| Nylon 6 (PA6) fiber has been widely applied in daily life and engineering fields. Currently, PA6 for melt spinning has been prepared by an approach of hydrolysis, polycondensation and addition reaction of ε-caprolactam. However, this hydrolysis polymerization method is a time-consuming process (requires about 20 hours), with complex post-treatment, high energy consumption and serious environmental pollutions. By comparison, an activated anionic polymerization method of ε-caprolactam is a more effective approach to get PA6 because this method has many advantages such as rapid reaction rate, high production efficiency, continuous process and less pollution. Therefore, the research and development on the anionic polymerization to prepare PA6 fiber with high properties has important application values.In this thesis, PA6 fiber was prepared successfully via the activated anionic polymerization of ε-caprolactam and melt spinning through a self-made device, and the polymerization process and PA6 properties under various reaction temperatures, catalyst amount, initiator amount and nanoparticle were investigated. Meanwhile, the effects of process condition and nanopartical on the preparation process and properties of PA6 fiber were studied systematically. Based on the above studies, some results were obtained as below.(1) The activated anionic polymerization can be carried out under the condition that reaction temperature above 130℃, catalyst amount above 1.0 mol% and initiator amount above 0.5 mol%, the reaction time could be controlled around 3 minutes and the monomer conversion could get to 96%. The PA6 fiber can be obtained by the combination of the anionic polymerization of E-caprolactam and spinning process. Moreover, the Young’s modulus, breaking strength and elongation at break of the as-prepared PA6 fiber reached to 607 MPa,67 MPa and 313% respectively, which is similar with those of commericial PA6 products.(2) During the melt spinning process, the diameter of PA6 fiber decreases steadily, and the crystallization temperature, crystallinity and mechanical strength increase gradually. The monomer content, molecular weight of PA6, spinning temperature and speed have a big effect on the mechanical properties of PA6 fiber. The lower content of residual monomer in PA6, or the higher PA6 molecular weight, may lead to the increase of mechanical properties of PA6 fiber. The melt spinning speed is the faster, the mechanical strength of PA6 fiber is the higher.(3) Although the introduction of multi-wall carbon nanotube (MWCNT) into the ε-caprolactam polymerization system could reduce the activity of the polymerization reaction and the molecular weight of the as-prepared products, the heterogeneous nucleation effects of MWCNTs can increase the crystallization temperature of PA6 by 6-12℃. Moreover, MWCNTs can be dispersed well in PA6 matrix, to improve the mechanical strength of PA6. As the addition of 0.5 wt% MWCNT to the polymerization system, the Young’s modulus and breaking strength of PA6/MWCNT were increase by 31.7% and 4.3% when compared with pure PA6, and further increase to 120.8% and 62.3% after melt spinning when compared with pure PA6 fiber. |
