Application Research Of Halogen-free Compound Flame Retardant In Natural Rubber

With the increasing awareness of safety and environmental protection,improving the flame retardant properties of natural rubber(NR)has received extensive attention.Traditional halogen flame retardants have problems of toxicity and environmental pollution.The emergence of halogen-free flame retardants has opened up a new way for the development of environmentally friendly flame retardant materials.Therefore,it is of great practical value to research and develop an efficient flame-retardant and green NR composite material.From the perspective of compounding,this paper aims to obtain a flame retardant,which can not only ensure the flame retardant properties of NR,but also take into account the mechanical properties of NR,and is committed to successful application in practical production.The main research contents are as follows:Research on the application of phosphorus-nitrogen flame retardants in natural rubber.Melamine polyphosphate(MPP)was compounded with pentaerythritol(PER)and guanidine sulfamate(GAS)into NR,respectively,to prepare flame-retardant NR composites.Effects of flame retardancy,thermal stability,and mechanical properties of NR composites.The results show that the optimal compounding ratio of MPP/PER is 3/1,and the optimal compounding ratio of MPP/GAS is 1/3.Under the optimal compounding ratio,as the dosage of MPP/PER and MPP/GAS increases,The flame retardant properties and thermal stability of MPP/PER/NR composites and MPP/GAS/NR composites were significantly improved,the heat release rate(HRR),total heat release(THR)and total smoke generation(TSP)is significantly reduced,greatly reducing the fire hazard.When the addition amount of MPP/PER is 60 phr,the LOI of MPP/PER/NR composites can reach 26.8%,the carbon residue content can reach 15.82%,the PHRR can be reduced by 48.1%,and the THR can be reduced by 17.2%.When the addition amount of MPP/GAS is 60 phr,the LOI of MPP/GAS/NR composites can reach 26.2%,the carbon residue content can reach 12.42%,the PHRR can be reduced by 31%,and the THR can be reduced by 14.4%.The flame retardant mechanism of MPP/PER and MPP/GAS composite systems is basically the same.Both of them promote the formation of the expanded carbon layer during combustion,and then insulate the external oxygen and heat,thus playing a good protective role on the NR.The two compounding systems have a certain negative impact on the mechanical properties of NR composites.In practical production applications,the comprehensive properties of NR composites should be fully considered,and the amount of flame retardant should be reasonably selected.Research on the application of inorganic additive flame retardants in natural rubber.Magnesium hydroxide(MH)was compounded with carbon black(N330),white carbon black(Si O₂),and zinc borate(ZB)into natural rubber to prepare flame-retardant natural rubber composite materials.MH,MH/N330 were studied.MH/Si O₂,MH/ZB compound system on the flame retardant properties,mechanical properties,thermal stability properties of natural rubber composites.The results show that the MH/N330,MH/Si O₂ and MH/ZB compound systems can effectively improve the flame retardancy,thermal stability and thermal oxygen aging performance of NR composites,and reduce the heat and smoke release during the combustion process.Improve the fire safety of NR.Among them,the three compound systems have their own characteristics.The N330/MH compound system has the best processing performance and mechanical reinforcement effect,the Si O₂/MH compound system has the best thermal oxygen aging effect,and the MH/ZB compound system has the best effect of thermal oxidation aging.Best flame retardant and thermal stability.In actual production and application,the type and amount of MH compound flame retardant can be reasonably selected according to the use conditions and performance requirements of the product.Study on application of mixed flame retardants in natural rubber.The flame retardant NR composites were prepared by adding TGD,DMMP,EG and ATH into NR.The effects of TGD/DMMP/ATH/EG on the flame retardant properties,thermal stability and mechanical properties of NR composites were studied.The results show that TGD/DMMP/EG/ATH can effectively improve the thermal stability and flame retardant performance of NR composites,and reduce the HRR,THR,TSP and SPR during combustion,and effectively reduce the fire risk.When the amount of TGD/DMMP/EG/ATH is 60phr,the LOI of NR composite can reach 28.4%and the carbon residue can reach 25.61%,PHRR was reduced by 95%and THR by 21%.TGD/DMMP/EG/ATH can form vermicular carbon layer in the combustion process,which can realize the flame barrier effect and achieve a good flame retardant effect.The negative effects of TGD/DMMP/EG/ATH on mechanical properties of NR composites are not great.When the addition amount of TGD/DMMP/EG/ATH is 30phr,the tensile strength and elongation at break of NR composites are 19.9MPa and 569%,respectively,and the Shore A hardness is 42.In practical production and application,the dosage of flame retardant can be reasonably selected according to the use conditions and performance requirements.