Sodium hypophosphite

About: Sodium hypophosphite is a research topic. Over the lifetime, 1695 publications have been published within this topic receiving 15932 citations.

Modification of hemicelluloses with polycarboxylic acids

Abstract: Polycarboxylic acids (PCAs) aroused interest as crosslinking agents for natural polymers, such as cellulose, starch, chitosan, and hemicelluloses (HC), for improving their water resistance and imparting them new properties. Here, PCAs were studied for the crosslinking of HC films. HCs were isolated from gray alder (Alnus incana L.) wood as a water-soluble fraction by sawdust extraction with 7% potassium hydroxide. Citric acid (CA), maleic acid (MA), and butane tetracarboxylic acid (BTCA) served as crosslinking agents in the presence of sodium hypophosphite as a catalyst. The crosslinking reaction was followed by the analysis of free and esterified COOH groups in HC films. At temperatures below 100–110°C, the HC esterification process with BTCA proceeded very slowly. At 140°C, most of the acids’ COOH groups reacted with HC during 1–1.5 h. BTCA had a higher esterification activity than CA and MA. The obtained films retained their form on immersing in water and subsequent drying in the open air. The water retention value of films followed the reaction kinetics, that is, decreased with increasing reaction time. Water-resistant films were obtained with no <10–11% of BTCA and 20% of CA based on the weight of HC. The water vapor sorption capacity of the films after modification with 10% BTCA decreased approximately twice in the whole range of the relative humidity of air compared with the case of unmodified HC films.

Interface with Substrates of High‐Phosphorus Electroless NiP and NiCuP Deposited from Nonammonia Alkaline Solutions

Abstract: Electroless NiP and NiCuP alloys with high phosphorus content (11 to 13 weight percent) are plated from nonammonia alkaline baths onto aluminum and iron substrates. Energy-dispersive spectroscopy analysis is used to examine the chemical composition of the coatings. Scanning Auger electron spectroscopy is applied to study elemental profiles and the interface with the substrates. The zincate layer transformation at the interface with the aluminum substrate is investigated at two bath temperatures. Nickel, phosphorus, and copper concentration is plotted against the coating thickness to examine the chemical homogeneity and to obtain information about the mechanism of electroless ternary alloy formation on both types of substrates.

Simultaneous reduction of perrhenate and nickel ions by hypophosphite

Abstract: Reduction of water by hypophosphite during Ni-P-Re alloy deposition proceeds in nearly the same proportion as that in the case of Ni-P deposition according to the mass spectrometric analysis of the gas evolved in deuterium-labelled electroless plating solutions. Perrhenate ion is reduced to metal rhenium as shown by the XPS analysis of the electrolessly deposited Ni-P-Re coating. Atomic hydrogen is expected to tkae part in perrhenate reduction at the catalyst surface resulting in a high hypophosphite efficiency in the overall electroless Ni-P-Re deposition process.