Synthesis Of Bromine-containing Polymeric Flame Retardant And Its Application In Flame Resitant PET

Polyethylene terephthalate (PET) has been widely used as an important engineeringplastic in automobile, electronics, domestic applicance and machinery industry owing to itsfavorable mechanical properties, excellent heat resistance, chemical resistance andexcellent insulation property etc. However, the largest shortcoming of PET is poor flameretardant and its oxygen index is merely up to24. Moreover, there are serious molten dropsduring the combustion process. As a result, it is very practical to develop fire-resistant PET.In this paper, a bromine-containing polymeric flame retardant polypentabromobenzylacrylate (PPBBA) was successfully synthesized from pentabromotoluene. Theflame-retardant master batch (FR-PPBBAS) was prepared on an internal mixer with thesynthesized PPBBA and antimony trioxide at the mass ratio of3:1. The PET/FR-PPBBASblends were prepared by melt compounding, and the morphology, properties and thermaldecomposition dynamics of the blends were investigated.The main works and results were listed as following:The limited oxygen index of PET/FR-PPBBAS blends was improved obviously andthe molten drops decreased with the increasing flame retardant amounts. As compared withthe pure PET, the flame retardant grades of the blends were enhanced. The limited oxygenindex was up to30.5and it passed V-0rating without melt drip at10wt%flame retardantloading level. The SEM morphology of the impact-fractured PET/FR-PPBBAS blendssurface showed that the obvious phase separation phenomena were not observed at nomore than10%FR-PPBBAS amounts, indicating that FR-PPBBAS is partially compatiblewith PET. Meanwhile, the blends showed excellent flame retardancy without seriouslydeteriorating mechanical properties.The results of DMA test slowed that the storage modulus of PET/FR-PPBBAS blends increased with the increasing flame retardant amounts, which demonstrating that thestiffness of the blends was increased with the incorporation of the FR-PPBBAS. However，the glass transition temperature has almost no obvious change after the addition ofFR-PPBBAS.The melting and crystallization behaviors of the PET/FR-PPBBAS blends wereinvestigated using DSC. Both PET and its blends displayed similar melting curves, atwhich the melting peak at about250oC. However, the addition of the flame retardantimproved the degree of crystallinity. The non-isothermal crystallization temperaturesshifted toward low temperature with the incorporation of the flame retardant at the samecooling rate. The crystallization rate of the blends was faster than that of the pure PET.The dynamic rheology of PET/FR-PPBBAS blends was inverstigated using DynamicRotational Rheometer. It demonstrated that PET/FR-PPBBAS blends were pseudo plasticfluid and all specimens exhibited shear thinning behavior. With comparison to the purePET, the PET/FR-PPBBAS blends gave higher storage modulus and loss modulus. Theanalysis results from the Han method showed that the phase separation did not occur in theblends.The thermal decomposition kinetics of the PET/FR-PPBBAS blends was investigatedby TGA, and the activation energy of thermal decomposition was calculated usingFlynn-Wall-Ozawa method, Friedman-Reieh-Levi method and Kissinger method. Theactivation energy of thermal decomposition for the blends was far higher than that the purePET, indicating that the thermal stability of the blends was improved by the incorporationof the flame retardant.