Determination of the Nitrogen Content of Cationic Cellulose Fibers by Analytical Pyrolysis

Summary.  Analytical pyrolysis in combination with gas chromatography and mass spectrometry or a nitrogen-phosphorus detector, respectively, were used to characterize the quaternization reagent glycidyltrimethylammonium chloride and a cationic cotton fabric. Trimethylamine was shown to be the most abundant nitrogen-containing product in the pyrolysis of glycidyltrimethylammonium chloride and was thus used for the quantification of the nitrogen content of the cationic cotton fabric. The results were compared to those obtained by traditional methods such as Kjeldahl and elemental analysis. It could be shown that pyrolysis is well suited for monitoring the nitrogen content of cellulose fibers. Received July 11, 2001. Accepted (revised) August 2, 2001     

Self-extinguishing cotton fabric with minimal phosphorus deposition

The phosphorus-containing acrylate monomer, 2-acryloyloxyethyl diethyl phosphate (ADEP), was synthesized and applied to cotton fabric by using the admicellar polymerization technique. A cationic surfactant (cetylpyridinium chloride, CPC) was used as the surfactant for admicellar polymerization. Results from FTIR-ATR and SEM showed that PADEP polymer film was successfully formed on the cotton fabric surface. TGA and DTG analyses showed that the phosphorus-containing PADEP lowered the decomposition temperature of the treated fabric resulting in a higher char yield than in the case of untreated cotton. The flammability tests showed that PADEP-coated cotton with the phosphorus content 4.18 mg/g cotton was self-extinguishing, with the flame extinguishing right after the removal of the ignition source leaving a small area of char formation.     

Synthesis and Evaluation of Technical Properties of Novel Cationic Mono‐s‐chloro Triazinyl (MCT) Reactive Dyes on Cotton

Two novel cationic mono‐s‐chloro triazinyl (MCT) reactive dyes together with their analogues were synthesized via reacting an N,N‐dimethyl dodecylamine with p‐nitrobenzyl bromide. The resultant was reduced using stannous chloride and hydrochloric acid to produce the primary amine. The quaternary ammonium salt containing primary amine was then diazotized and coupled to H‐acid/J‐acid reacted with cyanuric chloride and sulfanilic acid. The analogue dyes were prepared via the same route without quaternary ammonium salt making stage. The dyes were characterized using FTIR, ¹H NMR, UV‐Vis spectroscopy and elemental analysis. The substantivity, exhaustion and fixation of the dyes were investigated on cotton fabric. It was found that these functional dyes could be effectively introduced to cotton for achieving simultaneous coloration and functional finishing effects. All the dyed fabrics exhibited softening efficacy. The washing and light fastness of the dyed samples were further studied.     

Thermogravimetric analysis of polyester/cotton blends treated with Thpc-urea-poly(vinyl bromide)

Polyester/cotton fabric swith blend ratios of 0/100, 11/89, 20/80, 30/70, 50/50, and 65/35 were investigated via thermogravimetric analysis in both nitrogen and air atmospheres. The samples were heated from ambient to 750°C at a heating rate of 5°C min^?1. The same fabrics were analyzed after treatment with tetrakis (hydroxymethyl) phosphonium chloride-urea-poly(vinyl bromide) (Thpc-urea-PVBr) flame retardant.Weight losses observed during pyrolysis were assigned to the cotton and polyester portions of the blends. Both cotton and polyester thermally decompose to yield gases and solid char byproducts. In nitrogen the 100% cotton fabric undergoes one major weight loss between 270 and 370°C, with the maximum rate of weight loss, 0.15 mg/min-mg occurring at 346°C. Thermal decomposition of the 100% polyester occurs over a range of 335–470°C, with the peak rate of weight loss, 0.11 mg/min-mg, measured at 416°C. In an air atmosphere, both volatile gases and solid char by- products of pyrolysis undergo combustion. The combustion reactions are associated with measured weight losses. The maximum rate of weight loss for the cotton portion increases to 0.25 mg/min-mg and occurs at 317°C. The maximum rate of polyester decomposition remains the same in both air and nitrogen, but the temperature decreases to 405°C.     

Imparting durable antimicrobial properties to cotton fabrics using quaternary ammonium salts through 4-aminobenzenesulfonic acid-chloro-triazine adduct

A 4-aminobenzenesulfonic acid-chloro-triazine adduct was successfully synthesized in a laboratory scale and treated with cotton fabrics in order to increase the anionic sites and thereby % exhaustion of cationic compounds. Two Quaternary Ammonium Salts (QAS) was investigated namely, Cetylpyridinum chloride (CPC) and Benzyldimethylhexadecyl ammonium chloride (BDHAC) which are widely accepted as strong antimicrobial agents. The reaction mechanism involved in the synthesis of the reactive adduct as well its application to cotton fabric were demonstrated in detail. The effects of application parameters, namely pH, temperature and liquor ratio were examined. The reaction efficiency was determined through monitored % exhaustion of the adduct by cotton fabric. Antimicrobial activity of the treated cotton sample was studied against Staphylococcus aureus according to AATCC test method 100-1999. Results obtained show that the treated fabric shows higher antimicrobial activity compared with the untreated fabric. The results depict also that % exhaustion decreases as the pH, temperature and liquor ratio increase. Moreover, the appropriate predictable empirical models were developed using Excel solver function incorporating interaction effects of all variables to predict the % exhaustion and the satisfactory results (R² > 0.98) were obtained.     

Plasma-assisted regenerable chitosan antimicrobial finishing for cotton

In this study, nitrogen-plasma treatment was used to enhance the coating of chitosan onto cotton fabric and chlorine was introduced into nitrogen-containing groups on the chitosan coated fabric in order to make it antimicrobial by chlorination with sodium hypochlorite. The antimicrobial property and its rechargeability were investigated. FTIR, UV and scanning electron microscope were used to evaluate the surface properties, including the existence of chitosan on cotton fabric, the content of chitosan on cotton fabric and the surface topography of cotton fabric after modification. The results showed that nitrogen-plasma introduces nitrogen-containing groups into cotton fabric, the coating of chitosan on fabric was improved with nitrogen plasma treatment and chlorine was introduced into the chitosan coated fabric successfully which inhibits bacteria effectively and it is rechargeable. Thus, the antimicrobial property of cotton fabric coated with chitosan with the aid of nitrogen-plasma treatment after chlorination achieved good effects.     

Comparison of different reactive organophosphorus flame retardant agents for cotton. Part II: Fabric flame resistant performance and physical properties

N-Methylol dimethylphosphonopropionamide (MDPA) is one of the most commonly used durable flame retardant agents for cotton. In our previous research, we developed a new flame retardant finishing system based on a hydroxy-functional organophosphorus oligomer (HFPO) and bonding agents, such as dimethyloldihydroxyethyleneurea (DMDHEU) and trimethylolmelamine (TMM). In this research, we compared the flame resistant performance as well as physical properties of the cotton fabric treated with these two flame retardant finishing systems. The cotton fabric treated with MDPA/TMM has a higher initial limiting oxygen index (LOI) than that of the fabric treated with HFPO/TMM due to higher nitrogen content in the system. The LOI of the cotton fabric treated with the HFPO and MDPA systems becomes identical when the treated fabric contains equal amount of phosphorus and nitrogen. The MDPA/TMM shows higher laundering durability on cotton than HFPO/TMM system. The fabric treated with HFPO/TMM and MDPA/TMM has low wrinkle resistance and low strength loss whereas the fabric stiffness significantly increases when the TMM concentration is increased.     

A rheological study of cationic micro- and nanofibrillated cellulose: quaternization reaction optimization and fibril characteristic effects

Driven by the demand for various cationic biopolymers in recent years, the quaternization of cellulose nanofibers was carefully investigated to have tight control over their final characteristics. The addition of sodium hydroxide (NaOH) to the reaction mixture is crucial as it catalyzes the conversion of alcohol groups of cellulose into more reactive alcoholate groups. On the other hand, excessive concentration proves to inhibit the reactivity of hydroxyl groups. The addition of glycidyltrimethylammonium chloride (GTMAC) increases the yield of the trimethylammonium chloride content (TMAC) reaction, while in excess it affects the rheological properties of the quaternizated cellulose nanofibers. The effects of NaOH and GTMAC on the TMAC content and rheological properties have been investigated in detail and mathematically evaluated. Furthermore, a comparison of the viscoelastic behavior and shear thinning character of commercial cationic micro- and nanofibrillated cellulose is presented. The research allows to extend the possibility of using cellulose in many applications of cationic biopolymers.

     

Chemical cationization of cotton fabric for improved dye uptake

Cotton fabric is usually dyed with reactive dyes. During the dyeing process, a large amount of salt is required to achieve higher exhaustion of the dye from the dyebath onto the fiber. Dyeing of cotton with reactive dyes has a substantial environmental impact due to the discharge of a large volume of highly colored and saline effluents. Chemical cationization allows cotton fibers to be dyed without salt by chemically modifying cellulosic macromolecules to introduce positively charged sites. In this study, cotton fabric was cationized using (3-chloro-2-hydroxylpropyl) trimethyl-ammonium chloride (CHPTAC). Dye uptake was assessed using two reactive dyes, CI Reactive Blue 235 and CI Reactive Blue 19. Dye exhaustion kinetics were determined using a Datacolor-HueMetrix Monitor system. Analysis of variance demonstrated significant effects of CHPTAC concentration and exhaustion time on the percent exhaustion. Color strength at the end of the dyeing cycle was significantly higher for cationized fabrics compared to the control fabric. This work shows that treatment of cotton with CHPTAC enhanced dye uptake properties due to the introduction of cationic sites and resulted in superior dyeing without the addition of salt.     

Polyethylenimine-Containing Cotton Fabrics

Abstract

Polyethylenimine-containing cotton fabrics were prepared by reaction of 1-epoxyethyl-3, 4-epoxycyclohexane with cotton fabric impregnated with polyethylenimine of a moderately high molecular weight. Fabrics with a high unremovable polyethylenimine content and with a different degree of cross-linking were obtained. Adsorption of several heavy metal salts such as mercuric chloride and cupric sulfate by the fabrics was investigated. Adsorption was controlled by polyethylenimine content of the fabric, extent of cross-linking, and the pH of the solution.     

Controlled synthesis of novel reactive cationic copolymers of 3-chloro-2-hydroxypropylmethyldiallylammonium chloride and dimethyldiallylammonium chloride [P(CMDA-DMDAAC)s]: designed as useful polycationic dye-fixatives on cotton fabric

A series of novel reactive cationic copolymers [P(CMDA-DMDAAC)s] of 3-chloro-2-hydroxypropylmethyldiallylammonium chloride (CMDA) and dimethyldiallylammonium chloride (DMDAAC), were designed as useful polycationic dye-fixatives on cotton fabric. The structures of obtained P(CMDA-DMDAAC)s could be controlled by varying molar ratios of raw materials of CMDA to DMDAAC during polymerization, and their molecular weights were possibly controlled by adjusting different polymerization conditions. The results showed that under the same conditions when the polymerization temperatures were kept at 60 °C for 6 h and then heated to 70 °C for 2 h, when the initial monomer concentrations (w/w) were increased from 23 to 40 % and the initiator amounts were gradually decreased from 7 to 6 %, a series of novel products P(CMDA-DMDAAC)s with 2–20 % molar contents of reactive units (CMDA units) in main chains and controlled intrinsic viscosities of 0.15–0.76 dL/g were successfully synthesized, which were as designed and could be expected as novel useful reactive polycationic dye-fixatives on cotton fabric.     

NOx and N2O precursors from biomass pyrolysis

Chlorine content in agricultural straw is high, and HCl formation during straw combustion is a challenging problem. The relationship between HCl and the formation of NO_x and N₂O is important and unclear. Effect of HCl in atmosphere on nitrogen transfer during wheat straw and cotton stalk pyrolysis was performed using a thermogravimetric analyzer coupled with a Fourier transform infrared spectrometer. Pyrolysis of polyvinyl chloride supplies HCl. The pathway of nitrogen transfer in the presence of HCl was studied. The results show that in the presence of HCl, the temperature corresponding to NH₃ starting release during wheat straw pyrolysis increases, and those of HCN and HNCO reduce. HCl inhibits the conversion of straw–N into NH₃, however, favors the transformation of straw nitrogen into HCN and HNCO.     

Aftertreatment of Conventional Direct Dyeings of Cotton with a Bis-reactive Cationic Fixing Agent

A bis-reactive cationic fixing agent, ethylenebis[N-(2,3-epoxypropyl)-N,N-dimethylammonium chloride] has been used as an aftertreatment reagent to improve the wash fastness of direct dyes on cotton. The effects of different pH conditions and concentrations on the effectiveness of this cationic fixing agent have been investigated. The results showed that aftertreatment at pH 11 produced dyeings with higher colour strength and better wash fastness than that at pH 7. In addition, the cationic agent at a low concentration was found to be more effective under both neutral and alkaline conditions.     

电导滴定法研究阳离子乳胶粒的导电性能及其在棉织物上的吸附

阳离子乳胶粒与棉纤维存在静电作用而发生吸附,研究其导电能力与吸附作用具有重要理论和应用价值。 采用电导滴定法通过测定乳胶粒表面氯离子含量,研究了乳胶粒的导电能力,并探讨了乳胶粒在棉纤维表面的吸附模型。 结果表明,阳离子乳胶粒的浓度(cp)在0.05~0.3×10-8 mol/L 范围内与电导率(Λ)呈良好的线性关系(Λ=8.0913cp+1.8093,R2=0.9986);根据电解质理论计算得出阳离子乳胶粒中胶核的极限摩尔电导率在恒定温度（25 ℃）下随着乳胶粒浓度的增加呈降低趋势;此外,阳离子乳胶粒在棉纤维表面的吸附符合Langmuir型吸附模型。     

自支撑柔性氮掺杂碳织物电极的制备与性能研究

本文以纯棉织物为基底,吡咯单体为氮源,采用简单的原位聚合-高温煅烧的方法制备了自支撑柔性氮掺杂织物（N-CT）. 利用傅立叶红外技术、X射线光电子能谱、比表面积测试、扫描电子显微镜对所得产物进行结构与形貌表征. 结果表明,碳化后聚吡咯主要以纳米碳球包覆在碳织物表面,N-CT电极的比表面积为495.0 m²·g^-1,其含氮量为2.26%. 电化学测试表明,在0.5 A·g^-1的电流密度下N-CT电极的比电容器为256.2 F·g^-1,经过5000次的恒流充放电循环后电容保持率为98.3%,库伦效率保持率在98.8%左右,具有良好的柔性和机械性能.     

Effect of cationization on adsorption of silver nanoparticles on cotton surfaces and its antibacterial activity

Cotton was cationized by exhaustion method using 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTAC) as a cation-generating agent. Adsorption of silver nanoparticles on normal and cationized cotton was studied by exhaustion method at temperatures of 80°C and 100°C. Two exhaustion baths were used, containing nanosilver colloidal solutions stabilized by two different stabilizers and various concentrations of silver nanoparticles. Fourier-transform infrared (FT-IR) spectra of normal and cationized samples confirmed the existence of quaternary ammonium groups on cationized cellulose fibers. X-ray diffraction (XRD) patterns showed that crystallinity of the modified cellulose fibers was decreased. Scanning electron microscope (SEM) images revealed that the surface of the modified cotton was rougher than that of normal cotton. In addition, SEM images showed the presence of silver nanoparticles on the surface of treated fabric samples. The amount of silver particles adsorbed on the fabric samples was determined using inductively coupled plasma-optical emission spectrometer. Antibacterial tests were performed against Escherichia coli bacteria as an indication of antibacterial effect of samples. Cationized cotton samples adsorbed more silver nanoparticles and then had greater ability to inhibit bacteria.     

The fire-retarding effect of inorganic phosphorus compounds on the combustion of cellulosic materials

The pyrolysis and combustion of cellulosic substances treated with MAP and DAP have been studied using thermal analysis, flame spread tests and a specifically designed apparatus for smoldering combustion test. The samples used were: cotton string, cotton fabric and pure cellulose powder. Diammonium Phosphate (DAP) and Monoammonium Phosphate (MAP) can reduce the combustion and pyrolysis maximum mass loss temperature, decrease the initial pyrolysis temperature and considerably increase mass residue. Moreover, MAP and DAP reduce the flaming combustion rate of cellulosic materials and completely inhibit smoldering combustion. This study can facilitate a better understanding of the mechanism of pyrolysis and combustion of fire-retarded cellulosic materials.     

TG studies of synergism between red phosphorus (RP)–calcium chloride used in flame-retardancy for a cotton fabric favorable to green chemistry

The combined effect between calcium chloride and red phosphorus (RP) on the flame-retardancy of a cotton fabric (woven construction massing 152 g/m²) has been studied in this work. The laundered bone-dried massed samples were impregnated with suitable concentrations of individual aqueous red phosphorus suspensions and/or calcium chloride solutions and some bunches were impregnated with appropriate admixed solutions of the both chemicals. An acceptable synergistic effect was then experienced by using an admixed bath containing 0.20 F red phosphorus and 0.20 M calcium chloride for impartation of flame-retardancy to a cotton fabric. By using a vertical flame spread test the optimum mass of the mixture needed to donate flame-retardancy was obtained to be about 5.88 g anhydrous additives per 100 g dry fabric. Thermogravimetry (TG/DTG) results concerning untreated and treated cotton fabrics at the optimum addition were obtained and their curves were compared and commented, fortifying the flame spread tests outcomes. It can be deduced that the applied treatment functioned as a catalyst at the combustion’s temperature of the polymeric substrate and, thermosensibilized the combustion process. This synergism is in favor of green chemistry as well as the economical and industrial view points.     

Chemical Graft of Cellulose with the Ion-Pair Emulsion Containing the Reactive Groups and Its Dyeing Properties

Chemical graft of cellulose with ion-pair disperse emulsion containing the reactive groups was investigated. The ion-pair disperse systems were consisted of a 1,3,5-triazine derivative containing the reactive groups, 2,4,6-tri[(2-hydroxy-3-trimethyl-ammonium)propyl]-1,3,5-triazine chloride (Tri-HTAC) and 2,4,-bichloro[(6-sulfanilic acid)-1,3,5-triazine (Bi-CSAT). Compared with unmodified cellulose, the modified cotton exhibited different behavior towards dyeing. The modified cotton could be dyed with reactive dyes without the addition of salt. The color yield was higher than that on untreated cotton, despite of the addition of large amounts of salt in the latter case. Cotton fabric modified with ion-pair disperse emulsion was imparted good level dyeing properties. The dyeing rate was slower in the presence of the ion-pair compounds than that in the present of the only cationic compounds.     

Maintaining hand and improving fire resistance of cotton fabric through ultrasonication rinsing of multilayer nanocoating

Thin films of environmentally benign polyelectrolytes, cationic chitosan (CH) and anionic poly(sodium phosphate) (PSP), were deposited on cotton fabric via layer-by-layer (LbL) assembly to reduce flammability. This CH–PSP nanocoating promotes charring of the cotton, rendering the fabric self-extinguishing. The coated fabric was rinsed in an ultrasonication bath between deposition steps to improve the softness (i.e., hand) of the coated fabric. Ultrasonication is believed to remove weakly adhered polyelectrolyte, preventing the fabric from becoming stiff, while improving anti-flammable behavior at a given coating weight. At 17 bilayers, only 9.1 wt% was added to the cotton, yet the coated cotton consistently passed vertical flame testing. Electron microscopy provides evidence of intumescence and confirms the cleaner deposition afforded by ultrasonication. The reduction in peak heat release rate and total heat release, as measured by micro cone calorimetry, were 73 and 81 % respectively, which is a new benchmark in LbL flame retardant coating on cotton. The mechanical properties of the fabric were measured using the Kawabata evaluation system, which showed that ultrasonication rinsing significantly improved the hand. The ability to render cotton fabric self-extinguishing, while maintaining a soft hand, marks a major milestone in the development of these environmentally-benign nanocoatings.