What is swelling in polymer?
The swelling is defined as a penetration of a solvent into the polymer network that causes an abrupt change in the volume (Gugliuzza and Drioli 2007), moving the boundary from unsolvated glassy region to solvated and expanding rubbery domain.
How do you calculate polymer swelling?
and weigh the bag and then calculate the percentage of swelling through the following formula: (w2-w1)/(w1) % w1= weight of the polymer (Before swelling) w2= weight of the polymer (After swelling)
What is equilibrium swelling ratio?
The average value of three measurements was taken for each sample, and the equilibrium swelling ratio (ESR) is defined as follows: Equilibrium Swelling Ratio: ESR ¼ рWs А WdЮ=Wd; where Ws is the weight of swollen hydrogel at the particular temperature and Wd is the dry weight of the hydrogel.
What is swelling in chemistry?
The swelling process is, by definition, an increase in the volume of a gel or solid connected with the uptake of a liquid or gas [1]. In polymer dissolution, swelling is the first step in the interaction between liquid molecules and polymeric network, which is usually followed by solvatation of polymer chains.
When does the swelling equilibrium of a network occur?
The swelling equilibrium is reached when the chemical potential of the solvent in the swollen network μs is equal to that of the pure solvent μs0. At this point, the polymer volume fraction has the value φp = φp,m. The chemical potential of the solvent in the swollen polymer network is given by
How does Flory-Rehner theory of polymer network swelling work?
Flory-Rehner Theory of Polymer Network Swelling. where vs is the volume of a solvent molecule. The swelling equilibrium is reached when the chemical potential of the solvent in the swollen network μs is equal to that of the pure solvent μs0. At this point, the polymer volume fraction has the value φp = φp,m.
How does the swelling of a network affect entropy?
Under these conditions, swelling of the network will occur and an elastic retractive force develops. The driving force of the swelling process is mainly enthalpic in nature. As the volume of the network increases the chains are stretched which, in turn, causes a decrease in entropy because the extended configuration of the chains is less likely.
How to calculate the deformation factor of a polymer network?
From a knowledge of the densities of the solvent and polymer, one can calculate q = V / V0. Assuming that mixing occurs without an appreciable change in the total volume of the system (polymer plus solvent), the deformation factor for an isotropic polymer network may be written