Study On The Preparation Technology Of Aramid Cellular Core Filled With Phenolic Foams In Situ

Phenolic foams are widely used to transportation, building and ships, due to theirunique properties, such as light weight, acoustic and thermal insulation, fireproofing, lowsmoke and toxic, high specific strength and low thermal conductivity. Relative to other foams,the fire retardant properties of phenolic foam is outstanding, and it also has a cost advantage.However, poor mechanical property, the brittleness and the fragility limit the application of phenolicfoams. In order to solve these problems, aramid cellular as the skeleton reinforced material isemployed to improve mechanical properties of modified phenolic foam. In this idea, low density andhigh fire resistance of phenolic foam are used in combination with high strength and high modulus ofaramid cellular in order to obtain a light weight, high strength and fireproof composite. This paperfocuses on several key issues in manufacturing process of aramid cellular reinforced phenolic foam,such as synthetic and modified the resols, foaming of phenolic resin, toughening and enhancing ofphenolic foams, and compatibility between aramid cellular and phenolic foam.In order to obtain the optimum resols, the impact of the PH value of reaction system, thesynthesis temperature and F/P ratio on property of phenolic resin was discussed. The results show thatPH value of reaction system is8, the optimal F/P ratio is1.8and it is better to polymerize under thetemperature of90oC. On this basis, melamine was employed to reduce the free monomer of syntheticresols, the results show that the curing temperature of resols modified by melamine was higher, andthe free phenol and free aldehyde were significantly lower. When the quality ratio of melamine andphenol is1/15, the free monomer amount is the lowest(2.43%) in resols.The effect of each parameter of foaming process on the properties of phenolic foam wasanalyzed by orthogonal experiment design method. The optimal parameters of foaming processare:3%DC193as a surfactant agent, n-pentane as blowing agent in6%,6%the acid mixed byp-toluene sulfonic acid and phosphoric acid was thoroughly mixed with resols, poured into foammolds and heated to90oC. On this basis, HGB and toughening agent preparation by polyvinyl alcohol,polyethylene glycol, polyvinylpyrrolidone were employed to improve the performance of phenolicfoam, the experimental results show that the best performance of phenolic foam can be obtainedthrough adding10wt%HGB pretreated by silane coupling agent KH560and10wt%tougheningagent. Aramid cellular was employed to reinforce phenolic foams and improved the mechanicalproperties of phenolic foam significantly. The analysis results show that the thicker the honeycomband the smaller of honeycomb holes, the enhancement effect with phenolic foam becomes moreobvious. We found much tiny bubble hole near the honeycomb wall in the phenolic foam reinforcedby small holes honeycomb, which lead to the adhesion strength of between the honeycomb wall andthe phenolic foam is stronger. The phenolic foams reinforced by small holes honeycomb get a betterhigh temperature dimensional stability and heat insulation, and the flame retardant performancedeclined, but the final flame retardant properties still can meet the highest grade A national fireprotection standards.