NS改性对落叶松材干燥性能的影响

本文通过NS改性落叶松材和素材在相同干燥基准下干燥速度和干燥质量的对比试验，研究了NS改性对落叶松材干燥性能的影响。结果表明：NS改性可显著改善落叶松材的干燥性能，40mm厚板材平均干燥速度可提高48％以上，各项干燥质量指标均高于国家二级标准，完全可满足家具等生产的需要。     

科技商品信息

MR427型自动开齿机。该设备是用于带锯条连续开齿的自动机床。开齿速度每分钟35个。可开宽为150～200毫米、厚为0.9～1.5毫米、齿距在30～50毫米之间的带锯条、框锯条。研制单位愿实施技术转让。木材改性的研究。该项成果通过对劣质材(落叶松、杨木、桦木)进行简单水煮改性,可以实现劣材优用,代替红松用于门窗建筑。不仅提高了木材的使用价值,而且还能缩短木材干燥周期,提高了干燥质量,     

人工林落叶松髓心方材的高频真空干燥(英文)

对截面尺寸为100mm×100mm的人工林落叶松髓心方材进行系列高频真空干燥试验,分析研究不同高频真空干燥条件下干燥质量和干燥速度的变化规律,获得合理的高频真空干燥工艺基准;为了进一步减少试材表裂,干燥前对试材进行切口和过热蒸汽预处理。结果表明:沿试材长度方向的中心位置切口和过热蒸汽预处理都能有效减少试材表裂,提高干燥质量。     

常规—高温二段连续干燥松板脱脂的研究

马尾松是我国木材中数量最多的松属树种,因之,将其开发为家具和建筑材有着重要的价值。然而受自身材性的影响,要达到上述目的就需要改性。本文所讨论的是,马尾松板材的改性处理和干燥方法。近年来,各种快速节能的干燥方法已在生产实践中发挥着重要的作用。特别是常压过热蒸汽干燥,它与传统的常规干燥比较,既快速成本又低,尤其是干燥针叶材有着许多优越性。文献中关于马尾松、落叶松、桦木,木荷等的干燥报导已不少。但是改性后的木材有别于一般干燥素材,其化学组成有     

人工林落叶松板材的真空干燥工艺

探讨2种真空压力下,不同初始介质温度时,落叶松板材的干燥规律.结果表明:真空干燥工艺有效提高了落叶松的干燥速率.初始介质温度和真空压力均对干燥速率有显著影响;同一真空压力下,干燥速度随温度提高而加快;分段干燥速率随介质温度的升高呈递减趋势;间隙式真空干燥工艺减小了试材厚度上含水率偏差.     

白桦材尿素改性前后干燥特性的研究

对白桦材尿素改性前后的干缩性和干燥特性的研究结果表明,尿素改性材的干燥特性明显好于素材和水煮改性材,干燥速度快,干燥质量好。并探讨了尿素改善白桦材干燥特性的机理。     

落叶松小径木异型材实验室干燥工艺研究

选取黑龙江省落叶松小径木进行异型剖分,采用中温软基准和高温波动基准及高温硬基准3种不同的干燥基准,分别对剖分后的异型单元材进行实验室干燥试验。干燥过程中对含水率变化、分层含水率变化及干燥质量分别进行检测并记录,以确定和选用干燥基准。试验结果表明,高温波动干燥基准最适合落叶松小径木三角形剖分材的干燥。     

糠醇浸渍速生人工林木材的干燥特性研究

木材浸渍改性商业应用的主要技术难点之一是二次干燥速度慢、易开裂、易变形。本文以杨木和杉木为研究对象,使用浓度为30%和50%的糠醇水溶液对其进行浸渍改性,再以百度干燥法分析糠醇浸渍材的干燥特性,辅以干缩试验和剖面密度(VDP)试验探究干燥缺陷成因。结果表明：50%浓度浸渍材的干燥缺陷等级均大于30%浓度浸渍材,杨木浸渍材的等级均高于杉木浸渍材;杉木30%和50%浓度浸渍材百度干燥平均时间分别为24 h和29 h,而杨木30%和50%浓度浸渍材分别为20 h和30 h。浸渍材不同位置的干缩系数存在显著差异,浸渍后密度分布更加不均匀。杉木和杨木糠醇浸渍材二次干燥困难的主要原因为固化的糠醇堵塞了水分内部迁移通道,从而使干燥速度降低;糠醇分布不均匀导致干缩系数差异进一步加大,处理材易开裂、易变形。     

常温干燥过程中落叶松心材和边材材色变化研究

采用常温干燥基准,以恒定的干球温湿度为试验条件,对干燥过程中落叶松各颜色指标变化情况进行研究。结果表明,常温干燥条件下,落叶松材色仍能发生显著变化,尤其以边材最为明显。     

木材改性及其干燥研究现状北大核心

为提高速生材材性,弥补其天然不足,木材改性成为一大研究热点。由于改性物质易堵塞木材水分迁移通道或改性剂团聚,木材干燥难度有所提高。本文从功能型改性和增强型改性两方面进行综述,对目前改性木材干燥现状及优化进行分析,以期为我国木材及改性木材干燥提供理论依据。     

落叶松规格材加工利用技术研究

介绍"十一五"国家科技支撑计划"高强度结构材加工利用技术"课题中,对我国主要的商品林树种之一——落叶松,在规格材的优化加工、分级、无损检测、强度性能测试及木构件连接等关键技术研究方面,取得的重点创新成果。这些成果开创性地解决了我国利用国产资源加工结构用规格材的关键性和共性技术问题,并且为我国落叶松资源的高效利用,提供了新的技术途径。     

PF预聚物改性杨木的研究

采用低分子量酚醛树脂对杨木进行浸渍处理、干燥定型,使树脂固化制得改性材。PF预聚物对杨木具有较好的浸注性;对其密度进行检测和分析的结果表明:杨木改性材的密度可达到0.6~0.8 kg/m3。     

落叶松锯材外观分等与机械应力分等的试验研究

根据中国、日本、美国三国的外观分等标准,对落叶松试材进行了以强度为基础的外观分等;采用机械应力分等机对落叶松试材进行了应力分等试验,并分析比较了三国不同的外观分等结果与机械应力分等检测的相关关系。     

Analysis of moisture diffusivity of larch timber during convective drying condition by using Crank＇s method and Dincer＇s method

Two analytical procedures （Crank＇s method and Dincer＇s method） for porous solid materials were reevaluated and used to determine moisture diffusion coefficients and moisture transfer coefficients for larch lumber subjected to drying. A diffusion-like equation was used to describe drying process data. The lumber was idealized in the modeling as infinite plates. The moisture transport process inside the board was assumed to be one-dimensional. The macroscopic drying kinetics curves of larch timber at particular conditions were determined experimentally. Based on these data, calculation for both the moisture diffusion coefficients and moisture transfer coefficients by the Dincer＇s analytical procedure were made. The dynamic moisture diffusion coefficients by the traditional Crank＇s method were calculated. In general, diffusion coefficients calculated by the Dincer＇s method were all higher than those by Crank＇s method. These results could be due to the differences between two analytical methods and also different characteristics between solid moisture diffusion process and heat transfer process. Therefore the analysis and solution procedures of moisture diffusion differential equations need to be adapted in the future. With drying temperature＇s increasing moisture diffusion coefficient （D） and moisture transfer coefficient （k） increases accordingly. Also the relationships between diffusion coefficients and temperature as well as material moisture contents were analyzed by using Arrhenius equation and bound water transport theory.     

控制锯材变形的方法

针对影响锯材变形的因素。从降低原木残余生长应力、对干缩湿胀和干缩应力的干燥工艺处理，到下锯法的合理选择，以及通过木材改性达到尺寸稳定等几方面进行了全面探讨，为提高锯材和木材品产品质量供参考。     

蒸汽爆破预处理对柞木地板坯料干燥速率的影响

对柞木地板坯料进行了压力为0.25、0.4和0.55 MPa的蒸汽爆破预处理,并与未处理的对照材进行对比.结果认为:前者干燥速度分别提高了13.6%、27.3%和36.4%.蒸汽爆破预处理的压力越大,干燥速度提高的越多;在设定的试验压力范围内,柞木试材的力学强度未受影响.     

国产木桁架齿板连接件的研发

测试进口齿板与国产落叶松连接节点的拉伸性能,结果表明国产落叶松规格材完全可以替代美国南方松来制作齿板连接木桁架。提出3种国产齿板设计方案,使用国产镀锌钢板制作了国产齿板,并对国产齿板连接节点进行测试,指出国产齿板达到了批量生产的要求,改进方案可以提高齿板连接的性能,但国产齿板需要在加工工艺上进行调整,才能用于实际木桁架生产。     

Changes of major chemical components in larch wood through combined treatment of drying and heat treatment using superheated steam

The effects of the combined treatment of drying and heat treatment using superheated steam (SHS) were studied relative to the changes of the major chemical components in larch wood. The green lumber was dried and heat-treated in SHS conditions of 250 °C and 0.5 MPa for 18 h, and the relative percentage contents of sugars, lignin, and extractives were investigated and compared with the relative percentage contents in the lumber heat-treated in hot air conditions of 250 °C and atmospheric pressure for 18 h. After both heat treatment methods, the relative percentage contents of xylan, mannan, galactan, and arabinan were greatly decreased, whereas that of the Klason lignin was increased, additionally that of glucan and extractives remained almost unchanged. Lignin may bind with furan compounds decomposed from hemicellulose following heat treatment, thus contributing to the increase in the apparent relative percentage contents of the Klason lignin. In addition, the condensate collected in the condenser after combined drying and heat treatment using SHS was investigated qualitatively and quantitatively by high-performance liquid chromatography (HPLC). A large amount of furfural and acetic acid decomposed from hemicellulose was detected and some sugar components composed of cellulose and hemicellulose were detected in the liquid condensate.     

小型除湿干燥机干燥乐器用材的实践

本研究使用小型除湿干燥机对提琴用材进行了干燥工艺生产性试验。结果表明，干燥过程中试材未产生内裂和表裂；干燥后板材的含水率在材堆内分布均匀，在板材厚度方向分布有一定差异，平衡后可以使用；干燥成本在100元/m^3左右；干燥后的木材质量符合乐器制作的要求。本试验确定的干燥工艺可适用楔形不规则乐器用材，还可进行不同规格乐器用材的混合干燥。     

Effect of EMC and air in wood on the new in-process moisture content monitoring concept under radiofrequency/vacuum (RF/V) drying

To improve the accuracy of the new in-process moisture content (MC) monitoring concept under radiofrequency/vacuum (RF/V) drying, equilibrium moisture content (EMC) tests were carried out under various ambient pressures, and pressure curves in wood were analyzed during chamber evacuation and heating phases. The results showed that EMC increased with a decrease in ambient pressure regardless of temperature, relative humidity (RH), and species. The accuracy of MC estimation for Hinoki under RF/V drying was improved from 1.5% maximum absolute errors to 0.6% after EMC modification. The pressure curves for Hinoki and Sugi under RF/V drying showed similar tendencies to an idealized process. Russian larch showed different curves, indicating that the pressure in the wood did not reach the ambient pressure because of its low permeability. Therefore, MC could not be estimated using this monitoring concept because of the presence of much air in the wood of Russian larch.