Beate Rinderer

Quantitative Determination of BTCA Bound to Cellulosic Material by Means of Isocratic HPLC

1,2,3,4-Butanetetracarboxylic acid (BTCA) offers an alternative to the conventional N- methylol compounds as a crosslinking agent for cellulosic textiles. Thus, it is of particular interest to determine the amount of BTCA that reacts with the cellulosic material. In this research, we saponify the cured fabric by means of a NaOH solution. The BTCA concen tration in the saponification mixture is measured with the aid of isocratic HPLC using the strong cationic exchange column Aminex HPX-87-H in combination with a uv detector. We study the effect of different concentrations of NaOH and find that there is a significant saponification reaction with NaOH concentrations greater than 0.05 M. Measurements of the dry crease recovery angle (DCRA) and IR transmission spectra indicate that the sapon ification reaction is complete. We test the analytical procedure by investigating three dif ferent fabrics impregnated with finish solutions containing 2, 4, 6, and 8% (w/w) BTCA and 6% (w/w) SHP (sodium hypophosphite). To verify the accuracy of the quantitative determination, we use calibration curve and standard additions methods. Recovery is 97.4 - 103.2% depending on the weight fraction of BTCA in the finish bath and on the fabric. Our statistics confirm that this procedure proves a precise and accurate analytical method for quantifying BTCA that has reacted with cellulosic fabrics.

Investigation of the hydrolysis of (3-triethoxysilylpropyl)succinic acid anhydride by means of FT-IR

The kinetic data (rate constant, Arrhenius activation energy, frequency factor) of the hydrolysis reaction of the anhydride moiety of (3-triethoxysilylpropyl)succinic acid anhydride (TESP-SA) were investigated by means of FT-IR monitoring the decrease of the carbonyl stretching band at 1778 cm−1. The reaction had been conducted in an excess of water under acidic conditions (pseudo-first order reaction). In addition, the application of TESP-SA to cotton fabrics in conjunction with sodium hypophosphite as curing catalyst at elevated temperature (180 °C, 90 s) was tested. The dry crease recovery angle proved that no crosslinking reaction of the cellulose chains could be observed.

Non-formaldehyde, crease-resistant modification of cellulosic material by means of an organotrialkoxysilane and metal alkoxides

Cellulosic material is chemically modified to impart crease-resistant properties to textile products. Due to health considerations formaldehyde-free chemicals are preferred. For this purpose, (3-glycidyloxy)propyltrimethoxysilane (GPTMS) in combination with metal alkoxides aluminium isopropoxide (AIP), titanium tetraisopropoxide (TTP), zircon tetrabutoxide (ZTB) were applied to cotton raw material and cotton fabrics which were pre-treated with butane-1,2,3,4-tetracarboxylic acid (BTCA)/sodium hypophosphite. The as-prepared samples were tested for dry crease recovery angle, tensile strength, tear strength, air permeability, contact angle and whiteness index. The application of GPTMS/AIP resulted in excellent crease resistance values, whereas TTP and ZTB provided a moderate improvement of the wrinkle resistance. The application of the hydrophobic methyltriethoxysilane, octyltriethoxysilane and Dynasylan F8815 (fluoroalkylfunctional water-borne oligosiloxane) caused a significant increase in the contact angle. Fourier-transform-infrared spectroscopy proved the formation of an ester-linkage between BTCA and the cellulose.

Non-formaldehyde, crease resistant agent for cotton fabrics based on an organic-inorganic hybrid material.

1,2,3,4-Butanetetracarboxylic acid (BTCA) was reacted with (3-aminopropyl)triethoxysilane (APTES) to a poly(amic)acid (PAA). The molar ratios of BTCA and APTES were 1/1 (B/A-1/1), 1/2 (B/A-1/2), 1/3 (B/A-1/3), and 1/4 (B/A-1/4). The as-prepared precursor solution was applied to cotton substrates. After thermal treatment (180°C) the physical-mechanical properties of the cotton samples were tested by means of dry crease recovery angle and tensile strength. For B/A-1/1 treated fabrics a significant improvement of the crease resistance was observed. FT-IR spectra revealed the formation of an imide group and an ester linkage, indicating the cross-linking of the cellulosic material. SEM images showed a smooth surface. As evidenced by TGA data the thermal stability of the cotton samples was not increased. No hydrophobicity could be observed. For B/A-1/3 and (B/A-1/4) modified cotton samples no crease resistant properties were detected. However, enhanced contact angle values were measured. A reaction mechanism for the formation of the ladder-like polysilsesquioxane and the cross-linking reaction is proposed.

Nonformaldehyde Durable Press Finishing of Cotton Fabric: Quantitative Evaluation of Cellulose-Bound Glyoxal

Cellulosic material is treated with formulations containing 14.5% (w/w) glyoxal (40%) as a nonformaldehyde crosslinking agent in order to impart durable press properties. MgCl 2 · 6 H2O and Al2(SO4)3 · 16 H2O are applied as catalysts and different hydroxy carboxylic acids (citric, tartaric, and malic acids) as co-catalysts. The amount of cotton- bound glyoxal is measured by means of isocratic HPLC using HPX-87H as a stationary phase. Prior to chromatographic analysis, the cotton-bound glyoxal is converted to glycolate by means of an internal Cannizzaro reaction. The results indicate that MgCl2 · 6 H2O possesses lower effectiveness in comparison to Al2(SO4)3 · 16 H2O. A reduction of the cure temperature from 150 to 110°C does not influence the portion of glyoxal that has reacted with the cellulose when citric, tartaric, or malic acids are added to the formulations as co-catalysts.

Preparation and Characterization of An Aromatic Imide-Functionalized Polysilsesquioxane via the Sol-Gel Route

Phthalic acid (benzene-1,2-dicarboxylic acid, PA) and trimesic acid (benzene-1,3,5-tricarboxylic acid, TA) have been reacted with 3-aminopropyltriethoxysilane (APTES) at 110 °C and 220 °C (molar ratios 1:1 and 1:2). The reaction at 110 °C resulted in the formation of the corresponding poly(amic acid), whereas the thermal imidization at 220 °C gives rise to the formation of a cyclic polyimide moiety as shown by means of Fourier transform infrared spectroscopy (FT-IR). X-ray powder diffraction (XRPD) measurements revealed that a specific periodic arrangement in the as-prepared materials had been formed. Thermogravimetric analysis (TGA) made evident that the organic-inorganic nanocomposite materials showed improved thermal properties. The reaction of PA with APTES (1:1) at 220 °C is assumed to yield a ladder-like polysilsesquioxane.

Electrospun Ultrathin Poly(vinyl alcohol) Fibre Assemblies Modified by Means of Polycarboxylic Acid / Sodium Hypophosphite

A viscous solution consisting of poly(vinyl alcohol) (PVA), butane-1,2,3,4-tetracarboxylic acid (BTCA) and sodium hypophosphite monohydrate (SHP) has been prepared and subjected to an electrospinning process in an attempt to produce BTCA-crosslinked ultrathin PVA fibre mats. At elevated temperatures the carboxyl groups of BTCA react with the hydroxyl groups of PVA via a five-membered cyclic anhydride thus forming ester linkages. The measurement of the fibre diameters of the electrospun fibres created at various high voltages (10, 15, and 20 kV) revealed that the diameters of the fibres were in the range of 0.98 - 1.20 μm. Single layer and double layer fibre assemblies were prepared and thermally treated at 180 °C. The as-prepared ultrathin PVA fibre assemblies were analyzed by means of scanning electron microscopy (SEM), indicating that the morphology of the fibres had been changed. Fourier transform infrared/attenuated total reflection spectroscopy (FT-IR/ATR), X-ray powder diffraction (XRPD) and physical properties, such as water vapour absorption (WVA), water vapour transmission (WVT) and tensile strength were evaluated. The incorporation of BTCA resulted in an increase of WVA and a decrease of WVT. The tensile strengths of the cured PVA mats were remarkably decreased, when BTCA/SHP had been added.