Investigation Into Structure And Properties Of Ultra-High Molecular Weight Polyethylene/Carbon Nanotubes Composite Fiber

Ultra-high molecular weight polyethylene (UHMWPE) fiber is a kind of high performance fiber, with high orientation, crystallinity, extended chain crystal, highest specific strength and modulus among all kinds of man-made fibers. In addition, it also possesses low density, good UV and erosion resistance, outstanding impact and incision resistance. Consequently, UHMWPE has been widely used in many fields. However, some weaknesses, such as poor rheology flow behavior leads to low produce efficiency and high cost, poor heat resistance and easy to creep under tension greatly limit its further application in some special fields.Nanotube is a new carbon family member following with the discovery of C60. It has peculiar structure, unique properties andpotential application value, which bring great interests to scientists for about ten years. Nanotube is a hollow tube curled from the hexagon carbon gridding and "the cap of carbon" located in the two ends is closed by pentagon or heptagon carbon gridding. According to the number of graphite layer, nanotubes could be divided into single-walled nanotube(SWNT) and multi-walled nanotube(MWNT). The diameter of nanotubes is small and ranges from a few nanometer(nm) to tens nanometer(nm), but the length of nanotubes ranges from a few micron(μm) to a few millimeter(mm), Nanotubes are therefor thought as a typical one dimensional material. Nanotubes are ideal materials for functionalization and reinforcement of polymer matrix theoretically.Nanotubes/polymer nanocomposites have potential applications in the fields of spaceflight, textile, rope , automobile and so on. The studies on nanotubes/polymer nanocomposites have received great interests.In this paper, structure and properties of UHMWPE/CNTs composite fiber were studied. In order to improve the dispersion and interfacial adhesion to realize load transfer and to reinforce UHMWPE, the purification and functionalization of carbon nanotubes were carried out. Different test apparatus were used to characterize the pretreated carbon nanotubes and UHMWPE/CNTs composite materials. The conclusions follows.1. The results showed that, KMnO4 + H2SO4 oxidation was an effective method for CNTs purification, which could remove most impurities resulted during CNTs production. Furthermore, organic groups could be introduced onto carbon nanotubes during purification process, which could be great benefit for further functionalization of carbon nanotubes.2. The rheology studies on UHMWPE and UHMWPE/CNTs gels showed that the viscosity was reduced with the adding of CNTs, and the process behavior of UHMWPE could therefore be improved.3. Structure and morphology of extracted UHMWPE/CNTs fibers demonstrated that the purified and functionalized carbon nanotubes could be uniformly dispersed in UHMWPE matrix without observed aggregation. The results showed that good compatibility and adhesion existed between purified and functionalized carbon nanotubes and UHMWPE matrix. Furthermore the SEM study showed that the typical "towel gourd tendon like"structure of UHMWPE was changed into a very special "noodle like"structure when nanotubes were added, and a "restricted crystallization model" was proposed.4. The results derived from DSC, TGA, XRD and mechanical tests on UHMWPE/CNTs fibers indicated that the crystallinity, heatresistance, impact strength and modulus were increased and the creep was improved by the adding of carbon nanotubes into UHMWPE matrix. However all these properties would be inferior...