Sodium hypophosphite

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

Catalytic Actions of Sodium Salts in Direct Esterification of 3,3′4,4′-Benzophenone Tetracarboxylic Acid with Cellulose

Abstract: Aromatic polycarboxylic acids can directly react with cellulose to form ester cross-linking structures and provide wrinkle resistance functions to cotton fabrics, different from aliphatic polycarboxylic acids, which will form anhydrides as intermediates. Sodium hypophosphite is a catalyst proven effective in the reactions of both acids. In order to find alternative catalysts, the mechanism of the direct esterification and the role of the catalyst in the reaction were investigated in this study. Several sodium salts of phosphorous acid and dichloroacetic acid with varied pKa values were employed in the treatment of cotton fabric with 3,3′,4,4′-benzophenone tetracarboxylic acid (BPTCA). The results confirmed that the overall reaction follows the Fischer esterification mechanism, an acid catalyzed reaction. The acid anions also play an important role in the reaction. Results of wrinkle recovery angles, FTIR band ratios of ester bonds, and thermogravimetric analyses of the treated fabrics consistently support...

Characterization of electroless nickel plating on silicon solar cells for the front side metallization

Abstract: The selective deposition of nickel on silicon wafers from an electroless bath is a very attractive process for the front side metallization of silicon solar cells. The anti-reflection coating (ARC) at the front side of the wafers is used as a mask for the deposition. Nickel is plated from an alkaline nickel sulfate bath with sodium hypophosphite as a reducing agent and ammonia for pH control. Characterization of the deposition depending on bath conditions, substrate doping and light application will be presented in this paper. Silicon solar cells with SiO2 and SiNx as ARC have been processed featuring dielectric passivation and Laser Fired Contacts (LFC) at the back side. Efficiencies up to 18.9% have been achieved using this technology. The samples have been characterized by SEM and measurement of the IV curves.

A novel multifunctional cotton fabric using ZrO2 NPs/urea/CTAB/MA/SHP: introducing flame retardant, photoactive and antibacterial properties

Abstract: This study was aimed to investigate the possibility of producing multifunctional properties on cotton fabric using ZrO2 nanoparticles along with cetyltrimethylammonium bromide (CTAB) and urea. Maleic acid was also used as a cross-linking agent in the presence of sodium hypophosphite as the catalyst to stabilize fabric from creasing and nanoparticles on the fabric surface. The flame retardant properties of the treated samples were examined using char length and thermogravimetry analysis. The self-cleaning properties of treated cotton fabrics were also analyzed based on the discoloration of methylene blue under sunlight irradiation. The antibacterial activities of treated fabrics were examined against Escherichia coli through counting method. The surface of the treated cotton and microstructure of nanoparticles were characterized by scanning electron microscopy and transmission electron microscopy. Introducing urea as a nitrogen source enhanced both the flame retardant and photoactivity of the nano-ZrO2-tre...

Investigation on Functional Properties of 1,2,3,4-Butanetetracarboxylic Acid Cross-Linked Fabrics Impacted by Molecular Structures and Chemical Affinity of Catalysts

Abstract: 1,2,3,4-Butanetetracarboxylic acid (BTCA), catalyzed by sodium hypophosphite (SHP), brings good antiwrinkle property to cotton fabrics and causes significant strength losses due to cross-linking and acidic degradation of cellulose simultaneously. Previous studies presented optimum pH values for different catalysts based on wrinkle recovery angle but without analyzing the tensile strength losses (TSL) of the treated fabrics. Here, the differences in TSL were analyzed from catalyst diffusibility and affinity to BTCA and cellulose based on anion sizes and Hansen solubility parameters of the corresponding acids of catalysts, respectively. Results showed that smaller catalyst anions such as the SHP anion would diffuse into the fibers more deeply, causing more TSL due to more cross-linking (TSLC). Besides, the lower affinity of the catalyst to BTCA and cellulose would accelerate the cross-linking reaction, also resulting in more TSLC. Connolly accessible area of an acid anion, catalyst anion concentration, and ...