Showing papers on "Sodium hypophosphite published in 2000"

FTIR Spectroscopy Study of the Formation of Cyclic Anhydride Intermediates of Polycarboxylic Acids Catalyzed by Sodium Hypophosphite

Abstract: In recent years, extensive efforts have been made to find formaldehyde-free durable press finishes to replace the traditional formaldehyde-based N-methylol compounds. 1,2,3,4-Butane-tetracarboxylic acid (BTCA) has been the most efficient nonformaldehyde crosslinking agent for cotton, with sodium hypophosphite (NaH2PO2) being the most effective catalyst. In our previous research, we found that a polycarboxylic acid esterifies cellulose through the formation of a five-membered cyclic anhydride intermediate by the dehydration of two adjacent carboxyl groups. In this research, we use Fourier transform infrared spectroscopy (FTIR) to study the formation of cyclic anhydride intermediates by BTCA and poly(maleic acid) (PMA) with and without the presence of NaH2PO2. In the absence of NaH2PO2, BTCA forms the cyclic anhydride only when the temperature reaches the vicinity of its melting point. In the presence of NaH2PO2, however, the anhydride forms at much lower temperatures. We have found that NaH2PO2 weakens the...

Oil-and water-repellent finishes for textiles

Abstract: The present invention is directed to a water- and oil repellency-imparting preparation for fibrous and other substrates, the preparation comprising a fluorinated polymer and a tacking monomer, oligomer or polymer containing at least one anhydride functional group or a group capable of forming an anhydride functional group, optionally together with an anhydride-forming catalyst, such as sodium hypophosphite. The preparation can further optionally comprise other additives such as, for example, an extender; a softener; an antioxidant; a surfactant; and/or a plasticizer.

Durable Press Finish of Cotton Fabric Using Malic Acid as a Crosslinker

Abstract: It has been considered that malic acid,α-hydroxy succinic acid, could not form crosslinks in the cellulosic materials unless activated by other polycarboxylic acids such as butanetetracarboxylic acid or citric acid because there are only two carboxylic acids per molecule available for the formation of one anhydride intermediate. However we found that the dicarboxylic malic acid with sodium hypophosphite catalyst without the addition of other crosslinkers was able to improve wrinkle resistance of cotton up to 294° (dry WRA) and 285° (wet WRA), which is a measure of crosslinking level in cotton.1H FT-NMR, FT-IR and GPC analysis indicated the in-situ formation of an trimericα, β-malic acid with a composition of 1:3 through the esterification between hydroxyl group and one of carboxylic groups in malic acid during curing. The crosslinking of cotton was attributed to the trimericα, β-malic acid, a tetracarboxylic acid, which can form two anhydride rings during curing. The influence of crosslinking conditions such as concentrations of malic acid and catalyst, pH of the formulation bath, and curing temperature were investigated in terms of imparted wrinkle resistance and whiteness. The addition of reactive polyurethane resin in the formulation slightly increased the mechanical strength retention of crosslinked fabric coupled with additional increase in wrinkle resistance.

Flame Resistant Cotton/Polyester Carpet Materials

Abstract: Cotton/polyester carpet materials are resistant to surface flame spread after esterification of the cellulosic fibers with polycarboxylic acid and suitable catalyst. The crosslinked cellulose-containing materials passed the required flammability standards for carpet when subjected to the methenamine pill test. This test is much less severe than the rigorous vertical flame test method required for textiles designated for other end uses. Cotton-containing carpet materials finished with 5-10% polycarboxylic acid, such as 1,2,3,4-butanetetracarboxylic acid (BTCA) or citric acid, and sodium phosphate, sodium hypophosphite, sodium bicarbonate or sodium carbonate catalyst were found to meet test method specifications when proper processing and fixation conditions were employed. Specific details of processing conditions and results of flammability tests are presented.

Pulse plating of hard chromium from trivalent baths

Abstract: A trivalent chromium bath is relatively non-toxic compared with a hexavalent chromium bath. It is difficult, however, to obtain thick chromium electrodeposits from a trivalent chromium bath with direct-current plating. This paper describes a study using pulsed current to plate thick chromium electrodeposits for hard chromium applications from a trivalent chromium bath, using either ammonium formate or sodium hypophosphite as the complexing agent. It was found that the chromium plating rate using pulsed current was higher than that for direct current. Pulsed current improved the maximum coating thickness that could be obtained from the trivalent chromium baths. In addition, pulsed current decreased the internal stress of a trivalent chromium deposit by 25 to 75 percent. The internal stress decreased with decreasing current density, duty cycle and pulse frequency. When sodium hypophosphite was used as the complexing agent in the trivalent bath, a significant quantity (15 to 30% ) of phosphorus co-deposited on the chromium coating. The phosphorus content increased with decreasing duty cycle and with increasing pulse frequency. The microhardness of a trivalent chromium deposit obtained with pulsed current was in the range of 610 to 850 on Knoop's hardness scale. These values were comparable to that obtained with direct current. Increasing pulse frequency in the range of 10-1000 Hz increased the microhardness of the chromium deposit.

Electrooxidation of the hypophosphite ion on a palladium electrode

Abstract: Anodic oxidation of sodium hypophosphite on smooth Pd and Pd/Pt electrodes and a Pd membrane is studied. Thei vs.E curves for the Pd electrode exhibit two anodic current peaks. One is caused by oxidation of H2PO2-, and the other, by simultaneous ionization of Pd and oxidation of H2PO2-. The hypophosphite ion adsorbed on the Pd surface hinders the formation of the passive film. This brings about a rapid dissolution of Pd in the oxygen region and its subsequent deposition with the formation of palladium black. The oxidation probably includes a slow heterogeneous chemical reaction, specifically, a cleavage of the P-H bond of the hypophosphite ion. The change in the reaction stoichiometry following an increase in solution pH and in anodic polarization is probably due to changing conditions of the H2PO2- adsorption and the number of adsorption sites occupied by H2PO2- on the surface. Following an increase in polarization, the phosphite ion may undergo oxidation to phosphate.

Method for obtaining water-soluble polymers, resulting polymers and uses thereof

Abstract: The invention concerns a method for obtaining homopolymers and/or copolymers in aqueous solution using phosphorous acid and/or its salts or sodium hypophosphite and by neutralising during polymerisation ethylenically unsaturated monomers by continuously adding firstly bases such as sodium hydroxide, potassium hydroxide or lithium hydroxide, then alkaline-earth bases such as calcium hydroxide, magnesium hydroxide, calcium oxide or magnesium oxide. The invention also concerns the polymers obtained by said method and their uses.

Metal treating agent and treatment of metal

Abstract: PROBLEM TO BE SOLVED: To effectively and simultaneously detoxify metal and dioxins and also to detoxify an org. chlorine compd. even in the case when a treating temp. is low by making a composition contain phosphorus acids and/or hypophosphorous acids and an acidic material. SOLUTION: This metal treating agent used for treating metal-containing waste water, solid wastes, etc., contains phosphorus acids and/or hypophosphorous acids and an acidic material. Phosphorus acid or phosphite is used as phosphorus acids. Among these, phosphorus acid, sodium phosphite and calcium phosphite are preferable. And hypophosphorous acid or hypophosphite is used as hypophophites. Among these, hypophosphorous acid, sodium hypophosphite and calcium hypophosphite are preferable. On the other hand, an inorg. acid, acidic metal oxides, etc., are exemplified as acidic materials. Among these, acidic metal oxides are preferable such as aluminum sulfate, etc., are especially preferable.

Reduction treatment of hydrogen-storing alloy

Abstract: The reduction treatment is suitable for preparation of hydrogen storing alloy through fast solidification or other process It features that the alloy powder to be treated is placed into water in 1-10 times, where sodium hypophosphite solution is added while stirring The weight ratio between alloy powder and sodium hypophosphite solution is 1 to 05-15, the treatment temperature is 20-60 degC and the treatment period is 3-48 hr The present invention can raise the initial electrochemical activity of hydrogen storing alloy

Derivation and rapid spectrophotometric determination of iron in electroless nickel plating solution

Abstract: Experiment has proved that iron can be dissolved in an acidic electroless nickel (EN) plating solution during the plating process when plating iron sheet. The influence of nickel sulfate, organic acids, sodium hypophosphite, pH and temperature on the absorption of Fe(III) was investigated. A new method, using mono-wavelength, to determine the concentration of Fe(III) was developed. Fe(II) was oxidized to Fe(III) to determine the total iron in the range 0.02 to 19.42 mg/L with recovery of more than 96.6 percent. Results confirmed that this method is easy, uses simple instruments, is quick and offers high accuracy in the process of measurement. This method can be applied to rapid determination of total iron in EN solutions, as well as determining whether the substrate is completely covered by Ni-P alloy if iron sheets are used.

Thermally induced bond failure of electroless nickel/IVD aluminum coatings deposited on steel

Abstract: Experiments were conducted to investigate methods to improve the bond of an electroless nickel/ion vapor deposited (IVD) aluminum coating applied to a steel substrate for use at an elevated temperature of 482°C. Samples were prepared by coating steel panels with columnar IVD aluminum followed by the application of electroless nickel from a sodium hypophosphite plating solution. Surface treatment of the underlying aluminum was varied by physically compacting the columnar structure of the aluminum by glass-bead peening and/or grit blasting. The cooling atmosphere after application of the aluminum was also investigated by using nitrogen to reduce the potential of aluminum oxidation prior to application of the electroless nickel coating. Results show that at elevated temperatures atomic diffusion takes place creating voids that eventually lead to failure of the electroless nickel coating. Bond failure can be retarded, but not eliminated, by using a nitrogen atmosphere to prevent oxidation of the IVD aluminum and by retention of the aluminum columnar structure before overcoating with electroless nickel.

Method for regenerating electroless nickel plating solution

Abstract: PROBLEM TO BE SOLVED: To separate phosphite produced and accumulated in an electroless nickel plating solution exhaused in by plating operation as calcium phosphite therefrom and to reuse the same as a plating solution. SOLUTION: For regenerating a plating solution having a fundamental composition obtained by combining nickel hydroxide, nickel carbonate or nickel hypophosphite to form into a nickel source and hypophosphorous acid, nickel hypophosphite or sodium hypophosphite to form into a reducing agent, a calcium carbonate or calcium hydroxide is added to the plating solution. In this way, phosphite produced and accumulated in the plating solution by the oxidation of hypophosphite is precipitated and formed as calcium phosphite. At this time, the amount of calcium carbonate or calcium hydroxide to be added is controlled so that the pH of the solution upon the end of the reaction reaches 4.5 to 5.8, and moreover, hypophosphorous acid is added. The precipitated and formed calcium phosphite is separated, and the recovered mother liquor can be reutilized as a plating solution.

Microwave Thermolysis VII: Selective Diversity In The Reduction Using Sodium Hypophosphite Under Microwave Irradiation

Abstract: The selective reduction of nitro group into amine using sodium hypophosphite under microwave irradiation is described. The rapid reaction, solvent free conditions and selectivity over common functional groups like CN, OH, COOH, CONH2 and halogens are the distinct features of the procedure.

Molding polyamide resin composition excellent in sour gasoline resistance and tube

Abstract: PROBLEM TO BE SOLVED: To obtain a composition excellent in sour gasoline resistance and suitable for recycling by including a polyamide resin with a specified amount (in terms of the phosphorus atoms) of a phosphorus compound selected from among sodium hypophosphite, disodium hydrogenphosphite, disodium hydrogenphosphate, and trisodium phosphate. SOLUTION: This composition contains 100 pts.wt. polyamide resin and 0.001-2 pts.wt. (in terms of the phosphorus atoms) of a phosphorus compound selected from among sodium hypophosphite, disodium hydrogenphosphite, disodium hydrogenphosphate, and trisodium phosphate. The composition may optionally contain additives such as a flame retardant, a mold release, a lubricant, an ultraviolet absorber, an antistatic agent, and a colorant. The polyamide resin is obtained by e.g. the dehydrative condensation polymerization of a diamine and a dicarboxylic acid or the ring-opening polymerization of a lactam and is exemplified by polyamide 6, polyamide 11, polyamide 12, polyamide 66, polyamide 612, polyamide 6T, or polyamide 6/66.

Catalytic determination of ultra trace amounts of tellurium by 2.5-order differential oscillopolarography.

Abstract: A highly sensitive and selective catalytic method with 2.5-order differential oscillopolarographic detection is described for the determination of tellurium, based on its activation effect on the slow Pd(II)-catalyzed reaction of sodium hypophosphite and methyl red in hydrochloric acid medium at 100 °C. Methyl red exhibited a sensitive 2.5-order differential polarographic wave at –0.35 V ¶(vs. SCE) in the supporting electrolyte of pH 5.0 acetate buffer solution and was chosen as the indicating component for the indirect determination of tellurium. A calibration curve of tellurium in the range of 0.02–2.0 ng mL–1 was obtained by the fixed-time procedure. The detection limit was 0.007 ng mL–1. Possible interferences by co-existing substances were examined. The new method has been used to analyze trace tellurium in organs of white mice with satisfactory results. RSD was 0.54% to 2.10%, recovery 98.4% to 95.7%. The mechanism is also discussed.