Mechanical properties and thermal characteristics of different-density phenolic foams

Phenolic foam (PF) has excellent performance in fire resistance, thermal insulation and other fields. It has the advantages of lightweight, flame retardant, no dropping and low level of toxic gas emission during combustion. In order to learn the relationships between density and properties, PF samples with density of 40, 50 and 60 kg center dot m(-3) were obtained by adjusting the amount of blowing agent. Their micro-characteristics were analyzed with Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM) experiments. Mechanical properties were measured with universal extending machine. Thermal properties and stability were tested by laser thermal conductivity analyzer and thermogravimetry analysis (TG), respectively. FT-IR spectra of samples demonstrate that chemical structure will not be affected by the ratio of foaming agent. Higher density comes with better sealing property of the cell holes and leads to better compressive strength. Changing PF density with foaming agent dosage could affect insulation effect, and the sample with density of 60 kg center dot m(-3) showed poor performance compared with the other foams. TG-DTG curves of the PF samples are similar. Evaporation of water, volatilization of phenols and aldehydes, and pyrolysis of surfactant and curing agents are the main reason for the mass loss. Residues of samples increased with the increase in density at 900 degrees C. Results of this study can clarify that changing the density of PF with amount of foaming agent will not affect its chemical properties, but the ratio has impact on its physical properties.