Impact of wood surface pre-treatments on the behaviour of phosphorous additives
Järvinen, Malla (2018)
Järvinen, Malla
2018
Materiaalitekniikka
Teknisten tieteiden tiedekunta - Faculty of Engineering Sciences
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Hyväksymispäivämäärä
2018-06-06
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201805221730
https://urn.fi/URN:NBN:fi:tty-201805221730
Tiivistelmä
Wood is a versatile and widely used material in construction and furniture industries. However, easy flammability of plane wood prevents it from meeting the fire safety standards of buildings. To overcome this problem, the fire performance of wood can be enhanced by the use of fire retardant chemicals.
Fire retardant solution can be pressure impregnated or applied on the surface of wood. Pressure impregnation enables deep penetration of a fire retardant inside the wood, but it is an expensive method which requires special equipment and also affects the strength of wood. Surface applying of fire retardant is an easy and cheap method, but penetration depth is quite shallow, and typically, non-film forming chemicals are susceptible to leaching in moist environment.
In order to improve the durability and the penetration depth of fire retardant applied on the surface, different re-activating methods were tested on the wood surface. Planing, sanding, plasma treatment, microwave treatment or steam treatment was performed on the wood surface before the fire retardant application. The impact of treatments was evaluated first by the contact angle measurements and then by analysing the penetration depth of a fire retardant. Two fire retardants, a reactive and a two-component, were applied and compared with different burning methods; the small flame test, the in-house UL 94, the blow torch burning, the cone calorimeter test and the radiant panel test. All the available methods were evaluated in order to find an easy and fast in-house testing method before performing an official classification testing at an official test facility. Leaching of the fire retardants was tested by immersing the samples into distilled water for different times. The fire performance of samples after leaching was tested with the blow torch burning.
In all the burning tests, the reactive fire retardant presented more efficient fire retardancy than the two-component fire retardant, but no durable bond was formed between wood and fire retardants. After one hour in water immersion, half of the fire retardant was leached out and the fire performance was decreased.
Fire retardant solution can be pressure impregnated or applied on the surface of wood. Pressure impregnation enables deep penetration of a fire retardant inside the wood, but it is an expensive method which requires special equipment and also affects the strength of wood. Surface applying of fire retardant is an easy and cheap method, but penetration depth is quite shallow, and typically, non-film forming chemicals are susceptible to leaching in moist environment.
In order to improve the durability and the penetration depth of fire retardant applied on the surface, different re-activating methods were tested on the wood surface. Planing, sanding, plasma treatment, microwave treatment or steam treatment was performed on the wood surface before the fire retardant application. The impact of treatments was evaluated first by the contact angle measurements and then by analysing the penetration depth of a fire retardant. Two fire retardants, a reactive and a two-component, were applied and compared with different burning methods; the small flame test, the in-house UL 94, the blow torch burning, the cone calorimeter test and the radiant panel test. All the available methods were evaluated in order to find an easy and fast in-house testing method before performing an official classification testing at an official test facility. Leaching of the fire retardants was tested by immersing the samples into distilled water for different times. The fire performance of samples after leaching was tested with the blow torch burning.
In all the burning tests, the reactive fire retardant presented more efficient fire retardancy than the two-component fire retardant, but no durable bond was formed between wood and fire retardants. After one hour in water immersion, half of the fire retardant was leached out and the fire performance was decreased.