多元羧酸与木材酯化反应的固体核磁共振谱ＣＰ／ＭＡＳ^CNMR的表征

本研究要用以多元羧酸为酯化剂，以无机盐为催化剂的交联体系，这一体系是新型的，水溶的，无毒害，无染的非甲醛系试剂并联体系，本文采用固体核磁共振谱ＣＰ／ＭＡＳ^CNMR，测定木才主要组成酯化反应的ＣＰ／ＭＡＳ^13CNMR波谱，归属主要谱线，分析了多元羧酸与木材交联应过程中主要组分的化学结构变化，结果表明，酯化反应，羧基碳的比率增加，芳香放和碳和羧基碳的比率减少，烷基碳的变化随着羧基碳的变化而改变，这一变化趋势与采用ＦＴＩＲ和ＥＳＣＡ得到的变化趋势一致。     

多元羧酸与木材交联作用的反应中间体I.多元羧酸的空间效应和化学结构

本研究采用以多元羧酸类化合物为酯化剂 ,以无机盐类和含氮化合物为催化剂的关联体系。这一体系是一类新型的、水溶性的、无毒害、无污染的非甲醛系试剂交联体系。本文采用FTIR光谱 ,测定了木材及主要组分在交联化处理过程中的化学结构变化 ;推测了多元羧酸与木材各组分的酯化过程经历酸酐反应中间体。     

多元羧酸与木材酯化反应化学分析光电子能谱ESCA的研究

采用化学分析光电子能谱ＥＳＣＡ分析了多元羧酸与木材交联反应过程中主要组分的化学结构变化。ＥＳＣＡ波谱表明：产物中Ｃ１（烷基碳）和Ｃ４（羧基和酯基碳）增加,Ｃ２（羟基碳）减少;Ｏ１（羧基和酯基氧的比率）增加,Ｏ３（羟基氧的比率）减少。从而证实：在催化剂作用下,提高反应温度,木材的化学组分能与多元羧酸化合物——１,２,３,４－丁烷基四甲酸发生酯化反应。这一分析结果与ＦＴＩＲ和ＣＰ／ＭＡＳ１３ＣＮＭＲ波谱分析所得到的结论一致     

多元羧酸与木材酯化反应化学分析光电子ESCA的研究

采用化学分析光电子能谱ＥＳＣＡ分析了多元羧酸与木材交联反应过程中主要组分的化学结构变化。ＥＳＣＡ波谱表明：产物中Ｃ１（烷基酸）和Ｃ４（羧基和酯基碳）增加,Ｃ２（羟基碳）减少;Ｏ１（羧基和酯基氧的比率）增加,Ｏ３（羟基氧的比率）减少,从而证实;在催化剂作用下,提高反应温度,木材的化学组分能与多元羧酸化合物－－１,２,３,４－丁烷基四甲酸发生酯化反应,定分析结果在ＦＴＩＲ和ＣＰ－ＭＡＳ＾１３ＣＮＭＲ波     

多元羧酸与木材交联作用的反应中间体：Ⅰ.多元羧酸的空间效应和化学结构

本研究采用以多元羧酸类化合物为酯化剂,以无机盐类和含氮化合物为催化剂的关联体系。这一体系是一类新型的、水溶性的、无毒害、无污染的非甲醛系试剂交联体系。本文采用ＦＴＩＲ光谱,测定了木材及主要组分在交联化处理过程中的化学结构变化;推测了多元羧酸与木材各组分的酯化过程经历酸酐反应中间体。     

pH值对多元羧酸与纤维素交联反应的影响

采用以多元羧酸为酯化剂,以无机盐类和含氮化合物为催化剂的木材交联体系,这是一类新型的,水溶性的,无毒害,无污染的非甲醛系列交联体系。本文推导了这类反应的ＰＨ值与溶液中离子浓变化平衡关系式,采用ＦＴＩＲ光谱分析了ＰＨ值对酯化纤维素和反应中间体的影响,     

多元羧酸与木材酯化反应特征和交联反应参数

本研究采用以多元羧酸类化合物为酯化剂,以无机盐为催化剂的交联体系。这一体系是新型的、水溶的、无毒害、无污染、木材交联反应未采用过的非甲醛系试剂交联体系。本文采用ＦＴＩＲ和ＣＰ／ＭＡＳ１３ＣＮＭＲ的光谱法确定了多元羧酸类化合物与木材交联反应产物的形成特征和交联反应参数。     

的催化作用

采用以多元羧酸为酯化剂，无机盐为催化剂的交联体系。这一体系是水溶的、无毒害的纤维素交联反应的非甲醛系试剂的交联体系。作者采用傅立叶转换红外光谱(ITIR)分析了多元羧酸与纤维素交联反应过程中催化剂次磷酸盐(NaH2PO2)的作用机理。结果表明：催化剂NaH2PO2对多元羧酸与纤维素酯化反应的两个过程都有催化作用，其两个过程为：1)多元羧酸脱水形成五元环酸酐中间体，NaH2PO2可以降低五元环酸酐中间体形成的温度，加速五元环酸酐的形成；2)五元环酸酐与纤维素亲核取代形成酯，NaH2PO2提高了酯化产物转化率，具有明显的催化作用。     

多元羧酸与木材交联反应对木材振动特性的影响

采用以多元羧酸为酯化剂 ,以无机盐类为催化剂的交联体系 ,进行木材交联反应 ,这是一类新型、水溶性、无毒害、无污染的非甲醛系试剂交联体系。本文分析了化学改性木材的振动特性变化。结果表明 ,用不同质量分数 1,2 ,3,4 -丁烷基四甲酸 (BTCA)处理西加云杉和美国扁柏木材的振动性能有所变化 :2树种的损耗角正切tanδ在纵向和径向有所下降 ;比动态弹性模量E ρ在纵向变化均不明显 ,随着抗胀缩率ASE上升变化不规则 ;声辐射阻尼系数E ρ3的变化类似于比动态弹性模量E ρ的变化 ;纵向和径向的周期能量损耗参数tanδ E均下降。     

多元羧酸类化合物对木材大压缩量变形的固定作用

以多元羧酸类化合物为酯化剂、以无机盐类为催化剂的交联体系是一类新型的水溶性、无毒害、无污染、木材交联反应未采用过的非甲醛系试剂交联体系。本文研究了这类非甲醛系试剂对木材大压缩量变形的固定作用,结果表明浓度９％的１,２,３,４丁烷基四羧酸处理大青杨试件,干状态的变形恢复率较低,沸水中变形恢复率接近于２７０１％。用１,２,３,４丁烷基四羧酸交联处理木材可以固定压缩变形,适宜的树脂浓度为９％。材色由偏红向偏黄方向转变。     

Properties of wood plasticization with octanoyl chloride in a solvent-free system

Diffuse reflectance Fourier transform infrared spectroscopy (DRIFT), solid state cross-polarization/magic-angle-spinning ¹³C-nuclei magnetic resonance spectroscopy (CP/MAS ¹³C-NMR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and thermomechanical analysis (TMA) were used in this study to elucidate the characteristics of wood sawdust after esterification. Results revealed that thermoplastic wood was produced by solvent-free esterification using octanoyl chloride. Increasing the duration of treatment enhanced the extent of esterification. After octanoylation, the crystallinity of wood sawdust was decreased, whereas thermoplasticity, hydrophobicity, and thermal stability were enhanced. The complete flow of the octanoylated wood meal was achieved at around 300°C under a force of 0.01 N, indicating that octanoylated wood sawdust is a good thermoplastic material.     

不同结晶指数纤维素的X射线光电子能谱分析

以离子液体处理纤维素得到不同结晶指数(Icr)的纤维素样品。对所得样品首次采用X射线光电子能谱(XPS)的C1 s能谱图与O1 s能谱图,来分析不同结晶指数纤维素分子的化学状态。结合纤维素固体核磁共振(CP/MAS13C NMR)的分析结果可知,纤维素的C2峰及O1 s1峰与纤维素大分子中的氢键关系密切,其峰面积相对含量与纤维素的Icr值呈现高度相关性,相关系数分别为r10.9992和r20.9679。     

13C CP/MAS nuclear magnetic resonance study of the peroxide bleaching of ultra high yield chemimechanical pulp produced from sound and spruce budworm killed balsam fir

Summary The chemimechanical pulping (CMP) of sound balsam fir and the subsequent peroxide bleaching of the CMP pulp were investigated using solid state ¹³C CP/MAS NMR. A parallel study was made of a CMP pulp produced from spruce budworm killed balsam fir. Changes in the lignin and hemicellulose components were readily evident. The residual lignin and carbohydrate macromolecules in dead balsam fir CMP appeared to be the same as those in the sound wood CMP, before and after bleaching.We are indebted to Mr. S. S. Johal and Dr. J. V. Hatton of PAPRICAN, Vancouver, B.C., for generously supplying the wood and pulp samples. We also appreciate the assistance of Dr. N. R. Jagannathan with the ¹³C CP/MAS NMR measurements. Financial support from NSERC, in the form of a Postdoctoral Fellowship (JMW) and operating grants (FGH), is gratefully acknowledged     

Mechanical and interfacial properties of plastic composite panels made from esterified bamboo particles

In this study, different extents of acetylated and butyrylated bamboo particle/plastic composites (BPPC) were produced by the flat-platen pressing process. The effect of esterification on mechanical and interfacial properties of BPPC was evaluated by a universal testing machine, X-ray diffractometer (XRD), ¹³C CP/MAS nuclear magnetic resonance (NMR) spectrometer, and scanning electron microscope (SEM). The results showed that the internal bond (IB) and wood screw-holding strength of BPPC were significantly increased after acetylation, even though the weight gain of acetylated bamboo particles was only 2%. In addition, SEM micrographs revealed that acetylated bamboo particles were effectively trapped by the polymeric matrix on the IB-fractured surface of BPPC. These results indicate that the interfacial interaction between the bamboo particle and the polymeric matrix can be enhanced through acetylation.     

Formaldehyde emission and high-temperature stability of cured urea-formaldehyde resins

A test method for measuring formaldehyde from urea-formaldehyde (UF) resins at high temperature was developed and used to assess the influence of the reaction pH on the formaldehyde emission and heat stability of the cured resins. Additionally, solid-state¹³C CP/MAS nuclear magnetic resonance (NMR) techniques were used to investigate the structure of cured UF resins before and after high temperature heating. Formaldehyde emissions during the cure were related to the UF resins' methylol group content. The heat stability of cured UF resins synthesized under strongly acidic conditions was much higher than that of the other resins, which were prepared in weakly acidic and alkaline media. Solid-state¹³C CP/MAS NMR spectra showed that formaldehyde emission from cured UF resins after heating is mainly ascribable to decreased methylol groups and dimethylene ether linkages. Significantly, it was revealed that uron structures characteristically found in the cured UF resin synthesized under strongly acidic medium indicated high heat stability.Parts of this paper were presented at the 44th annual meeting of the Japan Wood Research Society, Nara, April 1994; and at the 52nd annual meeting of the Forest Products Society, Merida, Mexico, June 1998     

固体核磁共振法对低甲醛释放脲醛树脂化学结构的研究

在采用液体核磁对3种低甲醛释放脲醛树脂化学构造进行分析的基础上,利用13CCP/MASNMR对脲醛树脂固化产物的化学结构进行了研究.结果表明,不同固化体系下,3种低甲醛释放脲醛树脂胶黏剂的固化历程不同,固化后树脂的结构有所差别.不添加固化剂时,脲醛树脂的固化交联反应程度低,固化产物中羟甲基含量高,甲醛释放量也随之增加.加入固化剂后,促进了羟甲基的固化交联反应,脲醛树脂固化产物中羟甲基含量普遍降低.3种固化体系下,UF-3羟甲基含量最高;在氯化铵为固化剂的条件下,UF-2羟甲基含量最低,为0.0582;不添加固化剂和复合固化体系条件下,UF-1羟甲基含量最低,分别为0.0784和0.0713.不同固化体系对不同种类脲醛树脂的固化效果不同,固化后树脂的结构不同,其力学性能和甲醛释放能力也不同.