Leonard L. Ingram

Repellent properties of the host compound 4-allylanisole to the southern pine beetle.

The phenylpropanoid 4-allylanisole is a compound produced by loblolly pines (Pinus taeda L.), an abundant species in southern pine forests and a preferred host of southern pine beetle (Dendroctonus frontalis Zimmermann). Repellency of individual beetles was demonstrated in laboratory behavioral assays ofD. frontalis and other scolytids. Inhibition was demonstrated in natural populations ofD. frontalis using baited traps. In both tests, response to the inhibitory pheromone verbenone was used for comparison. In the laboratory, a higher proportion of newly emerged and reemergedD. frontalis responded negatively to 4-allylanisole than to verbenone. However, fewer reemergent than newly emerged individuals responded to either compound. In all field trials, the response ofD. frontalis to its attractant pheromone in funnel traps was significantly reduced by simultaneous release of 4-allylanisole. In most trials total reduction did not differ from verbenone; however, unlike verbenone, 4-allylanisole reduced male and female catches proportionally. Both compounds together did not significantly further reduce trap catch. The response of a major predator,Thanasimus dubius (F.), to the attractant pheromone ofD. frontalis, did not differ with the simultaneous release of either verbenone or 4-allylanisole. The results of preliminary field applications are presented and discussed.

Wood Enhancement Treatments I. Impregnation of Southern Yellow Pine with Melamine-Formaldehyde and Melamine-Ammeline-Formaldehyde Resins

Abstract Southern yellow pine (SYP) was impregnated with melamine-formaldehyde (MF) or melamine-ammeline-formaldehyde (MAF) resins. The dimensional stability, strength properties, weathering, fire resistance and chemical resistance of the impregnated wood were examined. The wood treated with two commercial MF resins or with a synthesized MAF resin exhibited greatly enhanced dimensional stability, fire resistance and resistance to weathering. The chemical resistance increased moderately.

Effect of solvents on the photodegradation rates of octachlorodibenzo-p-dioxin

Commercially produced pentachlorophenol that is used primarily as a wood preservative may contain up to 2,000 {mu}g/g of OCDD along with smaller amounts of less highly chlorinated dioxins and furans. The possibility that OCDD could be photolytically degraded to some of the more toxic CDDs has resulted in a number of publications that address that phenomenon. Studies of the formation of OCDD from pentachlorophenol (PCP) on the surface of treated wood indicated that the PCP carrier solvent could influence the levels of OCDD present. Generally, the more highly chlorinated CDDs are photolyzed more rapidly than the less highly chlorinated CDDs. A linear correlation between relative biological potency and photolysis half-lives was also noted for certain isomers of CDDs. Results indicate that OCDD is less rapidly degraded than some of the other chlorinated CDDs. Other studies with 2,3,7,8-TCDD examined the effects of solubilization, photochemical reduction, and of different surfaces. The primary objective of this study was to determine if the presence of different solvents affected the rate of photolysis of OCDD and also to determine the effect of these solvents on the photolysis products.

Optimization of hot-compressed water pretreatment of bagasse and characterization of extracted hemicelluloses

Developing optimum treatment and separation procedures for hemicellulose components of lignocellulosic biomass could be useful in ethanol fermentation processes and obtaining pure hemicelluloses as biopolymers. Sugarcane bagasse analyses indicate that xylose is the major hemicellulose component constituting 17.7% of dry bagasse weight. In this study the effects of treatment conditions such as time, temperature and pressure on the yields of extracted hemicelluloses were studied. The optimum conditions were achieved at 180 °C for 30 min and 1 MPa pressure, with the yield of xylose reaching to 85% and the concentrations of sugar degradation products such as HMF and furfural remaining minimal at 0.95 and 0.07 g/L, respectively. Further, isolation of hemicelluloses from extracted hemicelluloses solutions was performed using Alfa Laval M20 membrane filtration system in two steps: (1) concentration of high molar mass hemicelluloses by ultrafiltration; and (2) separation of low molar mass hemicelluloses and oligomeric sugars by nanofiltration. The isolated hemicelluloses with the optimum pretreatment conditions were characterized by FT-IR and (13)C NMR techniques, resulting in agreement with typical spectra of xylan-type hemicelluloses.

Laboratory and outdoor water repellency and dimensional stability of southern pine sapwood treated with a waterborne water repellent made from resin acids

Abstract A major consumer concern regarding lumber in above-ground exposure such as decking is the poor dimensional stability that leads to warping, splitting, and checking. One method to increase dimensional stability is to treat lumber with a water repellent. A waterborne water repellent made from the resin acid abietic acid or a commercial source of resin acids, tall oil rosin or TOR, was tested using southern pine sapwood. In laboratory water-swelling tests, the waterborne abietic acid provided water repellency that was almost equivalent to that provided by wax, while no water repellency was observed with solventborne resin acid. Wood treated with waterborne TOR also provided good water repellency in laboratory tests and fair water repellency at up to 13 months of outdoor exposure, but the laboratory efficacy was partially reduced by a water leach. The dimensional stability (cupping and checking) and mold growth on TOR-treated lumber in above-ground exterior exposure was better than for untreated boards, but not as good as for wax-treated lumber. Analysis of the wood in southern pine tree trunks of 14 or 29 years of age of various diameters and sampled at the bottom, middle and top showed that the resin acid content in southern pine wood is quite variable. This may explain the wide variation in natural water repellency and decay resistance previously observed with untreated southern pine sapwood.

Knot, Heartwood, and Sapwood Extractives Related to VOCs from Drying Southern Pine Lumber

Abstract The presence of knots or heartwood influences the amount and composition of volatile organic compound (VOC) emissions associated with drying of southern pine lumber. Experimental kiln charges of lumber containing 0 to 5% of knot volume gave VOC emissions ranging from 2.86 to 4.25 lb of carbon/dry ton of wood. Studies of emissions from sapwood and knots showed that knots contain about ten times the amount of volatile terpenes found in sapwood. Consequently half of the total volatile emissions would come from 5% of knot volume in sapwood. However, correlation coefficients of knot frequency or volume with VOC emissions obtained from experimental kiln studies were only 0.57 and 0.51, respectively. Southern pine heartwood contains about five times the amount of volatile terpenes found in sapwood and more of the volatile compounds present in heartwood are emitted than from knots. Therefore, small variations in the amount of heartwood result in large changes in VOC emissions in drying southern pine lumber.

Alkaline Hydrolysis of Nonphenolic ß-O-4 Lignin Model Dimers: Further Studies of the Substituent Effect on the Leaving Phenoxide

Reaction rates and activation parameters for the alkaline hydrolysis of nonphenolic β-O-4 lignin models [2-(4-substituted phenoxy)-1-(3,4-dimethoxyphenyl)-1-ethanol] were compared to 2-methoxylated B-ring analogues run earlier. The Hammett plot with the best fit used σ - values to give a ρ of 1.9 ± 0.2. while the 2-methoxyl-substituted compounds had a ρ of 2.3 ± 0.3. Compounds with a methoxyl group at the ortho position of the leaving phenoxide ion hydrolyzed slightly faster than the non-methoxylated analogues, indicating that the 2-methoxy group is a weak electron-withdrawer. The strong electron-withdrawing 4-CHO and 4-CF 3 substituents gave significantly different activation parameters than the unsubstituted compound. Experiments with 18 O-labeled water suggested that our earlier proposed S N Ar mechanism for the alkaline hydrolysis of strong electron-withdrawing compounds is not correct. It appears that all nonphenolic β-O-4 dimers are hydrolyzed by a neighboring group mechanism.

VOC extraction from softwood through low-headspace heating

Summary Volatile organic compounds (VOCs), principally terpenes, released during wood drying face present or potential regulation. Two approaches are reported to control VOC release: heating green wood, or irradiating it with microwave energy, both in a low-headspace environment where evaporation is minimized. Low-headspace heating of green flakes (for OSB manufacture) releases VOCs but proportionately much less water. Hence, it is feasible to extract and collect the VOCs from green wood prior to drying, and to then dry it with lowered emissions. Irradiating flakes with microwave leads to contrasting behavior. Water is released with very little VOC loss if the flakes are microwaved in an open container. Microwaving under low-headspace conditions removes the VOCs, but retains the water in the wood. The water trapped in the wood because of the low-headspace restriction drives the VOCs out of the hydrophobic regions (e.g., resin canals) where they are principally located, into hydrophilic zones. Movement out of the hydrophilic environment and out of the wood is then quite rapid. Hence, either VOC or water release can be targeted by adjusting the headspace during microwaving. Most of the VOCs lost during drying originate from the surface, and low-headspace microwaving releases this surficial material. Hydrogen isotope exchange work shows that microwaving increases water access to the exchangeable protons in dry, or partially dry, wood tissue. The terpenes are carried out with the small amount of steam generated. Similar results are obtained with low-headspace radiofrequency (RF) irradiation of lumber; RF treatment does not induce a significant change in strength.

POLYURETHANE RESINS-TREATED WOOD PALLETS WHICH ARE DECONTAMINABLE OF CHEMICAL WARFARE AGENTS*

Wood pallets manufactured by impregnating and coating wood with selected polyurethane resins performed comparably to steel control pallets in decontamination of major chemical warfare agents before and after being subjected to various rough-handling and strength test procedures. Cost calculations showed that the wood pallets would be competitive with steel pallets. * See Ref. [1].

WOOD MADE DECONTAMINABLE OF CHEMICAL WARFARE AGENTS AFTER SUNLIGHT WEATHERING OR ABRASION

Methods of making wood decontaminable of major chemical warfare agents were investigated using phenol-formaldehyde and polyurethane resins. Selected phenol-formaldehyde resins impregnated in southern yellow pine gave enhanced dimensional stability and fire resistance properties without decreasing strength properties, but the decontaminability for one major chemical warfare agent was inadequate. Selected polyurethane resins impregnated in southern yellow pine gave enhanced dimensional stability and strength properties with only a minor deterioration in fire properties, and southern yellow pine, red oak, and aspen impregnated with these polyurethane resins were adequately decontaminated of all three major chemical warfare agents. A polyurethane resin that performs adequately as a coating material for this purpose was also identified. *See Ref. [1].