Stretching induced interfacial crystallization and property enhancement of poly(l-lactide)/single-walled carbon nanotubes fibers

In this work, poly(l-lactide) (PLLA)/single-walled carbon nanotubes (SWNTs) fibers were first prepared at high drown ratio and low drown ratio, respectively. Then they subjected to tensile testing. It was found that the composite fibers obtained at low drown ratio showed no obvious enhancement of tensile strength and elongation at break, compared with the pure PLLA fibers obtained at the same low drown ratio. However, a significant property enhancement was observed for the composites fibers obtained at high drown ratio. Structure analysis of the as spun fibers before and after tensile testing suggests a possible stretching induced formation of brush-like hybrid structure in which the PLLA lamellae growing perpendicular to the SWNTs axis for fibers obtained at high drown ratio. This unique brush-like hybrid structure could largely enhance the interfacial interaction between PLLA and SWNTs, thus results in greatly improved tensile strength and elongation at break.