水溶性酚醛树脂游离苯酚水蒸汽蒸馏测定方法的研究

DETERMINATION OF FREE-PHENOL IN WATER-SOLUBLE PHENOLIC RESINS BY STEAM DISTILLATION

本文研究了用水蒸汽蒸馏法测定水溶性酚醛树脂中的游离苯酚,酸碱度、游离甲醛和树脂对苯酚蒸出率的影响。实验结果表明,我国林业部部标准和苏联国家标准,即在碱性和强酸条件下对水溶性酚醛树脂试液进行水蒸汽蒸馏,苯酚蒸出率低,游离苯酚测定结果偏低。树脂试液的最佳水蒸汽蒸馏条件是:试液体积控制在150—200ml,试液的pH=4.0—5.0。

This paper deals with the methodology of determing free-phenol in water-soluble phenol-formaldehyde resins and the influences of acidity, basicity, free-formaldehyde and resin on the yield of phenol distillated by steam.Results show that the yield of distillated phenol from water-soluble PF resins is reduced and the content of free-phenol is lowered, when determined in alkaline or strong acidic medium, as required by standard method of China or Soviet Union. For steam, distillation method, the optimum conditions of test resin are as follows: Sample volume should be kept in a range of 150-200 ml and pH value controlled in 4.0-5.0. The free -phenol content of the PF resins with high free-formaldehyde is reduced because of its interruption, when the bromination method is used.