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Structure of aqueous colloidal formulations used in coating and agglomeration processes: Mesoscale model and experiments

Jarray, Ahmed and Gerbaud, Vincent and Hemati, Mehrdji Structure of aqueous colloidal formulations used in coating and agglomeration processes: Mesoscale model and experiments. (2016) Powder Technology, vol. 291. pp. 244-261. ISSN 0032-5910

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Official URL: http://dx.doi.org/10.1016/j.powtec.2015.12.033

Abstract

In coating and agglomeration processes, the properties of the final product, such as solubility, size distribution, permeability and mechanical resistance, depend on the process parameters and the binder (or coating) solution properties. These properties include the type of solvent used, the binder composition and the affinity between its constituents. In this study, we used mesoscale simulations to investigate the structure of agglomerates formed in aqueous colloidal formulations used in coating and granulation processes. The formulations include water, a film forming polymer (Hydroxypropyl-methylcellulose, HPMC), a hydrophobic filler (Stearic acid, SA) and a plasticizer (Polyethylene glycol, PEG). For the simulations, dissipative particle dynamics (DPD) and a coarse-grained approach were used. In the DPD method, the materials are described as a set of soft beads interacting according to the Flory–Huggins model. The repulsive interactions between the beads were evaluated using the solubility parameter (δ) as input, where δ was calculated by all-atom molecular dynamics. The DPD simulation results were compared to experimental results obtained by cryogenic-SEM and particle size distribution analysis. DPD simulation results showed that the HPMC polymer is able to adsorb in depth into the inner core of SA particle and covers it with a thick layer. We also observed that the structure of HPMC-SA mixture varies under different amounts of SA. For high amounts of SA, HPMC is unable to fully stabilize SA. Affinity between the binder materials was deduced from the DPD simulations and compared with Jarray et al. (2014) theoretical affinity model. Experimental results presented similar trends; particle size distribution analysis showed that for low percentage of SA (below 10% w/w) and in the presence of HPMC, the majority of SA particles are below 1 μm in diameter. Cryogenic-SEM images reveal that SA crystals are covered and surrounded by HPMC polymer. SA crystals remain dispersed and small in size for low percentages of SA.

Item Type:Article
Additional Information:Thanks to Elsevier editor. The definitive version is available at http://www.sciencedirect.com The original PDF of the article can be found at Powder Technology website : http://www.sciencedirect.com/science/journal/00325910
HAL Id:hal-01338896
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS (FRANCE)
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Deposited By: Vincent GERBAUD
Deposited On:29 Jun 2016 10:35

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