Study On The Preparation And Performance Of Flame-retardant Rigid Polyurethane Foam

Economic development promotes energy consumption,and the development of building energy-saving and heat-insulating materials is an important part of promoting national energy-saving and emission reduction measures.Rigid polyurethane foam(RPUF)is widely used as a high-performance polymer material in the field of heat-insulating materials.However,RPUF is flammable and emits toxic gases when burned,which may cause fire and casualties.It is important to develop RPUF with flame retardant properties.Ammonium polyphosphate(APP)is widely used due to its high phosphorus and nitrogen content and low cost.However,as an inorganic phosphorus flame retardant,APP still has the disadvantages of easy moisture absorption and poor compatibility with pol ymer materials.To solve this problem,this article adopts a silane coupling agent to modify APP and explores the modification process conditions.At the same time,the application of modified APP and APP compounded flame retardant system in flame retardan t RPUF and the effect on RPUF performance were studied.The specific work is as follows:(1)Using a silane coupling agent(KH550)to modify APP(MAPP)and exploring the modification process factors.It was found that the solubility of MAPP decreased with the increase of reaction temperature;It was found that the increase of reaction temperature increased the solubility of MAPP;when the system p H=4,the solubility of MAPP was lower;the amount of KH550 added was 6wt%,the reaction time was 1h and 6h,and the solubility of MAPP also showed a relatively small value.The modification conditions were as follows:the reaction temperature was 70°C,the reaction p H was 4.0,the amount of KH550 was 6wt%,and the reaction time was 1h.The SEM-EDS,FTIR,particle size and thermal stability of the obtained MAPP were analyzed.(2)The effects of different APP and MAPP content on the density,mechanical properties,flame retardancy and thermal stability of flame-retardant RPUF were studied.It was found that with the increase of flame retardant,RPUF cells first decreased and then increased,and the corresponding core density,compressive strength and elastic modulus of RPUF increased first and then decreased.With the increase of flame retardant,the LOI of RPUF also inc reased,the flame retardant of RPUF was increased.But when the addition of flame retardant was 25 wt%,the HRR of RPUF/MAPP and RPUF/APP was the lowest,W hen the flame retardant was More than 25wt%,the HRR of flame retardant RPUF was increased.In addition,the thermal stability of RPUF/MAPP at high temperature was better than that of RPUF/APP.From the comprehensive results,the modified MAPP was more prominent in RPUF flame retardancy.(3)The classic APP/MEL/PER expansion system and APP/MEL/PEPA were to flame retardant RPUF.It was shown that with the increase of flame retardant,RPUF cell decreased,the apparent core density,compressive strength and compressive elastic modulus increased.Compared with RPUF/APP/MEL/PER flame retardant system,RPUF/APP/MEL/PEPA had better flame-retardant performance,which was mainly reflected in higher LOI value,faster p HRR reduction,and the lowest p HRR value was 49.875 k W/m~2 when added 30wt%flame retardant,and the thermal stability was also better.In addition,compared with RPUF/APP system,the two combined RPUF flame retardant combustion residues were denser and more beneficial to foam flame retardant.