Preparation Of Nano-particles Modified Ultra-high Molecular Weight Polyethylene Fibers

Ultrahigh molecular weight polyethylene (UHMWPE) fibers have plenty of excellent properties and have been used widely in the. field of industry and other special areas. But UHMWPE fibers also have many shortages, which limit the application of fibers in composite materials. So it's necessary to modify UHMWPE fibers.In recent years, the new application of nano-materials is being developed continually. Study on polymer nanocomposites has become hotspots of research. Now it's well known that nanocomposites can be stiffer and tougher than conventional materials, In this paper, nano-particles are added into UHMWPE fiber to modify the UHMWPE fiber.Firstly the technology of surface treatment of nano-particles is studied, and the optimal species and quantity of surface treatment agent are determined. The results show that the dispersibility of nono-particles become excellent after treated with 3wt% coupling agent of titanic ester, the average dimension of treated nono-particles in UHMWPE fibers is about 50nm, and no big agglomerated particles occur in it.After surface treatment, nano-particles are dispersed in mineral oil, and then add the UHMWPE powder and antioxidant, UHMWPE solution dispersed with nano-particles is prepared by swelling and dissolving for sometime at high temperature. The results show that nano-particles affect the solution viscosity and crystalline properties of UHMWPE. Owing to the strong interaction between nano-particles and PE molecules, the viscosity and △E_η ofUHMWPE solution increase with the increasing of nano-particles content. The adding of nano-particles and antioxidant can't affect the crystalline morphology of UHMWPE, but with the adding of antioxidant, the crystallinity increases andthe average crystal size decreases, while the adding of nano-particles, the crystallinity decreases and crystal size increases.There exists loose network structure in UHMWPE gel fiber after phase separation, many nano-sized and micro-sized poles occur in UHMWPE gel fiber after extraction, so nano-particles can diffuse into gel fiber. In this paper, nono-particles are dispersed in extracting agent, and UHMWPE fiber dispersed with nano-particles is prepared after extracted with the composite extracting agent. Compared with the method of adding nano-particles during dissolving stage, by the method of adding nano-particles during extracting stage, there have no big agglomerated particles in fibers owing to the limit of pole size in UHMWPE gel fiber. Whether there exists solvent in UHMWPE fibers or not, nano-particles could diffuse into UHMWPE gel fiber after immersed the gel fiber in nano-particles composite extracting agent, and gel fiber has quite strong absorption to nano-particles. Extracting speed of UHMWPE gel fiber becomes slow because of the adding of nano-particles, ultrasonic action can quicken the diffusing speed of nano-particles, meanwhile, it can also quicken the solvent removing speed of UHMWPE fibers.With the method of adding nano-particles during extracting stage, dry UHMWPE gel fiber dispersed with nano-particles is prepared, after multi-step hot drawing, modified UHMWPE fibers are prepared. The change of structure and properties of fiber during hot drawing is studied and the effect of the adding of nano-particles on the structure and properties of fiber is also investigated. Modification mechanism of UHMWPE fiber in nano-particles is discussed. The results indicate that: (1) As the drawing ratio increase, the mechanical properties, crystallinity and orientation of UHMWPE fiber all increase greatly, while the average crystal size decreases. (2) After modification with nano-particles, the strength of UHMWPE fiber has no obvious change, the modulus increases greatly, while the breakage elongation decreases a little. (3) After modification, the crystallinity and orientation of UHMWPE fiber has no obvious change, but the crystal size decreases greatly. (4) After modification,the equilibrium melting temperature and recrystallizing temperature both increase, at th...