摘要:

Methoxyhydroquinone was detected in the spent liquors of peroxide-bleached loblolly pine thennomechanical pulp. The potential effect of this leucochromophore and the corresponding quinone on the brightness and brightness stability of mechanical pulps bleached with peroxide is discussed.

ISSN:0277-3813    

DOI:10.1080/02773818208085132

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Kraft pulps contain a considerable amount of transition metal ions. It is demonstrated that unless these ions are thouroughly removed, alkaline hydrogen peroxide is an inefficient bleaching agent for kraft pulps due to a rapid decomposition into oxygen. If, on the other hand, the metal ions are removed from the pulp prior to bleaching under carefully selected conditions, alkaline hydrogen peroxide can be used to increase considerably the brightness of kraft pulps without seriously affecting the pulp viscosity.

ISSN:0277-3813    

DOI:10.1080/02773818208085133

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

A lignin - carbohydrate complex (LCC) fraction which was initially extracted with dimethyl sulfoxide from birch residual wood meal after stepwise MWL extraction (total yield 28%), contained about 7% qalacturonic acid together with about 4% glucuronic acid. Although galacturonic acid residue is well known to be a component of hardwood xylan, it also suggests the possibility of the existence of pectic substance in this LCC fraction.

ISSN:0277-3813    

DOI:10.1080/02773818208085134

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The reactions of 1-phenylethanol and 1-phenylethanethiol, either alone or together, with AMS in alkaline 50Z aqueous dioxane at 88* have been studied. The mercaptan is oxidized several hundred times faster than the alcohol. The results imply that benzyl mer-captans, such as those produced during the kraft pulping of wood, could serve as reaction partners in the reduction of anthraquinone to anthrahydroquinone during kraft/anthraquinone pulping.

ISSN:0277-3813    

DOI:10.1080/02773818208085135

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Differential thermal analysis (DTA) and gravimetric thermal analysis (GTA) were evaluated as techniques for determining the activation energy (E) of the pyrolysis of kraft black liquor. Although more time consuming, DTA gave more meaningful values that were independent of the heating rate and of the (usually unknown) order of the reaction. The use of GTA required assumptions concerning order of reaction, but might be useful for rapid screening. The results may be significant for recovery furnace operation, because the higher Ea, the more difficult it is to maintain combustion. Some typical values of E, in cal/mol, (obtained under a nitrogen atmosphere) for the first exothermic reaction (temperature, °C, in brackets) are: kraft black liquor, 19,400 (290–350); glucose, 9,610 (320–450); kraft liquor plus 10% glucose, 11,100 (240–330); kraft lignin, 7,860 (345–420); spruce wood, 38,100 (290–310).

ISSN:0277-3813    

DOI:10.1080/02773818208085136

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

A new procedure has been developed for the synthesis of g-substituted β-aryl ether lignin model dimers: models capable of generating quinonemethides in alkaline solutions. The process involves selective alkylation of the β-carbon of an unprotected a-keto-β-aryl ether model, followed by borohydride reduction and treatment with acetylchloride. A sampling of different alkylating agents Indicates that the process Is limited to very simple electrophiles. Attempts to prepare α-hydroxy-β-aryl ether lignin models by stereospecific ring openings of styrene and substituted styrene oxides met with no success.

ISSN:0277-3813    

DOI:10.1080/02773818208085137

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Solid wood panels (Acer saccharum Marsh.) were bonded with various bridging materials following nitric acid activation. These chemical bridging materials included tannin, furfuryl alcohol and mixtures of the two with and without maleic acid. High shear strengths were achieved with a tannin-furfuryl alcohol-maleic acid mixture (T-F-M) with or without the nitric acid activation.

ISSN:0277-3813    

DOI:10.1080/02773818208085138

出版商:Taylor & Francis Group    

年代:1982

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:10.1080/02773818208085131

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor