Tong Cheng

Using chitosan as a thickener for electrospinning dilute PVA solutions to improve fibre uniformity

Chitosan was added to PVA aqueous solutions as a thickener to improve the electrospinning process. The presence of a small amount of chitosan considerably improved the uniformity of as-spun nanofibres. This improvement is attributed to its significant effect on the solution viscosity and conductivity, with only a slight impact on the surface tension. The concentration of the PVA required to produce bead-free and uniform nanofibres was reduced with the increase in chitosan concentration. The chitosan thickener suppressed the jet break-up and facilitated the jet stretching so that fine and uniform fibres could be electrospun even from a dilute PVA solution.

Photochromic Wool Fabrics from a Hybrid Silica Coating

In this work, a photochromic wool fabric has been prepared by applying a photochromic-dye hybrid silica sol-gel onto the surface of fabric. The photochromic fabric was found to have a very quick optical response. Two types of silica were used as the matrix material, and the type of silica had a small effect only on the photochromic performance, the fabric washing fastness, and water contact angle, but affected the fabric handle property considerably. The silica from a precursor containing a long alkyl chain showed very little influence on the fabric handle and better photochromic performance than that containing a phenyl group.

Photochromic Textiles from Hybrid Silica Coating with Improved Photostability

Photochromic surface coating on textiles may create new fashion opportunities. It also enhances the ultraviolet (UV) protection ability of the coated products. In this study, a spirooxazine dye and a silane that bears a long alkyl chain have been used to produce hybrid photochromic silica coatings on wool fabrics. Four stabilisers are added separately to the photochromic silica coatings to examine their influence on photostability and photochromic behaviour. It is found that the addition of UV stabilisers slightly reduces the photochromic response speed and photochromic absorption. However, the addition of UV stabilisers to the photochromic coating considerably improves the photochromic lifetime. Among the four UV stabilisers studied, the quencher results in the best improvement to photostability with the lowest reduction in photochromic absorption.

Photochromic Wool Fabrics with Enhanced Durability and Photochromic Performance

In our previous work, we have produced a photochromic wool fabric by applying a thin layer of hybrid silica-photochromic dye onto the wool surface. The coating showed a very fast optical response, but had little influence on the fabric handle, however durability was low. In this context, we reported that durability of the hybrid layer can be improved by introducing epoxy groups into the silica matrix via co-hydrolysis and co-condensation of an alkyl trialkoxysilane (ATAS) and 3-glycidoxypropyltrimethoxysilane (GPTMS). The presence of epoxy groups in the silica enhanced both washing and abrasion durabilities. Also, the optical response speed was slightly increased as well. Effects of the type of alkyl silane and the GPTMS:alkyl silane ratio on the coating durability, fabric handle and optical response were examined.

Functionalised roving for structural health monitoring of composites

Abstract Here, we investigated photochromic glass fibre threads produced with the sol–gel coating technique and used it as sewing threads to produce stitched glass–polypropylene composites. The possibility of making sol–gel photochromic glass fibre threads, the morphology of the glass fibre thread and the tensile property of glass fibre sewing threads before and after sol–gel treatment have been studied in this work. The photochromic glass fibre thread was successfully stitched into glass–polypropylene composites as sewing threads and showed an efficient and effective response to UV light. Our results indicate that sol–gel coating is an efficient way to produce photochromic glass fibre. In addition, the sol–gel coating does not significantly affect the tensile performance of the glass fibre.