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प्रश्न
Write preparation of low density polythene.
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उत्तर
Preparation of low density polythene:
- LDP is prepared by polymerization of ethylene under high pressure (1000 – 2000 atm) and temperature (350 – 570 K) in presence of traces of O2 or peroxide as initiator.
\[\ce{{n} CH2 = CH2 ->[Traces of O2 or][peroxide at 350–570 K, 1000–2000 atm] LDP}\] - The mechanism of this reaction involves free radical addition and H-atom abstraction. The latter results in branching.
- Polymeric chains are loosely held due to branching and the polymer has low density.
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\[\begin{array}{cc}
\ce{(-CF2-CF2-), -[NH-(CH2)5-CO] -, -(CH2-CH-), (-CH2-CH2-)}\\
\phantom{............................}|\\
\phantom{..............................}\ce{CN}
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