Study On The Phenolic Resin Synthesized By Paraformaldehyde And Phenol And Phenolic Foams

This article deals with the study on expandable phenolic resins synthesized by phenol and paraformaldehyde in the presence of aqueous NaOH, and the manufacture of thermal insulation phenolic foams.Firstly, the effect of synthetic reaction conditions, such as reaction time, reaction temperature, the initial molar ratio of paraformaldehyde to phenol and the catalyst type, etc, on the structure and reactivity of the phenolic resins was researched by FTIR spectrometer and hot plate, which were employed to analyze hydroxymethyl index(CH₂OH Index) of phenolic resin and gelation time, respectively. The change of viscosity and solid content at different reaction conditions were also monitored. The experimental results showed that when reaction time was increased, the CH₂OH index of phenolic resin went up, the gelation time became shorter, and the viscosity and solid content of these phenolic resins were increased also. With the increase of reaction temperature, the CH₂OH index was decreased, and the gelation time was reduced too. When the initial molar ratio of paraformaldehyde to phenol was higher (changed from 1.8 to 2.6), the CH₂OH Index went up (from 1.5 to 3.1), the...