杨木爆破处理及制板的研究

用Ｉ－７２杨为原料，经高温高压爆破处理，处理后的杨木各化学组分发生变化，用不同的分析方法对各组分进行分析。在不加任何化学助剂的条件下，依靠自身化学组分的转化，对爆破处理过的试材，经热压制出刨花板。分析研究压板前后化学组成变化和板材物理力学性质，其结果为：①比较不同爆破条件下，同一种试样化学组成的变化，爆破条件越激烈，纤维素降解越显著，收获率超低；游离糖则相应增加；木质素含量先增加，然后降低；热水抽出物含量也是先增加，然后再降低。②扫描电镜观察爆破处理后的试样，纤维排列有变化，整齐的排列变为弯曲和分开。③经爆破处理的试样相对结晶度增加，结晶区增加。总之，爆破后的试材可压制出耐水性能好的刨花板。     

加热法对石膏刨花板性能影响的研究

研究了加热温度和加压时间对石膏刨花板性能的影响。试验结果表明石膏固化时加适量的热量有助于提高石膏刨花板的性能;加热温度较高时石膏刨花板的性能比常温条件下压制的板的性能低。石膏固化时是吸热反应,石膏刨花板加压固化时,外加一定的热量有助于提高石膏的固化强度,因此板具有较好的物理力学性能。     

采用固化剂缩短酚醛胶刨花板热压时间的研究

采用添加固化剂的方法，对降低酚醛树脂胶刨花板的热压时间进行了研究。通过筛选试验，选出了加速酚醛胶固化效果比较好的固化剂Ｎ，同时探讨了固化剂Ｎ的用量与酚醛树脂胶聚合时间之间的关系，进而确定了固化剂Ｎ的合适用量。试验结果表明，当固化剂用量为２％时，１６ｍｍ厚的酚醛树脂胶刨花板的热压时间可以从１４ｍｉｎ缩短到１０ｍｉｎ，热压时间缩短了２８．５７％。     

Veneer strand flanged I-beam with MDF or particleboard as web material II: effect of resin type,application rate,strand dimension,and pressing time on the basic properties

Optimization of the manufacturing conditions of the veneer strand flanged I-beam invented in the previous study was investigated using different combinations of strand dimensions, resin types between web and flange, different pressing times, and different wood–resin moisture contents under conventional hot pressing conditions. The main results revealed that the strand dimensions have no effect on the bending properties of the flange part and the dimensional stability of the I-beam. Increasing the resin application rate between strands was found to improve the dimensional stability of the I-beams. The use of isocyanate (MDI) resin between web and flange significantly improved the bond strength between web and flange, the modulus of rupture of the I-beam, and the modulus of rupture of the flange part. Dimensional stability was also improved. Shortening the pressing time from 20 to 12min was found to be feasible. Using low wood-resin moisture content was found to interfere with the curing of the phenol–formaldehyde (PF) resin at the flange part resulting in poor quality beams. Of the three moisture content levels tested, 12% was found to be the optimal level for producing I-beams with balanced mechanical properties and dimensional stability.Part of this work was presented at the 53rd Annual Meeting of the Japan Wood Research Society, Fukuoka, March 2003     

Compressive deformation of wood impregnated with low molecular weight phenol formaldehyde (PF) resin II: effects of processing parameters

To obtain high-strength phenol formaldehyde (PF) resin-impregnated compressed wood at low pressing pressure, the effects of resin content, preheating temperature, pressing temperature, and pressing speed on the compressive deformation of oven-dried low molecular weight PF resin-impregnated wood was investigated. With an increase of PF resin content, the Youngs modulus of the cell wall perpendicular to the fiber direction decreases, and collapse-initiating pressure decreases linearly with the Youngs modulus. This indicates that the occurrence of cell wall collapse is strain-dependent. By increasing preheating temperatures, the collapse-initiating pressure increases due to the increment of the Youngs modulus of the cell wall. An increase in pressing temperature results in the thermal softening of the cell wall and causes collapse at a lower pressure. The wood is compressed effectively despite accelerated resin curing. The pressing speed significantly affects the viscoelastic deformation of the cell wall and the wood is well deformed with decreasing pressing speed, although the differences in density and mechanical properties are relatively small after a pressure-holding period of 30min. In all the parameters examined in this study, the Youngs modulus and bending strength increase with increasing density.     

喷蒸真空热压水溶性酚醛胶杨木大片刨花板

我国防水人造板生产目前普遍采用酚醛树脂胶（PF），热压周期长，生产效率低。笔者采用南京林业大学饱和蒸汽喷蒸试验压机，压制水溶性PF胶杨木大片刨花板。结果表明，采用喷蒸真空热压（SIVP）技术，热压时间可缩短到传统热压的35％左右；板的吸水厚度膨胀率（TS）缩小33％；在相同施胶量下，板的内结合强度（IB）提高的15％，同时甲醛释放量降低约24％；但板的抗弯性能有较大幅度的下降；此外，板材芯层最低密度值比传统热压的板增高，断面密度分布趋于均匀。     

向日葵秆制备刨花板工艺研究

为了用向日葵秆制备性能优越的刨花板,本研究在不同的工艺参数下压制了12块刨花板样本进行比较,得出板材压制的最佳工艺参数分别为;热压温度155℃,热压压力4．0-5．0MPa,热压时间5-6min。并且采用了无毒脲醛树脂胶黏剂。该项技术具有环保、廉价、投资少等优点。     

Influence of pressing parameters on mechanical and physical properties of self-bonded laminated beech boards

Abstract

Five-ply self-bonded boards were obtained by pressing beech veneers parallel to the grain without additional adhesives, steam or pre-treatment. Fifteen different combinations of pressing parameters were tested, including temperature (200°C, 225°C and 250°C), pressure (4, 5 and 6 MPa) and pressing time (240, 300 and 360 seconds). Due to severe pressing conditions, the new product showed a higher density and different properties compared to a conventionally glued laminated wooden board. The self-bonding quality was assessed through dry shear strength tests, through a three-point bending test and a water-soaking test at 20°C. The dimensions in the cross section of the boards were measured after soaking in water. Results show that the choice of pressing parameters affects all the mechanical and physical properties tested. A statistical analysis revealed that the pressing temperature is the most influential parameter. Boards pressed at 200°C delaminated rapidly in water, whereas boards pressed at 225°C delaminated only at core-positioned layers after 48 hours and boards pressed at 250°C did not delaminate at all in water. Compared to panels pressed at lower temperatures, boards pressed at 250°C had the highest density, a higher shear and bending strength and a lower water absorption.     

应用ANSYS Workbench对大断面集成材压机机架的优化设计

利用ANSYS Workbench有限元分析软件对大断面集成材压机机架的单个框架进行了静力学分析,以其质量与强度指标为目标,采用ANSYS Gold Driven Optimization模块进行优化设计,旨在研究框架工作过程中的应力、应变分布状态,降低框架生产成本。研究结果表明:优化前,框架存在局部应力集中现象,但最大应力为156.2 MPa,明显小于框架的许用应力196 MPa,强度富余,有进一步优化的空间;水平和垂直方向的最大位移值分别为0.31、0.08mm,刚度可靠。优化后,框架的最大等效应力与最大位移分别为179.8 MPa与0.44 mm,保证框架强度与刚度的前提下,框架的质量降低了26.3%,可显著降低生产成本。     

西瓜染色体压片技术改进研究

以西瓜根尖和花蕾为试验材料,进行了不同取样时间、不同预处理、不同解离时间处理后压片观察染色体试验,确定了西瓜根尖和花粉母细胞染色体观察过程中的取样、预处理、固定、解离时间以及染色体压片观察中的主要参数和方法,建立了一套简便快捷的观察西瓜染色体的系统操作规程。