[article]
| Titre : |
Solubility of polymers |
| Type de document : |
texte imprimé |
| Auteurs : |
Tipanna Melkeri, Auteur |
| Année de publication : |
2020 |
| Article en page(s) : |
p. 73-78 |
| Langues : |
Anglais (eng) |
| Catégories : |
Paramètres de solubilité
Polymères -- Solubilité
Solutions de polymère
|
| Index. décimale : |
668.9 Polymères |
| Résumé : |
Polymer solutions are widely used in various applications such as paints, inks, adhesives etc., prepared by dissolving polymer in given solvent. Solubility of polymer in given solvent is important. The polymer solvent compatibility can be expressed by considering Hildebrand Solubility Parameter Δ. The solubility parameter is a numerical value that indicates the relative solvency behaviour of a specific solvent. It is defined square root of cohesive energy density (c)1/2. Materials with similar solubility parameters will be able to interact with each other, resulting in solvation, miscibility or swelling. The principal limitation of the solubility parameter approach is that it applies on ly to associated solutions ("liike dissolves like"). The reason for th is limitation is in kinds of polar contributions that give rise to the total cohesive energy densities in each case. These slight disparities in polar contributions result in considerable differences in solubility behaviour. Three types of polar interactions that are most commonly used in solubility theories, dispersion forces, polar forces, and hydrogen bonding forces. The Hildebrand solubility parameter is used in conjunction with only one or two of these forces (i.e. Hildebrand value and hydrogen bonding value). Hansen solubility parameters were developed by Charles M. Hansen in 1967. They are based on the idea that like dissolves like where one molecule is defined as being ‘like’ another if it bonds to itself in a similar way. To determine if the parameters of two molecules (usually a solvent and a polymer) are within range, a value called interaction radius (RO) is given to the substance being dissolved and (Ra), the distance between the solvent and the material in Hansen space are calculated and hence relative energy difference, RE = Ra/Ro. RED < 1 the molecules are al ike and will dissolve, RED = 1 the system will partially dissolve and RED > 1 the system will not dissolve. Flory-Huggins solution theory is a mathematical model of the thermodynamics of polymer solutions which takes account of the great dissimilarity in molecular sizes in adapting the usual expression for the entropy of mixing. In Flory-Huggins theory The polymer-solvent interaction parameter "chi" x is depends on the nature of both the solvent and the solute. The interaction parameter can be expressed as sum of an entropic and enthalpic contribution x = xH + xS. where xH is enthalpic component and xS is entropic component. The enthalpic component xH is expressed by Hildebrand Solubility Parameter xH = Vseg (6a - 6b )2 / R T .
Interaction parameter is also temperature dependence, x ~ 1/1-. As temperature is increase, x decreases. At particular
temperature the value of the x becomes 0.5. The temperature at which the value becomes 0.5 is called O (theta) temperature. For a given polymer — solvent O temperature is around room temperature then solvent is cal led O solvent for that polymer. In general, measurements of the properties of polymer solutions depend on the solvent. However, when a theta solvent is used, the measured characteristics are independent of the solvent. |
| Note de contenu : |
- Solubility of polymers
- Hildebrand solubility parameter : Hansen solubility parameter - Flory Huggins theory - Significance of interaction parameter x
- Table 1 : Solubility parameters of few polymers and solvents |
| En ligne : |
https://drive.google.com/file/d/1tFxQ2V1rblUhd32JAjVlAZGjU0tvCx-o/view?usp=drive [...] |
| Format de la ressource électronique : |
Pdf |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34681 |
in PAINTINDIA > Vol. LXX, N° 1 (01/2020) . - p. 73-78
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Solubility of polymers in PAINTINDIA, Vol. LXX, N° 1 (01/2020)
