混合阔叶木APMP制浆工艺条件探讨

本文对混合阔叶木APMP制浆工艺条件进行了探讨,着重研究了浸渍预处理各因素和打浆度对成浆质量的影响。     

用东北硬杂木制取磺化化学机械浆

对硬杂木制取磺化化机浆的适应性进行了研究。结果表明，水曲柳制取SCMP的适应性优于柞木，在实验条件下，除了白度以外，可以制得质量和杨木和桦木相当的SCMP。适当强化磺化处理的条件，可用柞木制取断裂长达3.5km以上的SCMP，且具有较高的不透明度；水曲柳和柞木SCMP白度较低，但具有较好的可漂性，分别用1％和2％的H2O2，就可以使二者的白度达到50％以上。     

GROUPING TROPICAL WOOD SPECIES FOR KILN DRYING USING MATHEMATICAL MODELS

Because of the large variety and diffuse occurrence of tropical hardwood species in the forest, an efficient method to kiln dry these hardwoods in groups is needed. However, tropical hardwoods have a wide variety of drying properties, which makes drying mixtures of species difficult. This paper describes a mathematical model for grouping species by similar drying times. Our goal is to kiln dry so that all species emerge at the same time within set limits of moisture content. The model, which uses previously reported data, incorporates specific gravity, initial moisture content, and thickness as criteria for grouping species based on estimated drying time. The model can be used to calculate drying times and moisture content distributions within multiple-step kiln schedules, followed by calculations to equalize all members of the mixture within final moisture content specifications. The model can also be used to base grouping on green weight density, thus eliminating the need for direct information on specific gravity and initial moisture content. Plans are to evaluate the dry-kiln grouping system in field tests.     

Behavior and survival ofReticulitermes hesperus banks (Isoptera: Rhinotermitidae) on selected sawdusts and wood extracts

Survival ofReticulitermes hesperus workers was assessed inPseudotsuga menziesii, Lysiloma seemanii, andTabebuia ochracea sawdusts; and on heartwood solvent extracts ofP. menziesii, L. seemanii, T. ochracea, Pinus ponderosa, Tabebuia guayacan, and aCentrolobium species. Survival inP. menziesii sawdust was 100% at 5 days and 81–87% at 15 days. Survival inL. seemanii andT. ochracea sawdusts was significantly less over both 5 and 15 days than in the starvation control, indicating toxicity. Survival on filter papers treated with solvent extracts ofT. ochracea andP. ponderosa was significantly less than that on control papers, but onlyP. ponderosa differed significantly from the starvation control. In behavioral assays with groups and with individualR. hesperus workers, extracts ofP. menziesii andP. ponderosa were preferred. In the individual behavioral assays, extracts ofT. guayacan andT. ochracea were repellent. Results of toxicity assays were not predictable from preference assays.     

可持续发展的美国硬木

美国硬木资源丰富,树种也较多,各硬木树种木材的材面美观、物理力学性能和加工性能良好,广泛用于家具、厨柜、建筑细木工制品、地板、木门窗,是世界上重要的温带木材资源。多年来,美国硬木森林采取可持续的经营策略,使美国硬木的生产不断上升,立木蓄积量还保持增长。近年来,美国阔叶木外销委员会对美国硬木的可持续发展开展了多个研究项目,促进了美国硬木的可持续发展。笔者介绍了美国硬木的资源、市场和可持续发展的低碳的森林经营情况。     

硬杂木硫酸盐浆的少氯漂白

对硬杂木硫酸盐浆的少氯漂白进行了研究。HHP三段漂与HP两段漂对比研究结果表明,HP两段漂浆料的黏度随H段有效氯用量的增大而降低,H段漂后浆料白度越高,经P段漂后浆料白度增值越低;在次氯酸盐段总有效氯用量相同时,HHP漂后浆料的白度均高于HP漂;HHP三段漂白的第1段有效氯用量3%、第2段有效氯用量2%、H2O2用量3%时,硬杂木KP可漂到78%~80%的白度。红外光谱分析结果表明,H2O2漂白主要使浆料中的共轭羰基减少或苯环结构的破坏与溶出。     

Soda Pulping of Hardwoods Catalyzed by Anthraquinone and Methyl Substituted Anthraquinones

Abstract

Black liquor gasification (BLG) as well as the recovery of lignin and other organic compounds from pulping black liquor would be aided if an efficient sulfur‐free pulping process could be developed. This has provided new impetus for research on soda pulping with redox catalysts instead of sodium sulfide that is presently used in the kraft process. Soda/anthraquinone (AQ) pulping afforded white birch (Betula papyrifera) and sugar maple (Acer saccharum) pulps with equal if not superior strength to kraft pulps. However, the delignification rate was significantly lower for soda/AQ pulping. When AQ was replaced by 2‐methylanthraquinone (2‐MAQ) a delignification rate only slightly lower than that of kraft pulping was obtained at the same effective alkali (EA). At a kappa number of ～20, a soda/2‐MAQ pulp was produced from sugar maple at a higher yield (1.2% on chips) than for a kraft pulp. 2‐MAQ was synthesized, as a powder, at 75% yield using an AlCl₃–mediated Friedel‐Crafts reaction that is one of the methods used for commercial production of AQ.     

Determination of lignin in herbaceous plants by an improved acetyl bromide procedure

A modified acetyl bromide procedure is proposed for the spectrophotometric determination of lignin in herbaceous plants. The digestion with 25 % acetyl bromide (AcBr) in acetic acid at 70°C is improved by including 4 % perchloric acid in the digesting solutions. This allows for more rapid, complete digestion and the use of coarser samples. On the basis of infrared spectra and nitrobenzene oxidation data for milled sample lignins, the value of 20.0 g^?1 litre cm^?1 for the specific absorption coeficient of AcBr-treated lignins of herbaceous plant samples gave lignin values which were consistent with nitrobenzene oxidation data, but were higher than those obtained by the acid detergent lignin method and the earlier AcBr method proposed for grasses. The lower lignin values obtained in the latter methods are considered to be due to partial lignin solubilisation in the sulphuric acid digestion.     

13C CP–MAS NMR spectra of tropical hardwoods

The carbon-13 cross-polarisation and magic angle spinning nuclear magnetic resonance spectroscopy studies of more than 20 tropical hardwoods are presented. Because of their productivity and area, the tropical evergreen forests are the location of more than one-third of the net primary production of the terrestrial biosphere, a product which is currently of the order of 5.1 × 10¹⁶ g of carbon per year. Samples are mainly from Nigeria, predominantly timberwoods such as Diospyros mespiliformis (ebony), Tectona grandis (teak), Nauclea diderichii (opepe), Chlorophora excelsa (iroko), Khaya ivorensis (lagos mahogany), Khaya senegalensis (sapele mahogany), Daniellia oliveri (ojia), Sterculia oblonga (aye), Brachystegia kennedyi (okwen), and Mitragyna cilliata (abura); also included are Hevea braziliensis (rubber tree) and Gmelina arborea, a source of paper pulp. Assignments of the various peaks of the spectra are given to the main components, lignin and holocellulose, and to other minor structures. The holocellulose features are those of cellulose, hemicellulose being masked, at least in woods in which it is known to be present. The signals from the holocellulose component indicate that about 35% of the material is cellulose in a recognisable crystalline form, presumably located at the centre of fiberes, but the type of crystal structure could not be identified because of interference from the rest of the holocellulose signals. The aromatic lignin signals were distinct, and were perceived to fall within a pattern of a smooth transition from the wood of aye, based upon a syringyl type of residue, to the woods of omo and mpingo, based on guaiacyl residues, the exceptions being the Khayas, ebony, teak and opepe, which contained a third structure. The proportion of lignin, according to the area of the aromatic region and the O—Me signals, was highest in mpingo (50%), a savanna wood; within the woods from the Nigerian rain forest, the population ranged from 22% for iroko to 44% for teak, a reasonable allowance being made for the extra lignin in the aliphatic network.     

Snow-covered Landsat time series stacks improve automated disturbance mapping accuracy in forested landscapes

Accurate landscape-scale maps of forests and associated disturbances are critical to augment studies on biodiversity, ecosystem services, and the carbon cycle, especially in terms of understanding how the spatial and temporal complexities of damage sustained from disturbances influence forest structure and function. Vegetation change tracker (VCT) is a highly automated algorithm that exploits the spectral-temporal properties of summer Landsat time series stacks (LTSSs) to generate spatially explicit maps of forest and recent forest disturbances. VCT performs well in contiguous forest landscapes with closed or nearly closed canopies, but often incorrectly classifies large patches of land as forest or forest disturbance in the complex and spatially heterogeneous environments that typify fragmented forest landscapes. We introduce an improved version of VCT (dubbed VCTw) that incorporates a nonforest mask derived from snow-covered winter Landsat time series stacks (LTSSw) and compare it with VCT across nearly 25 million ha of land in the Lake Superior (Canada, USA) and Lake Michigan (USA) drainage basins.Accuracy assessments relying on 87 primary sampling units (PSUs) and 2640 secondary sampling units (SSUs) indicated that VCT performed with an overall accuracy of 86.3%. For persisting forest, the commission error was 14.7% and the omission error was 4.3%. Commission and omission errors for the two forest disturbance classes fluctuated around 50%. VCTw produced a statistically significant increase in overall accuracy to 91.2% and denoted about 1.115 million ha less forest (− .371 million ha disturbed and − 0.744 million ha persisting). For persisting forest, the commission error decreased to 9.3% and the omission error was relatively unchanged at 5.0%. Commission errors decreased considerably to near 22% and omission errors remained near 50% in both forest disturbance classes.Dividing the assessments into three geographic strata demonstrated that the most dramatic improvement occurred across the southern half of the Lake Michigan basin, which contains a highly fragmented agricultural landscape and relatively sparse deciduous forest, although substantial improvements occurred in other geographic strata containing little agricultural land, abundant wetlands, and extensive coniferous forest. Unlike VCT, VCTw also generally corresponded well with field-based estimates of forest cover in each stratum. Snow-covered winter imagery appears to be a valuable resource for improving automated disturbance mapping accuracy. About 34% of the world's forests receive sufficient snowfall to cover the ground and are potentially suitable for VCTw; other season-based techniques may be worth pursuing for the remaining 66%.