Chain Transfer, Inhibhitors and Retarders
Chain Transfer, Inhibhitors and Retarders
Chain Transfer, Inhibhitors and Retarders
INHIBHITORS AND
RETARDERS
OUTLINES
POLYMERIZATION
TYPES OF POLYMERIZATION
CHAIN TRANSFER
INHIBHITORS
RETARDERS
BIBLIOGRAPHY
POLYMERIZATION
It is a process in which large number of low molecular
weight small molecules(monomers) combines
together to form a big molecule or macromolecule
(polymer) of higher molecular weight.
TYPES OF POLYMERIZATION
CHAIN- GROWTH POLYMERIZATION
STEP-GROWTH POLYMERIZATION
CHAIN POLYMERIZATION
Characteristics:
Free-radical Polymerization
Ionic polymerization
Co-ordination polymerization
FREE-RADICAL POLYMERIZATION
Initiator:
R-R R* + R*
Initiation:
R* + CH2=CH2 R-CH2-CH*-H
Propagation:
R-CH2-CH*H + CH2=CH2 R-CH2CH-H-CH2-CH*-H or
R CH2 -*CH-H
Termination:
CHAIN-TRANSFER
In case of transfer reaction however, while the growth
of one polymer chain is stopped or arrested, forming a
dead polymer, there is simultaneous generation of new
free-radical capable of initiating fresh polymer chain
growth
M* + RH MH + R*
Growing chain is now terminated, but a new free-
radical, R* is formed, which will now initiate the
polymer chain growth afresh, which is will be followed
by chain propagation
Butylchloride 35.0
Dichloromethane 1.5
P* + O*-O* P-O-O*
P-O-O* + P* P-O-O-P
USES OF INHIBITORS:
Used in preservation of monomers during production
and storage to avoid self-polymerization