摘要
本文用维氏法测定了棉油酸甲酯及其聚合物的碘值。首次发现,虽然未经聚合反应的棉油酸甲酯的碘值与称样量关系不大,但是聚合甲酯以及未聚合的单体酸甲酯的碘值不易测准,即随着试样称量的不同,测得碘值有明显变化。作者从聚合反应机理以及聚合产物结构上,分析了聚合甲酯和单体酸甲酯碘值不易测准的原因;同时指出控制试样称量在0.2～0.3克的范围内,而且每次称样绝对偏差不超过0.01克时,可获得近乎一致的碘值,相对误差不超过1％。这样测得的碘值可满意地表示棉油酸甲酯聚合产物的不饱和程度。
Iodine values of the polymer of methyl fatty acids from cottonseed oil have been determined by wijs method. Results of this experiment show that their absolute iodine values are not determined ex- actly,that is,they decrease with the increase in weight with regard to the tested samples. The fact is explained by the mechanism of the polymerization and the structures of the polymer of methyl fatty acids in this paper.Finaly,it is pointed out that the weight of the samples should range from 0.2 to 0.3 g,their absulute differences in weight being no more than 0.01g,and iodine values obtained can be used to compare relative unsaturation of the polymers.
关键词
棉油酸甲酯
碘值
维氏法
测定
methyl fatty acid from cottonseed oil
dimethyl dimer acids
methylated monomer fatty acid
iodine value
wijs Method
isostearic acid
