文档介绍：A REVIEW OF RUBBER OXIDATION
1
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The aging of rubber caused by
oxidative degradation leads to the deterioration
in the physical and mechanical properties of
vulcanized rubbers.
The critical review will cover the major develop-ments in our understanding of the oxidation of rubbers.
2
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The mechanisms relative to
oxidation of rubber
Methods of protection
3
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The mechanisms relative to oxidation of rubber
Polymer degradation is caused by chemical bond
scission reactions in initiation
modes of chemical degradation include thermal,
mechanical,photochemical,radiation chemical,
biological and chemical degradation of polymetric
materials.
In addition,we ofen find the aging phenomenon
of white, cracked surface , the deterioration of
physical and mechanical properties in the process
of rubber products used.
The aging of rubber is not a simple process
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The mechanisms relative to oxidation of rubber
R•+O2→RO2• (1)
RO2•+RH→ROOH+R• (2)
ROOH→RO•+•OH (3)
RO•+RH→ROH+R• (4)
RH+•OH→H2O+R• (5)
RO2•+RO2•→ROOR(stable)+O2 (6)
auto-accelerated oxidation
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The mechanisms relative to oxidation of rubber
the loss of unsaturation of α,β-unsaturated
oxidized products through crosslinking:
x-CH=CH-CH2- x-CH-CH-CH2-
→ ׀ ׀
-CH2-CH=CH-CH2- -CH2-CH-CH-CH2-
with:x=-C-, -C-OH, -C-, -C-H
׀ ׀׀ ׀׀ ׀׀
OH O O O
oxidative crosslinking reaction
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The mechanisms relative to oxidation of rubber
the formation of an ether linkage through
photooxidation:
CH3 CH3
׀ ׀ •C=C
-CH-CH=C-CH2- → -CH-CH=C-CH2- ------→
׀ ׀