The preparation of CaCO3/wood composites using a chemical precipitation method and its flame-retardant and mechanically beneficial properties

With the use of Paulownia wood as a substrate and a vacuum impregnation method, CaCO3/wood composites were prepared. The XRD results showed that a variety of types of calcium carbonates coexisted in the composite and the elevated temperature was favorable for the aragonite type. The SEM results showed the modified wood retained the original wood structure and that CaCO3 was uniformly distributed in the wood cell cavity and clung to the wood cells. The mechanical testing results showed that the mechanical properties of all the composites were obviously improved; the maximum value of strength of compression (SC) and modulus of elasticity (MOE) of the CaCO3/wood composites were 32.23 MPa and 0.92 GPa, respectively, values 44.2% and 53.3% higher than those of the original wood. The maximum value of proportional limit (PL) of the composites was 29.4 MPa (38.5% increase from original wood). A cone calorimeter was used to investigate the flame retardation properties of CaCO3 on the composites. The value of the heat release rate and total heat release of composites were lower than those of the original wood; the CaCO3 wood composites showed good flame retarding effects.