Qinguo Fan

The formation and performance of auxetic textiles. Part I: theoretical and technical considerations

Auxetic textiles belong to a class of extraordinary materials that become fatter when stretched. Sustained efforts to fabricate auxetic fabric structures are limited. Indeed, several geometrical configurations have been previously proposed but none has been engineered into functional auxetic textile fabrics. The use of auxetic materials has been limited because of problems with deploying them in their fabricated forms. Our thrust in this research is to combine our knowledge of geometry and fabric structural characteristics to engineer auxetic textiles and to determine the properties of such auxetic textile fabrics. In this paper, we have presented the technique we developed for producing several knit structures in which filling yarn inlays are used to effect compound repeating units. In these productions, the chain is used as a base structure and a minimum of two guide bars and maximum of six guide bars are deployed to produce such warp knit auxetic fabrics.

Nanoclay and Modified Nanoclay as Sorbents for Anionic, Cationic and Nonionic Dyes

The nanoclay, montmorillonite, and some modified nanoclays were used as sorbents for nonionic, anionic and cationic dyes. From the sorption differences among the different dye and clay structures, both chemical and morphological, the sorption forces that played important roles were identified. The nanoclay could easily have a sorption capacity of more than 600 mg sorbate per gram of sorbent at a liquor-to-sorbent ratio of 100 to 1. Furthermore, it could have a sorption of 90% at an initial dye concentration of 6 g/L, or 60% based on the weight of the sorbent, indicating an extremely high dye affinity. This study showed that with certain modifications the nanoclay, montmorillonite, could easily become an excellent sorbent for anionic, cationic and nonionic dyes.

The formation and performance of auxetic textiles. Part II: geometry and structural properties

Some exceptional materials become fatter when stretched and are described as auxetics or having negative Poisson’s ratio. Auxetic textiles belong to this class of extraordinary materials that are increasingly attaining some prominence in many applications of technical textiles. We have sustained the efforts to fabricate auxetic fabric structures based on non‐auxetic yarns. The focus is to combine our knowledge of geometry and fabric structural characteristics to engineer auxetic textiles and to determine the properties of such auxetic textile fabrics. To realize our objective, we designed and investigated hexagonal knit structures as auxetic textiles offering optimum performance. The factors that influence Poisson’s ratio are identified as yarn type, number of chain courses and strain level. Also, a method has been developed for quantifying the geometrical structural unit cell of the auxetic structure based on measured parameters, namely a 1, a 2, b 1, b 2, h and c, as detailed in this paper.

The vertical deposition self-assembly process and the formation mechanism of poly(styrene-co-methacrylic acid) photonic crystals on polyester fabrics

Three-dimensional (3D) photonic crystals with structural colors were successfully fabricated on soft polyester fabrics through the vertical deposition self-assembly of monodispersed poly(styrene-co-methacrylic acid) (P(St-MAA)) colloidal microspheres. The elaborate process was investigated by digital camera, 3D video microscope, and field emission scanning electron microscopy, and the formation mechanism and the self-assembly mode of photonic crystal on the fabrics were proposed. It was confirmed that during the evaporation of the colloidal dispersion medium, the surface of the dispersion moved down slowly, and the photonic crystal structure was deposited gradually onto the fabrics due to two effects of capillary force, one being from the meniscus between the P(St-MAA) colloidal microspheres and the vertical polyester fabric substrate, and another from the liquid bridges between adjacent P(St-MAA) colloidal microspheres. The array of colloidal microspheres underwent a disorder-to-order transition during the formation stage, generating a series of varying structural colors in the process. Different from those on solid nonporous substrates, the vertical deposition process firstly occurred in the gaps of fibers, then in the fiber surfaces, and eventually formed the ordered photonic crystal structure on polyester fabric substrates.

Size Reduction of Clay Particles in Nanometer Dimensions

Abstract : This research work focuses on combining ball milling and ultrasonication to produce nano-size clay particles. Our work also emphasizes on increasing the specific surface area of montmorillonite clay particles by reducing the particle size to nanometer dimensions. We have characterized the as-received clay particles by using particle size analysis based on laser diffraction and found that the size of the clay particles is not consistent and the particle size distribution is very broad. However, after the unique treatment and processing, the clay particles were obtained in nanometer dimensions with narrowed particle size distribution.

Synthesis process control and property evaluation of a low-viscosity urethane acrylate oligomer for blue light curable ink of textile digital printing

A low-viscosity urethane acrylate oligomer was synthesized under optimized conditions using a specially selected low molecular weight polyether diol. The synthesis process and the reaction endpoint were monitored by Fourier transform infrared spectroscopy. The rheological properties of the synthesized urethane acrylate oligomer were evaluated by rheology measurements in both steady and dynamic modes, and the blue light induced photopolymerization behavior of the oligomer with camphorquinone and ethyl-4-dimethylaminobenzoate as photoinitiators was examined with photo-differential scanning calorimetry analysis. A blue light curable pigment ink based on the low-viscosity urethane acrylate oligomer was prepared, and jet printed on cotton fabrics using a simulating digital printing device, then photo-cured under blue light irradiation. The printed fabric samples showed fine patterns with soft fabric handle.

Applications of Conducting Polymers in Electronic Textiles

As the textile industry increasingly engages with technical applications, interest in electronic textiles is growing. This paper reviews the research and development (RD the formation of polaron, soliton, and bipolaron. With regards to applications, the review presents conducting polymer applications, including antistatic packaging, microelectronics, rechargeable batteries, photovoltaic technology, LEDs, electrochromic devices, actuators, membranes, corrosion protection and biomedical applications, as well as applications of electric and electronic textiles (e-textiles) which include sensors, heaters, electromagnetic interference shielding, etc. Future trends in electrochromic and solar textiles conclude this paper.

Structural coloration of polyester fabrics with electrostatic self-assembly of (SiO2/PEI) n

(SiO2/PEI) n films with structural colors on polyester fabrics were fabricated using negatively charged SiO2 nanoparticles and positively charged polyethyleneimine (PEI) using the electrostatic self-assembly approach. The bright and variable structural colors of polyester fabrics coated with a (SiO2/PEI) n film were investigated through the color photos captured by a digital camera, and also through the reflectance spectra and the images measured by a DigiEye system and a multi-angle spectrophotometer. The morphological structure of (SiO2/PEI) n films was characterized by scanning electron microscopy (SEM), and the electrostatic self-assembly process and the driving forces of fabricating the (SiO2/PEI) n films were investigated and schematically illustrated. The results showed that the structural colors varied with the various assembly cycles and viewing angles; both the optical properties indicated by the structural colors and the morphological structures illustrated by the SEM images confirmed that the (SiO2/PEI) n film on a polyester fabric was a homogeneous porous composite monolayer, with structural colors originated from single thin film interference; the self-assembly process of (SiO2/PEI) n film on a polyester fabric was driven by multi-forces, with dominant forces equilibrium of electrostatic attraction and repulsion.

Improvements on Flame Retardant Properties of PET/Montmorillonite Nanocomposite Caused by Polyborosiloxane

A phenyl-containing highly cross linked polyborosiloxane (PBSiO) was synthesized as a flame retardant for polyethylene terephthalate (PET). We coated montmorillonite (MMT) clay, a very high aspect ratio and high specific surface area layered silicate with synthesized PBSiO to introduce synergism in flame retardation to the PET nanocomposite film that retained thermal and mechanical properties. This PBSiO has high thermal stability at the processing temperature (270-285° C) of PET and acts as a compatibilizer between PET and clay that are otherwise incompatible. During burning, the flame retardant PET containing PBSiO and MMT forms a protective borosilicatecarbonaceous intumescent char on the surface. Cone calorimeter tests were performed to evaluate key fire properties of the PET/PBSiO/MMT. The peak heat release rate (PHRR) of PET that contains 5 wt% PBSiO and 2.5 wt% MMT was reduced by 60% and similar trend in the reduction of mass loss rate of the nanocomposite was observed.

Optical properties of silk fabrics with (SiO2/polyethyleneimine)n film fabricated by electrostatic self-assembly

Structural coloration is a kind of biomimetic coloring technology. (Silica/polyethyleneimine) n (SiO2/PEI) n films with structural color on the surface of silk fabrics were fabricated by the electrostatic self-assembly method. The structural color of silk fabrics with (SiO2/PEI) n films was captured by a digital camera, and the reflectance spectra were measured by the DigiEye system and a multi-angle spectrophotometer. The morphological structure of (SiO2/PEI) n films on silk fabrics was observed by a field emission scanning electron microscope. The coloring mechanism of the silk fabrics is in agreement with single thin film interference theory, and the variability of the structural color on the silk fabrics is similar to those on polyester fabrics varying with the assembly cycles, particle sizes and viewing angles. However, the color brilliance, brightness and iridescence effect of the silk fabrics are inferior to those of polyester fabrics with the same films, due mainly to the differences in fiber surface structure and microstructure between silk fibers and polyester fibers.