人工林杉木胶合工艺优化研究

采用SAS全因子试验设计,研究了胶粘剂类型、涂胶量、单位压力、加压时间和胶合面纹理五个因子对人工林杉木木材胶合性能的影响,并对其胶合工艺进行了优化。研究结果表明:胶粘剂类型对杉木木材常态胶合剪切强度和木破率的影响不显著,但是老化处理后API和PF的胶合剪切强度和木破率比PVAc和UF的要高;在以API为胶粘剂时,涂胶量、单位压力、加压时间和胶合面纹理对杉木胶合剪切强度和木破率的影响显著,优化的胶合工艺为涂胶量250g/cm2,单位压力1.5 MPa,加压时间50 min和胶合面纹理为弦切面-弦切面。     

落叶松、桦木和柞木集成材胶接性能的研究

描述了应用水性高分子异氰酸酯(API)胶粘剂制造的落叶松、桦木和柞木集成材的胶接性能,试验结果表明:柞木的常态压缩剪切强度最高,其次是桦木,最小的是落叶松。而对于剥离率,柞木的最高,其次是落叶松,桦木最低。     

坡向对马占相思人工林生长和材质的影响

通过对阴坡和阳坡马占相思人工林生长特性和木材物理力学性质的测定和比较分析，结果表明：阳坡马占相思人工林林分胸径、冠幅、树高和枝下高大于阴坡；阴坡马占相思人工林木材密度、干缩系数和各项力学性质指标均小于阳坡马占相思人工林；阴坡马古相思人工林木材物理力学性质的分散程度略大于阳坡马占相思人工林，差异显著性t检验表明：阴坡和阳坡马古相思人工林林分胸径、树高、冠幅和枝下高以及差异干缩、顺纹抗压强度、抗弯强度、抗弯弹性模量、弦面抗劈力差异均为极显著或显著；而木材密度、径向干缩系数、弦向干缩系数和体积干缩系数以及顺纹抗剪强度、硬度、径面抗劈力和冲击韧性均差异不显著。研究结果为马占相思人工林培育和木材合理利用提供科学依据。     

基材对API胶黏剂粘接强度的影响

对水性高分子聚合物为主剂、异氰酸酯为固化剂的API胶合体系进行了研究,主要考察了被粘接基材的类型、试材的弦、径向以及偶联剂处理基材对API粘接强度的影响。实验结果表明:用于胶合试材的种类和试材的密度、试材的纹理走向对胶合强度均有影响,偶联剂HMR对改善胶的耐热、耐水性能,提高胶合面的木材破坏率效果显著。     

六种人工林木材胶合性能初步研究

初步研究了杉木、杨树、巨桉、尾巨桉、柠檬桉和窿缘桉等六种人工林木材的胶合性能,结果表明:胶合剪切强度沿杉木、杨树、巨桉、尾巨桉、柠檬桉和窿缘桉顺序增大;六种木材胶合性能差异显著,其中杉木、杨树、巨桉和尾巨桉胶合性能较好,表现为胶合剪切强度能达到标准要求、且木破率高;柠檬桉和窿缘桉木破率低,难于胶合,胶合性能有待改进;胶粘剂类型影响木材胶合性能,其中API和PF剪切强度和木破率平均值高于PVAc和UF;热压胶合的PF和UF的离散性比冷压胶合的API和PVAc要差。     

不同更新方式闽奥栲材质的比较研究

通过对3种不同更新方式（天然更新、人促更新、人工更新)闽奥栲木材物理力学性质和抽出物含量的测定和比较分析，结果表明：人促更新闽奥栲木材各项物理力学性质稍大于人工更新和天然更新；而天然更新闽奥栲木材抽出物含量稍大于人促更新和人工更新。经差异显著性R检验表明：人促更新和人工更新闽奥栲木材各项物理力学性质指标均差异不显著；人工更新和天然更新除冲击韧性差异显著外，其余物理力学性质指标差异不显著；天然更新和人促更新除抗弯弹性模量差异极显著，弦向干缩系数、体积干缩系数、顺纹抗压强度、径面顺纹抗剪强度、端面硬度、弦面抗劈力和冲击韧性差异显著外，其余物理力学性质指标差异不显著。研究结果为闽奥栲林分集约经营、优质高产培育和木材合理利用提供科学依据。     

抽提物抽提工艺对黎蒴栲木材弦界面性质的影响

采用分类试验方法,探索不同抽提工艺对黎蒴栲木材弦界面性质的影响。试验结果表明,黎蒴栲试件经苯-醇、热水、温水和冷水等抽提工艺处理后,用光学接触角测定仪测出水滴与其弦切面的接触角,比处理前均有不同程度的增大,表面自由能相应降低,而在碱抽提处理后,则水滴与其弦切面的接触角比处理前减小,表面自由能增大。可见,黎蒴栲木材可以通过不同的抽提处理来改变或控制其弦界面性质,达到界面设计的要求,从而改善其渗透性和胶合性能。     

俄罗斯樟子松物理力学性能的测定与分析

文章通过试验测定俄罗斯樟子松的密度、含水率、干缩率、顺纹抗压强度、横纹抗压强度、顺纹抗剪强度、抗劈力、抗弯强度、抗弯弹性模量等物理力学指标,并与国内樟子松进行比较发现,弦向气干干缩率、顺纹抗压强度、抗弯强度、抗弯弹性模量均低于国内樟子松,而气干密度和径向气干干缩率大于国内樟子松。     

家具实木胶接件剪切强度的测定与分析

在旧标准的基础上,完善了用力学试验机来测定实木胶接件剪切强度的试验方法。此次试验通过对钢制夹具进行的合理改良,提高了相关设备的精度,并分别选取楸木和柞木的胶接试件,在顺纹测试的基础上增加了横纹状态下剪切强度的测定。该试验的完善促成了新行业标准《家具实木胶接件剪切强度的测定》的修订,力求通过更为科学的测定方法和评价指标更好地确保家具产品的质量。     

PVC/木粉复合材料胶接件拉伸剪切强度的研究

参照国家标准GB/T 7124-2008《胶粘剂拉伸剪切强度的测定（刚性材料对刚性材料）》检测PVC/木粉复合材料胶合试件的拉伸剪切强度,发现：PVC/木粉复合材料胶合试件的断裂均发生在粘接区域外的复合材料本身,因而无法比较胶黏剂的粘接强度。为了能比较胶黏剂胶接接头的粘接强度,实验中将GB/T 7124-2008中规定的试件的厚度从1.6 mm加大至4mm。实验结果表明：采用环氧树脂粘接的PVC/木粉复合材料的拉伸剪切强度值高于用J-39丙烯酸酯胶黏剂粘接的复合材料的拉伸剪切强度。     

Influence of the degree of condensation of urea-formaldehyde adhesives on the tangential penetration into beech and fir and on the shear strength of the adhesive joints

The objective of this work was to evaluate the influence of the degree of condensation of urea formaldehyde (UF) resins on the tangential penetration into fir and beech and on the tensile shear bond strength of wood joints. Tangential penetration was determined by epi-fluorescence microscopy on microtome slides, exposing the bond line on a cross-sectional surface. The higher the degree of condensation (viscosity) of the resins, the lower is the possibility for penetration; beech showed higher penetration than fir. Bond strengths decreased with increased degree of condensation (viscosity) of the adhesives. Shear strength based on radial penetration was higher than for tangential penetration. The higher the penetration and the thicker, hence, the interphase, the higher was the achieved shear strength.     

常温固化大豆蛋白胶黏剂制备非结构集成材研究

研究利用豆粉、环氧类固化剂、水性弹性体乳液制备了一种常温固化大豆蛋白胶黏剂,并用于制备非结构集成材.结果表明,胶黏剂最优配方为18 g豆粉、82 g水、2.52 g环氧固化剂、36 g水性弹性体乳液,胶黏剂固体含量27.8％,适用期可达36 h;集成材优化制备工艺为涂胶量190～210 g/m2、加压时间3 h、加压压...     

Einfluß der Probengröße auf die Druckscherfestigkeiten würfelförmiger Fichtenholzproben

Shear strength parallel to the grain of solid spruce cubes was determined at different growth ring positions with specimens of varying dimensions. The smaller specimens showed higher shear strength values; they were cut precisely centrically from squared spruce timber. The lower values were found in the tangential shear plane, the higher ones in the radial plane. Solid specimens of varying sizes, taken from a lot of spruce logs showed almost the same shear strength. Glued cubic shear blocks of different sizes, taken side by side in axial direction from the same board, did not show any difference in shear strength. A clear influence of the specimens size could be observed with parallely laminated plywood ones. Tests with specimens of glue-laminated boards confirmed these observations. Smaller shear specimens, which were taken exactly centrical and immediately behind the greater ones presented always higher shear values than the larger ones. A joint test series of three research institutes resulted in absolute values of great concordance.     

胶黏剂种类对人造板内结合强度检测结果的影响

使用聚乙酸乙烯酯乳液（PVAc）、单组份聚氨酯（PUR）和热熔胶（EVA）3种胶黏剂粘结金属卡头与试件,检测并分析它们对强化木地板和地板基材用纤维板内结合强度检测结果的影响。结果表明：使用PUR粘结时检测的内结合强度值比使用PVAc、EVA高,其中强化木地板内结合强度高出0.47MPa,地板基材用纤维板内结合强度高出约0.40MPa。     

胶黏剂种类对人造板内结合强度检测结果的影响

使用聚乙酸乙烯酯乳液(PVAc)、单组份聚氨酯(PUR)和热熔胶(EVA)3种胶黏剂粘结金属卡头与试件,检测并分析它们对强化木地板和地板基材用纤维板内结合强度检测结果的影响。结果表明:使用PUR粘结时检测的内结合强度值比使用PVAc、EVA高,其中强化木地板内结合强度高出0.47MPa,地板基材用纤维板内结合强度高出约0.40MPa。     

Evaluation of glue line shear strength of laminated timber structures using block and core type specimens

Monitoring and evaluation of glued laminated timber structures in service is essential to warrant its integrity, where non-destructive techniques play an important role. This paper describes the results obtained on glued laminated timber beams of maritime pine, with and without preservative treatment, and of spruce, exposed to natural outdoor environment as well as to artificial weathering. The assessment of glue lines’ shear strength was investigated through the extraction and testing of cores parallel and perpendicular to the glued lines and block shear specimens with 50 mm?×?50 mm and 20 mm?×?20 mm shear area. The results highlight the different performances of the various types of specimens tested, showing that the measured shear strength depends on the specimen size and that the size effect depends on the material strength giving a decreasing modification factor with the increase of strength in opposition to the constant factor suggested by standard EN 14080. They also show that shear testing of cores drilled perpendicular to the glued joints may be a promising tool in the assessment of glulam structures on site.