28 documents found, page 1 of 3

Improvement of storage stability of UF resins by adding caprolactam

During storage, the structure of urea-formaldehyde (UF) resins suffers modifications due to reactions between monomers, oligomers, polymer and free formaldehyde, leading to increase in viscosity and decrease in pH. Eventually, viscosity reaches a value that renders the resin unusable, and it must be disposed off. This aging process is accelerated if storage temperature increases. The aim of this work is to obta...

Low-cost natural binder for particleboards production: study of manufacture con...

Nowadays, the majority of adhesives used in particleboards (PB) manufacture are formaldehyde-based. In the present research work a low-cost bioadhesive, based on the combination of thick spent sulfite liquor (TSSL) with wheat flour, was tested for the production of three-layer particleboards, at different conditions (particleboards target density, pressing time, pressing temperature, wood type and binder age). ...

Statistical evaluation of the effect of urea-formaldehyde resins synthesis para...

This work discusses the optimization of different synthesis parameters for a low emitting urea-formaldehyde (UF) resin. Industrially, this resin was synthesized using the alkaline-acid process (alkaline methylolation and acidic condensation) at different values of pH, temperature (T) and final viscosity and characterized according to different analytical methods. Particleboards (PBs) were produced using differe...

Scale-up of the Green Fluorescent Protein extraction process using an oscillato...

Exploiting autoencoders for three-phase state estimation in unbalanced distribu...

The three-phase state estimation algorithms developed for distribution systems (DS) are based on traditional approaches, requiring components modeling and the complete knowledge of grid parameters. These algorithms are capable of dealing with the particular characteristics of DS but cannot be used in cases where grid topology and parameters are unknown, which is the most common situation in existing low voltage...

Evaluation of bonding performance of amino polymers using ABES

In this paper, the use of Automated Bonding Evaluation System (ABES) for evaluation of bonding strength of wood adhesives is presented. A simple reactive model is proposed, which considers the phenomena involved during resin cure: formation of wood-resin-wood bonds. In the present study, experimental data of a standard urea-formaldehyde (UF) resin using different catalysts, phosphoric acid and ammonium sulphate...

Formaldehyde emission in wood based panels: Effect of curing reactions

The influence of hexamine formed as byproduct during the UF cure was ignored in the past. However, with the increasing interest on low formaldehyde emission boards, this issue has become more pertinent. Formaldehyde release from hexamine degradation is extensive and could limit the success of the development of low formaldehyde emission adhesives if the conventional latent catalysts remain in use. In this study...

Impact of thermal treatment on bonding performance of UF/PVAc formulations

Polyvinyl acetate (PVAc) adhesives present several advantages: ready to use, short setting time, flexible joint, easy to clean and long storage life. On the other hand, formaldehyde-based adhesives are less expensive and give a rigid bond. In this work, the combination of a PVAc glue and UF resin for surfacing MDF with wood veneer was assessed. The reactivity of different mixing ratios was evaluated using ABES ...

Sodium metabisulphite as a scavenger of air pollutants for wood-based building ...

This paper reports on different applications of sodium metabisulphite as a formaldehyde scavenger. The reduction in formaldehyde emission and the effect on physicomechanical properties of particleboards were studied. The scavenger was mixed with urea-formaldehyde resins with different formaldehyde to urea molar ratios and added separately in the production of particleboards. Several differences between the form...

Study of influence of synthesis conditions on properties of melamine-urea forma...

The aim of this work is to assess the differences in the polymeric structure and performance of melamine-urea formaldehyde (MUF) resins, when changing relevant synthesis variables: formaldehyde/amine groups [F/(NH 2) 2] molar ratio (both in the methylolation and the condensation steps) and the feedrate of urea during the condensation step. This synthesis process differs from the traditional alkaline acid proces...