Thermoset Alkyd-Acrylic Hybrid Emulsions for Coatings

Alkyd acrylic hybrid emulsions can offer cost/performance advantages over common 1K coatings such as polyurethane dispersions (PUDs), acrylic emulsions and blends. Hybrid emulsions with different ratios of alkyd resin to acrylic monomers were synthesized. Emulsion with resin-to monomer ratio of 1:1 (wt/wt) with total solids as high as 50% had a shelf stability of more than 8 months. Morphology of hybrid emulsions was studied by scanning electron microscopy. Hybrid emulsions were characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis. Films obtained from the hybrid emulsions were found to be homogeneous and exhibited excellent thermal and coating properties.     

Stability Constants of Complexes of Divalent and Rare Earth Metals with Substituted Salicynals

Summary.  5-Chloro-4-6-dimethyl-salicylaldehyde was synthesized from 4-chloro-3,5-dimethyl-phenol. A series of substituted salicynals were obtained by condensation of 5-chloro-4,6-dimethyl-salicylaldehyde with several amines. The amines were chosen such as to vary the basicity of salicynals by changing the substituents at one of the coordination sites. The stability constants of complexes of bivalent (Mg²⁺, Ca²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺) and trivalent (Y³⁺, La³⁺, Pr³⁺, Nd³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Tb³⁺, Er³⁺, Yb³⁺) metal ions with these salicynals and the pK values corresponding to the dissociation of the phenolic proton and the association of a proton to the azomethine nitrogen were determined potentiometrically using the Calvin-Bjerrum technique as adopted by Irving and Rossotti at 303 K and a constant ionic strength of 0.1 M in a 75:25 (v/v) dioxan-water mixture in an inert atmosphere. The influence of substituents on the proton affinity of the ligands was examined on the basis of inductive and mesomeric effects. It is also shown that some of the complexes possess antibacterial, antitubercular, antifungal, and anticoagulant activity. Received August 5, 1999./Accepted November 11, 1999     

Valorization of Oceanic Waste Biomass: A Catalytic Perspective

Efficacious waste utilization is vital in context of sustainability. The past decade has witnessed attempts of usage of land biomass and wastes for various applications, contributing towards a sustainable society. Exploitation of the marine biomass, which does not compete with habitation and food production like land biomass has been largely unnoticed and therefore not being utilized judiciously. Researchers have mainly exploited these resources as functional materials having significant potential applications. However, a catalytic perspective for the valorisation of these polymers arising from oceanic waste widens their scope and ameliorates its use. The objective of the present review is to demonstrate the effectiveness of chitin/chitosan as a catalyst and as a feedstock for deriving important fuels and chemicals. It displays all the reactions heterogeneously catalyzed by them along with the strategic methodology. Their important catalytic organic transformations attempted so far, have also been discussed. The future perspectives are also presented which if inculcated would improve the value addition of the waste, paving a way for greener and imperishable world.     

Polyaniline–graphene oxide nanocomposites: Influence of nonconducting graphene oxide on the conductivity and oxidation‐reduction mechanism of polyaniline

The present endeavor focuses on the unusual interactions between polyaniline and graphene oxide (PANi–GO) which radically affects the properties of nanocomposites as it is an emerging material for many potential applications. A series of nanocomposites have been synthesized by varying the weight percentage of highly nonconducting GO with respect to aniline which exhibit superior properties in terms of shelf life, processability and conductivity due to the synergistic effect of GO and PANi. A comparison of the resistances of samples reveal that though as‐synthesized GO is insulating (80 MΩ), when added to PANi (283 kΩ) in small amounts yields conducting composites (50–280 Ω). Up to 5 weight % concentration, GO renders conductivity to the composite probably by increasing the doping level of PANi. Nonetheless, no further increase in conductivity observed on addition of more than 5 wt% GO in the composite has dictated us to unravel the structure property relationship between PANi and GO, where GO facilitates the formation of partially reduced phase of PANi, thereby restricting the electronic transport. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3778–3786     

A monopole mass filter with a hyperbolic V-shaped electrode

In this article we compare the classical monopole mass filter of von Zahn and the monopole mass filter with a hyperbolic V-shaped electrode. The experimental results and those of computer simulation for both mass spectrometers are presented. We show that the replacement of a conventional 90 degrees V-shaped electrode by an electrode with a hyperbolic profile substantially improves the peak shape of any given mass, and increases the mass resolution by a factor of 3-4 and the abundance sensitivity by a factor of 100. The potential of high analytical performance combined with electroforming techniques for electrode manufacture indicate future practical uses of such instruments. Copyright 1999 John Wiley & Sons, Ltd.     

Stability Constants of Complexes of Divalent and Rare Earth Metals with Substituted Salicynals

 5-Chloro-4-6-dimethyl-salicylaldehyde was synthesized from 4-chloro-3,5-dimethyl-phenol. A series of substituted salicynals were obtained by condensation of 5-chloro-4,6-dimethyl-salicylaldehyde with several amines. The amines were chosen such as to vary the basicity of salicynals by changing the substituents at one of the coordination sites. The stability constants of complexes of bivalent (Mg²⁺, Ca²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺) and trivalent (Y³⁺, La³⁺, Pr³⁺, Nd³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Tb³⁺, Er³⁺, Yb³⁺) metal ions with these salicynals and the pK values corresponding to the dissociation of the phenolic proton and the association of a proton to the azomethine nitrogen were determined potentiometrically using the Calvin-Bjerrum technique as adopted by Irving and Rossotti at 303 K and a constant ionic strength of 0.1 M in a 75:25 (v/v) dioxan-water mixture in an inert atmosphere. The influence of substituents on the proton affinity of the ligands was examined on the basis of inductive and mesomeric effects. It is also shown that some of the complexes possess antibacterial, antitubercular, antifungal, and anticoagulant activity.     

Polyurethane Dispersions Based on Sardine Fish Oil,Soybean Oil,and Their Interesterification Products

Alkyd resins were synthesized from different ratios of sardine fish oil and soybean oil. Three alkyd resin samples were styrenated. The styrenated alkyd resins and alkyd resins were subsequently converted into the polyurethane dispersions. The physicochemical properties, such as iodine value, saponification value, and specific gravity were determined. Infrared spectroscopy and nuclear magnetic resonance techniques were used for structural elucidation of newly synthesized resins. The coating properties, such as adhesion, flexibility, scratch hardness, pencil hardness, impact, solvent, and chemical resistance were evaluated. Thermogravimetric analysis was used to investigate the thermal stability of alkyd resin and polyurethane dispersions. Cost effective volatile organic components (VOC) compliant coatings for various applications can be synthesized successfully by partly replacing soybean oil with commercially available, inexpensive sardine fish oil.