The effect of partial substitution of polyphosphates by aluminium hydroxide and borates on the technological and fire properties of medium density fibreboard

ABSTRACT

Aim of this study was to evaluate the effect of aluminium hydroxide and borates, separately or combined with ammonium polyphosphate (APP), upon the technological and fire properties of medium density fibreboard (MDF). Fire resistant MDF was fabricated in the laboratory from Scots pine (Pinus sylvestris L.) fibres bonded with a high molar ratio melamine-urea-formaldehyde resin. Overall, 24 h-swelling and water absorption properties of the treated boards were improved or remained unchanged compared to untreated ones. On the contrary, the internal bond strength (IB) of the fibreboards was significantly reduced up to 48%. The fire properties of the fibreboards were assessed by the determination of limiting oxygen index and cone calorimetry. As expected, the tested fire-retardants improved the fire resistance of the boards. Furthermore, the combination of aluminium hydroxide with ammonium polyphosphate considerably upgraded the fire retardancy while the incorporation of borates into APP showed much weaker effects.

KEYWORDS:

• Polyphosphates
• fire retardancy
• medium density fibreboard
• aluminium hydroxide
• borax
• boric acid

Acknowledgements

Fire-retardant additives used were prepared at the Lab of Wood Science and Technology (Karditsa, Greece), whilst the MDF panels were fabricated at the Univ. of Forestry (Sofia, Bulgaria). The authors acknowledge the laboratory support of Mr. Chia-feng Lin, PhD candidate at Luleå University of Technology, for carrying out the LOI tests.

Disclosure statement

No conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Slovak Research and Development Agency under the contract no. APVV16-0223.