Effect of Organo-Modified Nanosepiolite on Fire Behaviors and Mechanical Performance of Polypropylene Composites

The objective of the study was to investigate the effect of the organo-modified nanosepiolite(ONSep)on improving the fire safety of polypropylene(PP).The composites based on PP,flame retardant master batch(MB-FR,25 wt%PP+50 wt%decabromodiphenyl ether(DBDPE)+25%antimony trioxide(ATO))and ONSep were prepared via melt blending.The results of the limiting oxygen index(LOI)and vertical burning rating(UL-94)test indicated that PP/40 wt%MB composites had no rating with seriously dripping phenomenon,while the LOI value was only 22.5.However,as 4 wt%ONSep was added in PP/40 wt%MB composites,the composites achieved UL94 V-0 rating and the LOI value was 24.3.In comparison,PP/50 wt%MB composites could not reach the V-0 rating either.The TGA results revealed that the addition of ONSep enhanced the thermal stability of the PP/MB-FR composites.The cone calorimeter results indicated that the heat release rate,average mass loss rate,smoke production rate and smoke temperature of the PP/40 wt%MB-FR/4 wt%ONSep composites decreased in comparison with those of PP/40 wt%MB-FR composites.Simultaneously,the Young modulus and impact strength were also much better improved with the increase of ONSep loading.Therefore,the synergistic flame retardancy of ONSep in PP/MB-FR matrix significantly containing a halogen based flame retardant(DBDPE)significantly improved the fire safety and mechanical properties of the composites,and allowed to decrease the total amount of brominated fire retardants.