In this article, continuous PA6/single‐wall nanotubes (SWNTs) nanofiber yarns were obtained by a special electrospinning method; the mechanical and electrical properties and the electric resistance‐tensile strain sensitivity of the as‐spun yarns were specially studied. The main parameters in the spinning process were systematically studied. Scanning electron microscope images and mechanical tests indicated that the optimum parameters for the electrospinning process were operation voltage = 20 kV, spinning flow rate = 0.09 ml/h, and winding speed = 150 rpm. Transmission electron microscopy images showed that the SWNTs have aligned along the axis of the nanofibers and thus formed a continuous conductive network which greatly improved the electrical conductivity of the PA6 nanofiber yarn and the percolation threshold was about 0.8 wt%. The electric conductivities of the yarns at different stretching ratios were also measured with a custom‐made fixture attached to the high‐resistance meter, and for a given carbon nanotube concentration, the conductivity changes almost linearly with the tensile strain applied on the yarns. POLYM. ENG. SCI., 54:1618–1624, 2014. © 2013 Society of Plastics Engineers

Electrospinning is one of the few simple and effective ways to produce nanofibers, which can be used in various fields. However, the common assembled nanofiber mats are limited in some areas, so static bath was used as the negative collector to produce nanofiber yarns. In order to improve the yields, a novel multi-needle electrospinning using static bath collector was employed, the spinning state and the nanofiber orientation of the as-spun yarns in different numbers of spinning needles are described in details. The results showed that the critical voltages, keeping the electrospinning process stable, increased from 21KV to 28KV with the number of spinning needles increasing from 1-5. Nevertheless, the orientation degrees of the nanofibers in the yarn decreased from 94.40% to 81.29%. Based on the SEM images and orientation degrees of the yarns, the alignment of the nanofibers along the axis of the yarn was seemed still pretty well when the 1-4 needles used. But it was seemed a little disordered when the number of needles reached 5, which was not so well for applications.

Consecutive PA6/MWNTs nanofiber filaments were successfully fabricated by an improved electrospining method in this paper. The microstructure and the arrangement of MWNTs in the nanofibers both with the conductivities of the filaments in different MWNTs contents were studied. The results show that the orientation arrangement of the nanofiber and MWNTs in the fibers were both fine at different MWNTs contents .Besides, with the increase of the MWNTs contents, the diameters of the nanofiber increased, while the conductivity of the filaments increased and MWNTs became gathered in the fibers.

Poly(lactic acid) (PLA)/graphene nanocomposites were prepared by solution blending using chloroform as a mutual solvent. Transmission electron microscopy (TEM) was used to examine the quality of the dispersion of graphene in the PLA matrix. The isothermal crystallization behaviors of PLA and PLA/graphene nanocomposites were investigated by differential scanning calorimetry (DSC). The isothermal crystallization kinetics were analyzed by Avrami model based on the DSC data. The results showed that the well dispersed graphene nanosheets could act as a heterogeneous nucleating agent and lead to an acceleration of crystallization during the PLA isothermal crystallization process. According to the Arrhenius equation, the activation energies were found to be -106.9 and -46.6 kJ/mol for pure PLA and PLA/0.1 wt % graphene nanocomposite, respectively. The crystal morphology were characterized with polarizing optical microscope (POM).

Researchers have paid much attention to small-scale natural fibers among the biological materials to seek innovative methods in order to create new high performance materials. Recently, spider dragline silk fibers are being studied because of their unique combination of high strength to weight ratio and high extensibility, which leads to a tough and lightweight fiber. Biomimetic fibers based on spider silk have been a focus of research for the past decade. However, there are still many unanswered questions about the mechanisms by which silk achieves its unique mechanical properties, as well as challenges in mechanical testing of electrospinning silk nanofibers which are often hindered by both small diameters and limited material availability. A method to characterize local mechanical behavior in small diameter nanofibers was developed to both improve understanding of structure-property in natural fibers and provide a method for comparing mechanical behavior in natural and electrospinning fibers.