Preparation and properties of R-PP/BM/SEP composites
Recycled polypropylene(R-PP)waste plastics were used as raw materials and sepiolite(SEP)and boehmite(BM)as flame retardants to prepare R-PP/BM/SEP composites via melt extrusion.The limiting oxygen index(LOI),upright combustion grade of UL94 and mechanical properties of the composites were measured and analyzed.The results show that when the mass fraction of BM is 25%,the LOI of the composites is increased to 26.9%,the flame retardancy of the sample whose thickness is 3.2 mm reaches UL 94 V-1,the temperature at the mass loss of 5%(t5%),the temperature at the mass loss of maximum(tmax)and carbon residue are increased correspondingly.SEP and BM have synergistic flame retardant effect in R-PP.When the mass fraction of SEP and BM are 3%and 22%,the LOI of the composites is 31.4%,and the flame retardability of the composites reach UL 94 3.2 mm V-0 and 2.0 mm V-1,whose heat release rate peak,average heat release rate,total heat release and total smoke production are lower than those of R-PP/BM with the mass fraction of 25%of BM,whose ignition time,fire performance indexes,t5%,tmax and carbon residue are higher than those with the mass fraction of 25%of BM.SEP can improve the mechanical properties of R-PP/BM.
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