Study On Flame Retardant Properties Of PP-Based Composites

Polypropylene?PP?is used in a wide range of applications,such as cars,textiles,electrical insulation,architectural materials,furniture,chemical corrosion resistance,interior decorations and so on due to its performance-cost ratio and excellent physicochemical properties.However,PP is inflammable,and may therefo re be dangerous closing to fire.It may also enhance the fire propagation due to its drip ping tendency during the combustion.Application of PP in many fields is severely limited due to its flammability and dripping behaviors.Thus,the flame retardancy of PP has to be improved.In order to improve the flame retardant property of polypropylene,antimony trioxide nanoparticles?nano-Sb₂O₃?,brominated epoxy resin?BEO?,brominated polystyrene?BPS?,silane-modified MMT?MMT?were used as additives.Nano-Sb₂O₃/BEO-PP,nano-Sb₂O₃/MMT/BEO-PP,nano-Sb₂O₃/BPS-PP and nano-Sb₂O₃/MMT/BPS-PP composites were prepared by melt blending after mixing by a high energy ball milling technique.Then,the crystallization performance,flame retardant performance,thermal stability and mechanical properties of composites were investigated.Furthermore,flame-retardant mechanism of experiment PP-based composites is analysed.The research achievement shows as follows:1.There is synergistic effect between modified nano-Sb₂O₃ and BEO.It can prolongs residence of the halogens in the flame zone,thus more hydroxyl and hydrogen radicals can be replaced by the bromine radicals.It is confirmed that 7 wt.%is the optimal loading of modified nano-Sb₂O₃ in the BEO-PP?21/72,wt./wt.?system,in which LOI value of nano-Sb₂O₃/BEO-PP was improved to 28.6%and reached V-0grade in UL-94 testing.2.The addition of MMT can not only improve the tensile strength of nano-Sb₂O₃/MMT/BEO-PP composites,but also improve the flame retardant performance by increasing the tensity of carbon layer.Incorporation of 13 wt.%BEO,7 wt.%modified nano-Sb₂O₃ and 7 wt.%silane-modified MMT within PP matrix resulted in a top in the thermal and flame retardance properties,The LOI value of nano-Sb₂O₃/MMT/BEO-PP composites is improved to 27.9%and the UL-94 testing reaches to V-0 grade.At the same flame retardant level?V-0?,the addition of MMT can reduce the useage of BEO.3.With the same flame retardant effect,the dosage of BPS is lower than BEO in PP matrix.The MMT fillers induce obsenvably improvement of crystallization property,tensile strength and flame retardant performance.The LOI increase from 26.9%?3.5%nano-Sb₂O₃/8%BPS-PP?to 29.0%?3.5%nano-Sb₂O₃/8%BPS-PP?in the presence of MMT and meets the UL-94V-0 standard.4.The addition of MMT and nano-Sb₂O₃ particles that resulted in heterogeneous nucleation crystallization of PP lead to increasing of the crystallinity and tensile strength.Therefore,PP based nanocomposites with both mechanical and flame retardant properties can be obtained.