Synthesis and evaluation of low viscosity melamine urea formaldehyde for bulking treatment of wood

Abstract

This study attempted to produce a low viscosity melamine urea formaldehyde (MUF) resin. The MUF resins were diluted into concentration of 20% and 30% based on solid content with different melamine contents (20 to 30%), formaldehyde contents (50 to 60%) and urea contents (15 to 25%). Performance of the formulated resins was evaluated by measuring solid content, viscosity, pre-curing time, curing time, curing behaviour and molecular weight. The pH values were set to 9.5 to 9.8 during synthesis. A very low viscosity resin was produced with the viscosity ranges from 6 to 9 cp and the solid content ranged from 21 to 36%. The fastest pre-curing time at 70 °C was observed in formulation 1 for both 20% MUF and 30% while the fastest curing time was obtained from 30% MUF (F2) for 22 min. Analysis of differential scanning calorimetry found that 30% MUF (F2) yield the lowest peak temperature at 95.79 °C and the highest peak was obtained from 30% MUF F4 at 109.47 °C. The gel permeation chromatography shows that 30% MUF (F4) had weight average molecular weight (Mw) of 1988 g/mol and number average molecular weight (Mn) of 1769 g/mol.