Table of Contents
What does the Flory Huggins parameter mean?
Abstract: The FloryHuggins parameter describes the excess free energy of mixing and governs phase behavior for polymer blends and block copolymers. For chemically-distinct nonpolar polymers, the value of is dominated by the mismatch in cohesive energy densities of the monomers.
What is Flory Huggins equation?
The FloryHuggins equation deals with molecules that are similar chemically, but differ greatly in length. The model is based on the idea that the chain elements arrange themselves randomly on a three-dimensional structure.
What is the Flory interaction parameter?
Flory-Huggins Parameter This parameter was first introduced by Flory1 and Huggins2 independently to describe the interaction between solvent and polymer molecules in their lattice model of polymer solutions. Thus, the effect of solvent interactions can be expressed in terms of a single parameter.
What is thermodynamic polymer solution?
It is based upon the quasilattice theory of solutions , and leads to an equation for the free energy of mixing polymeric solute with monomeric solvent which contains a combinatorial entropy of mixing term and a regular solution theory enthalpy of mixing term.
What are the assumptions of Flory Huggins?
It is assumed that the critical value, which is sufficient in ensuring miscibility between a high molecular weight polymer and a plasticizer, is 0.5. The FloryHuggins interaction parameter constitutes a popular miscibility criterion.
What is Huggins constant?
The constant kH is termed the Huggins constant and has values ranging from 0.3 in good solvents to 0.5 in poor solvents. It contains information about hydrodynamic and thermodynamic interactions between coils in solution.
What is regular solution theory?
From Wikipedia, the free encyclopedia. In chemistry, a regular solution is a solution whose entropy of mixing is equal to that of an ideal solution with the same composition, but is non-ideal due to a nonzero enthalpy of mixing.
What is degree of polymerization in chemistry?
The degree of polymerization, or DP, is the number of monomeric units in a macromolecule or polymer or oligomer molecule. … This number does not reflect the variation in molecule size of the polymer that typically occurs, it only represents the mean number of monomeric units.
What is the interaction parameter?
Definition. The interaction parameter gives a measure of the interaction between molecules, for example, surfactants or polymers, or between the molecule and the medium in which it is dissolved. Various interaction parameters can be described as follows: (1) surfactant mixtures with no net interaction.
What is cohesive energy density?
The cohesive energy density is the amount of energy needed to completely remove unit volume of molecules from their neighbours to infinite separation (an ideal gas). This is equal to the heat of vaporization of the compound divided by its molar volume in the condensed phase.
How do you calculate theta temperature?
The theta temperature can be evaluated by plotting the value of the second virial coefficient and finding where it is equal to zero.
What is K in Mark Houwink equation?
is intrinsic viscosity. K is a constant. With known values for and K it is easy to take the values from an intrinsic viscosity experiment and calculate .
What is the thermodynamics behind the polymer dissolution?
During the process of dissolution the chains of glassy polymer become flexible under the influence of a solvent. Since the glass possesses excess enthalpy over the elastomer, this process is accompanied with enthalpy relaxation and evolution of heat.
What is aqueous solution polymer?
Polymer solutions are solutions containing dissolved polymers. These may be liquid solutions (e.g. in aqueous solution), or solid solutions (e.g. a substance which has been plasticized).
What are the two categories of polymers?
Polymers fall into two categories:
- thermosetting plastic or thermoset.
- thermoforming plastic or thermoplastic.
What is a primary reason that polymer solutions are not accurately described by ideal solution theory?
We noted the two important flaws with ideal solution theory, namely the fact that polymers are large in comparison to solvent and that there are intermolecular interactions to account for. … We are going to imagine that a polymer has a bunch of segments, where each segment is the size of the solute.
What is reduced and specific viscosity?
Reduced viscosity is equal to the ratio of the relative viscosity increment () to the mass concentration of the species of interest.
What is meant by relative viscosity?
Relative Viscosity (rel) Definition: The ratio of the viscosities of the polymer. solution (of stated concentration) and of the pure. solvent at the same temperature. Also known as SOLUTION. SOLVENT VISCOSITY RATIO.
How do you calculate relative viscosity?
Dividing the viscosity of the polymer solution () by the viscosity of the pure solvent () gives the relative viscosity with the dimensionless unit. Equation 7: Relative viscosity is the viscosity of the polymer solution divided by the viscosity of pure solvent.
What are regular mixtures?
The term regular mixture describes a liquid mixture for which the rational activity coefficients f1 and f2 are given by equations (d) and (e) where the property w is independent of temperature and liquid mixture composition [1-5].
What is an ideal solution in chemistry?
: a solution in which the interaction between molecules of the components does not differ from the interactions between the molecules of each component usually : a solution that conforms exactly to Raoult’s law compare activity sense 6b, activity coefficient, fugacity sense 2b.
What is excess Gibbs energy?
In liquid: Activity coefficients and excess functions. designated by GE, called the excess Gibbs (or free) energy. The significance of the word excess lies in the fact that GE is the Gibbs energy of a solution in excess of what it would be if it were ideal.
What is Tacticity and explain?
Tacticity (from Greek taktikos of or relating to arrangement or order) is the relative stereochemistry of adjacent chiral centers within a macromolecule. … A tactic macromolecule in the IUPAC definition is a macromolecule in which essentially all the configurational (repeating) units are identical.
How do you calculate polymerization?
Divide the molecular weight of the polymer by the molecular weight of the monomer unit to calculate the degree of polymerization. If the molecular mass of tetrafluoroethylene is 120,000, its degree of polymerization is 120,000 / 100 = 1,200.
What is degree of polymerization used for?
The degree of polymerization, or DP, is the number of repeat units in an average polymer chain at time t in a polymerization reaction. The length is in monomer units. The degree of polymerization is a measure of molecular weight. For most industrial purposes, lengths in the thousands or tens of thousands are desired.
What is interaction parameter thermodynamics?
W is known as an interaction parameter (volume interaction parameter in this case) because non-ideal behavior results from interactions between dissimilar species. The interaction parameter is a function of T, P, and the nature of the solution, but not of X.