26 сентября, 2015 
Malyar Similar to the investigations described above for the aminoplastic resins, NMR results of the liquid phenolic resins can be correlated with certain board properties [199]. For this purpose various structural components are determined by means of 13C-NMR and the ratios of the amounts of the various structural components are calculated, e. g.:
methylol groups to methylene bridges
ratio of free ortho and para sites in relation to all possible reaction sites methylol groups in relation to all possible reaction sites methylene bridges in relation to all possible reaction sites ether bridges in relation to all reaction sites
These ratios are then correlated to various properties of the wood-based panels,
e. g., internal bond strength after boiling or after boiling + redrying, and subsequent formaldehyde emission.
Also for phenolic resins it is not clear whether universally valid correlation equations will exist or if they will differ for different types of resins and boards, although the correlations obtained appear to have a lower coefficient of variability than for the aminoplastic resins. Nevertheless, it can be safely assumed that the various parameters used with at least be the same in most cases, even if the actual numerical values of the coefficients within the individual equations might differ.
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