After carbonization, all of the CMDF boards had a uniform thickness of 11 mm.
The original CMDF had a porosity of 58.9 percent, but after resin infusion, the porosity decreased to 4.8 percent for epoxy-infused samples and to 29.1 percent for the phenolic-infused samples (Fig.
Both the original CMDF and resin-infused samples displayed the abrupt fracture behavior typical of brittle materials as shown by their tensile stress-strain profiles (Fig.
The tensile properties of the original CMDF were considerably improved after resin infusion (Table 1), with tensile strength increasing 434 percent and 235 percent for the epoxy-infused CMDF and phenolic-infused CMDF, respectively, and the tensile modulus increasing 138 percent and 97 percent for the epoxy-infused and phenolic-infused samples, respectively.
Because the sandwich structure was retained after carbonization, no significant difference was found between tensile and bending strength of uninfused CMDF. After resin infusion, density differences between the surface layers and the core were reduced because more resin penetrated into the lower density material.
It is conceivable that the use of the CMDF material would significantly reduce the production cost as complex fiber handling and forming procedures can be reduced or eliminated for some applications.
Selected physical and mechanical properties of resin-infused CMDF were investigated.