Viscosities of Unbleached Alkaline Pulps. II. The G-Factor

Kubes, G. J.; Fleming, B. I.; Macleod, J. M.; Bolker, H. I.; Werthemann, Dietrich P.

doi:10.1080/02773818308085166

Cited by 18 publications

(21 citation statements)

References 4 publications

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“…12 The enhanced amounts of vinyl ether products observed here and by others when using amines may be related to elimination reactions of the adducts. Based on our results, the accelerated delignification rates by amines, in comparison to kraft, 5 are not due to enhanced fragmentation of QMs. Other explanations have been offered: enhanced fragmentation of nonphenolic structures 14 and changes in cooking liquor redox potentials.…”

Section: Discussionmentioning

confidence: 54%

“…The phenol selected for reaction with model 1 was 2,6-xylenol (5). This phenol has been studied by others and is generally considered to be a highly reactive phenor in alkaline systems.…”

Section: Reactions Of Model 1 With Phenols and Carbohydratesmentioning

confidence: 99%

“…The former two were examined because they are present in pulping liquors and their reactions with lignin quinone methide (QM) intermediates can lead to residual lignin products: phenol-lignin condensation and lignin-carbohy- drate complex (LCC) products, respectively. 3 -4 Amines were investigated because they have been reported to enhance delignification and produce strong pulps; 5 we wanted to rank their ability to fragment lignin with that of other pulping additives. The rate of initial phase delignification is dominated by quinone methide formation.…”

Section: Introductionmentioning

confidence: 99%

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Competing Reactions Affecting Delignification in Pulping Systems

Brogdon¹,

Dimmel²

1996

Journal of Wood Chemistry and Technology

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Reactions of l-(4-guaiacyl)-2-(O-guaiacyl)-l,5-pentanediol (1) provide information on the relative rates of pulping reactions that involve quinone methides (QM). The lignin model was treated with 2,6-xylenol, 1,5-anhydrocellobiitol, amylose, and amines; the levels of fragmentation and cyclization were determined. The results indicate that condensation reactions between the QM derived from 1 and phenolates or carbohydrates are much slower than fragmentation reactions of 1 with sulfide or anthrahydroquinone. The addition of amines to soda cooks of 1 provided little additional model fragmentation; instead, a vinyl ether was observed in substantial amounts.

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Section: Discussionmentioning

confidence: 54%

“…The phenol selected for reaction with model 1 was 2,6-xylenol (5). This phenol has been studied by others and is generally considered to be a highly reactive phenor in alkaline systems.…”

Section: Reactions Of Model 1 With Phenols and Carbohydratesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Competing Reactions Affecting Delignification in Pulping Systems

Brogdon¹,

Dimmel²

1996

Journal of Wood Chemistry and Technology

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“…11-11. (Fleming et al 1978;Kubes et al 1980;Algar et al 1980;Eckert, Amos 1981). the reduced form of anthraquinone (AHQ) reacts with lignin and is itself oxidized to AQ.…”

Section: Hzc-k)mentioning

confidence: 99%

“…AQ causes an oxidation of aldehyde end-groups to alkali-stable aldonic acids of different types and amounts, itself being reduced to anthrahydroquinone (AHQ) (Löwendahl, Samuelson 1977. ), itself being oxidized to AQ (Fleming et al 1978;Kubes et al 1980). ), itself being oxidized to AQ (Fleming et al 1978;Kubes et al 1980).…”

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confidence: 99%

11. Reactions in Alkaline Medium

1983

Wood

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Pulp

Brännvall¹

2020

Kirk-Othmer Encyclopedia of Chemical Technology

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Global virgin pulp production in 2017 was 196 million tonnes. Combined with recycled fibers, the global paper and paperboard production was 413 million tonnes with packaging paper being dominant. The two major chemical processes, kraft and sulfite, cook wood chips at high temperature and pressure to liberate fibers after about 90% of the lignin is dissolved to allow the release of pulp fibers without mechanical force. The mass yield of chemical pulp is 45–55% because most hemicelluloses and some cellulose are also dissolved. Kraft pulp represented 83% of a total chemical pulp production of 123 million tonnes in 2018. Mechanical pulp fibers are obtained by pure mechanical action such as grinding and refining and are called groundwood pulp (GWP) and thermomechanical pulp (TMP), respectively. However, because of its global dominance, this article focuses on kraft chemical pulp. The wood anatomy and chemical composition and fiber dimensions and properties of different species are described. The ultrastructure of pulp fibers and cell walls is interpreted in terms of their relevance for lignin removal during pulping and the structural properties of the final chemical pulp, respectively. Flow sheets for the production of softwood and hardwood bleached kraft and sulfite pulps are presented. Different unit operations of chemical pulping and the governing physical and chemical phenomena are described. The article reviews the mechanisms and kinetics of delignification and carbohydrate degradation and retention that occur inside the wood chips during impregnation with and subsequent pulping in cooking liquor. Oxygen delignification and pulp bleaching conclude this article.

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Viscosities of Unbleached Alkaline Pulps. II. The G-Factor

Cited by 18 publications

References 4 publications

Competing Reactions Affecting Delignification in Pulping Systems

Competing Reactions Affecting Delignification in Pulping Systems

11. Reactions in Alkaline Medium

Pulp

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