Preparation And Properties Of Flexible Polyurethane Foam With Synergistic Flame Retarded By Graphene And DOPO

Flexible polyurethane foam(FPUF)has been widely used in cushion material,fabric composite material,sound-absorbing material and other fields due to its low density,good resilience and sound absorption properties.The seat cushion in the cabin is made of polyurethane flexible foam.However,the oxygen index of FPUF is very low(only about 18%),it is flammable in the air,and a large number of toxic gases and smoke are released during combustion,which is of great fire hazard.More and more attention has been paid to the flame retardant technology of polyurethane flexible foam.With the continuous enhancement of people's awareness of environmental protection and the improvement of environmental protection laws and regulations,the halogen-free and environmental protection of flame retardant has become a research hotspot.This thesis is supported by the general program "Preparation and research of DOPO/graphene composite flame retardant(J2018-7)" of Civil Aviation Flight University of China.In order to reduce the fire hazard and smoke production of FPUF and reduce the loss of life and property caused by the fire,two kinds of flame retardants,DOPO and graphene,were selected.The foaming formula of FPUF with different amount of flame retardant was designed.And through oxygen index,smoke density,flue gas analysis,thermogravimetric analysis,cone calorimetric analysis,carbon residue analysis and other testing and characterization methods.The flame retardant effect of DOPO and graphene on FPUF was systematically investigated,and the flame retardant mechanism was also discussed.The main work of this thesis is that DOPO,graphene,DOPO and graphene were added to FPUF to prepare flame retardant FPUF composite,and the physical properties,thermal stability,micro-morphology and combustion performance of the composite were studied.The main conclusions are as follows:(1)DOPO flame retardant can significantly improve the oxygen index of FPUF,while graphene cannot significantly improve the oxygen index of FPUF.DOPO cannot reduce the CO production,and graphene can effectively reduce CO production during the FPUF combustion process.(2)DOPO and graphene can improve the thermal stability of FPUF and increase the initial decomposition temperature of FPUF.(3)Both DOPO and graphene can improve the char yield of FPUF after combustion.When DOPO content is 4wt%,the carbon residue rate is the highest,and the carbon residue rate of FPUF increased with the increase of graphene content.(4)DOPO can play an important role in the gas phase and condensed phase simultaneously during the combustion of FPUF.Graphene mainly plays the role of condensed phase flame retardant by means of forming a dense carbonization protection layer on the surface of FPUF.It has good flame retardant effect.There is a synergistic flame retardant effect between graphene and DOPO in FPUF system.