Study On Modification Of Rigid Melamine Foam By Long-chain Diols Modifier

Rigid melamine foam contains a large number of rigid three azine rings,making it have good flame retardancy and thermal stability.However,it has many shortcomings such as pulverization rate and poor toughness.It has many limitations in the application of external wall insulation,cold storage and other fields.In this paper,the modified melamine foam with good properties was prepared by modifying the molecular structure of melamine resin prepolymer with long-chain diols and blending with foaming formula and process.The main research contents are as follows1)In the synthesis stage of prepolymer,long-chain diols modifier(1,5-pentanediol,1,6-hexanediol,1,8-octanediol)was introduced to study the effects of its type and dosage on the properties of prepolymer and modified melamine resin.The storage stability of the prepolymer was improved by the modification of long-chain diols.The addition of long-chain diols increased the impact strength,but decreased the bending strength of melamine resin.With the increase of alkyl chain length of long-chain diols,the bending strength decreased first and then increased,while the impact strength increased first and then decreased.With the increase of the amount of long-chain diols modifier,the impact strength of melamine resin increased first and then decreased.When the amount of modifier was 15wt%,the impact strength of melamine resin was better.2)Based on 15wt%long-chain diols modified melamine prepolymer,modified melamine foam was prepared.The water absorption,compressive strength,flexural strength,pulverization rate,closed-cell ratio and limiting oxygen index of the melamine foam modified by long-chain diols were better than those of the non modified system.Among them,the 1,5-pentanediol modified melamine foam has better comprehensive properties,such as the water absorption,compressive strength,pulverization rate,closed-cell ratio and limiting oxygen index were 13.4%,267.4k Pa,6.86%,79.5%and34.5%,respectively.3)The matching of foaming component formula and foaming process of modified melamine resin prepolymer was explored by orthogonal experiment.It was found that the main influencing factor of foam water absorption and compression strength were foaming temperature and hexane foaming agent,respectively.The suitable foaming formula of 1,5-pentanediol modified melamine resin prepolymer was:3wt%n-pentane/5.5wt%n-hexane as mixed foaming agent,0.63wt%sulfuric acid/0.5wt%p-toluenesulfonic acid as mixed catalyst.The suitable foaming temperature was 90?.The apparent density,pulverization rate,compressive strength,closed-cell ratio,water absorption,thermal conductivity and limiting oxygen index of optimized modified melamine rigid foam were55.72kg/m~3,6.53%,287.3k Pa,82.1%,10.6%,0.039w/(m·K)and 35.1%,respectively.