Studies On The Antistatic Modification Of PAN By PAN-b-PEG Copolymerization And PAN/ZnO-whisker Blend

The purpose of this paper is to improve the antistatic property of polyacrylonitrile (PAN) fibers by using blend and copolymerization two methods.The triblock copolymer PAN-PEG-PAN was obtained by using Ce (IV)/PEG as redox initiation system in acidic aqueous. Meanwhile, the diblock copolymer PAN-b-PEO was first prepared by using PEO macromonomer containing amine end group (PEO-NH2) as the reduce agent in the same condition. The FT-IR measurement showed that the conformation of PEO in the block copolymer changes greatly. The effects of the concentration and the Mw of PEO on the polymerization are investigated. The results showed that the yield of product increased with the increasing of PEO concentration at first, and then decreased above the critical concentration due to the polymer chain's entanglement. By comparison the difference between Ce(IV)/PEG and Ce (IV)/PEO-NH2 system, it was found that the polymerization rate of Ce (TV)/PEO-NH2 system was slower than the former.The thermal and crystalline properties of PAN-b-PEO block copolymers were studied by WAXD and DSC. The results showed that PEO content had great influence on the crystalline properties of PEO segments in the block copolymer. There was one PEO melting peak at high temperature in the DSC curves of isothermal crystallinized block copolymers with low content of PEO, and then two melting peaks were observed with increasing the PEO content, however, only one melting peak remained but at low temperature in the DSC curve of samples with higher content of PEO. The reason may be because of the fraction or second crystallization of imperfect PEO crystals in the PAN-b-PEO. This phenomenon has not been reported in the literature. The effect of PAN block length on the thermal properties of PEO and PAN was also study. It was found that the Tm of PEO and the Tg of PAN decreased as the increasing of PAN bloc length. The crystallinity difference of PEO segment in PAN-PEG-PAN and PAN-b-PEO two types block copolymer was first studied. The experimental results indicated that the crystallization of PEO segments would decrease in the following order:PAN-b-PEOPAN-PEG-PAN. The property of non-isothermal crystallization of PAN-b-PEG has been studied for the first time. The influence of PEO content on the crystallization mechanism was discussed. It was found for the first time that the crystallization mechanism of PEO segment in the block copolymer with low content of PEO is homogeneous nucleation. On the contrary, the mechanism is heterogeneous nucleation in higher content PEO of block copolymer.The rheological property of PAN-b-PEO concentrated solution was first studied carefully. The results showed that the solution was lower viscosity at higher shear rate and at higher temperature in the range of 40-60℃. But, a very strange phenomenon was found for the first time that the viscosity of PAN-b-PEG concentrated solution was higher at 70-80℃ than 60℃ especially at low shear rate. It may be due to the melting of secondary crystallization of PEG segments at such condition. Activation energy for PAN-b-PEG solution increased with the PEG content.The spinnability of PAN-b-PEG block copolymers were discussed and the hygroscopicity and antistatic property of PAN-b-PEG fiber and PAN/PAN-b-PEG blend fiber were also studied. It was found that the hygroscopicity and antistatic property were improved and the fiber had good mechanical properties. Furthermore, the volume resistivity of fiber becomes lower after washing. Therefore the PAN-b-PEG would be used widely for antistatic fibers.The tetrapod-shaped zinc oxide whisker (ZnOw) was first added to PAN spinning dope to improve its antistatic property. The results showed that the size and the dispersion of ZnOw had a great influence on the volume critical resistivity and mechanical properties. The electric resistivity of PAN/ZnOw fiber decreased as the increasing of ZnOw content in the composites. The analysis of the conductive mechanism indicated that the charge concentrating effect at the needles' tip of the wh...