Development of fire retardant composite panels. Part X. Improvement of fire performance of ceiling tile via fiber treatment with glass fiber, fire retardants and nano-particles
A laboratorial study was carried out to improve the fire performance of low-density fiberboard (ceiling tile) by incorporating various commercial fire retardants (FR), nano-particles (NP) and glass fiber (GF) into fibers during the mat forming process. Five FR (CROS 349, CROS 481A, CROS 334, Optibor, Polybor), two NP (Nano Al2O3 and Cloisite 25A) and one GF were examined. The ceiling tiles were evaluated for mechanical properties (transverse load at rupture and modulus of rupture) according to CAN/ULC-S706-09 and ASTM C 209-07, and fire performance (flame advance, panel consumption, insulation value and char index) according to ASTM D 3806-98.
An element analysis of aluminum (Al) in a ceiling tile made with Nano Al2O3 was performed to evaluate the chemical distribution in fibers. The test result indicated that Nano Al2O3 only penetrated into the top layer of the panel. Based on this result, it was expected that the chemical penetration was likely limited on the top layer when other NP and FR were used. Thus, the procedure employed in this work for incorporating an additive into fibers would not cause any leaking problem which in turn might contaminate the white water and possibly destroy the bacteria used in the cleaning of the water for recycling.
Addition of an additive in ceiling tiles showed some negative impact on the transverse load at rupture or modulus of rupture (MOR) of the panels, depending on each individual additive used. The use of FR at 10-15 wt% on dry fiber weight significantly improved the fire performance of ceiling tiles in terms of reduced net flame advance by 81%, 59% and 57% respectively, and lowered panel consumption by 56%, 29% and 40% respectively, as observed for CROS 481A, CROS 349 and CROS 334. FR Polybor also resulted in reduced net flame advance by 46%, but it caused more reduction in board strength than other additives: by 41% for transverse load and 17% for MOR. The insulation values of ceiling tiles were reduced by 20% for NP Cloisite 25A, 10% for Nano Al2O3 and 7% for FR Polybor when these additives were applied at 5 wt% based on the dry fiber weight. Adding GF (10% by weight) or NP Cloisite 25A (5% by weight) in ceiling tiles also lowered the char index by 35%.
This study also showed that no additive could perform consistently better than others in terms of both mechanical and fire properties of ceiling tiles. By taking board mechanical properties into account, it can be concluded that three FR (CRSO 349, CROS 481A, CROS 334) showed potential for protecting ceiling tiles against flaming regarding lowered net flame advance and panel consumption. One nano-particle (Cloisite 25A) also showed potential in terms of reduced insulation value and char index.