Table of Content - JFBI 3.4

The human skin is the largest organ which protects the body from disease and physical damage. When the skin has been seriously damaged through disease or burns, the body cannot act fast enough to produce necessary replacement cells. Artificial skin grafts were developed as a way to prevent such consequences. This work is related to the design of advanced dermal scaffolds (non-woven fibrous mats) to provide multifunctional properties. Defined target properties are attained by distributing specified base materials at multiple length scales ranging from several nanometers to millimeters. Tissue scaffolds were developed using the electrospinning process, which creates a non-woven fibrous construction of high permeability and proper mechanical integrity similar to the scale of the extra-cellular matrix of cells.

Colorectal stents have been reported as an effective alternative to surgery for the palliation or as a “bridge to surgery” for patients with obstructing colorectal cancers. This review discusses the need for colorectal stent placement, distinction from colostomy and resection with primary anastomosis, the requirements for placement, and the many efforts over the past century to accomplish this goal experimentally and clinically. This work briefly presents both commercially available stents and relevant newly developed stents with experimental bio-functional materials, including elastic polymers (polyurethane), the biodegradable and bioresorbable materials, and the naturally occurring materials, focusing on their potential applications in the development of future colorectal substitutes. This paper also examines the critical issues and scientific challenges that require further research and cooperation of multidisciplinary teams.

Several nonwovens are studied to explore the relationship between their structural characteristics, permeability and acoustic absorbing behavior. Fundamental structural parameters had been considered including thickness, gram square meter and porosity. Results show that the permeability is not just linear to porosity, but also related to many other complex and difficult-to-measure parameters. Further in this the paper we have compared absorption coefficient of nonwovens with and without air back, the sound absorption principles of those are completely different. For nonwovens with rigid back, the absorption coefficient increases with increasing thickness. For samples tested with air gap, the increasing air moves the absorption curve towards lower frequency, and enhances the initial slopes of the curves. And also the absorption coefficients over the whole tested frequency range are found to be increasing with air. This indicates that the capillary effect can not sufficiently explain the acoustic absorbing behavior of nonwovens; accurate theories which can illustrate sound absorption property of nonwovens still need to be improved; more precise model is still to be developed.

Optimization of cured cotton textiles through self-cleaning property constructs the main goal of present investigation. Cotton textiles with 0.1, 0.3, 0.5, 1 and 1.5 wt% were cured by Nano-titanium dioxide (P25 Degussa) with and without using cross-link method. Stability of the TiO2 coatings is a particular requirement for textiles because they are subject to frequent washing hence use of a suitable coating condition is necessary. During this study sucsinic acid was used as spacers to attach TiO2 to cotton. Viscosity degree of titania particles to cotton fabrics is studied by burning method by determining the percentage of titania coated. Further, following experiments were conducted: thermal behaviour of curing samples with TGA, self-cleaning degree of curing cotton fabrics and stained samples with Dark green BN green 6 and Reactive orange V-2G dyes under irradiation of 20 & 400 W UV lamps using reflectance spectrophotometer, structure and morphology of titania coated cotton fabric through scanning electron microscopy (SEM) and crystallinity of titania coatings by X-ray diffraction (XRD). Tearing strength of cured cotton fabrics was investigated before and after employing irradiation process. Results show that stability of Nano TiO2 coating and degree of self-cleaning cured with cross-link method is extremely higher than in non cross-link operation and cotton cellulosic chains are not decomposed by photocatalytic activity of titania.

This study surveys the electrical conductivity of multi-walled carbon nanotube (MWNT) /polyurethane (PU) nanocomposites film according to the dispersion conditions. For this purpose, various kinds of polyurethane block copolymer (PU)/multi-wall carbon nanotube (MWNT) with different MWNT contents were mixed and dispersed, and their characteristics related to the dispersion were investigated. Multi-walled carbon nanotubes (MWNT) are of interest in many areas of nanotechnology and used in a number of novel applications. However effective dispersion remains a problem and one solution is to functionalize the nanotubes. In this work, MWNTs are functionalized using an oxidative technique, including dry thermal treatment. The dispersion variation of the PU/MWNT nanocomposite films with MWNT content ranging from 0.1~5.0 wt% was examined. The various characteristics of the dispersed PU/MWNT nanocomposite film were characterized using thermo gravimetric analyser (TGA), scanning electron microscope (SEM) and measuring instrument of electrical conductivity. The degree of dispersion of PU/MWNT nanocomposite films according to the dispersion conditions was shown in various situations. The bad dispersion of PU/MWNT film was revealed during the phase separation between PU matrix and MWNT. Also PU/MWNT nanocomposite film shows good electro-conductivity on its surface because MWNT was collected on the surface of composite film due to its low density.

The dispersion property of modified nano-TiO2 and the effect factor as well as applied properties were studied. The results show that the stability of nano-TiO2 sol was related to the concentration of the modifier and the pH values of the system. The experimental result shows that washing fastness of the finished fabric treated with modified nano-TiO2 had been increased and the antibacterial property of finished fabric was also related to the concentration of the modifier.

A series of novel superabsorbent nanocomposites based on 2-hydroxyethyl methacrylate (HEMA) and acrylamid (AM) were prepared via in situ free radical polymerization, using clay (Laponite XLS) as a crosslinker and ammonium persulfate (APS) as an initiator. The structure and surface morphology of the superabsorbent nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The water absorbency was found to be 612.5 and 182.6 g H2O g-1 in distilled water and 0.2% NaCl solution, respectively. In addition, the superabsorbent nanocomposites reported here might be a potentially smart material in some range of applications including adsorption materials, superabsorbent fiber and drug-delivery devices.

The Bombyx mori silk fibroin gels were prepared by adding various types of polyalcohol (Ethylene glycol, Polyethylene glycol 600) into the regenerated silk fibroin aqueous solution.The gelation time was recorded respectively. Gel structure was analyzed by X-ray diffraction, Fourier transform infrared spectroscopy, laser Raman spectroscopy and scanning electron microscopy. It was found that adding polyalcohol into the regenerated silk fibroin aqueous solution can accelerate the gelation process, with increase in the percentage of the polyalcohol except at 100%. Silk fibroin gels with Ethylene glycol mainly consist of silk II crystal structure. Ethylene glycol almost has no effect on the molecular conformation or crystal structure of silk fibroin gels. However, adding PEG600 to the solution can promote the silk fibroin molecules to form clusters rapidly, while it can also obstruct the structural transformation of silk fibroin molecules from random coil or α-helix to β-sheet. The crystallinity of silk gels was found to decline with an increase in the adding percentage of PEG600. While adding 100% polyalcohol of the mass of silk fibroin into the solution, whether it was Ethylene glycol or PEG600, the silk fibroin gels have more uniform morphology and pores distribution.

In this study, the mechanical model of the woven PVC-coated membrane materials has been built. By the FEM analysis, it was found out that when tensioned under uni-axial loads, the tensile modulus in the warp and fill direction of woven membrane materials could be predicted nicely, especially after the revision of the properties for the fiber materials. The effect of the tensile moduli of the fiber and the PVC coating materials on the modulus of the woven membrane fabrics has been discussed. It could be consulted that with the proper improvement of the modulus of the fiber materials in the fill direction, the discrepancy between the modulus of woven membrane materials in the warp and fill direction could be reduced to a certain extent. When it comes to the prediction of the modulus of the woven membrane materials under bi-axial loads, large difference could be noticed between the predicted results and the experimental results, especially in warp direction. This was due to the fact that the mechanical analysis model could only show the differences of the geometry configuration between the warp and fill directions. However, the reinforcement of membrane materials in warp direction during weaving and coating processes has been ignored.

Textile is certainly a complex multi-pore structure, which can be described as parallel pore structure or pellets accumulation pore structure. The heat and moisture transfer through textile is affected by its structure. Based on the parallel pore structure of textile and a system of human-textile-environment, this paper will report a model of heat and moisture transfer through the parallel pore textiles. It is a system of coupled ordinary differential equations on temperature, water vapor pressure and water vapor mass flux through textile and condensation on the surface of textile. By solving the coupled ordinary differential equations, three formulae are acquired to describe temperature, water vapor pressure from human skin surface to environment and water vapor transfer through textile respectively. Then we obtain the numerical solution of temperature and the rate of condensation by finite difference method (FDM). Numerical simulation is achieved for down and polyester material in order to verify the validity of methods. The numerical results are well matched with the experimental data on the “Walter” Manikin.