Study On Properties And Mechanism Of EVA Chemical Intumescent Flame Retardant

In this paper, according to chemical intumescent flame retardant mechanism, EVA flameretardant composites were designed. The effect of flame retardant and its content on flameretardant properties, mechanical properties and rheological behaviors were studied. Thestructure of charry layer and intumescent layer were studied by OL and SEM. At the sametime, the analysis of FT-IR and TG for flame mechanism was investigated. The main resultswere obtained as follows:As air source in EVA/MCA system, LOI and the grade of Vertical burning wereimproved with incorporation of MCA. When MCA were80phr, LOI reached25%, and comeup to FV-0by Vertical burning test. It became difficult burning materials. Breaking strength,toughness and rheological behaviors of system were reduced with incorporation of MCA. Butthe yield strength of composites were improved. By the analysis of OL and SEM, the imagesindicated that charred layers appeared more compact with increasing addition of MCA. Also,it was found that the apertures of EVA/MCA system were increased, and the dimension of theaperture was larger with more addition of MCA. It means that MCA was an effective airsource, and it enhanced the charry content.As double air source in EVA/MH/MCA system, the addition of MCA reduced LOI alittle. The grade of Vertical burning improved with incorporation of MCA. It also reformedthe mechanical properties and rheological behaviors of EVA/MH system. The analysis fromOL had proved that MH and MCA as double air source had synergy greatly. The SEM imagesindicated that charred layers appeared more compact with increasing addition of MCA. Fromthe analysis of TG, it found that MCA and MH improved the heat stability properties, andincreased the content of residual char.In EVA/MCA/APP system, MCA as air source and APP as acid source were flame retar-dant. LOI and the grade of Vertical burning were improved with incorporation of APP. Also,Toughness and modulus of the composites were enhanced. Rheological behaviors werereduced. By the analysis of OL and SEM had proved that APP as acid source make charrylayer with greatly obstruct efficiency, and MCA was finer air source. By the analysis from FT-IR, it was found that ester of composites turned to dehydration when the system wasburning. Through the burning test, it found that the color of char layer became hoariness frombrown, then black with more addition APP in system. It means that APP improved thecapability of charry in EVA/MCA/APP system.Comparing with other systems, it was found that EVA/MCA/APP system has greatflame retardant properties.