Self-assembly of alkyl chains of fatty acids in papermaking systems: A review of related pitch issues, hydrophobic sizing, and pH effects

Abstract

This review article considers the role of fatty acids and the mutual association of their long-chain (e.g. C18) alkyl and alkenyl groups in some important aspects of papermaking. In particular, published findings suggest that interactions involving fatty acids present as condensed monolayer films can play a controlling role in pitch deposition problems. Self-association among the tails of fatty acids and their soaps also helps to explain some puzzling aspects of hydrophobic sizing of paper. When fatty acids and their soaps are present as monolayers in papermaking systems, the pH values associated with their dissociation, i.e. their pKa values, tend to be strongly shifted. Mutual association also appears to favor non-equilibrium multilayer structures that are tacky and insoluble, possibly serving as a nucleus for deposition of wood extractives, such, as resins and triglyceride fats, in pulp and paper systems.

Detergency mechanisms and cellulosic surfaces: A review

“…A tendency of the tail groups of surfactants to associate into tight films has been attributed to a hydrophobic effect (Tanford 1980;Hubbe et al 2020). The driving force for such association is the relatively high energy of hydrogen bond interactions in aqueous systems.…”

“…When comparing the effects of different oily materials, researchers have found it advantageous to categorize compounds in terms of their equivalent alkane carbon numbers (EACN) (Phaodee et al 2020;Chen et al 2022). Thus, the presence of a carbon-carbon double bond within a linear alkyl chain often leads to properties equivalent to those of a saturated chain with two less carbons in it (Brito et al 2011;Hubbe et al 2020). The difference has been attributed to the poorer packing ability of the unsaturated alkyl chains.…”

“…21, the tail groups are relatively long (e.g. 16 or more carbons in the alkyl chain), unbranched, and unsaturated (for instance stearic acid), then a strong self-association within the film can be expected (Kanicky and Shah 2002;Hubbe et al 2020). The cohesive energy due to the London dispersion forces embodied in such a condensed monolayer is about -20 kJ/mole (Zana 1996).…”

“…25. There is a cooperative tendency of surfactant molecules to self-associate with those already present within a monolayer film at an interface (Penfold et al 2007;Hubbe et al 2020). This tendency can be expected to contribute to a progressive extension of such films within adhesion zones between dirt and textile.…”

Dissolution of organic components of straw by ionic liquid

“…This showed that, as time increased, the dissolution rate of the triglyceride fats on the straw in the ionic liquid decreased slowly. According to the dissolution mechanism of the ionic liquid, the anions and cations in the ionic liquid directly acted on the triglyceride fats and broke bonds that held together mainly by van der Waals forces therein, thereby dissolving the triglyceride fats (Hubbe 2020). With regard to the dissolution of polysaccharides by ionic liquids, Remsing et al (2006) used a carbon tracer to confirm its occurrence when they studied the dissolution of cellulose by ionic liquids.…”