Preparation Of Waterborne Research Articles

Preparation of waterborne polyurethane/β-cyclodextrin composite nanosponge by ion condensation method and its application in removing of dyes from wastewater

Currently, polymer nanosponges have received extensive attention. However, developing new synthetic techniques for novel nanosponges remains a challenge. Furthermore, to date, composite nanosponge adsorbents based on waterborne polyurethane (WPU) and β-cyclodextrin (β-CD) have not been reported. Herein, a novel green method, ion condensation method, was developed in this study for the preparation of polymer nanosponge adsorbents for efficient removal of dyes from wastewater. Based on the principle of charge repulsion between nanoparticles to maintain emulsion stability, waterborne polyurethane/β-cyclodextrin composite nanosponges (WPU-x,y) were prepared by coagulating the emulsions synthesized from 2,2-dimethylolpropionic acid, polypropylene glycol and hexamethylene diisocyanate as raw materials in a mixture of hydrochloric acid and anhydrous ethanol. The structure and appearance of WPU-x,y were characterized by attenuated total reflectance Fourier transform infrared spectroscopy, thermal gravimetric analyzer, scanning electron microscope and mercury intrusion porosimetry. The adsorption capacity of WPU-x,y was tested by parameters such as cross-linking degree, β-CD dosage, contact time, initial dye concentration and pH value. The study found that WPU-4,4.62 had the best adsorption effect on methylene blue (MB), the maximum removal rate was 93.42%, and the maximum adsorption capacity was 136.03 mg·g−1. Moreover, the Sips isotherm and pseudo-second-order-model were suitable for MB adsorption. Therefore, this study provides some perspectives for the fabrication of nanosponge adsorbents.

Preparation of waterborne polyimide‐modified epoxy resin with high thermal properties and adhesion properties

AbstractIn response to the theme of environmental protection and green development in the world in the recent years, waterborne epoxy resin has received more and more attention. Waterborne epoxy resin has lower toxicity, but its low toughness limits the application range of waterborne epoxy resin. Here, we first proposed a method of toughening waterborne epoxy resin with aqueous polyamide salt solution. In this article, a series of waterborne polyamic acid salts is used as modification polymer to improve the high‐temperature resistance and other properties of waterborne epoxy resins by copolymerization modification. Waterborne polyamic acid salt is dispersed uniformly in the epoxy resin. After curing, by compared with the pure epoxy resin, a semi‐interpenetrating network is formed, the cross‐linking density and the high‐temperature resistance of the material are increased, and the glass transition temperature increases from 105°C to 116°C. The storage modulus at 300°C increases from 6.15 to 15.76 MPa. Thermogravimetric Analysis results reveal that the corresponding temperatures of 5% and 10% weight loss increase from 403°C and 419°C to 415°C and 435°C, respectively. At the same time, the toughness of the imide chain segment and polar groups lead to the improved adhesion of the epoxy system, the peeling strength increase from 0.51 to 1.24 N cm−1, and the lap shear strength at high temperature (100°C) increase from 0.58 to 16.97 MPa. The water absorption decreases from 1.51% to 0.66%. The developed waterborne epoxy resin is expected to be used as a high‐temperature waterborne epoxy coating in high‐temperature coatings and other applications.

Preparation of waterborne P-N containing epoxy resin curing and its performances

Purpose The flammability of epoxy resin is a major disadvantage in applications that require flame resistance. Epoxy monomers and hardeners containing flame-retardant elements are molecularly incorporated in the resin network are expected to exhibit better flame resistance than those borne on an additive approach. In recent years, because of health and environmental regulation, the use of waterborne coatings has received many attentions. However, waterborne epoxy resin curing agent with excellent flame retardancy has been seldom reported. The paper aims to study the preparation of waterborne P-N-containing epoxy resin curing agent and its performances (P-N – phosphorous and nitrogen). Design/methodology/approach Waterborne P-N-containing epoxy curing agent was prepared in this study using reactive flame retardant 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-xa-10-phosphaphenanthrene-10-oxide, liquid epoxy resin, triethylenetetramine and butyl glycidyl ether at the mole ratio of 1.0:2.0:2.0:2.0. Findings The results show that the epoxy thermoset from the prepared P-N-containing curing agent presents good flame retardancy and can pass the V-1 rating, and the cured epoxy thermoset film presents excellent performances such as water resistance, adhesion, impact resistance and pencil hardness. This study provides useful suggestions for the application of the water-borne flame retardancy epoxy resins in coating industry. Research limitations/implications Each step of products during the preparation of waterborne P-N-containing epoxy curing agent cannot be accurately tested. Originality/value This method for synthesis of waterborne P-N-containing epoxy curing agent is novel and could be used for various applications in epoxy coating industry.

Performance of Waterborne Cu(II) Octanoate/Ethanolamine Wood Preservatives

Summary Various aqueous wood preservative solutions containing Cu(II) in the form of copper(II) sulphate or copper(II) octanoate, ethanolamine and in one case octanoic acid were investigated by spectrophotometry, polarography and Electron Paramagnetic Resonance (EPR) spectroscopy. Results have shown the same coordination environment around Cu(II) in all solutions with ethanolamine. Computer simulation of the EPR spectra also revealed that the coordination in the first coordination sphere of copper is the same at low concentration of ethanolamine. At 20% ethanolamine concentration, a mixture of two complexes (one with two nitrogens and the other with three) could be detected. The active compound in the investigated ethanolamine containing solutions is the same when previously synthesised copper(II) octanoate was used, or when copper(II) sulphate and octanoic acid were utilized instead. Fungicidal and leaching experiments with the treated wood resulted in the same conclusion: it is not necessary to use pre-synthesised copper(II) octanoate for the preparation of waterborne copper/ethanolamine wood preservatives. Preservative preparation time and costs can be reduced by simply dissolving copper(II) sulphate and octanoic acid in aqueous ethanolamine solutions.