i) High density polythene | (a) Isoprene |
| (ii) Neoprene | (b) Tetrafluoroethene |
| (iii) Natural rubber | (c) Chloroprene |
| (iv) Teflon | (d) Acrylonitrile |
| (v) Acrilan | (e) Ethene |
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: Olefinic monomers undergo addition polymerisation.
Reason: Polymerisation of vinyl chloride is initiated by peroxides/ persulphates.
Assertion: Polytetrafluoroethene is used in making non-stick cookwares.
Reason: Fluorine has highest electronegativity.
By which reaction ethene is obtained from ethyne?
Which one of the following can be used as monomer in a polymerisation reaction?
The Ziegler Natta catalyst are
Which one of the following polymers are prepared by addition polymerisation?
Which one of the following polymers is prepared by addition polymerisation?
Which of the following statements about low density polythene is false?
