Synthesis Of THEIC-based Charring Agent And Its Flame Retardancy Properties For Polylactide

Due to the environmental-friendly property of polylactide,it is very appropriate to employ intumescent flame retardant to improve its flame retardancy,which has the advantages of little smoke and low toxicity.But the conventional IFR system exhibits high loading,poor dispersion and low flame retardant efficiency.So adopting new method and exploring better intumescent flame retardant is very significant for the application and development of polylactide.In this paper,two macromolecular charring agents were synthesized based on THEIC and its derivative.The different formula and synergistic systems have been studied.Their flame retardancy and combustion properties were investigated through LOI,UL-94 and cone calorimetry tests,and their thermostability were analyzed by TG.The structure and morphology of char layers were studied by FTIR,XPS and SEM,and the flame retardant mechanism was deduced accordingly.The main research contents are summarized as follows:(1)A novel intumescent flame retardant TPM was synthesized by using THEIC,PPA and MEL as raw materials,and its structure was characterized by FTIR,1H NMR and 31P NMR.It was found that PLA with 25wt%APP/TPM(0.5:1)achieved LOI 36.5%and reached UL-94 V-0 rating without melt dripping.(2)A macromolecular charring agent CT was synthesized by TGIC.It was found that the LOI for PLA with 30wt%APP/CT(4:1)and 25wt%APP/CT/EP(4:1:1)were 41.2%and 39.8%respectively,and the both could achieve UL-94 V-0 rating without melt dripping.(3)The synergistic effect of AHP to IFR1(APP/THEIC=4:1)and IFR2(APP/CT=4:1)on the flame retardancy of PLA was discussed contrastively.It was found that PLA with 25wt%IFR1/AHP or IFR2/AHP could achieve the best flame retardancy just as the ratio was 3:1,and the latter was more efficient than the fomer.