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在以甲基烯丙基磺酸钠为第三单体,硫氰酸钠为溶剂的腈纶一步法工艺试验中,发现用不同批号的硫氰酸钠所得聚丙烯腈共聚物的粘度相差很大,经用红外光谱法、化学分析法等方法鉴定出硫氰酸钠中的主要杂质为甲酸钠。经过试验证明甲酸钠对硫氰酸钠浓水溶液中丙烯腈—丙烯酸甲酯—甲基烯丙基磺酸钠的共聚有严重的影响。因此建议硫氰酸钠中甲酸钠的含量可以作为腈纶生产中考核硫氰酸钠质量的一个重要指标,同时提出了硫氰酸钠中甲酸钠含量的测定方法。此法采用碱性介质中硝酸银沉淀法,除去 CNS-的干扰,然后用高锰酸钾—一碘量法测定滤液中的甲酸钠。操作较简便,数据重现性好,甲酸钠含量在0.5%以上,相对误差在1%以内。可供工业分析之用.
In the one-step experiment of acrylic fiber with sodium methallyl sulfonate as the third monomer and sodium thiocyanate as the solvent, it was found that the viscosity of polyacrylonitrile copolymers obtained with different batches of sodium thiocyanate varied greatly , By infrared spectroscopy, chemical analysis and other methods identified as the main impurity in sodium thiocyanate sodium formate. Experiments have proved that sodium formate has a serious impact on the copolymerization of acrylonitrile-methyl acrylate-methallyl sodium sulfonate in concentrated aqueous solution of sodium thiocyanate. Therefore, it is suggested that the content of sodium formate in sodium thiocyanate can be used as an important index to evaluate the quality of sodium thiocyanate in the production of acrylic fiber. At the same time, the determination of sodium formate in sodium thiocyanate is proposed. This method uses silver nitrate precipitation method in alkaline medium to remove CNS- interference, and then potassium permanganate - an iodometric method for the determination of sodium formate in the filtrate. The operation is simple, data reproducibility, sodium formate content of more than 0.5%, the relative error of less than 1%. For industrial analysis purposes.