Mohamed Hashem

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.

Smart Options for Functional Finishing of Linen-containing Fabrics

This study examined an innovative approach to functional finishes of linen-containing fabrics. Modification of surface properties along with creation on new interactive site onto the fabrics surfaces, i.e., —COOH or —NH2 groups, using oxygen-or nitrogen plasma followed by subsequent treatments with selected ionic dyes, certain metal salts, nano-scale metal or metal oxides, quaternary ammonium salt or nominated antibiotics were carried out to obtain linen-based textiles with upgrade UV-protection and/or antibacterial functions. The results detailed in this paper demonstrate that: (i) post-basic dyeing of oxygen plasma-treated substrates with C.I. Basic Red 24 brings about a significant improvement in the UV-protection and antibacterial activity against the G +ve (Staphylococcus aureus) and G —ve (Escherichia coli) bacteria, (ii) post-reactive dyeing of nitrogen plasma-treated substrates with C.I. Reactive violet 5, results in a remarkable improvement in both UV-blocking and antibacterial properties. (iii) the extent of improvement in the above-mentioned properties of the obtained dyeings is determined by the type of substrate, kind and concentration of the ionic dye, (iv) loading of the metal ions onto the preactivated fabric surfaces upgraded their UV-protection valued as well as their antibacterial efficiency, and the extent of enhancement is governed by the kind and concentration of metal salt as well as type of bacteria, (v) loading of nano-scale Ag, TiO2, or ZrO onto the plasma-treated substrates brings about a remarkable improvement in their functional properties, (vi) loading of the used antibiotics or choline chloride onto the plasma-treated substrates gives rise to better antibacterial ability, (vii) both the UV-protection ability and the antibacterial activity of selected samples were retained even after 10 laundering cycles, and (viii) the options described here for attaining linen-containing fabrics with high functional properties are effective, simple and applicable.

One-step UV-induced modification of cellulose fabrics by polypyrrole/silver nanocomposite films

Cellulose fabrics were coated with polypyrrole-silver (PPy/Ag) nanocomposite films via one pot photopolymerization in aqueous media. This process was optimized for various concentrations of pyrrole/textile weight ratios with fixed molar ratio of [pyrrole]/[AgNO(3)] as 2.5. Simple weight measurements of the fabrics indicated progressive coating of PPy/Ag versus initial pyrrole/fabric weight ratio and photopolymerization time. X-ray diffraction (XRD) data confirm the nano-size (10-30 nm) and metallic state of Ag crystallites. The metallic state of silver particles was also confirmed by X-ray photoelectron spectroscopy (XPS). We demonstrate that UV-induced polymerization of pyrrole in the presence of AgNO(3) is simple and fast compared to chemical oxidative polymerization in the absence of UV light. More importantly, it permits to coat cellulose fabrics in one pot by polypyrrole/Ag nanocomposites films in environmentally friendly aqueous solutions at room temperature.

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.

New Development for Combined Bioscouring and Bleaching of Cotton-Based Fabrics

A thorough investigation into conditions appropriate for effecting combined eco-friendly scouring and bleaching of cotton based fabrics was undertaken. Loomstate cotton and blend fabrics were desized by α-amylase enzyme. Fabrics were the target for bioscouring using alkaline pectinase enzyme, bleaching by in-situ formed peracetic acid using TAED and H2O2 as well as concurrent bioscouring and bleaching which is considered by all means a new development. Also, practiced were the conventional scouring using NaOH followed by bleaching using H2O2 and other bleaching processes vis-a-vis the new current development. The comparison reveals unequivocally that the environmentally sound technology brought about by current development is by far the best. The new development involves a single-stage process for proper purification / preparation of cotton and blend fabrics . through removal of noncellulosic impurities and colouring matters . by padding the fabrics in a bath containing alkaline pectinase enzyme, TAED, H2O2, nonionic wetting agent and sodium silicate. In addition to the advantages related to major technical fabric properties, the new development is eco-friendly and reproducible, which advocates the new development for mill trials.

Inducing Durable Press in Ionically Crosslinked Cotton Fabric

Significant enhancement in the performance of durable press cotton fabric could be achieved through the utilization of non- formaldehyde crosslinking agents along with ionic crosslinking. Ionic crosslinking was first effected by subjecting cotton fabric succesively to partial carboxymethylation using monochloroacetic acid and sodium hydroxide, then by cationization using 3-chloro-2-hydroxypropyl trimethyl ammonium chloride known commercially as Quat-188. While the partial carboxymethylation reaction introduces the negatively charged group in the cellulose chains of cotton, the cationization reaction introduces the positively charged groups, thereby causing ionic crosslinking. The ionically crosslinked cotton was then crosslinked using either glyoxal, epichlorohydrin, or gluteral-dehyde. Most of the results obtained indicated that a balance between wet and dry wrinkle recovery angles that acquired a value as high as 300° could be obtained without loss in tensile strength and elongation at break. The results also revealed that the degree of ionic crosslinking relies on the nitrogen and carboxyl contents of the finished fabric as well as on the nature of the non-formaldehyde finishing agent used. Indeed the results of this work present a new approach to the durable press finishing of cotton, and mill trials should be conducted.

Cellulase Enzyme in Bio-finishing of Cotton-Based Fabrics: Effects of Process Parameters

Cotton-based fabrics, namely loomstate cotton fabric, grey mercerized cotton fabric, loomstate cotton/polyester (50/50 and 35/65) blended fabric were bio-desized by α amylase enzymes and bio-scoured by alkaline pectinase enzymes. The obtained bio-scoured substrates were subject to bleaching with peracetic acid and proceeded for bio-polishing under a variety of conditions. Results show that the extent of bio-polishing depends on the conditions of the treatment. The loss in fabric weight exhibits values which are comparable at 50° and 60°C and substantially higher than those obtained at 40°C. Temperatures of bio-polishing, specifically 40° and 50°, decrease the whiteness index; higher temperature, i.e. 60 °C, does not cause further decrease in the whiteness index whereas the tensile strength decreases. The temperature has a positive effect on surface roughness particularly when bio-polishing is performed at 50°and 60 °C. It was also found that cellulase is more active in mercerized cotton than in either 100 % cotton or cotton/polyester blend. The scanning electron micrograph of fibers after the enzymatic treatment reveals smoothened faces. The ridges that are present in the untreated fiber samples are not found in the case of cellulase-treated fibers. Bio-polishing of cotton fabrics can offer unmatched results by optimizing the process conditions, which can be otherwise achieved with chemical finishes. Reasonably good results were obtained from all the cotton and cotton blend fabrics and show high flexibility and versatility of the treatment in the manufacturing process.

IONIC CROSSLINKING OF COTTON

Cellulose crosslinking is a very important textile chemical process, and is the basis for a vast array of durable press and crease-resistant finished textile products. Formaldehydecontaining N-methylol crosslinkers give fabrics desirable properties of mechanical stability (e.g., crease resistance, anti-curl, shrinkage resistance, durable-press), but also impart a loss of strength and the potential to release formaldehyde, a known human carcinogen. Other systems, such as polycarboxylic acids, have been tested with varying degrees of success. We have developed methods of forming ionic crosslinks that provide outstanding performance in crease angle recovery while completely retaining the strength of treated goods, without the potential to release any reactive materials of low molecular weight, such as formaldehyde. Our work is based on the reactions of cellulose with materials that impart an ionic character to the cellulose; e.g., chloroacetic acid for negative charges or 3-chloro-2-hydroxypropyl trimethyl ammonium chloride for positive charges. These reactions produce ionic celluloses that can then absorb a polyionic material of opposite charge to form crosslinks. Cellulose treated with cationized chitosan after carboxymethylation showed significant increases in crease recovery angles without a loss of strength.

Bioscouring Aided by EDTA and β-Cyclodextrin for Purification of Loomstate Cotton and Blend Fabrics

Incorporation of either EDTA or β-cyclodextrin in the bioscouring treatments and its onset on the bioscoured fabrics performance was intensively studied. Biotreatments involved single use of alkaline pectinase enzyme or in combination with cellulase enzyme in a subsequent treatment. EDTA and β-cyclodextrin were entailed independently in the bioscouring by using two strategies: 1) they were applied to the fabrics as a pretreatment and; 2) they were added to the bioscouring treating solution. Fabrics used were enzymatically desized. Desized fabrics under investigation comprised cotton fabric, mercerized cotton fabric, cotton/polyester (50/50) blend fabric and cotton/polyester (35/65) blend fabric. Results showed that pretreatment of fabrics with EDTA followed by subsequent bioscouring by alkaline pectinase enzyme in single use or in combination with cellulase enzyme in a separate step decreases the performance of bioscoured fabrics. On the other hand, incorporation of EDTA in the bioscouring solution contai...