Sulfonic acid group-containing thin films prepared by plasma polymerization

Plasam polymerization of hydrocarbon/sulfure dioxide mixtures, C₂H/SO₂, C₂H₄/SO₂, and CH₄/SO₂ mixtures, was investigated to obtain thin films containing sulfonic acid groups. Plasma polymerization of C₂H₂/SO₂ and C₂H₂/SO₂ mixtures gave filmlike products but that of the CH₄/SO₂ mixtures did not. The plasma polymers possessed much amount of sulfur and oxygen moieties with hydrocarbon chains. The sulfur moieties involved thio, sulfite, and sulfonic acid groups. This groups was a main product and reached 70–80 mol % of the total sulfur moieties. The remains (20–30 mol %) were sulfonic acid and sulfite groups. The oxygen moieties were hydroxyl and carbonyl groups with small amount of carbonxyl groups. The plasma polymers showed and hydrophilicity (the surface energy was 54–56mN/m) and good antithrombogenity.     

Chemical modification of polystyrene. V. Sulfonic acid resins from anhydride substituted polystyrene

Chemically modified polystyrenes based on the condensation of polystyrene with phthalic anhydride, trimellitic anhydride, and cis-1,2,3,6-tetrahydrophthalic anhydride have been processed into sulfonic acid cation exchange resins. The effects of variation of sulfuric acid amount and the temperature of sulfonation on the synthesis and the ion-exchange capacities of the resins have been established. The resins have finally been characterized with respect to their structures by IR and elemental analysis data. The total ion exchange capacity as well as the salt-splitting capacity and the pH-metric titration characteristics of these resins have also been determined. These resins posses better ion-exchange capacities than the conventional styrene based resins.     

Surface modification of bovine bone ash prepared by milling and acid washing process

Bovine bone ash is the main raw material for fabrication of bone china, a special kind of porcelain that has visual and mechanical advantages when compared to usual porcelains. The properties of bone china are highly dependent on the characteristics of the bone ash. However, despite a relatively common product, the science behind formulations and accepted fabrication procedures for bone china is not completely understood and deserves attention for future processing optimizations. In this paper, the influence of the preparation steps (firing, milling, and washing of the bones) on the physicochemical properties of bone ash particles was investigated. Bone powders heat-treated at temperatures varying from 700 to 1000 °C were washed and milled. The obtained materials were analyzed in terms of particle size distribution, chemical composition, density, specific surface area, FTIR spectroscopy, dynamic electrophoretic mobility, crystalline phases and scanning electron microscopy. The results indicated that bone ash does not significantly change in terms of chemistry and physical features at calcination temperatures above 700 °C. After washing in special conditions, one could only observe hydroxyapatite in the diffraction pattern. By FTIR it was observed that carbonate seems to be mainly concentrated on the surface of the powders. Since this compound can influence in the dispersion stability, and consequently in the quality of the final bone china product, and considering optimal washing parameters based on the dynamic electrophoretic mobility results, we describe a procedure for surface cleaning.     

Microbiological modification of organic fibres

Conclusions Treatment of organic fibres with microorganisms makes it possible to change the surface microrelief without reducing fibre strength. The action of the microorganisms is selective: its intensity depends both on the nature of the fibre and also on the variety of microbe.As a result of the life-activity of the microorganisms, the following occur as a rule; smoothing out of coarse projections and filling in of depressions on the fibre surface, while the number of fine (0.1–0.3 µm) structural elements increases significantly. Simultaneously smooth excrescences of size up to a few micrometers appear.Modification of the surface of fibres using microorganisms leads to an improvement in their wetting with melts of polymeric binders, and also to an increase in adhesion at the interface in organoplastics.Translated from Khimicheskie Volokna, No. 3, pp. 18–21, May–June, 1993.     

Carbochain ion-exchange fibres prepared by the graft polymerization method

Conclusions A comparative analysis has been made of the laws governing the process of graft polymerization of partially hydrolyzed PAN fibres with monomers of ionogenic and nonionogenic character.It has been shown that the activity of the investigated monomers in graft polymerization reactions and their effective conversion are reduced, as a rule, with increase in the charge of the monomer, and the homopolymer content is increased.In selecting optimum conditions for a graft polymerization as a method of preparing fibrous ion-exchangers, along with the yield of graft copolymer and the effective conversion, one should also take into account the proportion of active functional groups in the graft copolymer.Leningrad Institute of Textile and Light Industry. Translated from Khimicheskie Volokna, No. 1, pp. 19–22, January–February, 1987.     

High-modulus fibres of nylon-6 prepared by a dry-spinning method

Nylon-6 filaments with tensile strengths at break up to 1 GPa and initial moduli in the range of 16 to 19 GPa have been produced by dry-spinning of solutions of nylon-6 in cosolvent mixtures of formic acid and chloroform followed by hot-drawing at 200°C–240°C. Tensile strengths and elastic moduli of the nylon-6 fibres were strongly dependent on the draw ratio, on the molecular weight of the polymer, on the polymer concentration in the spinning solution and on concentration of nonsolvent in the spinning solution. At high concentrations of nonsolvent in the spinning solution, the as-spun fibres of nylon-6 were composed of ball-like structural units, formed possibly due to the liquid-liquid phase separation in the polymer/solvent/nonsolvent ternary system. Formation of ball-like structures reduced the ultimate mechanical properties of hot-drawn fibres of nylon-6.     

Preparation and modification of activated carbon fibres by microwave heating

Thermal treatment of activated carbon fibres (ACF) has been carried out using a microwave device, instead of a conventional furnace. The results show that microwave treatment affects the porosity of the ACFs, causing a reduction in micropore volume and micropore size. More importantly, the results also show that microwave treatment is a very effective method for modifying the surface chemistry of the ACFs with the production of pyrone groups, detected by FTIR. As a result very basic carbons, with points of zero charge approximately equal to 11, are readily obtained.     

Surface modification of high-strength aromatic polyamide fibres

A modifying (finishing) composition for aromatic polyamide fibres which improves their properties in use was developed, extending the area of application of these fibres. The optimum composition of the finish was determined: an aqueous emulsion of oligoethyl hydride siloxane with SnCl ₂ catalyst. The finish is fixed and reacts with the fibre primarily in the surface layer, causing certain structural changes. Dedicated to the memory of Academician G. I. Kudryavtsev. Translated from Khimicheskie Volokna, No. 3, pp. 10–12, May–June, 1998.     

改性污泥制备泡沫混凝土的可行性研究

由于污泥在建材利用安全性方面存在较多质疑,致使污泥的建材利用一直得不到广泛推广。鉴于此,本实验对剩余污泥进行了改性处理,对改性后获得的泥渣与污泥蛋白液的特性进行了分析,同时对不同泥渣与泡沫掺量下的泡沫混凝土强度和耐火特性进行了研究。结果表明,改性污泥制备泡沫混凝土不存在安全隐患,获得的污泥蛋白发泡剂具有良好的发泡性能。制备的泡沫混凝土具有良好抗压强度、抗折强度,满足行业标准;同时泡沫混凝土的干密度、抗压强度及抗折强度都随着泡沫量的增加而降低;随着污泥渣的增加,泡沫混凝土的干密度和抗折强度下降,抗压强度则呈现先增加而后降低的趋势,在污泥渣质量分数为4%时,抗压强度最佳。耐火试验显示泡沫混凝土具有良好的耐火性能。因此,应用改性污泥制备泡沫混凝土具有较强的可行性。     

Mullite fibres prepared by sol–gel method using polyvinyl butyral

Mullite fibres with uniform diameter and smooth surface have been synthesized using commercial grade polyvinyl butyral (PVB) as binder. The sol with good spinnablity was obtained at reaction temperature of 60 °C for 1 h. The results of X-ray diffraction indicated that the Al–Si spinel was obtained before complete mullization, which implied the addition of PVB retarded the phase transformation of mullite. The fibres showed a rough surface and lateral cracks at 800 °C. Smooth and dense surface was observed when fibres were sintered at 1200 °C and completed transformation to mullite was achieved. This technique offered the possibility of synthesizing mullite fibres at considerably lower cost than at present.     

Chemical modification of carbon fibres by esterification —optimization of fibre pretreatment

Electrochemically oxidized PAN-based carbon fibres were modified by attachment of anm-dinitrobenzene group. Chemical modification was performed by esterification of the –OH groups of the oxidized carbon surface with 3,5-dinitrobenzoyl chloride. The higher modification extent was achieved in the case of d.c. oxidized carbon fibres, which bear a large number of –OH groups. The attachment of the dinitrobenzene species was supported by cyclic voltammetry carried out on the modified carbon fibre electrodes in aqueous solutions. The quantity of attachedm-dinitrobenzene groups was determined polarographically, after hydrolysis of the esteric bonds; it corresponds to a charge density of ca 0.2 kAh kg^–1 carbon fibres, which is of the order of magnitude of battery electrodes.     

Active center formation in the modification of fibres by a gas discharge

Conclusions The basic feature of radical processes in polymers of various chemical structure on treatment in a gas discharge plasma is that the type of radicals formed in the polymer as a result of transfer of plasma energy to the macromolecule does not depend on the chemical composition of the plasma-forming gas.Radicals formed in the surface layer are mainly stabilized in the bulk of the polymer due to migration of a free valence. This plays an important role in carrying out chemical grafting in modifying the surface of fibres.Translated from Khimicheskie Volokna, No. 1, pp. 35–36, January–February, 1989.     

The modification of wild silk fibres with methacrylamide

Wild silk and cultivated mulberry silk fibres have been graft copolymerised with methacrylamide, and the changes in the dyeing behaviour when dyeing with the levelling acid and milling acid dyes investigated. The tensile properties of the fibres and their durability during laundering have also been examined. The amount of the levelling acid dye adsorbed by all the fibres decreased with increasing polymer add-on, while the amount of milling acid dye adsorbed by the mulberry silk fibres was almost unchanged by the graft treatment. The breaking loads of the fibres were almost unchanged whereas rigidity of the fibres increased following graft treatment. The tensile properties of the grafted silk fibres were not diminished by laundering at polymer add-on levels greater than 50%.     

Patterned polymer surfaces with wetting contrast prepared by polydopamine modification

Patterned polymer surfaces with contrasting wettability are prepared by polydopamine (PD) modification. The fabrication process involves spraying dopamine solution droplets on hydrophobic polymer surfaces and PD deposition derived from the oxidative polymerization of dopamine. Each dopamine solution droplets functions as microreactor leading to the formation of patterned PD thin films on the solid/liquid interfaces. Multiple kinds of polymer substrates, including polypropylene, polystyrene, polycarbonate, polyethylene and polytetrafluoroethylene, are endowed with PD patterns using this method. Two types of wetting behaviors are achieved in relation to the micro morphology of the substrates. If smooth or porous substrates are used, the as‐formed film exhibited hydrophilic‐hydrophobic pattern. When a hierarchical‐structured film is used, the uncoated and coated regions have similar static wettability but different dynamic wetting behavior. This PD modification method is also proved to be suitable for flexible and curved surfaces. The results along with the fact that PD could deposit on virtually any surfaces makes this method find wide practical applications in many fields. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41057.     

Oxygen plasma modification of pitch-based isotropic carbon fibres

An isotropic carbon fibre was surface-treated by microwave oxygen plasma at different conditions and characterised by scanning electron microscopy (SEM), scanning tunneling microscopy (STM), N₂/CO₂ adsorption, Raman spectrometry, X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption (TPD). It is shown that the structure of the fibre suffers only limited alterations upon plasma treatment in such a way that the local disorder on its surface, which was already large in the fresh material, barely increases after the plasma exposure, as detected by Raman measurements. At the nanometre scale, STM images revealed a moderate increase in surface roughness. Evidence for chemical changes undergone by the fibre following the etching was provided by XPS and TPD, showing that stable oxygen functionalities were introduced by the plasma exposure, a result of practical importance for the application of this treatment not only to this type of carbon fibre, but to carbon materials in general. It was also observed that very gentle plasma exposures were generally sufficient to provide the fibre surface with a large amount of oxygen functional groups and that more intense treatments had a negative effect in this respect (i.e. they were not able to supply oxygen to the surface in larger amounts than the softer treatments did).     

Surface modification of hybrid fibres for fire protection

The formation of polyaluminosiloxane networks through surface modification of cellulose-polysilicic acid hybrid fibres with inorganic aluminium compounds enhances flame retardancy and laundry performance of these fibres. Fibres of cellulose-polysilicic acid (VISIL) have been reported as a flame retardant. In contrast to their thermal property, these fibres undergo a significant change, in terms of flame retardancy, when subjected to alkaline conditions (pH > 10). Surface modification of these fibres with inorganic aluminium compounds not only reduces the solubility behaviour but also increases the flame retardancy.     

Modification of polyacrylonitrile fibres to improve the properties of carbon fibres prepared from them

Conclusions -- It has been found that treatment of acrylonitrile fibres obtained by the wet dimethyl formamide method before thermal oxidation with inorganic salts considerably changes the properties of the thermally oxidized fibres.-- On treatment of the fibres with an aqueous solution containing copper ion in a reducing medium, their sorptive powers are considerably impaired, the fibre diameter is increased, and the electrical conductivity is increased, plus processes of cyclization and oxidation are accelerated.-- On treatment with a solution of aluminum chloride in the presence of orthophosphoric acid, the fibre structure is made denser and its strength is increased.-- Sodium thiosulfate as a modifier considerably changes the functional composition of polyacrylonitrile fibres; thereupon, a process of structural amorphization takes place.Translated from Khimicheskie Volokna, No. 5, pp. 48–50, September–October, 1991.     

Structure of hydrocellulose fibres prepared from cuprammonium solutions by the spin probe method

Conclusions The structure of hydrocellulose fibres has been investigated by the spin probe method.Broad possibilities of this method for investigating the dependence of fibre structure on preparation conditions have been demonstrated.Translated from Khimicheskie Volokna, No. 1, pp. 28–30, January–February, 1988.