| Autor: |
Richard Duane Jenkins, V. Tirtaatmadja, D. R. Bassett, Kam Chiu Tam |
| Rok vydání: |
1999 |
| Předmět: |
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| Zdroj: |
Colloid & Polymer Science. 277:276-281 |
| ISSN: |
0303-402X |
| DOI: |
10.1007/pl00013756 |
| Popis: |
Hydrophobically modified alkali-soluble emulsion (HASE) polymer is solubilized by the addition of a base. When the pH is increased to greater than 6.5, methacrylic acids on the polymer backbone are neutralized and the carboxylated latex polymer goes into solution causing a large increase in the viscosity due to inter-molecular associations of the hydrophobes. The stability of the viscosity of the polymer solution at pH in the range 9–10 was studied in the presence of a strong (NaOH) and a weak [1-amino-1-methylpropanol (AMP)] base. No change in the viscosity or the moduli was observed for the polymer in AMP. Reduction in the viscous and elastic properties of the polymer solution in NaOH was observed after 4 weeks. Such small changes are detectable using the superposition of oscillation on the steady shear technique. The decrease in the viscoelastic properties is attributed to the hydrolysis reaction of the urethane groups of the macromonomer, which resulted in a decrease in the number of hydrophobes per polymer chain. It is recommended that a weak base be used to neutralise the HASE polymer in order to avoid the possibility of compositional changes in the polymer after neutralisation for more than 6 weeks. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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