Preparation, Modification And Performance Of Phenolic Foam And Its Composites

Phenolic foam has excellent properties of fire resistance, less smoke during burning, low heat conductivity, and good balance between cost and mechanical properties, compared with other foams. It is widely applied across large areas, such as transportation, buildings and ships.However, poor mechanical property and the brittleness limit its clinical application. In this manuscript, glass fiber mat was employed to improve mechanical properties of phenolic foam through dipping and foaming processes. In this idea, low density and high fire resistance of phenolic foam were used in combination with high strength and high modulus of glass fiber in order to obtain a lightweight, high strength and fireproof composites.This paper focused on several key issues in manufacturing process of glass fiber reinforced phenolic foam, such as synthesize of resols, toughening of phenolic resin, and heat resistant modification and compatibility between glass fiber and phenolic foam.In order to obtain the optimum technological conditions for producing resols, Na OH, Ca O and Zn(CH3COO)2?2H2O was employed as a catalys. The impact of the type ofcatalyst, p H value of reaction system and F/P ratio on structure and property of phenolicresin was discussed. The results showed that Ca Owasthe best catalyst, the optimal F/P ratio is 1.8,p H value of reaction system is 8 andit is better to polymerize under the temperature of 97℃.PVB and PSBS was employed to toughenphenolic resin.The mechanical property testing showed that with the increasement of the amount of PVB and PSBS, toughness of phenolic resin increases.The toughening effect of phenolic resin was better when using PSBS, with an amount of 20% toughnessof phenolic resin increased 83.3% and the glass transition temperature of phenolic resindecreased 24.1℃.Graphene and graphene oxide were employed toimprove thermal performance of phenolic resin, the interactions between graphene oxide and phenolic resin was analyzedsystematically.The results showed that graphene oxide was better than graphene in improving the heat resistant property of phenolic resin. Tg of phenolic resin increased 31.4 ℃ with 0.5% graphene oxide. Addition of graphene oxide improved residue rate of phenolic resin by 6.9%. Esterification reaction happens between the carbonyl group on graphene oxide and hydroxyl in phenol resin under acidic and high temperature conditions to form an ester bond between the two binding.Ester bonds between graphene oxide and phenolic foam matrix may be considered as “nails”, while graphene oxide may be considered as a “net”. The “net” mantle up the matrix tightly with those “nails” and stoped separating of particles whose size was smaller than the “net”.The effect of blowing agent and surfactant on the properties of phenolic foam was analyzed by orthogonal experiment design method.The optimal parameters of foaming process are: n-hexane as blowing agent in 6%, 2% DC193 as a surfactant agent, 0.5% phosphoric acidwas thoroughly mixed with resols, poured into foam molds and heated to 180 ℃.Glass fiber mat was employed to reinforce phenolic foams and improved the mechanical properties of phenolic foamsignificantly.The results showed that the pressure strength, bending strength and impact toughness increased 56.02%, 101.99%, and 131.07%respectively with 10% glass fiber mat.Calcium carbonate putted as nucleating agent can effectively suppressnucleus of the bubble on the surface of glass fiber.Thereby further improving the mechanical properties of the material.