Gel - Improving gel characteristics
3 important questions on Gel - Improving gel characteristics
How does the pH influence the gel strength at a high concentration of biopolymers?
Change in pH --> increased repulsion
- Flexibility is decreased, chains more straight and stiff --> increased gel hardness (higher fracture stress) and increased brittleness (decreased fracture strain).
- Repulsion between junction zones or within helices --> more difficult for chains to come together and interact. Especially for small distance interactions (hydrogen bonds). Too much repulsion, less junction zones are formed --> decreased gel hardness (lower fracture stress)
What is the effect of salt addition on the gel strength?
Charged polymers (because of pH) --> adding salt will screen charges, reduce electrostatic repulsion
- Helix formation enhanced --> stronger network
- Distance between the chains is reduced, flexibility enhanced --> chains more mobile and network becomes weaker --> gel strength decreases
How does the interaction of proteins and polysaccharides effect the gel strength?
- (-)polymers + (-)proteins --> (-)proteins requires space, less space for polymer network to form. Electrostatic repulsion --> less mobile network, stronger network
- (-)polymers + (+)particles --> attractive interactions between polymers and particles. Interactions stronger than between polymers themselves, particles withdraw the polymers from the network. Gel network is disrupted. Aggregation can occur and aggregates can sediment.
The question on the page originate from the summary of the following study material:
- A unique study and practice tool
- Never study anything twice again
- Get the grades you hope for
- 100% sure, 100% understanding
Remember faster, study better. Scientifically proven.
