Effect Of Inorganic Filler On The Flame Retardant Property Of The Nylon6/ Melamine Cyanurate Composites

Nylon 6(PA6) has the excellent property, which is widely used in modern industry,but the limiting oxygen index of PA6 is only 23%, limiting its applications in some areas. So it is important to modifyits flame retardany. Halogen flame retardant is the most important flame retardant. but in burning process it will release a lot of toxic flue gas, which is not conducive to the protection of environment, so non-halogen flame retardant has become an inevitable trend, one of the non-halogenflame retardants is melamine cyanurate(MCA), because it is non-toxic, it has high nitrogen content and good flame retardant property, it iswidely applied in the PA6. And in order to improve the dimensional stability and heat distortion temperature of PA6, and reduce the cost in some extent, so the inorganic fillers are filled. Due to the PA6 has the poor dimensional stability and processing performance.In the practical application, the inorganic filler is generally filled with PA6. However, inorganic fillers have a certain influence on the property of materials, such as slowing the drop speed, reducing the amount of smoke, so it has an important significance for practical application to study the effectof inorganic fillers on the flame retardant of PA6/MCAsystem.In this paper, the four fillers which included talc, wollastonite, calcium carbonate and montmorillonite were added to PA6/MCA. The PA6/MCA, PA6/MCA/talc, PA6/MCA/wollastonite, PA6/MCA/calciumcarbonate and PA6/MCA/montmorillonite composites were prepared. The fire-retardant properties(limiting oxygen index, vertical, glow-wire test), the mechanical properties(tensile strength, Izod impact strength) and thermal properties(thermal testing, thermal deformation temperature) and micro-topography were tested, based on the above analysis of testing methods, the results are as follows:(1) Talc, wollastonite, calcium carbonate and montmorillonite were added to the PA6/MCA, the composite of stretch strength and impact strength has reduced when the calcium carbonate was added. Talc, wollastoniteand montmorillonite were added to the PA6/MCA, the composite of stretch strength and impact strength has reduced, but with content of fillers were increased, the composite of stretch strength and impact strength has improved, when the content of talc, wollastoniteand montmorillonite were 20wt%, 20wt% and 5wt%, the tensile strength and impact strength increased up to a maximum, which was the optimal mechanical properties. At the same time, the composite of vertical flame grade can be reached V-0.(2) The vertical flame gradeabove V-0 and the optimal mechanical properties of composite materials were selected, which were composites when the content of talc, wollastonite and montmorillonite were 20wt%, 20wt% and 5wt%. Comparing this materials with PA6/MCA in other macro-properties, the results were as follows:The limiting oxygen index and heat distortion temperature of these composites were improved when added talc, wollastonite and montmorillonite, especially the use of montmorillonite. The limiting oxygen index and heat distortion temperature for composites compared with the PA6/MCA, has greatly improved, by 18% and 9.6%. In addition, the water absorption of these composites with the three kinds of fillers was decreased.The research on the glow-wire test shows, PA6/MCA/wollastonite, PA6/MCA/montmorillonite composites can pass 850℃tests.In summary, to synthesize the results of mechanical properties and flame retardance performance analysis, when the content of wollastonite and montmorillonite were 20wt% and 5wt%, respectively, the PA6/MCA composite had the optimal performance.(3) The infrared spectroscopy test shows that, the wollastonite composite in 452 cm-1,there is a clear Si-O stretching vibration peak, Si-O-C stretching vibrations at 1015cm-1; 667-730cm-1 found in the PA6/MCA/montmorillonite composite,it is the characteristic absorption peak of Al2O3, 1015cm-1 is the Si-O-C stretching vibrations, suggesting the SiO2 is existed in the surface of PA6/MCA/wollastonite, PA6/MCA/montmorillonite composites after combustion. In addition, the Al2O3 was found in the surface of PA6 / MCA / montmorillonite composites after combustion.(4) From the scanning electron microscopy test, the surface morphology of the residue about PA6/MCA/wollastonite and PA6/MCA/montmorillonite composites were discussed, the surface morphology of the residue about PA6/MCA/montmorillonite composites after combustion was smooth and uniform, dense carbon layer,which was consistent with the results that were measured in flame retardant properties tests.(5) From the TG test about PA6/MCA, PA6/MCA/wollastonite and PA6/MCA/montmorillonite composites, the decomposition temperature of the composite were decreased, the carbon yield were increased when added wollastonite and montmorillonite in PA6/MCA, for PA6/MCA/montmorillonite composites, the decomposition temperature of the compositewas decreased 14℃, the carbon yield of the composite was increased 16.7%.(6)From the cone calorimeter analysis, it showed that peak heat release rate(PHRR) corresponding times about PA6/MCA, PA6/MCA/wollastonite and PA6/MCA/montmorillonite composites were retardation. And the THR of PA6/MCA/wollastonite and PA6/MCA/montmorillonite composites were decreased. For the PA6/MCA/montmorillonite composite,the THR of PA6/MCA/montmorillonite composite suffered the largest decline, which is declined to 33%.