Southern pine acid content

Fig. 4.6.9. Correlation of the 1595 cm 1 band height with lignin content of Southern pine wood meal after acid chlorite treatments. Data points in top right-hand corner correspond to lignin in untreated wood...

Our estimates of the acid contents of heartwoods and sapwoods of red oak, hickory, southern pine, white fir, and Douglas-fir are given in Table I. The acid contents were correlated with the gel times of urea-formaldehyde resins (36) in contact with the same sample lots of the different species of wood. The correlations are presented in Table II. It is seen from Table II that the best correlation of gel times is obtained with insoluble acid content for each of the empirical fits that were tried. Similarly, the pH of the sodium acetate extracts showed better correlations with the gel times than the pH of the water extracts (37). 

Figure 7. Formaldehyde liberation from particleboards and CH20-sorbed wood at 27°C and 33 percent relative humidity (RH) weighing bottle test with -80 mesh materials (o Southern pine impregnated with pH 2 tartaric acid and vapor-equilibrated with CH20/salt solution at pet RH O as before except heated 4 min. 16O°C after CH2O sorption 0 urea-formaldehyde particle board (b) phenol-formaldehyde particleboard, values approximate P = Perforator value at indicated moisture content (MC)).

The resin content of wood and its composition vary considerably, depending on such factors as place of growth, age of the tree, and genetic factors. For example, the resin content of Norway spruce (P/cea abies) is considerably higher for stems grown in the northern than in the southern parts of Scandinavia. The resin content within the same stem also varies, but in a very irregular manner. In all pines, the heartwood contains much more resin than the sapwood, whereas the opposite seems to be true for P/cea species as indicated by data for Norway spruce. The heartwood extractives in both pine and spruce contain resin acids and free fatty acids as main components,... 

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