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Abstract
Synthesis of graft copolymers from highly deproteinised
Natural Rubber
Higly deproteinised natural rubber (HDPNR)
latex was prepared by incubation of commercial high-ammonia latex with a
proteolytic enzyme in the presence of a surfactant, followed by repeated
centrifugation for two times. The nitrogen content of HDPNR was less than
0.02%, suggesting the nearly complete removal of protein from the rubber.
A graft copolymer of natural rubber with styrene was made from HDPNR latex
using tertbutyl hydroperoxide/tetraethylenepentamine (TBHPO-TEPA) as an
organic redox initiator. The styrene content, grafting efficiency and molecular
weight of grafted polystyrene were significantly increased by deproteinisation.
The number of grafting sites for graft copolymer from HDPNR latex was about
three times larger than that determined for graft copolymer from untreated
natural rubber latex. The difference between the behaviour of HDPNR and
untreated natural rubber was due to the removal of protein and of naturally
occurring antioxidants present in untreated natural rubber latex.
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