International audienc

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7 pagesInternational audienceAs a part of a study on detergent tablets, investigations were carried out to elucidate the compression behavior of a powdered surfactant, sodium dodecyl sulphate (SDS), based on a comparison with the main component of the formulation, i.e. the chorine provider (DCCNa). The compacted SDS exhibited poor cohesion as well as delayed dissolution whatever the compression pressure. The microscopic observations and the mercury porosimetry measurements both demonstrated that a residual porosity existed in the tablets but the dissolution times were always long. A modification of SDS in contact with water, forming a structure like a gel, probably occurred, inducing the closing of the pores and thereby limiting the water intrusion into the tablets

11 pagesInternational audienceThe functional characteristics (mechanical strength, disintegration and dissolution times) of effervescent detergent tablets containing chlorine provider were investigated according to the presence of a surfactant, sodium dodecyl sulphate (SDS). Tablets were compared for similar total porosity. The end-use property study highlighted that the presence of 2% of sodium dodecyl sulphate was not favorable to the tablet mechanical characteristics, inducing a lower ''bonding ability''. The linear relationship between the disintegration and dissolution times showed that the disintegration time was relevant to express the behavior of the tablets in water. The disintegration data showed two zones: when porosity was higher than 20%, the disintegration time was always lower than 2 min g-1 and similar for both formulas; for lower porosities, the disintegration time increased and was higher in the presence of the surfactant. In this second case, the released CO2 due to the reaction between adipic acid and sodium bicarbonate in water was slowed down in the presence of the surfactant, confirming the disintegration data. However, this negative effect of SDS on the disintegration time could not be linked to a difference of pore size distribution between the two formulas. So, despite the creation of weak interparticle bonds with the other compounds of the formula, the presence of SDS increased the disintegration by limiting the water uptake, independently of the porous texture. Moreover, no preferential localization of the surfactant at the surface of the tablet might be involved to explain the effect of SDS on the tablet accessibility by water