Performance of Cunninghamia lanceolata / Uncaria Composite Particleboard: Part 2

Abstract

Thinned Chinese fir (Cunninghamia lanceolata) and waste stems of Uncaria were used as raw wood materials with melamine–urea–formaldehyde as a co-condensation resin adhesive to produce particleboard. The effects of Uncaria stem incorporation on the composite’s nail-holding capacity, antibacterial activity, decay resistance, insect resistance, and fire retardancy were investigated. GC-MS analysis identified 19 bioactive compounds in Uncaria stems, including esters, terpenes, carboxylic acids, and indole alkaloids. At 50% Uncaria stem mass fraction, nail-holding strength peaked at 170.8 N/mm, a 10.3% increase over pure fir boards. Anti-mold, decay, termite resistance, and fire-retardancy tests demonstrated that Uncaria’s active components significantly mitigated fir’s inherent vulnerabilities via a dual “chemical inhibition + physical barrier” mechanism. A 50% substitution reduced mold coverage from 100% to 3%, while 75% substitution decreased white-rot fungal mass loss from 35.8% to 25.7% and linearly lowered termite-induced mass loss from 18.2% to 7.5%. Cone calorimetry revealed that 75% Uncaria-substituted composites exhibited a 4.6% reduction in peak heat release rate, a 4-second ignition delay, and increased char residue from <5% to 11%, achieving GB/T 8624 Class B1 fire-retardant rating. Uncaria waste stems thus serve as a functional filler for fir particleboard, endowing it with multi-bio-durability and flame-retardant properties. This offers theoretical and technical support for the high-value utilization of agro-forestry waste and development of green wood-based composites.