Polyurethane Electrospun Fiber Biomimetics Membrane for Constructing the Structure of Grain Layer with Good Breathability for Cattle Split Leather

The traditional thick coating on split leather does not have the ability to breathe like full grain leather. The air and water vapor permeabilities of full grain leather are well known properties due to its fiber woven structure. Simulating the fiber morphology and weaving structure of the dermis or grain layer is very important to construct a top surface layer for split leather. In this paper, a PU (polyurethane) foam layer is put first on the split to enhance the adhesion of a second application of a superfine fibrous PU resin. This foam uses well-known waterborne polyurethane foaming technology. This dried foam has good breathability because of high porosity. A superfine fiber membrane is next put atop of the foam layer by using an electro-spun polyurethane resin. This second resin imitates collagen fibers in the network structure of the leathers’ grain layer. Thus, this resultant electrospun fiber biomimetics membrane simulated the grain layer of natural leather. SEM showed the morphology and structure of this electrospun fiber biomimetic membrane to be like that of the grain layer of natural leather. The porosity and apparent density were basically the same as the grain of leather, which were 63.65% and 583.878 kg/m3 respectively. The air and water vapor permeability of the biomimetics membrane were also as high as 2250 mL·cm-2·h-1 and 8753.02 μg·cm-2·h-1 respectively. Therefore, the biomimetics membrane largely restored the ability to breathe of split leather. Thus, this method simulates the performance and structure of full grain leather and is a novel method for industrial production

Preparation and Properties of Halogen-Free Flame Retardant Polyurethane for Superfine Fiber Leather

Polyurethane (PU) superfine fiber leathers have been widely used in people's life. However, the flammability brings potential risks to their application. Therefore, more and more attention has been paid to the flame retardant modification of PU leathers. In the 1980s, researchers found that some brominated flame retardants produced dioxins during combustion. In 2007, the EU began implementing the REACH regulation, which restricted the use of certain halogenated flame retardants, so a majority of studies focused on halogen-free flame retardant modification. In addition, the halogen-free flame retardant PU should own a better alkali resistance, because alkali treatment is needed in the forming process of the superfine fiber leather. In this paper, two different halogen-free flame retardants were blended with solvent-based PU. The flame retardant properties and alkali resistance of the flame retardant PU were studied by limiting oxygen index (LOI) test, vertical burning (UL-94) test, and thermogravimetry-infrared spectroscopy (TG-FTIR). It was found that BY-90 system flame retardant could be uniformly dispersed in the PU matrix. And when its additive volume was 27%, the LOI value of the flame retardant PU was 27.1%, the vertical burning test could reach V-0 level. Moreover, it also had good alkali resistance. The LOI value remained at 26.1% after the alkali treatment at 90 °C for 40 min in the 30g/L NaOH solution.

Неупругость и наноструктурная дислокационная деформация сплава алюминия с кремнием с супермодифицированной эвтектической структурой

Young’s modulus and the logarithmic decrement of oscillations at a frequency of ~100 kHz as well as the subgrain size and residual stresses in the strontium modified alloy of aluminum with 15 wt % silicon have been studied. The alloy was obtained with a solidification rate of 1 mm/s at the shifted eutectic point. The dependence of inelastic dislocation deformation on the applied oscillating stress has been obtained and analyzed. The effect of strontium modification on the microstrain diagram can be accounted for by transformation of the lamellar fiber structure of eutectic silicon into a superfine fiber structure.

Modification of PA/PU superfine non-woven fiber for “breath” property using collagen and vegetable tannins

Unfigured sea-island superfine fiber PA/PU non-woven (USFSLB) is used to mimic leather’s microstructure as the base of artificial leather. USFSLB has many characteristics and advantages resembling those of natural leather. However, compared with natural leather, the wearing comfort of artificial leather is inferior due to its poor moisture adsorption and permeability. In this work, a “two-step” method of chemical treatment is proposed, in which collagen/chromium-vegetable tannin (C-CrT) is immobilized on nylon fiber of USFSLB to improve its moisture adsorption and permeability (“breath” property). The two-step surface modification involved sulfuric acid hydrolysis and modifying the C-CrT on nylon fiber. Compared with the pristine USFSLB, the tensile strength, the elongation at break, the anti-static performance, the thickness, and the uniformity of C-CrT-treated USFSLB were improved at different levels. Importantly, the C-CrT-treated USFSLB showed excellent moisture adsorption and permeability, especially the liquid wicking rate (LWR) improved by 344%. The self-assembly mechanism of collagen/chromium-vegetable tannin (C-CrT) modified on nylon fibers was analyzed and discussed.

Effects of Anti-Clogging in Ultra-Soft Soils Using Different Composite Filter Material

An experimental study on drainage of different composite filter material in Wenzhou ultra-soft soils was carried out, to investigate the effects of anti-clogging for these composite material. A new instrument was designed to simulate draining process of the ultra-soft soils under vacuum loadings. Based on the experimental results in the form of pump quantity of water, the average settlement of the sludge, the pumping rate and the water content, a comparison was made among six composite filter material (e.g., PVA-1, PVA-2, SAP, superfine fiber, coral cashmere fiber and bamboo fiber) and a traditional non-woven fabric material. The results demonstrate that, PVA-2 composite material is the best way to keep from clogging in the ultra-soft soils. The effects of the anti-clogging is depended on the characteristics of the water absorbency and retention.