Flame Retardant Modification Of Polyformaldehyde

Polyoxymethylene(POM) is a kind of engineering plastic with excellentperformance. Its soft chain and regular conformation lead POM to high crystallinity(approximately70%～85%). High density and high crystallinity make POM havemany excellent properties, such as high modulus, high hardness, good dimensionalstability, creep resistance, fatigue resistance, low water absorption rate, the goodself-lubricating, wide range of temperature (-40℃～+120℃).With the POMapplication domain expands increasingly, every aspect of its performance requireshigher and higher. As the oxygen index of POM is14.9%, it is easy to burn with meltdripping. Obviously, POM can not achieve the demand of the field which requiresthe high property of flame retardant. And this limits the application range of POM,so POM needs to be flame retardant modified.It studied about the effect of single flame retardant and intumescent flameretardant on the flame retardant POM modification. It was found that single flameretardant is unsatisfactory. POM would burn unless a large number of single flameretardant added. The intumescent flame retardant with thermoplastic elastomerpolyurethane (PUR-T) that possesses good compatibility with POM as carbon source,using melamine cyanurate (MCA) as gas source, flame retardant ammoniumpolyphosphate (APP) and red phosphorus as acid source, and studied the effect ofintumescent flame retardant on the properties of POM. Based on the flame retardant,we modified the POM to improve its mechanical properties. Experiments show that,with the red phosphorus as acid source, polyurethane (PUR-T) as carbon source,melamine (MCA) as gas source condition, POM/red phosphorus/PUR-T/MCAmass ratio was70/20/5/5, it reached the inflaming retarding effect. The flameretardant POM,its melt index was2.47g/10min, the tensile strength was36.15Mpa,elongation at break was7.52%, the notched impact strength was1.89KJ/m2, flexuralstrength was53.05MPa. Adding diffrent compatibilizer to the flame retardant set of optimal, the addition of compatibilizer KT-3was the best, both the tensile strengthand bending strength had greatly improved. In the best of compatibility groups withdifferent mass ratio of glass fiber, after verification, the comprehensive mechanicalproperties of POM adding5%glass fiber components improved. Then addingPUR-T and KT-28A to the best group of enhanced modification, the group with5%KT-28A component obtain good mechanical property. Although tensile strengthreduced some, the other properties loose to a minimum. And in the modificationgprocess of mechanical properties of POM, there was no loss of flame retardant. Thiskind of POM has great market value.