Peter J. Hauser

Modifying Nylon and Polypropylene Fabrics with Atmospheric Pressure Plasmas

Polypropylene and nylon 66 fabrics are subjected to atmospheric pressure He and He-O2 plasmas for selected exposure time intervals. Scanning electron microscopy anal ysis of the fabrics shows no apparent changes in the plasma-treated nylon fiber surfaces, but significant surface morphological changes for the polypropylene. Surface analyses of the nylon filaments reveal small differences in the surface carbon and oxygen contents between the treated and control groups. The surface oxygen and nitrogen content of the polypropylene fabric increases significantly after treatment in both He and He-O2 plasmas. There is a slight decrease in nylon fabric tensile strength after treatment in He plasma for 3 minutes, while. there is no significant change in tensile strength of the nylon fabric treated with He-O2 after exposure times of up to 8 minutes.

Reaction Efficiency for Cellulose Cationization Using 3-Chloro-2- Hydroxypropyl Trimethyl Ammonium Chloride

A major cost factor of cationizing cellulose with 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHTAC) is the reaction efficiency, which is less than perfect due to a competing hydrolysis reaction. The efficiency of the cationization reaction sequence is analyzed in terms of chemical kinetics, and experimental results are presented for several reaction methods including pad-batch, pad-steam, pad-dry-steam, exhaust, and pad-dry- cure. The effects of CHTAC and alkali concentrations, additives to the treatment bath, pretreatments, time, temperature, reaction method, and sequence of events are investigated in terms of percent fixation of CHTAC. In addition, data are presented for the reaction in non-aqueous solvents.

Wrinkle Recovery for Cellulosic Fabric by Means of Ionic Crosslinking

Methods are developed for imparting crease angle recovery performance to cellulosic fabrics based on durable ionic crosslinks. These methods, which avoid the formaldehyde release of conventional finishes, include treating cellulose with chloroacetic acid (or an other reactive anion) and cationized chitosan (or another polycation). Alternative methods include treating cellulose with 3-chloro-2-hydroxypropyl trimethyl ammonium chloride or another cationization reagent) and a polyanion, or with chloroacetic acid and 3-chloro- 2-hydroxypropyl trimethyl ammonium chloride. A method for producing highly cationic chitosan is also presented. Crease angle recovery and strength data are correlated to the amount of polyelectrolyte add-on.

Conferring flame retardancy on cotton using novel halogen-free flame retardant bifunctional monomers: synthesis, characterizations and applications

Two novel halogen-free phosphorous-nitrogen flame retardant bifunctional monomers were synthesized and characterized using attenuated total reflectance/Fourier transform-infrared (ATR/FT-IR) and electrospray ionization mass spectrometry ((+)ESI-MS). The monomers were applied separately and graft polymerized on cotton in the presence of the thermal initiator K(2)S(2)O(8). The performance of each monomer was evaluated using thermal gravimetric analysis (TGA), grafting efficiency, and vertical flame test. It was shown that the performance of N,N-dimethyl di(acryloyloxyethyl)phosphoramide (DMDAEP) (monomer 2) as flame retardant outperformed that of ethyl di(acryloyloxyethyl)phosphorodiamidate (EDAEP) (monomer 1). The superior performance of DMDAEP was attributed to the presence of more nitrogen atoms compared to EDAEP. The increased nitrogen content in DMDAEP increased the synergistic effect of the P-N system. Cotton treated using padding methods showed more promising results than cotton treated by exhaust methods.

Evaluating Hydrogen Peroxide Bleaching with Cationic Bleach Activators in a Cold Pad-Batch Process

Bleach activators generate peracids in the presence of hydrogen peroxide and alkali that are more potent oxidizing agents than hydrogen peroxide under comparable bleaching conditions. The effects of key bleaching parameters (activator concentration, hydrogen peroxide, chelant, and pH) on the performance of cold pad-batch bleaching on cotton are investigated. Optimized recipes are determined for two cationic activators, N-[4-(triethylammoniomethyl) benzyl]ca prolactam chloride and 6-(N,N,N-trimethylammonio) hexanoyl caprolactam p-toluenesulfo nate, using a central composite experimental design. The laboratory optimized conditions are used for pilot plant scale bleaching of cotton knit fabric. CIE whiteness index values are calculated from measured reflectance data of the pilot scale bleaching and are in close agreement with those predicted by the experiment. A high level of whiteness (CIE WI > 70) is achieved for both activators with 8-hour batching, and measurements of the degree of polymerization of the bleached and greige fabrics show little fiber damage in each case.

Enhancing the Durability of Linen-Like Properties of Low Temperature Mercerized Cotton

In order to develop durable linen-like cotton yam with low temperature mercerization, pretreatment methods ensuring efficient and uniform penetration of the low temperature alkali solution into cotton yarn are studied. Pretreatments consisting of an alkaline scouring at higher NaOH concentrations and of a cellulase treatment and subsequent alkaline scouring are evaluated for their efficiency in removing wax and enhancing absorptive properties. The cellulase treatment/alkaline scouring is more efficient at re moving wax than alkaline scouring at higher NaOH concentrations. The cellulase treat ment and subsequent alkaline scouring result in wax contents lower than 0.1%. The cellulase treatment appears to degrade the cellulose on the surface of the cotton fibers, making it more accessible to the scouring agent and making wax removal easier. Swelling and wetting times are compared to identify a pretreatment sufficient for developing linen-like cotton. In low temperature mercerization, the pretreatment consisting of cellu lase treatment and alkaline scouring yields a linen-like cotton yarn whose stiffness is durable to knitting, wet processing, and even ten laundering cycles. The durability appears to be sufficient for practical applications of the process for producing linen-like cotton.

Printing Cationized Cotton with Direct Dyes

This paper investigates improved direct dye printing of cotton by cationization. For the cationization, a 100% cotton woven fabric is pretreated with 2,3-epoxypropyltrimethyl ammonium chloride by a cold pad-batch method. All printing conditions are constant, and four different direct dyes are used to print both unmodified and cationized cotton fabrics. The effects of cationic reagent concentration, steaming time, dye concentration, color yields, colorimetric properties, fastness properties, staining of the white ground, and penetration behavior are evaluated. This research reveals that printing with direct dyes on cationic cotton is a very simple, cost effective printing method with high wet fastness properties.

Multilayers of Low Charge Density Polyelectrolytes on Thin Films of Carboxymethylated and Cationic Cellulose

Multilayers with low charge density polyelectrolytes assembled on thin films of cellulose were studied by piezoelectric microgravimetry. The substrates were produced from colloidal suspensions of cotton fibers before and after modification with cationic and anionic groups via epoxy intermediates of quaternary ammonium and carboxymethylation, respectively. Two different levels of ionicity were used for each cellulosic substrate in order to investigate the role of the supporting surface in the buildup of the multilayer. It was found that while electrostatic interactions were leading factors in the assembly of high molecular weight, low charge density polyelectrolytes, other effects such as van der Waals and secondary cooperative forces played important roles. The charge properties of the substrate and the adsorbing polymer were relevant to the behavior of the self-assembled multilayers. Sequential additions of weak polyelectrolytes formed viscoelastic layers on all cellulose substrates. Adsorption of the first layer depended heavily on the charge characteristics of the substrate while the buildup of subsequent layers was mainly affected by the outermost adsorbed polymer. The polyelectrolyte multilayer formation with highest total adsorbed mass occurred on unmodified cellulose surfaces; therefore, in the case of the low charge density polyelectrolytes studied, substrate ionicity and functionalization may not be a requirement. Finally, the effect of anionic weak polyelectrolytes added after the first adsorbed polymer pair is highlighted in the context of reported observations for polyelectrolytes of high charge density.

Optimization of Ionic Crosslinking Process: An Alternative to Conventional Durable Press Finishing

Cotton fiber has a natural tendency to wrinkle. In order to overcome this undesired property several durable press finishes were proposed and have been used for a long while. However, most of these chemical finishes release formaldehyde, a suspected human carcinogen, which causes fabric to lose strength and to yellow. Non-formaldehyde alternatives to these finishes are expensive. Thus, a non-formaldehyde finish prepared by using common and more available chemicals is required. In this study, we prepared anionic cotton fabric and further treated it with a novel crosslinker, namely cationic glycerin. We focused on optimizing an ionic crosslinking process in terms of the treated fabrics wrinkle recovery angle (WRA). Our results showed that high WRA results may be achieved and the strength of fabric may also be increased.

Enhancement of Wrinkle Free Properties of Carboxymethylated Cotton Fabric via Ionic Crosslinking with Poly(vinylpyrrolidone)

Incorporation of poly(vinylpyrrolidone) (PVP) in the structure of cotton, carboxymethylated cotton (CMC) or ionically crosslinked cotton fabric induces besides ether crosslinking of cotton cellulose, strong columbic forces and weaker forces such as dipole—dipole, hydrogen bonds, van der Waals, or hydrophobic interactions. The ether bonds are formed in the dry state (i.e., un-swelled state), whereas, the other interactions are formed in wet state (i.e., swelled state) of cotton fabrics. Both interactions greatly enhance wet and dry wrinkle recovery angle of cotton fabric without strength loss. Fixation of PVP onto cotton or CMC fabric was achieved thermally by curing the treated fabric at 140°C for 5 minutes. Higher wet and dry wrinkle recovery angles (WRA and DRA) were obtained with lower molecular weight PVP (3000 Da) compared with higher molecular weight one (8000 Da). The results obtained also show that a balance between WRA, DRA as high as 228° and 225°, respectively, could be obtained without loss in tensile strength and elongation at break by treatment CMC fabric having carboxyl content 115 meq/100 g fabric with 4% PVP then cured at 140°C for 5 minutes. Additionally, treatment of the ionically crosslinked fabric (having 115 meq/100 g fabric carboxyl content and 0.22% nitrogen content) with 4% aqueous PVP enhances the DRA and WRA to reach a value of 289° and 286°, respectively, without any loss in the strength properties of the fabrics. These values of WRA and DRA are much higher than those obtained with cotton fabric (blank) or carboxymethylated cotton. The existence of ionic interaction and ether bonds as well as functional groups introduced into cotton fabrics were confirmed by FTIR spectroscopy.