Eco-friendly approach on wool pretreatment and effect on the wool structure and dyeability

This research investigated the effect of various proteolytic enzymatic pretreatment on morphological and chemical features and the dyeability properties of wool fibres. Scoured merino wool fibres are treated with protease, papain, trypsin, and pepsin in specified conditions. Each enzyme activity measurement was provided by appropriate methods such as Bradford, BAPNA (N-benzoyl-1-arginine-p-nitroanilide), and BSA (Bovine Serum Albumin). Enzymatic processes were carried out for 24 h in the incubator set at 40°C, 100 rpm, and specified pH with 1 mg/ml enzyme concentration. Whiteness index (Stensby) and yellowness index (ASTM D 1925) were examined after enzymatic pretreatment. Pepsin and trypsin-treated wool fibres showed the highest whiteness index as 61.3 and 61.1, respectively whilst untreated wool fibres had 52.2. Fourier-transform infrared (FTIR) analysis revealed the increase in the intensity of amide-related bands and hydroxyl bands after enzymatic treatment. Scanning electron microscopy (SEM) photomicrographs manifested the cuticle layer is partially removed in enzyme-treated fibres. Elemental identification was provided by SEM–energy-dispersive X-ray spectroscopy (EDX). It appears that the sulphur bonds decreased after the treatment and the pepsin-treated fibres have fewer bonds of all. To examine the damage to the structure, photomicrographs were taken using fluorescence and light microscopes. The alkali solubility test (ASTM D1283) was also conducted to compare different enzyme types. Wool fibres were dyed in 2.0% concentration with reactive dyestuff. Dyeability and colorimetric features of fibres were measured by a spectrophotometer. The washing fastness test showed that all the samples have good results and the colour change after washing was better in enzyme-treated samples (grade 5) compared to untreated wool fibres (grade 4–5).     

Improving the dyeability of polyimide by pretreatment with alkali

Polyimide fabric, as a high‐performance fabric, possesses advantageous properties, such as outstanding thermal stability and chemical resistance, but has poor dyeability. In this paper, polyimide fabric was dyed successfully with disperse dyes by high‐temperature and high‐pressure dyeing in the presence of a swelling agent and auxiliaries. Under optimal dyeing conditions, it is pretreated with NaOH 6 g l^?1 and dyed with disperse dyes 5% o.w.f., NaCl 1 m , benzyl alcohol 60 ml l^?1 at 135 °C for 45 min to obtain a satisfactory colour yield with good washing fastness and dry rubbing fastness with 93.3% strength retention. The experimental results demonstrate that the Nernst adsorption isotherm is a favourable model for polyimide fabric dyeing with disperse dyes.     

Effects of atmospheric plasma treatment on the dyeability of cotton fabrics by acid dyes

Cotton fabrics were treated with air and argon atmospheric plasma for surface activation. Activated surfaces were grafted with two different amine compounds: ethylenediamine and triethylenetetramine. Pretreated cotton was dyed with acid dye and the effects of pretreatment on the colour strength, as well as the washing, rubbing and the light fastness of the dyeings, were investigated. Colour yield results showed that grafted ethylenediamine and triethylenetetramine enhance the dyeability of cotton fabric with acid dyes. Fourier transform infrared spectra confirmed the formed groups on the surface and scanning electron microscopy showed the etching effect of plasma.     

Chemical functionalization of polyamide 6.6 fabrics

Polyamide 6.6 (PA 6.6) fibers, produced from adipic acid and hexamethylenediamine, are among the most consumed synthetic textile fibers used for garments. Fibers are hydrophobic, which makes dyeing difficult and affects wearing comfort. In the present work, chemical treatments of PA 6.6 fibers were carried out and compared with respect to their effect on fiber properties and obtained surface modifications. Scoured knitted PA 6.6 fabrics (opaque) were treated with hydrochloric acid (0–3 M) and sodium hydroxide (3 M) for up to 3 h at 60 °C. The fibers were characterized with respect to bulk and surface modifications such as amino and carboxyl end groups, superficial dyeing below the T_G of the fiber, surface structure with SEM and AFM analysis. Furthermore a new analytic procedure for the determination of surface amino groups was tested. Both chemical treatments resulted in a significant increase in the amount of amino groups on the fiber, but especially the treatment with HCl 3 M caused a more drastic surface modification of the fibers, however, not only restricted to the fiber surface. AFM and SEM analysis have shown a significant change in surface roughness on the nanoscale, which in addition to the creation of surface functional groups increases the fiber’s hydrophilicity and reactivity.     

Dye diffusion and the phenomenon of barriness on polyamide fabrics

Dyed polyamide fabrics tend to exhibit barriness, particularly when acid dyes of good wet fastness are used. The causes of this phenomenon have been investigated by studying the diffusion kinetics of the dyeing process. The conditions used in the pretreatment of the yarn have been considered, in particular the effect of mechanical and thermal conditions during thermal pretreatment. It has been demonstrated that barriness is dependent only on the kinetics of diffusion. If drawing is increased, the rate of dye diffusion is reduced, whereas an increase in the texturising temperature tends to increase it. The influence of dye diffusion decreases as the dyeing temperature rises. The traditional practice of dyers to attempt to reduce barriness by raising the dyebath temperature very slowly therefore makes matters worse. To reduce barring it would be preferable to introduce the dyestuff to the dyebath only once the dyeing temperature has been reached.     

Surface modification of polyester and polyamide fabrics by low frequency plasma polymerization of acrylic acid

In this study, the surface characteristics of polyester and polyamide fabrics were changed by plasma polymerization technique utilizing acrylic acid as precursor. This monomer was used to produce hydrophilic materials with extended absorbency. The hydrophilicity, total wrinkle recovery angle (WRA°) and breaking strength of the fabrics were determined prior and after plasma polymerization treatment. The modification of surfaces was carried out at low pressure (<100 Pa) and low temperature (<50°C) plasma conditions. The effects of exposure time and discharge power parameters were optimized by comparing properties of the fabrics before and after plasma polymerization treatments. It was shown that two sides of polyester fabric samples were treated equally and homogeneously in plasma reactor. For polyester fabrics, the minimum wetting time, 0.5 s, was observed at two plasma processing parameters of 10 W–45 min and 10 W–20 min, where untreated fabric has a wetting time of 6 s. For polyester fabrics, the maximum value was obtained at 60 W–5 min with the wrinkle recovery angle of 306° where the untreated fabric has 290°. The optimum plasma conditions for polyamide fabrics were determined as 30 W–45 min where 2 s wetting time was observed. Wrinkle recovery angle of untreated polyamide fabric was 264°. In this study, after plasma polymerization of acrylic acid, wrinkle recovery angle values were increased by 13%. No significant change was observed in breaking strength of both fabrics after plasma treatment. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2318–2322, 2007     

The effect of low molecular weight additives on the properties of aromatic polyamide membranes

Salts contained in aromatic polyamide solutions were found to have a considerable effect on the performance and structure of reverse osmosis membrannes cast from these solutions. As in cellulose acetate membranes, certain salts greatly increase membrane fluxes without a detrimental effect on rejection. Highly dissociated salts such as LiClO₄ or Mg(ClO₄)₂ exert a stronger influence than the commonly used LiCl. With mixtures of different salts, stronger effects may be obtained than with a single additive. Many experimental facts indicate that the “salt effect” in aromatic polyamide membranes is due to a general effect on solvent activity and thus on the kinetics and equilibria associated with evaporation and coagulation process.     

A new approach for dyeability of cotton fabrics by different plasma polymerisation methods

The increased dyeability of cotton fabrics in low temperature media using two different plasma polymerisation methods was investigated in this study. In the first method, fabrics were directly treated in amine plasma (ethylenediamine or triethylenetetramine). In the second method, they were first treated in argon plasma and then immersed in an aqueous amine bath. The treated fabrics were then dyed with a reactive dye (Remazol Black B) and the colour yields and fastness properties of the resulting fabrics measured. The K/S values obtained were significantly improved when compared to the untreated fabric.     

Photomodification of the cell membrane complex of wool-the effect on dyeability

Wool fibres have been selectively stained in the region of the cell membrane complex with eosin Y, fluorescein and rose bengal. Dye distribution patterns were determined by fluorescence microscopy and electron-induced X-ray emission (in conjunction with scanning transmission electron microscopy). Irradiation of the stained fibres with visible light caused a reduction in the rate of dye uptake when the wool was subsequently treated with an aqueous solution of the dye CI Acid Red 18. The change in the dyeability of wool was attributed to selective photomodification of the cell membrane complex.     

高密度澄清技术在低温低浊度海水淡化预处理中的应用

海水淡化是目前解决淡水匮乏问题的重要方法之一,为了节约海水淡化的成本,加强处理效果,进行适当的预处理是很有必要的.在低温低浊度地区,传统的海水淡化预处理工艺很难解决由于海水的低温低浊度带来的水体中悬浮物和胶体难去除的问题.高密度澄清技术具有很多优良的特性.作者对用该技术预处理低温低浊度海水的效果进行了研究.     

The effect of benzenesulfonamide plasticizers on the glass transition temperature of an amorphous aliphatic polyamide

The plasticizing effect of benzenesulfonamides (BSAs) on an amorphous aliphatic polyamide (AAPA) has been studied using dynamic mechanical analysis of copper‐supported spin‐coated mixtures. It follows that N‐(n‐butyl)BSA (BBSA), an amorphous liquid hydrogen bonding BSA, is fully miscible with AAPA because their mixtures are characterized by a single glass transition (T_g) throughout the compositional range. The T_g–composition dependence, however, is not linear because experimental results suggest a 20 K fall in T_g occurring around 0.65 BBSA units per amide unit, which coincides with the system shifting from a polymer‐like to a liquid‐like glass‐forming material. When considering a crystallizable hydrogen‐bonding plasticizer such as ethylBSA (EBSA), AAPA/EBSA mixtures become fully crystalline at a 1.3 EBSA unit per amide group. Nevertheless, melting point depression together with the single T_g observed throughout the compositional range on quenched (and therefore amorphous) samples confirms the miscibility of AAPA chains with the plasticizer. N,N‐DialkylBSAs, which lack the sulfonamide proton and therefore the possibility of hydrogen bonding with amide groups, quickly phase separate from AAPA, the glass transition of the latter staying mainly unaffected apart from a small (9 K) decrease at 10–15 mol% plasticizer. © 2001 Society of Chemical Industry     

Syntheses of intrinsically flame-retardant polyamide 6 fibers and fabrics

In this study, flame-retarded polyamide 6 (FR-PA6) was prepared via the direct co-condensation of ε-caprolactam with two different organophosphorus compounds in a typical melt-polymerization process. Polymer microstructures, especially the incorporation of the phosphorus-containing comonomers, as well as the thermal and physical properties of the resulting copolyamides have been studied in detail. The phosphorus-modified PAs have a P-content of 0.10–0.30 wt %, possess high relative viscosities of 2.2–2.4 and good thermal stability. FR-PA6 multifilaments were prepared by melt spinning and show tensile strengths up to 40 cN/tex and tenacities up to 0.5 GPa. Knitted fabrics of FR-PA6 exhibit high limiting oxygen index values around 35%. Due to the very low phosphorus content, there is no impairment of the material properties of PA6. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47829.     

低共熔溶剂预处理提高甘草渣酶解效果优化

近年来,低共熔溶剂（deep eutectic solvent,DES）以易制备、成本低、易回收等优势,在生物质预处理方面受到广泛关注。本研究以氯化胆碱为氢键受体,乙醇胺为氢键供体,合成DES,研究了不同温度、时间和固液比预处理条件对中药渣组分和酶解效果的影响。结果表明：固液比1∶20、120℃、预处理4h后原料中木质素去除率达到78.42%,纤维素回收率为83.89%。随后对不同条件下所得底物进行酶水解,反应96h后发现,较优条件下所得底物酶解效率为78.57%,较未处理中药渣（30.40%）提高了1.58倍。类分形动力学分析表明,预处理温度对酶解效果影响最大。SEM、XRD和FTIR检测发现,预处理后底物形貌、结晶指数和官能团变化有利于酶解效果的提高。     

Improving the dyeability of synthetic fabrics with basic dyes using in situ plasma polymerisation of acrylic acid

The in situ polymerisation of acrylic acid using low temperature plasma treatment was carried out on polyester, polyamide and polypropylene fabrics with the aim of improving their dyeability with basic dyes. The overall colour strength obtained was significantly increased as a result of this treatment. However, while the wash fastness was acceptable on polyamide, it was unsatisfactory on polyester and polypropylene fabrics, probably due to lack of penetration of these fibres by the acrylic acid monomer. Scanning electron microscopy and Fourier transform infrared spectroscopy confirmed that grafting of polyacrylic acid had taken place only on the surface of the polyester and polypropylene fibres, but in the case of polyamide the interior of the fibre was also modified.     

低温耐硫甲烷化催化剂硫化过程

采用燃烧法制备MoO₃/ZrO₂催化剂,该催化剂由于具有比表面积大、粒径小的优点,表现出很高的低温耐硫甲烷化活性。通过考察硫化工艺条件的影响发现,硫化过程中硫化时间、硫化压力、硫化氢浓度的影响不大,而硫化温度的影响较明显,300℃下恒温硫化效果最佳,表征结果表明,300℃下恒温硫化可以使催化剂完全硫化,得到较多的MoS₂晶格条纹,有利于提高催化剂的甲烷化活性。恒温硫化时,硫化温度低于300℃时,催化剂硫化不完全,形成的MoS₂晶格条纹较少;硫化温度过高会导致催化剂过度硫化并发生团聚,从而导致催化剂的耐硫甲烷化活性降低。分步硫化时目标温度为400℃时效果最佳,且与300℃恒温硫化的效果接近,对于MoO₃/ZrO₂催化剂,可选择300℃恒温硫化,适宜的硫化条件为：硫化压力0.1 MPa,硫化温度300℃,硫化氢浓度3% H₂S/H₂,硫化时间4 h。     

Characteristics of sludge hydrolysis by ultrasound and thermal pretreatment at low temperature

Ultrasonic treatment and thermal treatment at low temperature were employed together to analyze and compare the effect of temperature on ultrasonic sludge hydrolysis. Waste activated sludge was more susceptible to ultrasound than anaerobic sludge and primary sludge. In ultrasonic treatment of waste activated sludge for 1 hour, ΔSCOD/(−ΔVSS) ratio decreased from 2.40 to 0.44, indicating that high COD components were solubilized faster than the low COD components. Ultrasonic treatment increased the temperature significantly and the heat effect on sludge hydrolysis was not negligible. Primary sludge was more susceptible to heat than waste activated sludge. A sequential treatment of heat and ultrasound of primary sludge showed that hydrolysis efficiency was more affected by the ultrasonic power than the temperature and the time duration. In case of waste activated sludge, the overall hydrolysis efficiency increased with the temperature up to 50°C, and it remained almost constant at higher temperature. From the results the contribution of shear force by cavitation bubbles decreased at higher temperature. The effects of shear and heat in ultrasonic sludge treatment need to be analyzed separately for the optimum sludge pretreatment.     

Nucleation effect of polyamide on polyoxymethylene

The crystallization behavior and morphology of polyoxymethylene (POM) and POM with polyamide (PA) were studied by polarized light microscopy (PLM), isothermal and nonisothermal differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The isothermal crystallization kinetics were analyzed with the Avrami equation. Compared with the virgin POM, the addition of PA can reduce the spherulites size and improve the crystallization growth rate and crystallinity (X_c) of POM, which demonstrates that the nucleation effect of PA as the high‐molecular nucleus is favorable to the mechanical properties and dimension stability of POLYM. ENG. SCI., 45:1174–1179, 2005. © 2005 Society of Plastics Engineers     

Long term ageing of polyamide 6 and polyamide 6 reinforced with 30% of glass fibers: temperature effect

Because the prediction of the durability of polyamide materials is a very important issue for designers and users, the effect of environment conditions on their mechanical properties is an active field of research. For this reason this experimental investigation was conducted in order to study the effect of temperature on long term ageing of polyamide 6 (PA6) and polyamide 6 reinforced with 30 wt% of glass fibers (PA6GF30). Ageing was realized in distilled water (pH?≈?6; 100% RH) at 30 °C, 50 °C, 70 °C and 90 °C for up to 80 days. Results highlighted the impact of ageing temperature on both conditioned materials. Thus, several surface damages such as crazing and yellowness were recorded especially at high temperatures indicating the materials degradation. These structure changes were induced by the combined effects of water and temperature. As the water diffuses within the polymer, the glass transition temperature T_g drops progressively with ageing temperature to reach the lowest value for samples aged at 90 °C for both tested materials. This tendency was also observed for Young’s modulus, tensile strength and the elongation at break. Thus, a significant loss in stiffness and strength of both materials was recorded as a function of conditioning temperature. This loss of mechanical properties is mainly caused by hydrolysis process and/or interfacial debonding. The appearance of this irreversible phenomenon rises with ageing temperature. Moreover, contrarily to PA6GF30, the temperature effect was also pointed out on SEM observations of PA6 samples. Thus, the hygrothermal ageing induces a change in the mode of fracture from ductile to moderate brittle one according to the ageing temperature. Accordingly, it seems that the ageing temperature has a great effect on the severity of damage of tested materials after long term immersion.     

载体预处理对Fe-Mn/AC催化剂低温脱硝活性的影响

以活性炭为载体,采用硝酸及热处理对载体进行预处理,用浸渍法制备Fe-Mn/AC催化剂,通过FTIR、SEM、N_2吸附-脱附、NH_3-TPD、H_2-TPR和XPS等进行表征,考察载体预处理对催化剂脱硝活性的影响。结果表明,载体预处理会影响载体的官能团、酸位、孔结构及比表面积等,进而影响活性组分的价态及分散性,活性组分的高价态和高分散性是其低温具有高活性的主要原因,载体经硝酸及300℃热处理的催化剂在140～250℃内活性提高近38%。