Reducing free formaldehyde emission, improvement of thickness swelling and increasing storage stability of novel medium density fiberboard by urea-formaldehyde adhesive modified by phenol derivatives

Abstract

Notwithstanding the enormous benefits of medium density fiberboard, free formaldehyde emission and low water resistance are the significant disadvantages to reducing their application. In this research, phenolic compounds such as phenol, 1,2,4-trihydroxy benzene (hydroxyquinol), and 4-tert-butyl catechol in various amounts were added to an industrial-grade liquid urea-formaldehyde polymer in an attempt to alleviate these defects. Medium density fiberboard panels were manufactured from the modified urea-formaldehyde resins. The panels' physical and mechanical properties, such as thickness swelling, water absorption, formaldehyde emission, modulus of rupture, modulus of elasticity, and internal bond strength were then investigated. The results showed that the free formaldehyde emission contents for the modified composite panels ranged from 25.4% to 50.1% lower than for the unmodified panel. Also, the lowest and highest levels of thickness swelling occurred with the medium density fiberboard panels bonded with UF-P1 and the unmodified urea-formaldehyde, respectively. The results clearly showed that the urea-formaldehyde polymer's storage capacity increased substantially with the addition of phenolic derivatives. The produced novel medium density fiberboard results can be said to substantially lower environmental and health hazards associated with these materials and have a beneficial effect on the water transport characteristics exhibited by these materials. Consequently, this research may play a role as a useful stepping-stone for solving the fundamental problems of medium density fiberboard production industries.