Effects of Bamboo Fiber Length and Loading on Mechanical,Thermal and Pulverization Properties of Phenolic Foam Composites

In order to improve the mechanical properties and toughness of phenolic foams,a reinforcement method using two kinds of bamboo fibers was optimized with respect to the fiber contents.The compressive and flexural properties,thermal stability,friability and morphology of the phenolic foam composites were studied.The mechanical properties of the pristine foam and composites were evaluated by measuring the compressive strength.The results showed that the greatest mechanical properties were achieved by incorporating 2.5wt%of the reinforcement,and the compressive and flexural strengths of the two composites increased by 26.21%and 24.35%,respectively,compared with that of the pristine foam.The results of thermogravimetric testing demonstrated that the addition of bamboo fiber imparted better thermal stability to the phenolic foam,which was mainly attributed to the higher initial thermal decomposition temperature of the bamboo fiber.However,the influences of both reinforcements on the thermal stability of the material were negligible.The incorporation of bamboo fiber decreased the friability of the phenolic foam.Furthermore,the reduction in friability of the foam composites with longer lengths were higher than that in foams with shorter bamboo fibers.Moreover,the morphology and cell sizes of the fiber-reinforced phenolic foams were analyzed by scanning electron microscopy,the results indicated strong bonding between the fibers and phenolic matrix,and the incorporation of the bamboo fibers into the foam resulted in increased cell size of the material.Finally,the thermal conductivity and flame resistance of the phenolic foams reinforced by the bamboo fibers were also measured.