Viscoelastic and dynamic characteristics of wood-melamine-urea-formaldehyde composites prepared by in situ polymerization

The viscoelastic behavior and the dynamic mechanical properties were studied for wood-melamine-urea-formaldehyde composites prepared from fast-growing poplars using in situ polymerization. The changes in stress relaxation (SR), storage modulus (E′), and damping parameter (tan δ) were considered. The relationship between the dynamic mechanical properties and the modifier concentration was also studied. The SR value decreased as the modifier content increased in all the samples examined. The urea content had a greater impact than the melamine-urea-formaldehyde mixture content on the SR value of the wood samples. A similar trend was observed for E′. The modified wood samples exhibited a higher tan δ. The results confirmed that a better interfacial interaction between melamine-urea-formaldehyde and wood fiber contributed to the improvement of mechanical properties in the fast-growing poplar wood.