Eugene J. Blanchard

Effect of Sonication on Cotton Preparation with Alkaline Pectinase

Pectinase bioscouring of greige cotton fabric is a very promising new approach for preparing cotton textiles for subsequent wet processing treatments such as mercerizing, bleaching, dyeing, printing, or finishing. Such biopreparation of greige cotton fabric is an energy efficient and environmentally benign process. Our research has shown that at the laboratory scale, introducing ultrasonic energy into the reaction chamber during enzymatic scouring of the greige cotton fabric significantly improves pectinase efficiency, but does not decrease the tensile strength of cotton fabric. In line with our previous data, current research also confirms that sonication of pectinase processing solutions does not impair the complex structures of the enzyme molecules, but significantly improves their performance. Data show that alkaline pectinase appears to be a more efficient agent for biopreparation of greige cotton than acidic pectinase, resulting in better wettability and whiteness. We also establish that the combination of pectinase bioscouring with desizing and after-washing insures sufficient fabric wettability with adequate uniformity. The results are comparable to or better than those for fabric after traditional alkaline scouring. Introducing ultrasonic energy into the reaction chamber during enzymatic treatment of cotton fabric could help overcome the major disadvantage of pectinase scouring—a longer processing time compared to conventional alkaline scouring.

Characterization of tri-o-methylcellulose by one- and two-dimensional NMR methods†

Tri-O-methylcellulose was prepared from partially O-methylated cellulose and its chemical shifts ( 1 H and 13 C), and proton coupling constants were assigned using the following NMR methods: (1) One-dimensional 1 H and 13 C spectra of the title compound were used to assign functional groups and to compare with literature data; (2) double quantum filtered proton-proton correlation spectroscopy ( 1 H, 1 H DQF-COSY) was used to assign the chemical shifts of the network of 7 protons in the anhydroglucose portion of the repeat unit; (3) the heteronuclear single-quantum coherence (HSQC) spectrum was used to establish connectivities between the bonded protons and carbons; (4) the heteronuclear multiple-bond correlation (HMBC) spectrum was used to connect the hydrogens of the methyl ethers to their respective sugar carbons; (5) the combination of HSQC and HMBC spectra was used to assign the 13 C shifts of the methyl ethers; (6) all spectra were used in combination to verify the assigned chemical shifts; (7) first-order proton coupling constants data (J H,H in Hz) were obtained from the resolution-enhanced proton spectra. The NMR spectra of tri-O-methylcellulose and other cellulose ethers do not resemble the spectra of similarly substituted cellobioses. Although the 1 H and 13 C shifts and coupling constants of 2,3,6-tri-O-methylcellulose closely resemble those of methyl tetra-O-methyl-β-D-glucoside, there are differences with regard to the chemical shifts and the order of appearances of the resonating nuclei of the methyl ether appendages and the proton at position 4 in the pyranose ring. H4 in tri-O-methylcellulose is deshielded by the acetal system comprising the β-1→4 linkage, and it resonates downfield. H4 in the permethylated glucoside is not as deshielded by the equitorial O-methyl group at C4, and it resonates upfield. The order of appearance of the 1 H and 13 C resonances in the spectra of the tri-O-methylcellulose repeat unit (from upfield to downfield) are H2 < H3 < H5 < H6a < H3a < H2a < pro R H6B < H4 < pro S H6A « H1 and C6a < C3a < C2a < C6 < C5 < C4 < C2 < C3 « C1, respectively. Close examination of the pyranose ring coupling constants of the repeat unit in tri-O-methylcellulose supports the 4 C 1 arrangement of the glucopyranose ring. Examination of the proton coupling constants about the C5-C6 bond (J 5,6A and J 5,6B ) in the nuclear Overhauser effect difference spectra revealed that the C6 O-methyl group is predominantly in the gauche gauche conformation about the C5-C6 bond for the polymer in solution.

Phosphorylation of Cellulose with Some Phosphonic Acid Derivatives

Cellulose is readily phosphorylated with phosphonic acid derivatives upon heating at elevated temperatures. In this paper, various properties of cotton fabrics phosphorylated with 1-hydroxyethylidene-1,1-diphosphonic acid, phenyl phosphonic acid, 2-carboxyeth ylphosphonic acid. and N-(phosphonomethyl)iminodiacetic acid are investigated. Phos phorylation occurs only in the presence of urea as expected. Without urea, there is discoloration as well as severe degradation of the fabric, as indicated by tensile strength reduction. Good reactivity is achieved by curing at 170°C for 2-4 minutes, and reaction efficiency is determined by phosphorus analysis. The best overall results are achieved with 1-hydroxyethylidene-1,1-diphosphonic acid. Although there is fabric discoloration upon curing with this agent, it is much less than that with the other derivatives. Discoloration upon curing of phosphorylated cottons is reduced by incorporating 1-4% dicyandiamide in the treatment formulation. Physical properties of the phosphorylated fabrics are dis cussed, along with thermogravimetric analyses of the substrates.