What affects polymer solubility?
The solubility of polymers also depends on temperature. Usually, the temperature coefficient is positive, i.e. fractional dissolution can be carried out with a given solvent (or a non-solvent/solvent mixture at constant composition) by raising the temperature.
When polymer is dissolved in solvent the viscosity increase?
High molecular weight polymers greatly increase the viscosity of liquids in which they are dissolved. The increase in viscosity is caused by strong internal friction between the randomly coiled and swollen macromolecules and the surrounding solvent molecules.
What is the effect of molecular weight on solubility of polymer?
When solubility of the polymer in a given solvent is low, then it decreases exponentially with the molecular weight. Hence the larger polymers would have a exp(10) times lower solubility than the smaller.
How is the amount of solvent affect the solubility of a substance?
Solubility is the maximum amount of a substance that will dissolve in a given amount of solvent at a specific temperature. There are two direct factors that affect solubility: temperature and pressure. Temperature affects the solubility of both solids and gases, but pressure only affects the solubility of gases.
How can you increase the viscosity of a polymer solution?
The method of increasing the viscosity of polymer solution The addition of Na2C2O4 as a complexing agent for the removal of Ca2+ and Mg2+ eliminates the settling effect of divalent ions on polymer chains and increases the viscosity of the polymer system.
How do you increase the viscosity of a polymer?
The polymer viscosity increases when the polymer concentration increases, as shown in Figure p27. The molecular weight of polymer is related to its molecular size, which means that polymers with a larger molecular size have a higher molecular weight.
How do you reduce the molecular weight of a polymer?
Control of radical polymerization in order to get a polymer with lower average molecular mass can be done by one of these ways:
- Increase the amount of initiator relative to monomer (i.e. double or triple the amount).
- Use a chain transfer agent such as a thiol or mercaptan (R-S-H).
What happens when you dissolve a polymer?
The dissolution of a polymer into a solvent involves two transport processes, namely solvent diffusion and chain disentanglement. When an uncrosslinked, amorphous, glassy polymer is in contact with a thermodynamically compatible solvent, the solvent will diffuse into the polymer (Fig. 1).
What factor affect the solubility of solvent and solute?
The size of solute particles, stirring, and temperature, are the three factors that affect the solubility of a solid solute in a solvent.
Why does viscosity increase with polymer concentration?
The more concentrated a polymer solution, the more large molecules you have exerting drag and interacting with each other. Higher concentration leads to a higher viscosity measurement.
What is concentration effect on viscosity of polymer solution?
The polymer concentration is associated with solution viscosity, which increases with the increase of the polymer concentration and then leads to a larger fiber diameter. However, if the concentration is too low, continuous polymer fibers cannot be achieved, and polymer beads are obtained.
How do you increase the molecular weight of a polymer?
Cross-linking can be thought of as reducing the number of chain ends and, effectively, increasing the molecular weight of a polymer system [61]. In general, cross-linking will increase the strength of material [62].
Which factor determines the molecular mass of polymer?
The molecular masses of polymers are determined by osmotic pressure method and not by measuring other colligative properties.
What happens to the strength of the polymer if the molecular increases?
A High molecular weight increases the chemical resistance – to a point. It takes more damage to the main chains of the molecules before it will affect the strength of the material. A High molecular weight increases the viscosity of the material – makes it harder to process the material using conventional methods.
What is the relationship between pH and solubility?
For ionic compounds containing basic anions, solubility increases as the pH of the solution is decreased. For ionic compounds containing anions of negligible basicity (such as the conjugate bases of strong acids), solubility is unaffected by changes in pH.
Why do Polymers dissolve at low pHs?
Remarkably, the polymer is still well dissolved at this low pH, although it has become progressively protonated. A likely explanation for these results is a transition from an extended coil conformation of the polymer at high pH to a collapsed conformation at low pH.
How does pH affect the conformational change of polymers?
NR fluorescence experiments revealed that at a pH of ∼5.5, this polymer variant undergoes a conformational change from a random coil at high pH to a collapsed conformation in which the polymer contains hydrophobic domains at low pH.
What is the emission maximum of a polymer at pH 6?
However, from pH 6.0 to pH 4.0 the emission maximum decreases to a value of ∼615 nm, consistent with a transition of NR to a more hydrophobic environment. Remarkably, the polymer is still well dissolved at this low pH, although it has become progressively protonated.
What happens to SMA polymer at low pH?
Indeed, in previous studies it was found that at low pH the 1:1 SMA variant collapses into a globular conformation that contains hydrophobic domains while the polymer is still water soluble ( 23 ).