Stress transfer properties of carbon nanotube reinforced polymer composites at low temperature environments

Multi-scale modeling method was used to study tensile properties of single-walled carbon nanotube (SWCNT) and double-walled carbon nanotube (DWCNT) reinforced polymer-based composites at room temperature (RT) and cryogenic temperature (like liquid nitrogen temperature 77 K) conditions. At RT, Young's Modulus of a SWCNT reinforced polymer composite is 1.88 times of a DWCNT reinforced polymer composite due to a weak interfacial bonding between layers of DWCNT, which is bound by the weak Van der Waal interaction. The Young's Modulus of DWCNT reinforced polymer composite is significantly improved with the decrease of temperature and the difference in Young's Modulus between SWCNT and DWCNT reinforced polymer composites has been largely reduced. The radial stress imposed on an outer surface of nanotubes due to the contraction of polymer at liquid nitrogen environment is examined to explain the stress transfer mechanism in a composite system. The extra stresses imposed on the surface of DWCNT increase bonding forces between outer and inner layers of DWCNT. This tendency agreed well with experimental results found in other literature.