Synthesis Of Triazine Ring Containing Nitrogen-Phosphorus Flame Retardants And Its Modified Inherent Flame-retardant Polyamide 66

Polyamide 66(PA66) possess excellent comprehensive performance, which was mainly used in electronic, instrumentation, automotive, aerospace and other industries as one of the most widely engineering plastics. However, applications of PA66 products were confined by its flammability and poor thermal stability. Therefore it is necessary to improve their flame retardancy to meet the industrial safety standards. In general, additive materials were used for achieving flame retardancy and thermal stability in polymers. Nevertheless, there was a variety of problems such as poor compatibility, leaching, and deterioration in the mechanical properties of composites. This article revolves around the synthesis of containing P-N reactive flame retardant and its modified inherent flame-retardant PA66. The modification approach was the effective way because it covalently incorporates the flame retardant unit in the polymer backbone and thus imparts permanent flame retardancy.(1) A novel Nitrogen- Phosphorus flame retardants containing triazine ring, 2- dimethyl phosphonate-4,6-aminobenzoic acid- sym-triazine(DPTPO) was synthesized by reaction with cyanuric chloride(TCT), trimethyl phosphate(TMP) and 1,4-aminobenzoic acid(PABA),and the optimum synthetic process was determined. The chemical structure and composition of DPTPO was characterized and confirmed by NMR, FTIR and elemental analysis. The TGA results show that the initial thermal decomposition temperature of DPTPO was 260? and this does not cause decomposition of flame retardants when the DPTPO was introduced into the macromolecular chains of PA66. Carbon residue rate as high as 22% when the temperature was 700 ?.(2) The inherent flame-retardant polyamide 66(IFR-PA66) was prepared through acylation and polycondensation of polyamide 66 salt(PA66 salt) and flame retardant salt(DPTPO salt). It can be inferred that the DPTPO was embedded on the PA66 macromolecular structure by NMR, FTIR. The phosphorus content of IFR-PA66 was measured by spectrophotometric method, the results show that the phosphorus content was 0.646% close to the theory of phosphorus content when 7 wt% of DPTPO salt content was introduced PA66.(3) The comprehensive flame retardant properties of IFR-PA66 results show that the LOI values and UL-94 increase with increasing of DPTPO content, and the highest reached 30.2 and V-0 level. The values of THR, HRR, SPR and TSR of the IFR-PA66 samples were less than that of pure polyamide 66. There was fallen by 34.8%, 26%, 55% and 38.6%, respectively. The thermal behavior of IFR-PA66 was investigated by DSC and TGA measurements. The DSC results showed that the introduction of DPTPO would lower the melting temperature and the crystallinity of IFR-PA66. TGA results indicated that IFR-PA66 possessed significant thermal stability and high char yield compared with neat PA66. The mechanical properties of the IFR-PA66 were tested, It can be seen that the introduction of PDPPD have negligible effect on the mechanical properties of PA66.