摘要:

Fractions of tissue from the secondary wall and middle lamella of black spruce wood were pulped by the kraft, acid-sulphite and acid-chlorite methods. In all cases, the delignification of the secondary wall tissue was more rapid than that for the middle lamella tissue. This topochemical effect was largest in kraft pulping. In acid-sulphite pulping the effect was less than in kraft, while in acid-chlorite pulping the effect was smallest. Thus the results confirmed in general the previously reported trends based on microscopic observation. However, in earlier work there was no topochemical difference found in acid-chlorite pulping, even at high delignification. In the present work, the topochemical effect in acid-chlorite pulping increased rapidly above 50% delignification.

ISSN:0277-3813    

DOI:10.1080/02773818108085108

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Vanillyl alcohol, a simple lignin model, has been heated with alkali under a variety of conditions and in the presence of several additives. The level of condensed products, principally dimers and trimers, has been determined in each case. Some additives, such as sulfide and anthraquinone, showed few differences from the control. Other additives, such as anthrahydroquinone, dithionite and 3,5-dinitrobenzoic acid, greatly depressed the levels of condensation products. The detection of a minor product, a head-to-head dimer, suggests some radical intermediates are present under these reaction conditions. The degree of condensation and ratio of products was quite temperature dependent. The influence of selected additives on the condensation reactions of a dioxane lignin has also been studied.

ISSN:0277-3813    

DOI:10.1080/02773818108085109

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Several experiments have been performed to show the effects of anthrahydroquinone (AHQ), the reduced form of anthraquinone (AQ), on the self-condensation reactions of simple lignin models. These experiments were aimed at understanding the role of AQ as a wood pulping catalyst. The experiments led to some very complex product mixtures. A detailed analysis of the product mixtures by gas chromatography - mass spectrometry (GC/MS) was undertaken in order to understand how AHQ retarded phenolic-quinonemethide condensation reactions. The interpretation of the mass spectra is reported here. Two principal classes of compounds are discussed: phenolic condensation products and adducts derived from the reactions of quinonemethides with AHQ and anthrone. A method of volatilizing the sample prior to GC/MS analysis, namely derivatization with dimethyl sulfate In alkaline THF, produces by-products which contain incorporated THF.

ISSN:0277-3813    

DOI:10.1080/02773818108085110

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Different mixture rates of the redox pulping additives anthraquinone with anthraquinone-2-sulfonate, and of benzindazoledione with rosindonesulfonate were investigated. The experimental results showed that additives in mixtures very strongly influence each other's efficacy. The degree of coupling indicates that the square root relationship is best explained by kinetics of the chemical reaction mechanism and not by mass transfer processes.

ISSN:0277-3813    

DOI:10.1080/02773818108085111

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The efficacies of phenazine, phenazone and rosindone derivatives as additives in alkaline pulping were investigated and compared. Phenazones and rosindones are superior to the phenazines described earlier. Equimolar charges of rosindone sulfonate stabilize carbohydrates more than anthraquinone (vM∼l.l) but the de-lignification effect is slightly inferior (rM= 0.72). Due to low solubility rosindone does not follow the square root relationship. Low rosindone charges (<0.1%) catalyze delignification as efficiently as anthraquinone (rM∼1).

ISSN:0277-3813    

DOI:10.1080/02773818108085112

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Graft polymerization techniques were applied to induce bonding in wood composites. Wood surfaces were activated with an oxidant such as hydrogen peroxide, nitric acid, peracetic acid, potassium ferricyanide or sodium dichromate. The activated wood surfaces were then chemically crosslinked with polymerizing materials such as furfuryl alcohol, ammonium lignosulfonate, mixtures of lignosulfonate with furfuryl alcohol, with formaldehyde or with maleic acid. The wood composites were pressed using conventional manufacturing conditions. The strength and water resistance properties of the wood composites were suitable for exterior structural applications. The various methods proposed to induce chemical bonding of wood are briefly reviewed.

ISSN:0277-3813    

DOI:10.1080/02773818108085113

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The conversion of cellulose in homogenous solution to hydrolysis, dehydration,and oxidation products was investigated. A reaction sequence involving acetylation and degradation by aqueous acids led to humic acid, hydroxymethylfurfural, and levulinic acid as the isolated end-products. The influence of various reaction parameters upon the yields was studied.In the presence of ferric chloride some furfural was formed in addition to the other products.

ISSN:0277-3813    

DOI:10.1080/02773818108085114

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:0277-3813    

DOI:10.1080/02773818108085107

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor