FR performance of various UL94 classified materials exposed to external ignition sources

摘要

The flammability of eight halogen-free styrene resins were characterized by UL 94 VB,LOI and con calorimeter test.Their burning behavior was also measured when exposed to three external ignition sources (methenamine tablet,candle,paper ball).Four resins were used for 19" Monitor housings and the others for 25" TV.The LOI values of UL 94 V-2,V-1 and V-0 rated resins were higher than that of HB.Heat release rate decreased as the UL 94 ratings increased from HB to V-0.When these resins were exposed to three external ignition sources,UL 94 V-1 and V-0 rated resins showed self-extinguished property after the removal of fire and did not cause fire growth in both 19" Monitor and 25" TV housings in all cases.However,UL 94 V-2 and HB rated resins were easily ignited and spread fire by dripping burning trickles.The burning rate of V-2 resin was slower than that of HB.