Use of ultrasonic degradation to study the molecular weight influence of polymeric admixtures for mortars

Abstract

The aim of this paper is to provide a methodology to study the influence of the molecular weight of polysaccharidic admixtures on mortar properties. A wide range of admixtures with different molecular weight and constant structure was prepared. This has been made possible by the use of ultrasonic treatment, a simple, effective, and without additive method. It appears that cellulose and guar gum derivatives, used as water retention agents, exhibit a significant molecular weight reduction according to the ultrasonic treatment duration. The water retention capacity of the mortars mixed with ultrasonically degraded admixture solutions increases with molecular weight for a same admixture. However, comparing water retention values obtained with similar molecular weight of a same family shows that effectiveness of polysaccharides as water retention agent is not linearly linked to their molecular weight.

Modification of water retention and rheological properties of fresh state cement-based mortars by guar gum derivatives

“…They exhibit roughly the same molecular weight, around 2.10 6 g.mol -1 since they are all from the same original guar gum (GG) [28]. for the study are summarized in Table 4.…”

Study on the influence of advanced treatment processes on the surface properties of polylactic acid for a bio-based circular economy for plastics

“…[29] and atmospheric DBD plasma [30] . Most of those processes (chemical degradation, as well as thermal [31] and enzymatic [32] methods) are working randomly and lead to unwanted mono- and oligomers and to modifications of the chemical microstructure of the side groups [33] . On the other hand, it has been reported by several authors, that ultrasonication represents a suitable method when products with lower molecular weight are desired [34] , [35] .…”

Combination of superplasticizers with hydroxypropyl guar, effect on cement-paste properties

“…1(b). The both polysaccharides exhibit similar molecular weight, around 2.10 6 g.mol -1 [21]. The number of hydroxypropyl groups per anhydroglucose unit, characterized by the molar substitution (MSHP) was less than 3 for the two HPGs (value provided by the manufacturers).…”

“…Several studies were devoted to the estimation of the water retention capacity induced by the HPGs and to their mechanism of action [16][17][18][19][20]. The chemical structure of the HPGs, such as the molecular mass, the amount of hydropropyl groups grafted on the backbone, characterized by the MS (MSHP), and the nature of the grafting, appear as crucial parameters for the water retention properties [20,21]. Indeed, these structural parameters affect the dosage necessary to reach the coil overlapping concentration, corresponding to the concentration from which, the isolated polymer coils, existing at low polymer concentration, come into contact.…”