The effects of various additives such as benzoyl peroxide, 2, 2'-azobisisobutyronitrile, anthraquinone, benzoquinone, anthracene, acetic acid-boron trifluoride complex, tin chloride, zinc chloride, zinc stearate, lead naphthenate and sodium methoxide on the thermal polymerization of linseed oil under the decreased pressure at 280°C were studied.
In all of the case, the following relationship between the reaction time and the viscosity of the obtained oil was found.
logη
t=logη
0+
kt (η
t<<100st.)
wherein η
0; initial viscosity of linseed oil
η
0; viscosity of the obtained oil after reaction time
tt; reaction time
k; constant
There existed the above relationship when the viscosity of the obtained oil was below 100 st. and when it was above 100 st., the viscosity increased very rapidly without any relationship.
In the structures of double bond and the fractionation by acetone, all of them showed the same behavior. The molecular weight of the acetone soluble part (yielded 15-20%) was about 1,000 and that of the acetone insoluble part (yielded 80-85%) was about 2,000.
From the measurement of the viscosity of the obtained oil, it was found that anthraquinone, tin chloride, zinc chloride, and lead naphthenate accelerated the thermal polymerization reaction of linseed oil markedly.
The addition of tin chloride or zinc chloride gave the dark coloured products due to the thermal decomposition reaction occurred during the thermal polymerization. Adding of zinc or lead salts, the obtained products were turbid by the insoluble heavy metal soaps in the polymerized oils.
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