(333a) Polymeric Composite Enhanced by Carbon Nanotube Yarns

Carbon nanotubes (CNTs) belong to a class of nanomaterial that has remarkable physical and mechanical properties. Their superlative mechanical properties make them the filler material of choice for composite reinforcement. The reinforcement of the CNT-polymer composites is mainly influenced by three factors: dispersion of the CNTs in the polymer matrix; interfacial bonding between CNTs and polymer; and alignment of the CNTs in the polymer matrix. In this work, we developed processing methods to fabricate CNT-polymer composites. Instead of dispersing CNTs into a polymer matrix, we used solid-state processes: twist spinning CNTs from CNT forests to form a CNT yarn, making a CNT yarn array, and immersing the yarn array into a polymer matrix through a hot-press process. Twist spinning assembles the CNTs into a highly organized structure without damaging them or lowering their aspect ratio. Our approaches allowed us to form well designed CNT networks inside polymer matrices and it meets the fundamental requirements for filler: high aspect ratio, good distribution in polymer matrix, good alignment and better interfacial stress transfer. When we made the CNT-polymethylmethacrylate (PMMA) composites, we found that the composite with 4 wt% CNT yarns showed an increase of 100% and 300% in tensile strength and modulus respectively with a little deduction in elongation. Since the yarn's strength is over 1 GPa, it is expected that the properties of the CNT-PMMA composite would be dramatically improved by further increasing the content of CNT yarns and this approach can be applied to other polymeric composites.