Sodium hypophosphite

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

Polymerization of maleic acid and itaconic acid studied by FT‐Raman spectroscopy

Abstract: In this research, we used a new redox free radical initiation system consisting of potassium persulfate (K2S2O8) and sodium hypophosphite (NaH2PO2). In the presence of NaH2PO2, the thermal decomposition of K2S2O8 is accelerated, and the temperature required for the formation of free radical is reduced. We polymerized maleic acid (MA) using the K2S2O8/NaH2PO2 initiation system in an aqueous solution, and monitored the polymerization process with FT-Raman spectroscopy. The Raman spectroscopy data indicate the formation of a saturated carboxylic acid with the disappearance of the characteristic bands of MA as the thermal decomposition of K2S2O8 progresses, thus indicating the formation of poly(maleic acid) (PMA). We also found that itaconic acid (IA) polymerizes in the presence of the new initiation system. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 223–228, 2001

Effect of heat treatment on age hardening behaviour of electroless nickel–phosphorus coatings

Abstract: Electroless nickel–phosphorus (EN) coatings have been widely used in various industries such as oil, gas, electronic, chemical, automotive, aerospace, and mining. The EN coating process is based on a redox reaction in which a reducing agent is oxidised and Ni2+ ions are reduced on the substrate materials. Once the first layer of Ni is deposited, it acts as a catalyst for the process. Consequently, a linear relation between coating thickness and time usually occurs. If the reducing agent is sodium hypophosphite, the deposit obtained will be a nickel–phosphorus alloy. Also, the actual nickel and phosphorous levels in the EN deposit depend on the composition, temperature, and pH of the plating bath used. In this work, three types of EN coatings have been studied: low, medium, and high phosphorus Ni–P alloys. The techniques used were: differential scanning calorimetry (DSC), SEM, and hardness measurements. Heat treatment resulted in precipitation of nickel phosphides, e.g. Ni3P, and nickel crystallit...

Preparation and Characterization of Electroless Ni-P and Ni-P-Si3N4 Composite Coatings

Abstract: SUMMARYThe present work pertains to the study of electroless Ni-P and Ni-P-Si3N4 composite coatings. The deposits are obtained from a proprietary high phosphorus electroless nickel plating bath, comprising nickel sulphate, sodium hypophosphite, complexing agents and stabilizers. The maximum weight percent of Si3N4 incorporated in the electroless deposit is obtained at a concentration of 10 g/l in the bath. The electroless Ni-P deposits having 0%, 2.01%, 5.81% and 8.10% of Si3N4, respectively, obtained from baths containing 0, 2, 5 and 10 g/l of Si3N4, are characterized by optical microscopy, XRD and TEM. Hardness is found to increase with the incorporation of Si3N4 at all heat treatment temperatures studied. Also hardness increases with an increase in weight percent of Si3N4 incorporated in the deposit. The analyses of the composite coatings by XRD and TEM reveal that the inclusion of Si3N4 particles does not change the amorphous nature of the Ni-P matrix.

Cross-Linking Cotton Cellulose by the Combination of Maleic Acid and Sodium Hypophosphite. 2. Fabric Fire Performance

Abstract: Multifunctional carboxylic acids have been used as durable press finishing agents for cotton with sodium hypophosphite (NaH2PO2) as the most effective catalyst. In our previous research, we found that cellulose cross-linking takes place when cotton fabric treated with a combination of maleic acid and NaH2PO2 is cured at ≥150 °C. The data suggested that H−P−H of hypophosphite likely reacts with >C═C< of the maleic acid already esterified with cotton cellulose, thus making it possible to form cross-linking on cotton. In this research, we studied the effect of the maleic acid (MA) and NaH2PO2 treatment on the fire performance of cotton using microscale combustion calorimetry. We found that esterification of cotton by MA reduces the flammability of the cotton cellulose. NaH2PO2 catalyzes the esterification of MA on cotton, thus further reducing the cotton fabric’s flammability by increasing esterification on cotton. The quantity of ester formed on cotton reaches the optimum range when the curing temperature i...