Two phenol-formaldehyde resol resin series with different methylationand condensation-stage alkalinities were studied. The first series was impregnation resins having a methylation alkalinity between 0.5 and 1.5 wt % and a condensation alkalinity of 1.5 wt %. The second series was adhesive resins with a methylation alkalinity between 0.5 and 3.5 wt % and a condensation alkalinity of 6.0 wt %. The chemical structure was analyzed by 13 C-NMR spectroscopy, and reactivity, by differential scanning calorimetry (DSC). The methylation alkalinity was found to affect the distribution of the structural groups of both phenol-formaldehyde impregnation and adhesive resins, but not to the same extent as did the total condensation alkalinity. Also, the results of the DSC analysis illustrate best the reactivity differences due to the condensation alkalinity.

ABSTRACT:The experimental time of 13 C-NMR quantitative analysis of phenol-formaldehyde resins was reduced so that quantitativeness was maintained. The quantitative spectra of 14 model resins were obtained using a gated decoupling technique suppressing the NOE. The paramagnetic additive, Cr(acac) 3 , was used to shorten relaxation times of carbon atoms. The use of Cr(acac) 3 was optimized in two deuterated solvents, DMSO and acetone. To reach short relaxation times and further the measurement times, the concentration of relaxation reagent, the delay time, and the number of NMR scans were optimized. Quantitativeness was proved by analyzing the spectra of accurate mixture of model compounds, and the spectra of the condensed model resins.

Foaming of a phenol formaldehyde resin was studied. Twenty-one foaming agents were tried out in the experiments. Foaming was evaluated by viscosity, density, and surface tension measurements. The study shows that spray dried blood and ␤-lactoglobulin-enriched whey were the best foaming agents to foam phenol formaldehyde resin. There are also some other materials, which might work as foaming agents for phenol formaldehyde resin after some formula optimization. They include sodium lauryl sulfate, sodium-n-alkyl (C 10 -C 13 ) benzene sulfonate, and a fatty acid amine derivate.