Synthesis Of Hypophosphite Flame Retardants And Investigation Of Flame Retardant Nylon 6

Polyamide are important thermoplastics with a wide range of engineering applications, such as automobile, Electronic and Electric(E&E)aspects. However, PA6 is a flammable polymer with a low limiting oxygen index(LOI)value and severe dripping, resulting in its applications being restricted seriously. Therefore, how to improve the flame retardance of PA6 has become an important research topic.(1)Synthesised of a series of hypophosphites, including aluminum hypophosphite, magnesium hypophosphite, lanthanum hypophosphite, yttrium hypophosphite, praseodymium hypophosp-hite, cerium hypophosphite and melamine hypophosphite. The reaction products were characterized by FTIR and the phosphorus content test, the data of experiment showed that we obation the aim reaction products. TGA was used to characterized the reaction products, the data of experiment showed that hypophosphites were thermal stability and the thermal degradation temperature of hypophosphites were higher than the process temperature of PA6.(2)Hypophosphites were added to PA6 with different contents, tested the flame retardancy and mechanical properties of FR-PA6, the data showed that aluminum hypophosphite was the best flame retardant of hypophosphites to PA6. When the addition of aluminum hypophosphite was 18wt%, the LOI of composite was 25, composite reached UL94 V-0 level at 3.2mm thickness and had good mechanical properties.(3)The phosphorus content of aluminum hypophosphite and magnesium hypophosphite was almost same, but the flame retardancy of them was different. The TGA and DSC data showed that thermal degradation temperature of aluminum hypophosphite and PA6/aluminum hypophosphite was lower than that of magnesium hypophosphite and PA6/magnesium hypophosphite. The SEM and XPS were used to characterized the PA6/hypophosphite composites. The SEM result showed the morphological structure of the char residue containing aluminium displayed more homogenous and compact structure than the one containing magnesium, the char residue surface containing aluminium may effectively stop the transfer of heat and flammable volatiles. The XPS result showed the carbon content, oxygen content, phosphorus content on the char residue surface of PA6/aluminum hypophosphite were obviously higher than that of PA6/ magnesium hypophosphite. This result indicateed that aluminum hypophosphite can effectively promote the char formation of PA 6 during burning, resulting in a good flame retardancy.