Preparation And Performance Of Urea-formaldehyde Resin Foam Insulation Material By Microwave Radiation

It is an important way to realize building energy-saving to adopt thermal insulation wall with good thermal insulation performance for building thermal insulation materials.Because of its low thermal conductivity,light weight,good thermal insulation effect and convenient construction,foam materials have been widely used in building thermal insulation materials.At present,polyurethane foam and polystyrene foam commonly used in building thermal insulation system are easy to burn,and produce droplets in the process of burning,and release a large amount of heat and toxic smoke,which seriously threatens the safety of human beings.In recent years,flame-retardant thermosetting resin foam has become a hot research topic of thermal insulation materials.Phenolic resin foam has good flame retardance,but its high production cost limits its application.Urea-formaldehyde resin foam,which is also a thermosetting resin foam,has more development potential and application prospect due to its outstanding price advantage.In this paper,urea-formaldehyde resin foam was prepared by microwave radiation heating method,which is different from conventional foaming method.The optimum process and foaming mechanism of urea-formaldehyde resin foam prepared by microwave radiation method were discussed.The results showed that the comprehensive properties of the foam were best when the microwave radiation power was 100%and the radiation time was 1 min 15 s～1 min 20 s.The apparent density was between 0.072 and 0.076 g/cm3,the compressive strength was between 180 and 240 kpa,the pulverization rate was about 15%,the thermal weight loss occurred mainly at about 270 ℃,and the final residual amount was 18.6%.Oxygen index is greater than 34%.The thermal conductivity is about 0.021 W/(m K)and the thermal insulation performance is good.The effects of foaming agent and surfactant on the properties of urea,formaldehyde resin foam were studied.the results showed that with the increase of n-hexane content,the foaming ratio,apparent density,mechanical strength and pulverization rate of urea-formaldehyde resin foam increased.The addition of Arabic gum on the basis of surfactant tween-80 can improve the pulverization rate and thermal stability of the foam.On this basis,in view of the characteristics of high pulverization rate and low strength of urea-formaldehyde resin foam.PVA,PEG and montmorillonite were selected to toughen and strengthen the foam composites.It was found that the best modification effect was obtained by adding 1.5 wt%PVA.The strength is increased by about 1.2 times,the pulverization rate is reduced by about 18%,meanwhile,the cellular structure of the urea-formaldehyde resin foam is improved,and the closed-cell rate of the foam is improved.But reduces the flame retardancy of the foam material.The modification effect of PEG 400 was better than that of PEG2000.When the content of urea-formaldehyde resin foam was 1.5wt%,the compressive strength of urea-formaldehyde resin foam was increased by 1.02 times,and the pulverization rate was decreased by 29%.And the introduction of PEG improved the combustion performance of the foam,and the oxygen index was between 33.6～34.7%.The flame retardancy,thermal stability and mechanical strength of urea-formaldehyde resin foam were improved by montmorillonite intercalation modification.Dk-1N montmorillonite had the best modification effect,and the best addition was 0.7wt%.