The 4 processes of paint defoaming

2021-09-25   Pageview:188

The 4 processes of paint defoaming:
1. The defoamer is adsorbed to the surface of the bubble film
2. The defoamer penetrates to the surface of the bubble film
3. The defoamer diffuses on the surface of the bubble film and adsorbs the surfactant
4. The surface tension of the bubble film is unbalanced

 

 

 

 

 

 

 

 

 

 

 

Unmodified cellulose is completely insoluble in water. Starch granules swell into granules several times the original particle size in water at 55-80°C, and then dissolve into a viscous colloidal hydrated polymer dispersion. These hydrated polymers are gathered together by the dissolved molecules and form a pseudoplastic gel after cooling. This type of starch can be used as a binder for adhesives, paper sizing and polymer dispersion thickeners.
Starch has a tendency to form gel through hydrogen bond hydration, especially linear amylose (polysaccharide) is rapidly hydrated and becomes water-insoluble again.

This tendency to become insoluble can be retarded by the formation of derivatives, such as ethoxylation or propoxylation modification. Hydroxyethyl or hydroxypropyl starch is easily soluble in water and forms a transparent and stable gel solution. Just like cellulose, chemical derivatization will affect the properties and practicality of starch colloids.

Ethoxy or propoxylated starch as a thickener can be used in paper sizing, textile industry, tile adhesives and high-PVC low-cost coatings. It can also be used as an additive for building materials. For a long time, starch, ptfe powder india modified starch and dextrin have been widely used as protective gums for polymer dispersions, that is, the production of redispersed latex powder E292. Heating dry starch to produce acid-catalyzed dextrin, guar gum can be dissolved in cold water, and shows a high thickening effect, through hydroxypropyl derivatization modification can improve its xanthan gum in water
The transparency and solubility.

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