Preparation of Magnesium Carbonate Trihydrate Fibers and Their Application in EVA
Magnesium carbonate trihydrate fibers were synthesized by co-precipitation method using magnesium sulfate heptahydrate(MgSO4·7H2O)and potassium carbonate(K2CO3)as raw materials and sodium dodecylbenzene sulfonate(SDBS)as structural guiding agent.EVA composites were prepared by melt blending using silane-modified magnesium carbonate trihydrate fiber as a flame retardant.The effects of modified magnesium carbonate trihydrate fibers on the mechanical properties,thermal stability and flame retardancy of EVA composites were investigated by means of a universal testing machine,a limiting oxygen index meter(LOI),a thermogravimetric analyzer(TG),and a cone calorimeter(CCT).The results show that at 40℃,the stirring rate is 350 r/min,the molar ratio of MgSO4·7H2O to K2CO3 is 3∶1,and the addition amount of SDBS is 3%of the theoretical production fiber mass,MgCO3·3H2O fibers with good dispersibility can be prepared.The mechanical properties of EVA can be significantly improved by MgCO3·3H2O fibers modified by silane coupling agent,and the tensile strength of the composites is increased to 13.7 MPa and the elongation at break is increased to 176%when the addition amount is 40%.The heat release rate and smoke release rate are greatly reduced to 231 kW/m2 and 0.029 m2/s,respectively.
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