Vapor phase reaction of wood with maleic anhydride (II): mechanism of dimensional stabilization

The vapor phase reaction of wood with maleic anhydride (MA) was investigated from the aspect of the mechanism of dimensional stabilization. Notably the existence of cross-links was examined by detailed analyses of dimensional stability and related properties, diffuse reflectance infrared Fourier transform (DRIFT) spectra, and changes in mechanical properties such as creep property and vibrational property. Higher reaction temperature resulted in less leaching of reagent. Also a peak in DRIFT spectra at 1730 cm⁻¹ showed the esterification of wood components with MA, while that at around 1780 cm⁻¹, which became remarkable with increasing reaction temperature, suggested the formation of cross-linking. The loss tangent decreased and the creep deformation was restrained for the specimens treated at high temperature. From these results it is plausible that MA mainly forms monoester with wood components at lower temperature; however, at elevated temperature cross-linking appears in addition to formation of the monoester.     

双戊烯合成萜马加成物反应的动力学及主产物结构的研究

以稀土金属氧化物为催化剂，催化工业双民顺丁烯二酸酐连续进行异构／Ｄｉｅｌｓ－Ａｌｄｅｒ反应，合成出萜烯／马来酸酐加成物；用气相色谱法跟踪研究了反应的进程，并模拟了反应反动力学方程，鉴定了主产物的结构，结果表明动力学方程的拟合精度好，平均相对误差小于２．５％；产物中绝大部分是正常的双烯加成物。     

汽蒸处理改善木材尺寸稳定性初探

木材经过汽蒸处理及干燥后,制成的木地板在潮湿或干燥的自然环境中使用,其尺寸稳定性优良,大大提高了木地板的质量。     

木纤维－聚乙烯复合材料中聚乙烯改性的研究

本研究采用马来酸酐（ＭＡ）对线型低密聚乙稀（ＬＬＤＰＥ）作改性处理，并找出用于木纤维－塑料复合材料的聚乙稀－马来醚酐共聚物的适宜制备工艺条件。研究结果表明，在自由基引发条件下，ＬＬＤＰＥ－ＭＡ共聚物的形成是可行的。红外光谱及接枝率测定显示了在非极性的ＬＬＤＰＥ分子中极性基团的存在。通过改变工艺多数，ＭＡ对ＬＬＤＰＥ的接枝率有较大提高。极性共聚物对木纤维－塑料复合材料的制备具有现实意义。     

国外结构人造板尺寸稳定性的研究技术

国外结构人造板(如定向结构板、大片刨花板、华夫刨花板等)主要用作建筑材料,对产品的尺寸稳定性要求很高,许多研究者在如何提高产品尺寸稳定性方面作了大量的研究工作。文中综述了大量的科研成果,介绍了国外结构人造板尺寸稳定性的研究技术,包括引起结构人造板尺寸不稳定的缘由,结构人造板尺寸稳定性的评价方法,影响结构人造板尺寸稳定性的工艺因素以及提高结构人造板尺寸稳定性的措施。     

高温热压干燥对紫椴小径材材性的影响

研究了椴木薄板热压干燥基本规律,以及热压温度、时间与含水率的关系;并对经热压干燥的板材与103℃烘干板的吸湿性、脆性进行对比。研究结果表明:高温热压后的板材吸湿性降低,尺寸稳定性好,但热压温度过高会产生木材热分解,冲击强度略有降低。高温热压干燥板材能满足铅笔用材要求。     

中密度纤维板的尺寸稳定性改良技术

中密度纤维板(MDF)是目前家具、室内装修等最常用的木质复合材料之一,其尺寸稳定性直接影响到产品的使用性能、使用寿命以及产品应用领域的拓展和附加值的提高.笔者概述了中密度纤维板尺寸稳定性的影响因素以及中密度纤维板尺寸稳定性方面的相关研究进展,并在此基础上提出今后研究的方向.     

后期热处理对酚类胶室外用刨花板尺寸稳定性的影响

研究了后期热处理对酚类胶室外用刨花板尺寸稳定性的影响,结果表明,后期热处理可以有效降低酚类胶刨 花板的吸水厚度膨胀率（ＴＳ）,提高刨花板的尺寸稳定性,对强度性能指标影响不显著。在１９０℃温度下处理１５ｍｉｎ, 酚醛胶杨木刨花板的ＴＳ下降了１８．５３％,酚醛胶落叶松刨花板的ＴＳ下降了２４．６３％,单宁胶杨木刨花板的ＴＳ下 降了３０．６４％,单宁胶落叶松刨花板的ＴＳ下降了２４．４９％。     

杉木／二氧化硅复合材料的制备及其尺寸稳定性

用满细胞法将高固含量的二氧化硅溶胶压注入杉木,制备出杉木/二氧化硅复合材料,并用扫描电子显微镜(SEM)对复合材的微观结构进行了表征。研究表明:复合材的抗膨胀系数(ASE)、阻吸湿系数(MEE)分别增加了32.6%和14.8%,材料的尺寸稳定性能明显提高。     

PARTICLEBOARD STRESS RELAXATION THROUGHOUT MECHANO-SORPTIVE CREEP OF GLUELINES

Anumberofinveshgationsonmethodslbrcontrollingpaticleboardstabilityhavebeenmade,andmostofthemconcentrateonstabilisingthewood.substance.MakuandSasaki(l956)foundthatswellingandtvaterabsorptionofboardsmadefromheattreatedflakesdecreasedwiththeseverityoftreatment.ThisagreeswiththeworkofLehmann(l964)whofotmdthestabilityofparticleboardtoim-provewhenmadewithparticlestreatedat2o5C\"forl5,3o,45niinutes.ThemechanicaIpropertieswere,however,adverscl}'affcctedbecauscofen1brittlementofthextood.Tl1iseffecthas…     

超薄锯材尺寸稳定性的热改性研究

超薄锯材厚度方向约束力小,易受周围环境影响,极小的应力应变易导致变形。针对超薄锯材的特点,采用高温热压工艺对其表层进行了改性处理。研究结果表明,在温度170℃、压力0.5MPa、时间5min的工艺条件下,采用双面覆网处理,可有效改善阿尤斯超薄径切锯材的尺寸稳定性;热改性材随周围介质状态变化影响较小,吸水性及吸湿性明显降低,表明锯材已发生部分高温热降解。     

碱处理兴安落叶松材改性的研究

采用１％ＮａＨＣＯ＿３水溶液对兴安落叶松（Ｌａｒｉｘｇｍｅｌｉｎｉ）木材进行了处理，并用红外光谱、扫描电子显微镜和化学分析等方法对处理前后木材的尺寸稳定性、吸湿性、官能团和超微构造的变化进行了比较和分析。从而确定影响兴安落叶松木材尺寸稳定性的主要因素。本究研为兴安落叶松木材的改性和利用提供了理论依据。     

松油烯与马来酸酐的环加成反应的条件研究

研究了松油烯与马来酸酐的D iels-A lder环加成反应和松油烯的异构转化率。使用相对于α-松油烯过量的马来酸酐,在65~70℃、100~105℃和135~140℃时α-松油烯的异构转化率分别为15%、38%和69%。采用异核远距离关联(HMBC)等核磁共振测试手法解析了环加成产物的结构,归属了各原子的化学位移。     

马尾松,麻栎,江南桤木用聚乙二醇改性的研究

本文研究了马尾松、麻栎、江南桤木三种木材用聚乙二醇（ＰＥＧ）改性的工艺条件及效果。结果表明，三种改性材经过长时间自然存放，抗收缩率可这８０％以上，并且其耐腐性能提高，尺寸稳定性好。     

Potassium acetate-catalyzed acetylation of wood at low temperatures II: vapor phase acetylation at room temperature

Ezomatsu wood blocks were impregnated with potassium acetate (KAc) and then exposed to acetic anhydride vapor at 25°C and 120°C. The KAc-impregnated wood was rapidly acetylated at 120°C, and only 6 min was needed to achieve 20% weight percent gain (WPG). The WPG increased with increasing catalyst loading (CL), but it turned to decrease above 20% CL probably because the diffusion of acetic anhydride vapor was hindered by excess KAc depositing in the cell lumina. Thus, careful control of CL is necessary in the vapor-phase acetylation. KAc was also effective in catalyzing the vapor-phase acetylation at 25°C: the KAc-impregnated wood attained 20% WPG within 7 days, whereas the WPG did not exceed 10% even after 1 month in the uncatalyzed system. Irrespective of treatment methods, the hygroscopicity of wood was reduced and its dimensional stability was improved with an increase of WPG. These results confirm that the use of KAc simplifies the acetylation process at room temperature with minimal loss of acetic anhydride.     

Dimensional stability of wood acetylated with acetic anhydride solution of glucose pentaacetate

Five wood species were acetylated with acetic anhydride (AA) solution of glucose pentaacetate (GPA) at 120°C for 8h, and the effect of GPA on the dimensional stability of the acetylated wood was investigated. Some GPA was introduced into the wood cell wall during acetylation. The GPA remaining in the cell lumen penetrated the cell wall effectively after heating to more than 140°C for 10min. The bulking effects of GPA resulted in a 10%–30% increase in the anti-swelling efficiency of the acetylated wood with 20% GPA/AA solution in place of AA. Hydrophobic GPA did not deliquesce under highly humid conditions and it remained in the cell wall after boiling in water.Part of this paper was presented at the 51st Annual Meeting of the Japan Wood Research Society, Tokyo, April 1988     

改性异氰酸酯稻草刨花板的吸湿特性

在实验室压制的改性异氰酸酯稻草刨花板,采用室温水浸法,揭示板子在高湿环境中的尺寸稳定性以及吸湿行为,探讨密度(0.60、0.75、0.90g/cm3)、施胶量(3％、4％、5％)和石蜡含量(0、1％、1.75％、2.5％、3.75％)对板子湿性能的影响。结果表明,稻草刨花板具有明显的湿膨胀行为,该过程受到密度和施胶量的影响。石蜡的施加,对板材的力学性能没有明显的影响,但有效地控制了尺寸的变化。吸着饱和点SSP是刨花板吸湿变形的临界含水率。     

木材的尺寸稳定性处理

尺寸稳定性处理是提高木材应用范围的主要途径之一，处理方法很多，效果各异。本文广泛收集当今在木材尺寸稳定处理方面的研究成果，对各种处理方法作了概括性的阐述，可为从事该方面研究和应用的人员提供理论支持和参考。     

Potassium acetate-catalyzed acetylation of wood at low temperatures I: simplified method using a mixed reagent

Ezomatsu wood blocks were acetylated in a mixture of acetic anhydride and acetic acid containing excess potassium acetate (KAc). The mixture method enabled rapid acetylation at 120°C: a 20% weight gain (weight percent gain; WPG) was achieved within 30 min while the WPG did not exceed 18% after 120 min of conventional uncatalyzed acetylation. At 40°C, however, a satisfactory WPG was not achieved with the mixture method because both the wood swelling and KAc concentration in the reagent solution were limited at that temperature. In addition, the antiswelling efficiency attained by the mixture method was irregularly low, probably because of nonuniform reaction involving shrinkage of the cell lumina. These results suggest that the mixture method is not advantageous for low-temperature acetylation, whereas it enables simple and rapid acetylation at high temperature.