The Study Of Synthesis Of Phosphonate Ester And Its Flame Retardancy In ABS Resin

The phosphonate esters are ones of important parts of organophosphorous flame retardants, some of them are free-halogen, high flame retardancy effectivity, low smoke and low toxicity to human beings, which accord with the today current of flame retardants. A novel flame retardant of phosphonate ester was synthesized with a new solvent and catalyst, and characterized by elementary analysis, FTIR, ~1H-NMR and thermogravimetric in this thesis. The phosphonate ester named by IUPAC is 2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane,3,9-dimethyl-,3,9-dioxide (DMDP). The results showed that the reaction time was decreased and the color of DMDP was little yellowy during 150℃～170℃.TG results under air showed that the weight loss was less than 2 percent at 260℃, and showed that DMDP had higher thermal stability.The application of the flame retardants DMDP and DMDP combined with melamine transition metal salts (melamine silicon tungstate, MSW; melamine phosphotungstate, MPW; melamine tungstate, MW) were investigated, and were compared with APP and MPP in ABS resin. A series of flame retardant ABS blends (FR-ABS) were manufactured and experiment data were obtained by means of some instruments such as a tensile machine, an impact machine, limit oxygen index instrument, thermogravimetry and so on. The studies clearly showed that the compound of DMDP and MSW had a higher efficiency, horizontal burning test reached UL94 V-2 with higher tensile property and lower impact property. When the compound ratio of DMDP and MSW was at 2:1, the flame retardant content was 30%, LOI of the FR-ABS had reached 25.4% and tensile strength was 35.72MPa, impact strength was 16.40 MPa.The mechanism of the flame retardancy and thermal degradation performance of DMDP and DMDP/MSW flame retarded ABS were studied on the base of the analysis TG-FTIR, Py-GC-MS and SEM. The TG results illustrated the residual ratio of FR-ABS was 16.74% at 600℃, but the pure ABS’s was only 1.88% at the same temperature, and the comparison of FTIR between pure ABS and FR-ABS showed DMDP and MSW had accelerated char formation. The initial degradation temperature of FR-ABS was reduced due to the decomposition of flame retardants before ABS to promote char formation, and air and heat conduction could be restrained by the char layer of the surface of flame retarded ABS, then the degradation of ABS was further resisted or delayed. The Py-GC-MS and SEM results also showed that DMDP and MSW had promoted char information. The main flame retarded mechanism is protective char layer in the condensed phase.The kinetics of the thermal oxidative degradation of DMDP and DMDP/MSW flame retarded ABS blends were investigated by non-isothermal thermogravimetric analysis. Kissinger method, Flynn-Wall-Ozawa method had been used to calculate the activation energies of ABS and FR-ABS degradation, and the values were 157.99kJ/mol, 163.23kJ/mol and 159.65kJ/mol (Kissinger method) respectively. The results showed that DMDP and MSW had a little influence on the thermal stability of FR-ABS.