Study On The Synthesis And Flame Retardant Properties Of Melamine-Based Flame Retardants

Melamine-based flame retardants have the advantages of free-halogen, low smoke, low toxicity, environmentally friendly and high flame retardant efficiency. They are widely used in many kinds of polymers. This paper synthesized two kinds of melamine-based flame retardant—melamine phthalates(POME) and melamine phytate(PHAM) using melamine, phthalic acid and phytate. This paper determined the preparation of POME and PHAM respectively. Melamine and phthalic acid react for 4 hours with the molar ratio of 1:1. Melamine and phytate react for 3 hours with the molar ratio of 2:1. The two reactions are all with water as solvent. The structure of the two products was characterized by infrared spectrum analysis(FTIR), nuclear magnetic resonance(1H-NMR, 31P-NMR) and elemental analysis(EA). The thermal properties of the products were analyzed by thermal gravimetric analysis(TG). The results showed that the target product was successfully synthesized, and two kinds of flame retardant were prepared to meet the processing properties of nylon 6(PA6) and poly(lactic acid)(PLA).PA6 is an important engineering plastics, it is widely used in various fields because of its good mechanical properties. But its poor flame retardant properties limited its application and development in the field of electronic electrical appliances and construction. The flame retardant modification of PA6 was carried out by POME. And then study the flame retardant properties, mechanical properties and thermal properties of the flame retarded PA6. The results showed that POME and its compound system could improve the flame retardant properties of PA6, but had a great influence on the mechanical properties, especially the elongation at break. When adding 7wt% of POME, the vertical burning level of flame retarded PA6 get to UL-94 V-0. Compared with the pure PA6, the tensile strength retained 83.6% and the impact strength retained 62.7%, while the elongation at break only retained 5.7%. The compound system of POME with melamine cyanurate(MCA) and melamine trithiocyanurate(MAS) can make the vertical combustion grade of PA6 up to UL-94 V-0, and the mechanical properties of the flame retarded PA6 also have different degrees of decline. But POME and its complex system does not promote the charring of PA6.PLA is one of the most important biodegradable plastics. It has good mechanical properties and recycling performance. It can be used in many fields instead of petroleum-based plastics. In order to make it better applied in the automotive, electronics, construction and other fields, it is necessary to carry on the flame retardant modification. PHAM respectively compound with sepiolite powder, zeolite powder, aluminum hypophosphite and calcium lignosulfonate, then applied to PLA. After that, study the flame retardant properties, mechanical properties and thermal properties of the flame retarded PLA. The results showed that the PHAM compound system can better improve the flame retardant property of PLA, and the addition of the compound system can still make the PLA to maintain good mechanical properties. Comprehensive comparison of the various properties of flame retardant PLA can be concluded that PHAM and zeolite powder mixture has the best effects, the sample of flame retarded PLA can reach UL-94 V-0 level(1.6mm). Compared with pure PLA, the tensile strength, elongation at break and impact strength retained 68.7%, 78.6% and 87.1%, respectively. Thermal decomposition temperature is increased and the residual mass at 700℃ increased by 5.33%.