Low-Cost And Highly-Efficient Purification Of Polymerization Raw Materials Of PAN-Based Carbon Fiber

The raw materials of synthetic PAN-based carbon fiber include the sovent of dimethyl sulfoxide (DMSO) and the monomer of acrylonitrile(AN). They both contain large amounts of organic and inorganic impurities, these impurities have a great impact on polymerization reaction itself and the final properties of PAN-based carbon fiber. The existence of impurity will destroy the structure of polymer chain, cause pore defects of fiber, destroy the continuity carbon fiber crystallization, finally make carbon fiber property decline; therefore, purification of raw material is very important. This dissertation investigated the purification of raw materials and established a set of low-cost, highly-efficient resin purification processing technology.This thesis first studied the influence of various organic impurities on the polymerization of AN. We adopted reversible addition-fragmentation chain transfer (RAFT) polymerization, which is very stable and can eliminate the effects of other factors. Through the studies and contrastes, we found out a suitable chain transfer agent for RAFT polymerization of AN, BTPADS, and then synthesized this chain transfer agent. We discussed the stability and the optimum reaction conditions of acrylonitrile RAFT polymerization, the results of the research showed that with BTPADS as RAFT polymerization of AN using BTPADS as chain transfer agent can stable the polymerization, don't be affected by external conditions and randomness, so we can aimd at single variable. The resulting polymers had high molecular weight, which could satisfy the requirements of spinning and had narrow molecular weight distribution. We eliminated the effects of other factors by changing the content of impurity under the optimum reaction conditions, and finally provided a maximum permissible content of impurity in industrial production.We tried to look for a series of quick, convenient and inexpensive impurities test method in this paper and we finally established a test system against various impurities in acrylonitrile and dimethyl sulfone. We used ultraviolet spectrophotometry to examination the contents of inorganic metal ions. We employed 1,10-phenanthroline monohydrate to measure the concentration of Fe3+, chlorophosphonazo I to measure the concentration of Ca2+,Mg2+,18-crown-6 ethern to measure the concentration of K+. We draw out the standard curves for four kinds of metal ions, provided a convenient and quick test method for the follow-up work. In this paper,we determined the organic impurities by gas chromatography, and given the best conditions through the experiment of various impurities test. We have established a set of raw materials purification method under the practical and effective detection method in this paper. Through to the studies on resin types, temperature, time, regeneration use of resin,we formulated the purification methods by comprehensive consideration.The methods were:Used D315 resin for purify of inorganic impurities, D101 resin for of purify organic impurities. And given the best conditions of resin usage through experiments. The best conditions of D315 resin was:40℃, V:M (V for DMSO or AN volume (mL), M is quality of resin (g)) is 500:1,blend, airtight mix 4 hours(DMSO) or 30 minutes(AN). The best conditions of D101 resin was:, V:M (V is volume of AN (mL), M is quality of resin (g)) is 500:1,blend, airtight mix 5 hours.