破碎-絮凝法分离细长碳纳米管与碳纤维

Breaking and Flocculating Purification of Thin-long Carbon Nanotubes from Carbon Fibers

根据碳纤维与细长碳纳米管耐磨性能与絮凝沉降性能的差异,提出了一种有效分离细长碳纳米管与碳纤维的物理方法———破碎-絮凝法.该方法包括研磨破碎、液相分散、絮凝沉降、过滤分离等步骤,可高效去除混杂于细长碳纳米管样品中的碳纤维,同时还可去除螺旋状碳纤维及细小碳颗粒等易悬浮杂质.纯化过程对细长碳纳米管无损伤.用电子显微镜和热重分析表征了纯化效果,并初步分析了纯化机理.

An efficient method for separating thin-long carbon nanotubes(CNTs) from carbon fibers is presented. The process involves grinding, dispersion, flocculating deposition and filtration treatments. SEM, TEM and TGA were used to evaluate the purification effect. The as-prepared CNTs specimen consists of large amounts of thin-long entangled CNTs that are 10 similar to 20 nm in outer diameter and some larger carbon fibers with diameters of more than 100 nm. After grinded, carbon fibers can be broken, while thin-long CNTs are undamaged. Dispersed in a water/surfactant solution under ultra-sonic treatment, most pieces of fibers and carbonaceous impurity were left suspended in a kinetically stable colloidal solution, while many thin-long CNTs flocculated into agglomerates and settled down. Most CNTs were extracted from the suspension as flocculated agglomerates leaving pieces of carbon fibers and other carbonaceous impurity in the filtrate. The purification mechanism is based on the difference of tensile strength and dispersibility of thin-long CNTs with that of carbon fibers.