GMS Composites (Melbourne, Australia) has developed GMS EP-540, a new high-performance flame retardant (FR) epoxy prepreg with good toughness and a short gel time, which passes the UL94 V0 flammability rating. GMS EP-540 is a non–halogenated epoxy resin matrix prepreg, replacing EP-530, a previously developed FR grade that had an average 16 minute gel time at a 120°C mold temperature; the new EP-540 grade has a gel time down 6 minutes at 120°C for thinner laminates, with parts fully cured within 2 hours. According to GMS Composites EP-540 has a tensile strength of 460 MPa, flexural strength of 578 MPa, with an Izod Impact strength of 230 J/m. Fire performance data provided shows that the UL94 V0 rating is comfortably achieved in the most demanding vertical flame test, recording an average burning time of only 3 seconds, 7 seconds less than the maximum allowable combustion time to meet the V0 rating, and 2 seconds less than the old EP-530 grade it replaces. The resin formulation of GMS EP-540 provides a high degree of processing versatility, with a range of cure cycles, pressures and ramp up rate options possible depending on the part being produced; the tack can also be varied. The curing cycle for GMS EP-540 can be as low as 80°C up to a maximum of 150°C.
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