Synthesis Of THEIC-MAH Charring Agent And Its Application In Improving The Flame Retardancy Of Polypropylene

In recent years, the demand of nontoxic and environmental friendly flame retardants increases rapidly. Intumescent flame retardant (IFR) has drawn more and more attentions in recent years due to its environmental characters, such as low smoke, non-production of toxic gases and corrosive fume. Its flame retardant mechanism is based on the foamed char layer acting as physical barrier to slow down mass and heat transfer between the gas and condense phase. Normally, a typical IFR is consist of three ingredients, an acid source, usually ammonium polyphosphate (APP), a charring agent usually pentaerythritol (PER), and a foaming agent, usually melamine. However, PER has some drawbacks when it is used as charring agent, such as low molecular weight, easy migration to the surface of matrix and poor water resistance.In this paper, a novel charring agent named MT was synthesized by THEIC and MAH, and charactered by FTIR,1H NMR and elemental analysis. An intumescent flame retardant (IFR) system containing ammonium polyphosphate (APP) and MT was used to enhance the flame retardant behavior of polypropylene (PP). The combustion properties and thermal stability of PP/IFR composites were evaluated by UL-94 burning test, limiting oxygen index (LOI), cone calorimeter test and thermogravimetric analysis (TGA). Results show that 30 wt.% IFR increase LOI value from 17.4% to 35.2% and increases char residue at high temperature.Attapulgite and ZnO as synergist agents were used to enhance the flame retardant behavior of PP. The combustion properties and thermal stability of PP/IFR/ATP and PP/IFR/ZnO composites were evaluated by UL-94 burning test, limiting oxygen index (LOI), cone calorimeter test and thermogravimetric analysis (TGA). Results show that 5.0 wt.% ATP loading in IFR increases LOI value from 32.0% to 38.0% and 1.5% ZnO loading in IFR increases LOI value from 32.0% to 35.9%, and both of them increase char residue at high temperature.The synergistic effect between the synergistic agent and IFR was investigated through TGA, scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) analysis of the residual char.