Thermo-oxidative decomposition and combustion behavior of Scots pine (Pinus sylvestris L.) sapwood modified with phenol- and melamine-formaldehyde resins

Modification of wood with phenol-formaldehyde (PF) and melamine-formaldehyde (MF) resins is known as an efficient strategy to improve wood’s dimensional stability, mechanical strength, and durability. This study systematically examined the effects of these types of modifications on the thermo-oxidative decomposition and combustion behavior of Scots pine (Pinus sylvestris L.) sapwood treated to weight percent gains ranging from 10 to 55 %. Thermo-gravimetry results showed that treatment with PF and MF reduced the decomposition rate, thereby thermally stabilizing the wood. Bench-scale cone calorimetry results indicated that the treated wood exhibited longer ignition times and yielded more char than the untreated control. Treatment with PF did not substantially change the heat release of wood, but led to a considerable increase in CO and smoke production. New compounds in the smoke from the treated wood were identified as phenols and its derivatives resulted from incorporation of PF resin as evidenced by pyrolysis/gas chromatography/mass spectrometry of the volatile organic compounds. Treatment of the wood with MF resulted in greater heat release due to complete combustion; however, smoke production was significantly suppressed. These findings demonstrate that both treatments cause different fire risk patterns: smoke issues for the PF-treated wood and heat hazard for the MF-treated wood.