Wash fastness of fluorocarbon finishes on polyester fabrics

A fabric's surface tension provides a measure of its ability to repel water and oil, while water penetration can be evaluated from a fabric's hydrostatic pressure, which depends mainly on the pore size and thus on the weave. One way of making a surface hydrophobic is to coat it with fluorinated polymers, which confer a low surface tension, reducing the fabric's wettability while preserving its breathability. We have shown that polyester microfibre fabrics (which already have a tight weave and hence high hydrostatic pressure) can be treated with fluorinated finishes to increase water and oil repellency. Observation of a piece of fluorinated polyester microfibre fabric over a number of washings has shown that a regenerative heat treatment preserved the repellency of the fabric but had little influence on the decrease in hydrostatic pressure that occurs with washing.     

The effect of heat setting on the dyeability of differentially dyeable polyester fibres

Apparent diffusion coefficients of two disperse dyes for so-called easily dyeable/cationic-dyeable polyester (ED-CDPET) and cationic-dyeable polyester (CDPET) fibres of identical linear density and sulphonic acid group content have been calculated. It was found that the diffusion coefficients of dyes for ED-CDPET were far greater than those of dyes for CDPET. The dyeability at the boil without carrier, using disperse and cationic dyes on various ED-CDPET and CDPET fibres, has been studied. ED-CDPET was found to have higher dyeability at all levels of heat setting (irrespective of the dye used). The finest ED-CDPET fibres showed maximum dye uptake as a result of increased surface area. Heat setting in the taut condition reduced dye uptake.     

The surface polymerising of fluoromonomer and the shade-darkening effect on dyed polyester microfibre fabric

The surface polymerising of fluoromonomer on dyed polyester microfibre fabric is investigated. The shade-darkening effect of perfluoropolyester acrylate polymer is discussed by colour yield, reflectance spectrum and the colour differences. The surface polymerising of fluoromonomer on dyed polyester microfibre fabric had an excellent shade-darkening effect. After surface polymerising, the dyed fabrics had no significant effect on washing and wet rubbing fastness.     

The effect of heat transfer characteristics of macromolecule fouling on heat exchanger surface: A dynamic simulation study

At the city gate gas pressure reduction stations (CGSs), to prevent natural gas from forming a hydrate in the throttle valve, the natural gas is heated by the heater before reaching the pressure relief valve. Heat exchangers are an essential component of industrial processes that contribute significantly to total system energy. Since the element impacting heat exchanger performance is the fouling process, all fouling processes and models were dynamically simulated in this study. Through coding in the C++ language and simultaneous use of fluent functions, or, in other words, user-defined function (UDF), fouling-related models were defined for this software. The dynamic simulation was performed, and parameters such as fouling strength and layer thickness were calculated. The effects of changing operating conditions, such as gas inlet velocity, surface temperature, and fouling species concentration on fouling growth, were also evaluated. As the concentration of fouling species increased, the fouling rate also increased. The amount of supersaturation and fouling rate increased as the surface temperature increased. Due to the operational limitations of the system, to reduce the fouling rate, the gas inlet velocity should be as high as possible, and the fluid inlet temperature, surface temperature, and concentration of fouling species should be as low as possible. In this study, the required time to reach the efficiency of 70% of the heat exchanger was calculated using the modelling of this chamber, which was equivalent to 190 days. Additionally, the critical thickness of the fouling layer at this time was 3.5 cm.     

Effect of plasma treatment on surface structure and properties of polyester fabric

Poly(ethylene terephthalate) fabric was treated by plasma initiated in various gases: nitrogen, oxygen, air, carbon dioxide and ammonia. Plasma-treated fabric showed a considerable change in surface structure and wettability. It was observed that the change in the surface structure of the polyester fibres was closely dependent on the gas type and treatment conditions. The wetting time of plasma treated fabric considerably drops in comparison to untreated fabric and the best results were obtained by treatment in nitrogen, oxygen and air plasma. A good correlation exists between change in the surface structure of the fabric and its wettability. Infra-red a.t.r. spectroscopy showed some differences in the spectra of plasma treated fabrics but these changes are only moderately dependent on the gas type and plasma conditions. Modification of the surface structure of the polyester fibres depends on the current frequency within the studied range of 0.05–100 kHz.     

热定形对超亮光涤纶长丝染整加工的影响

在超亮光涤纶染整加工过程中,探讨了热定形温度和时间对4种不同截面形状的超亮光涤纶长丝热收缩性能和染色性能的影响。结果表明:在热定形温度120～220℃,热定形时间45～90 s条件下,经热定形后,4种纤维的临界溶解时间均显著增加,热收缩率大幅度降低,纤维表面光泽变化不大,上染率提高;经200℃热定形后,相比圆形和扁平形纤维,三角形和三叶形纤维的上染率提高更为显著。     

Self-assembly of the polysiloxane modified with cationic and perfluorocarbon groups on the polyester surface and its effect on the color shade of the dyed polyester

The polysiloxane modified with cationic and perfluorocarbon groups could form film on the polyester surface by macromolecular self-assembly process. The thin film on the polyester surface could affect the color shade of dyed materials. The effect of the polysiloxane film on the color shade of the dyed polyester was investigated by reflectance spectra, color yield (K/S) and the color differences (ΔE). The colorimetric data of CIELAB was discussed. The results show that the thin film of the polysiloxane modified with cationic and perfluorocarbon groups on the polyester surface had good water repellency. The effect of the polysiloxane film on the color shade of dyed polyester was noticeable. The K/S of the dyed polyester fabrics with the modified polysiloxane film obviously increased. The reflectance spectra of the dyed fabrics treated without and with the modified polysiloxane had not significant change.     

凹槽表面的流动与传热特性

采用大涡模拟对底面为凹槽的矩形通道内湍流流动与传热特性进行了研究,为验证所采用数值方法的准确性与可靠性,将平直矩形通道内模拟结果与文献中的直接数值模拟结果进行了比较,换热面Nusselt数与采用Dittus-Boelter公式计算所得Nu进行了比较,计算误差小于5%。以凹槽表面为底面的矩形通道的数值模拟结果表明:通道底面的凹槽结构改变了凹槽表面处流动结构,不同的凹槽高度和长度对流动阻力和换热效果的影响不同,在特定的几何参数下,与平直矩形通道相比,凹槽表面时均Nusselt数提高了近50.5%,时均摩擦阻力系数减小了近35.17%,综合系数增加了73.89%。通道内的流动结构显示:凹槽表面附近存在流体垂直流向壁面区域,在垂直流动区域内流体出现前、后分流,分流位置处Nusselt数增加明显,摩擦阻力系数没有明显增加,其综合流动特性最好。     

Antifogging effect of cellulose films by chemical modification of the surface using nonionic fluorocarbon surfactant

Wettability and antifogging effect on the surface of the transparent thin film of cellulose esters were studied by fixing chemically nonionic fluorocarbon surfactants on the film surface and were compared with the properties of the surface fixed with the corresponding nonionic hydrocarbon surfactants. These antifogging properties on the surfaces covered by the monomolecular layer of fluorocarbon surfactant were found to be more excellent than those of the nonionic hydrocarbon surfactants from the measurement of contact angle for water droplets and also from the data of Zisman's plots. The surface of the thin film setting in the closed chamber filled with water vapor at 60°C were confirmed to be transparent during a long time without fogging. Antifogging effect may be due to so-called double structure consisting of fluorocarbon and nonionic ethyleneoxide chains in the monomolecular layer.     

The effect of sand surface treatment on sand-filled composites

Sand/unsaturated polyester composites, 50/50 composition by weight, were prepared from sand treated with different silane solutions. N-2-aminoethyl-3-aminopropyl-trimethoxy silane (A0700) and 3-aminopropyltriethoxy silane (A0750) were used. Water and styrene solutions were employed to treat the sand. It was found that A0750 in styrene produced better composites than other surface treatments. As the interfacial bond was improved, the tensile strength and the tensile modulus increased whereas the strain to failure decreased. The acoustic emission data was a function of the sand surface treatment where a better interfacial bond resulted in more acoustic activity. Dynamic mechanical analysis showed that the interfacial bond affects the dynamic shear modulus, the loss shear modulus, and the damping of the sand-filled composites. The glass transition temperature (T_g) of the composite was also affected by the surface treatment. The thermogravimetric analysis did not show a well-defined trend between the decomposition temperature and the surface treatment.     

The effect of fluorination on the surface characteristics and adhesive properties of polyethylene and polypropylene

Polyethylene and polypropylene have been treated with fluorine/nitrogen or fluorine/oxygen/nitrogen mixtures at atmospheric pressure. Changes in surface chemistry and topography as well as depth of fluorination have been examined using Fourier transform infra-red analysis, X-ray photoelectron spectroscopy (X.p.s.), atomic force microscopy (AFM) and ellipsometry. Even very short exposure times caused a large substitution of the hydrogen atoms by fluorine. No change in surface topography was noticed at magnifications of up to 5000 times with the scanning electron microscope (SEM), but AFM showed that fluorination led to an increase of microroughness. The influence of fluorine or fluorine/oxygen concentration, as well as time of treatment and time of storage before adhesive bonding, on adhesion of polypropylene to steel was investigated with a bending peel test. Significant improvement in peel strength was already achieved with minor fluorination intensity. Increase of fluorination intensity did not lead to further improvement in peel strength. Analysis of the fracture surfaces was carried out with the SEM and by energy dispersive X-ray spectroscopy and X.p.s. The findings showed that the samples failed cohesively in the polymer or directly beneath the fluorinated layer. A model to describe the formation of specific interactions between substrate and adhesive is suggested.     

撞击速度对连续液滴撞击热圆柱壁面局部传热特性影响的实验

借助高速摄像机捕获连续液滴撞击热圆柱壁面后的动力学行为,通过直接测试与数值计算方法相结合,获得了不同撞击速度下沿周向和轴向的局部对流传热特性。结果表明,当液滴撞击速度较小,液膜未发生飞溅时,由于圆柱面的各向异性,沿轴向的对流传热系数单调减小,而沿周向,对流传热系数先减小后略有增大;根据对流传热系数沿周向的变化,将圆周划分为撞击区域、热扩散区域和尾部脱离区域;增大液滴撞击速度主要提高撞击区域和热扩散区域的对流传热系数,而对尾部脱离区域对流传热系数的影响并不明显。当液滴撞击速度超过某一临界值(在本文的实验条件下约为1.53 m/s)时,液膜发生飞溅,此时继续增大撞击速度,壁温的降低不再明显。     

The effect of acid treatment on the surface chemistry and topography of graphite

Highly oriented pyrolytic graphite (HOPG) samples were investigated as model catalyst supports. The surfaces were treated with dilute HCl and HNO₃ under ambient conditions and examined with atomic force microscopy and scanning tunnelling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). Raised features were formed on the HOPG surface after acid treatment. These protrusions were typically 4–6 nm in height and between 10 and 100 nm in width, covering 5–20% of the substrate for acid concentrations between 0.01 and 0.2 M. Both width and surface density of the features increases with acid concentration but the heights are not affected. STM images show that the graphite lattice extends over the protrusions indicating that the features are “blisters” on the surface rather than deposited material, a view that is supported by the XPS which shows no other significant adsorbates except for oxygen in the case of the nitric acid. We propose that penetration of the acid at defective sites leads to a decrease in the interplanar van der Waals forces and a local delamination similar to the “bubbles” reported between exfoliated graphene sheets and a substrate. These findings are important in the context of understanding how carbon supports stabilise active components in heterogeneous catalysts.     

The effect of sputter etching on the surface characteristics of dyed aramid fabrics

Three kinds of aramid fabrics, Technora (modified p-aramid), Conex (m-aramid) and Kevlar (p-aramid), were subjected to sputter etching and argon low-temperature plasma treatments after dyeing in black with disperse dyes. The depth of shade increased considerably on Technora and Kevlar with the sputter etching treatment, but not on Conex fabrics. Argon low-temperature plasma treatment had virtually no effect on the depth of shade on the aramid fabrics.     

The effect of heat treatment and cooling rate on the properties of lightweight aggregates

Lightweight aggregates (LWA) were produced from clay in the laboratory. After firing different heat treatments and cooling rates were applied and the resulting material was investigated with respect to strength and microstructure. Fast cooling led to the formation of micro cracks and weakened the material whereas slow cooling enhanced the strength of LWA. The residence time at temperatures between 700 °C and 900 °C led to differences in average oxidation state of iron in the matrix phase leading to substantial changes in thermal behaviour of the matrix phase. The combination of a highly oxidized shell and a reduced core proved to enhance the strength of LWA. A two hour heat treatment at 800 °C in air combined with a subsequent slow cooling rate (0.7 °C/min) applied to LWA produced in an industrial rotary kiln led to a strength increase of 114% compared to material of the normal production without changing any other property.     

碱-等离子体处理涤纶织物的时效性研究

将涤纶织物分别进行30,60,90℃的碱处理后再进行等离子体处理,探讨了碱预处理对等离子体处理效果的时效性的影响;测定处理后纤维的润湿、芯吸和染色等性能以及放置过程中的性能变化,并对纤维的微观形态及其表面化学成分进行了表征。结果表明:经碱-等离子体联合处理后,涤纶织物的润湿、芯吸和染色等性能的提高较经单独等离子体处理更显著,且在放置过程中织物性能的衰减较单独等离子体处理减缓;碱预处理使等离子体处理的时效性得到改善。