Southern pine treated

Rowell, R.M. (1978). Distribution of reacted chemicals in southern pine treated with aUcylene... 

Ostmeyer JG, Elder TJ, Winandy JE (1989) Spectroscopic analysis of southern pine treated with chromated copper arsenate II Diffuse-reflectance Founer-transform infrared spectroscopy (DRIFT) J Wood Chem Technol 9 105-122 Owen NL, Thomas DW (1989) Infrared studies of hard and soft woods Appl Spectrosc 43 451-455... 

After fixation, precipitated preservative salts can be seen in the wood structure. Comparison of photomicrographs of untreated southern pine (Figure 22a) and southern pine treated with 2.5 lb CCA/ft (Figure 22b) reveals that the salts in the treated wood form a rough coating on the lumen walls. The exact final location of these fixed salts is still subject to discussion. Undoubtedly, most of these injected hydrolytic preservatives remain in the cell lumen, but the extent to which these preservatives enter the cell wall and react with the cell wall substance dictates the preservative s effect on strength. 

Figure 22. Untreated southern pine shows the absence of crystalline materials. ( X 4(XX)) (a), and southern pine treated with the wood preservative...

Other possibilities are a) surface tension, b) molecular size, c) chemical activity, d) solvency, and e) ability to swell wood. Some of these factors may be operative in treatments with propylene oxide which have been carried out by Rowell (33). In this study, he used a mixture of 95% propylene oxide and 5% triethyl-amine (v/v). He was able to completely treat southern pine and red pine heartwood, both of which were classified as being refractory. This work clearly shows that with the proper treating medium, heartwood can be fully penetrated. 

Douglas-fir, birch, southern pine, and sweetgum blocks were treated with 1% aqueous ammonia or sodium hydroxide for various times, temperatures, and pressures (9). These samples were submitted to soil-block tests with two brown-rot fungi Poria monticola (Madison 698) and Lentinus lepideus (Madison 534) and two white-rot fungi Polyporus versicolor (Coriolus versicolor) (Madison 697) and P. anceps (F 784-5) as well as outside exposure tests (10). In the soil-block tests, the treated wood was resistant to the two brown rotters, but was not resistant to the two white rotters. In the outdoor stake tests, the average lifetime was 3.5 years while untreated controls had an average lifetime of 3.6 years. The outdoor tests show that there is no increase in rot resistance by this treatment. 

Southern pine, Douglas-fir, and yellow poplar stakes were impregnated with phenolic resin and cured (impreg) or impregnated with phenolic resin, compressed, and cured (compreg). Separate samples were treated with urea-formaldehyde and cured. These samples were placed in the ground and their average lifetime determined. The results are shown in Table I (18). 

In preliminary tests, alkylene oxide-treated southern pine (28) was found to be resistant to termite attack and attack from the marine borers, Teredo (shipworm) and Limnoria. 

Detailed resistance tests against decay fungi and termites have been conducted on epoxide-treated wood. Brown-rot fungi, L. lepideus and G. tra-beum, yielded 44.2% and 62.9% weight loss (WL) of control southern pine, respectively, after 12-week soil block tests. 

Tables I, II, and III give volumetric swelling coefficients for southern pine sapwood for various potential reagents, catalysts, and solvents (JO). These coefficients were determined under two sets of conditions. Specimens from oven-dried southern pine sapwood blocks were measured and their volumes were determined. Ten specimens from this set were submerged in a solution and either treated at 120 °C and a pressure of 150 Ib/in. for 1 h, or they were soaked at 25 for 48 h.

Figure 23, Southern pine fiber treated with the fire-retardant NHaH FOa...

The long-term effectiveness of TBTMA as a biocide has been confirmed (23). The deterioration of southern pine wood specimens impregnated with TBTMA has been compared with specimens that were treated with pentachlorophenol methacrylate (PGPMA) or pen-tabromophenol methacrylate (PGBMA). The three esters were incorporated as the copolymer by in situ copolymerization with methyl methacrylate (MMA) at different molar ratios of the comonomers. 

The coating durability of organolead-treated southern pine in exterior exposure was reported (144), Significant improvement in the durability of a vinyl-acrylic latex and an alkyd paint on treated wood was demonstrated. Improved durability appeared to be independent of the type or concentration of the organolead-treated compounds. 

Figure 27. Cross section of southern yellow pine treated with 0.1% chromic acid solution after exposure to UV light for 500 h (700 x ).

Figure 30. Microchecks of cell wall of southern yellow pine treated unth...

Figure 3. Infrared spectra of methyl isocyanate-modified southern pine. Key A, unreacted wood (control) B, 17.7 WPG C, 47.2 WPG D, holocellulose from sample treated to 17.7 WPG E, lignin from sample treated to 47.2 WPG.

Additional evidence that bonding has occurred in the cell wall of methyl isocyanate-modified southern pine can be seen by considering the volume increase in the treated wood and comparing that to the theoretical volume of chemical added after thorough leaching of the treated wood. If the chemical has entered the wood cell wall, the increase in wood volume as a result of modification should be proportional to the volume of chemical added. 

Figure 5. Scanning electron micrographs of radially-split southern pine showing swelling of wood treated with methyl isocyanate. Key A, untreated control (245)0 B, 16.0 WPG (224X) C, 32.2 WPG (224X) D, 36.9 WPG (224x) E, 47.4 WPG (224X) F, 72.3 WPG (196X)-...

Table V. Soil block test of isocyanate-treated southern pine inoculated with Gloeophyllum trabeum...

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