Synthesis Of Aromatic Diphosphate And Investigation Of Flame Retardancy In ABS Resin

Two aromatic diphosphates , which are tetra-(2,6-dimethy phenyl) resorcinol diphosphate(DMP-RDP) and tetra-(2,6-dimethy phenyl) hydroquinone diphosphate (DMP-HDP), were synthesized and characterized by FTIR and 1H-NMR in this thesis. Some factors affecting the reaction, such as dropping temperature and time, reaction temperature and time , catalyst, the ratio of reaction system and the like were investigated. The two diphosphates and RDP (resorcinol diphenyl diphosphate), which are very important phosphorus-containing flame retardants (PFRs) exhibiting higher evaporation temperature, were added to ABS or ABS/PC. But, the aromatic diphosphates are not so efficient flame retardants for no-charrable polymers like ABS as to for charrable plastics like ABS/PC according LOI results. Because, on the one hand, in condensed phase, they cannot be involved in charring process, on the other hand, in gase phase, they cannot act as radical scavengers due to their high evaporation temperature. Novolac phenol resin(NP), which can create char at high temperature, was incorporated into PFRs as co-flame retardants to investigate whether the synergistic effect could be observed on the flame retardancy of ABS. For this purpose, a series of ABS/PFR/NP compounds were manufactured and experiment datas were obtained by means of all kinds of instruments such as a tensile machine, an impact test machine, thermogravimetry analysis(TGA), limit oxygen index(LOI) instrument and so on. The highest LOI is obtained in the system, in which the portion of ABS/PFR/NP is 75:20:5. TGA results under pure nitrogen showed that the flame retardants reduced the initial temperature of thermal degradation of ABS and promoted crosslinking and char formation compared with control sample, especially in the portion of ABS/PFR/NP=75:20:5, the LOI obtained is increased awfully. The reason for this founding was believed to be originated from the crosslinking reaction between -OH of NP and -OH from the combustion of PFRs. It has been reported that PFRs themselves generates phosphoric acids during thermal degradation and the reaction among phosphoric acids generated takes place and gives a birth to pyro phosphoric. The effect of different PFRs on the flame retardancy and mechanicalperformance of the compounds is also discussed. The results showed the mechanical properties are decreased in flame-retarded polymers. The TGA results demonstrate that the more stable the char generated is in high temperature, the better flame retardancy obtained.