The impact of altering the molar ratio on formaldehyde content and the physical and mechanical properties of MDF panels

© 2024 Informa UK Limited, trading as Taylor & Francis Group.This study aimed to evaluate the influence of the molar ratio of urea-formaldehyde resin (UF) on formaldehyde content and the physical and mechanical properties of MDF panels. The goal was to determine the optimal composition, i.e. the one that exhibits the lowest formaldehyde content without compromising the properties. To that end, there were five treatments. They were characterized by five F:U molar ratios (0.9:1; 1.0:1; 1.1:1; 1.2:1; and 1.3:1). The panels had a nominal density of 750 kg.m−3, dimensions of 40 × 40 × 1.5 cm, 12% resin, 1% paraffin. They were produced with a pressing cycle with a temperature of 170 °C and pressure of 3.6 MPa per 10 min. The physical-mechanical properties of the panels and the formaldehyde content were determined and evaluated following the NBR 15316-2 (2019) standard. Results showed that the formaldehyde content was lower for panels produced with resin molar ratios of 0.9:1, 1.0:1, and 1.1:1, classified as E1. Panels with a resin molar ratio of 1.2:1 were classified as E2. The molar ratio of 1.3:1 exceeded the limits of the standard. Panels with resin molar ratios of 1.1:1, 1.2:1, and 1.3:1 met the standard requirements for all physical-mechanical properties of non-structural MDF for use in dry conditions. These results indicate that the most suitable UF resin molar ratio for producing MDF panels is 1.1:1. This radio provides low formaldehyde content and technological properties compatible with the reference standard.