The objective of this research was to provide a useful approach of polymer synthesis for accelerating the fast cure of phenol-urea-formaldehyde (PUF) resin as wood adhesive by optimizing its structure and composition. The PUF resins containing high contents of very reactive groups such as para-methylol groups were synthesized by reacting methylolurea, phenol, and formaldehyde in the presence of...

The reactions of di-hydroxymethylurea with phenol under alkaline (pH = 10), weak (pH = 6) and strong acidic (pH = 2) conditions were investigated via the 13C-NMR method. Based on the proposed reaction mechanisms, the variations of the structures of different condensed products were analyzed and the competitive relationship between selfand co-condensation reactions was elucidated. The required e...

1. The thermal denaturation of DNA from rat liver was studied spectrophotometrically. In sodium phosphate buffers denaturation led to a single-stranded form having, at 25 degrees , about 25% of the hypochromism of the intact double helix. 2. The hypochromism of the denatured form was the same in 1mm- as in 10mm-sodium phosphate buffer and was scarcely affected by reaction with formaldehyde. The...

Understanding wetting behavior and surface coverage of resins on a wood surface is important to obtain satisfactory adhesion and optimize adhesive application for wood composite manufacturing. Sessile and micro-droplets of ureaand phenol-formaldehyde (UF and PF) resins were generated on wood surfaces to observe wetting behaviors using three directional image generation system and atomic force m...

CommunIcations to the Editor genesis ofthe pulmonary edema in this patient. Indeed, endorphins are released in stress situations and they can adversely affect physiologic systems, such as respiration and circulation.’ In the human fetus at term, plasma levels of beta-endorphins and betaLPH are inversely correlated with arterial pH and Po5 suggesting that hypoxia and secondary acidosis may be im...

condensation reaction of urea, casein and formaldehyde in the presence of varying proportion of resorcinol under alkaline condition. All the prepared resins were characterized by free-formaldehyde content, free-phenol content, viscosity measurements and infrared spectroscopy (IR). The resin samples were cured isothermally at 120oC using two different curing agents, p-toluene sulphonic acid (PTS...

Abstract Chestnut bur is an agro-waste material generated in the chestnut production. It a tannin-rich lignocellulosic which might be promising raw for low-formaldehyde composite particleboard production when using urea–formaldehyde (UF) as bonding adhesive. In this study, characteristics of were analyzed to assess its application value panel. Five-type particleboards manufactured from mixture ...