Realizing the full nanofiller enhancement in melt-spun fibers of poly(vinylidene fluoride)/carbon nanotube composites

Strong interfacial interaction is extremely important for achieving efficient mechanical reinforcement in polymer/inorganic nanoparticle composites. In this study, it was demonstrated for the first time that largely improved interfacial interaction could be obtained in continuously melt-spun fibers of poly(vinylidene fluoride) (PVDF)/multi-walled carbon nanotube (MWCNTs) composites, just by an increasing of the deformation extent (draw ratio). The superior interaction is attributed to high deformation inducing a formation of charge-transfer-type F-C bonding between all-trans conformation PVDF chains and extended MWCNTs. As a result, a large mechanical enhancement has been achieved. For the fibers prepared at the highest draw ratio of 200, the tensile strength and modulus are improved for 235% and 109%, respectively, after adding only 0.5 wt% MWCNTs to PVDF. More importantly, a mechanical model fitting, based on the rule of mixtures, indicates that in the case of the highest draw ratio the theoretical strength of MWCNTs is comparable to its real failure strength measured directly between two opposing AFM cantilever tips (Yu et al 2000 Science 287 637). Our present study suggests a great deal of promise for achieving highly efficient CNT enhancement via the non-covalent interaction arising from simple physical fabrication like melt-spinning.