Determination Of Residual Solvent Content Of PAN Fiber By Gas Chromatography

The solvent DMSO plays a very important role in precursor preparation.For example,the temperature,content and pH of coagulation bath(DMSO solution)can determine the quality of primary fibers.On the contrary,the residual DMSO needs to be cleaned and removed in the process of water washing,because when DMSO is precipitated,holes are easily formed on the surface of the precursor,the surface of the precursor is uneven,which is not conducive to spinning and ultimately affects the quality of the finished product.The pretreatment method of PAN fiber in this topic is water boiling method.It firstly puts PAN fiber into oven to dry,takes out and cools it,then puts it into water boiling reflux device to boil and reflux,and then detects the concentration of DMSO in pretreatment liquid to calculate the amount of DMSO in PAN fiber.The main two steps of water boiling method are oven drying and water boiling reflux.Through a large number of experimental analysis,it is found that the optimal drying time for DMSO precipitation is 2h and the optimal reflux time is 2h.In order to strengthen the precipitation effect of DMSO,the two are combined.Since DMSO is easy to decompose when heated,and there is a heating reaction in our experiment,it is inferred from the thermal decomposition verification experiment that DMSO did not undergo a thermal decomposition reaction during the experiment.Finally,starting from the detection method,gas chromatography,high performance liquid chromatography and ultraviolet spectrophotometry are respectively used to determine the DMSO content in pretreatment solution.Through data comparison,we find that ultraviolet spectrophotometry cannot test samples with too low or too high concentration,and the presence of oil can also affect ultraviolet testing.However,in the testing process of high-performance liquid chromatography,although the oil does not affect its normal detection,it is easy to pollute the chromatographic column,thus affecting the detection effect.Gas chromatography has the advantages of fast analysis rate,good separation effect and low requirements on chromatographic columns,etc.After eliminating the defect that DMSO did not undergo thermal decomposition reaction during the experiment,it can be confirmed that the most suitable method for testing the residual DMSO content in PAN fiber is gas chromatography.