Preparation And Performance Of Flame-retarded Rigid Polyurethane Foam With Acoustic Absorption Properties

With the development of society,more and more noise hinders people's normal life and even evolves into noise pollution.Noise can not only cause hearing damage,but also adversely affect reproductive ability and psychology.Therefore,noise control measures in our lives need to be implemented urgently.Open-cell rigid polyurethane foam is a very competitive acoustic absorption material for containing pore structure connected to external environment.However,polyurethane foam is a kind of flammable polymer material,so that the potential safety hazards in combustion cannot be ignored.The development of corresponding flame retardant technology is very necessary.This paper studied the influence of different factors on the synthesis,characterization and acoustic absorption of open-cell rigid polyurethane foam.The flame-retarded open-cell rigid polyurethane foam was prepared by introducing ammonium polyphosphate and diethyl ethylphosphonate and its flame retardant properties were explored.First,the preparation process of rigid polyurethane foam and the establishment of optimal parameters were studied.Synthesizing rigid polyurethane foam by one-step foaming method,the influence of factors such as polyisocyanate,polyether polyol,catalyst,foam stabilizer,cell opener,foaming agent,etc.on the performance of rigid polyurethane foam was studied.The experimental results showed that high polyisocyanate dosage could obtain dense and closed cell with a compressive strength of 239 k Pa.The increase in the amount of catalyst had different effects on the foaming reaction and the gel reaction.Non-silicon type cell opening agent had better pore opening effect than silicone type cell opening agent.When the dosage was 3 g,the water absorption rate of the foam produced by the non-silicon type cell opener was 7.67 %,while the silicone type cell opener was 4.44 %.Increasing the amount of water was beneficial to increase the open-cell structure of the foam.When the amount of water was 3 g,the water absorption rate of the foam reached 46 %,but the compressive strength foam dropped seriously.At the same time,standing wave tube method was used to determine the foam acoustic absorption coefficient,and the influence of the type of cell opener,foam water absorption and thickness on the foam sound absorption performance was investigated.The results showed that the foam made from non-siloxane type cell opening agent had better acoustic absorption ability than the foam made from silicone type cell opening agent in the frequency range of 2000 ?3000 Hz.The higher the water absorption rate of the foam,the better the sound absorption capacity.The increase in thickness was conducive to improving the sound absorption capacity of the foam,but the increase in volume may increase the cost.Based on comprehensive considerations,the basic formula of open cell rigid polyurethane foam with good sound absorption capacity was 75-80 parts by mass of polyisocyanate,50 parts by mass of polyether polyol,1 part by mass of catalyst,0.5 part by mass of foam stabilizer,2 parts by mass of cell opening agent,2 parts by mass of water.Then,using ammonium polyphosphate and diethyl ethyl phosphonate as flame retardants,flame-retarded rigid polyurethane foam was prepared by one-step foaming method.Tests like SEM,density,water absorption,compressive strength,standing wave tube test,thermal analysis,vertical burning test,limited oxygen index were conducted to investigate the effects of flame retardants on the foam's apparent morphology,mechanical properties,acoustic absorption properties and flame retardant properties.The experimental results showed that the addition of ammonium polyphosphate destroyed the flatness of the cell wall,while the addition of diethyl ethylphosphonate improved the morphology of the cells,and the influence of the two on the morphology of the foam was in a competitive relationship.When the addition amount of ammonium polyphosphate was 20 g,the average acoustic absorption coefficient of the foam in the frequency range of 125 ? 5000 Hz reached 0.535,and the sound absorption coefficient remained above 0.6 in the range greater than 1000 Hz,showing excellent acoustic absorption capacity.In the flame-retardant performance test,the flame-retardant system composed of ammonium polyphosphate and diethyl ethylphosphonate showed good flame-retardant performance,with a limiting oxygen index of 25 %,after flame time of less than 3 s and carbon residue over 80 %,reaching self-extinguishing and V-0 flame retardant grade.