Molecular weight solution properties relationship

Most properties of linear polymers are controlled by two different factors. The chemical constitution of tire monomers detennines tire interaction strengtli between tire chains, tire interactions of tire polymer witli host molecules or witli interfaces. The monomer stmcture also detennines tire possible local confonnations of tire polymer chain. This relationship between the molecular stmcture and any interaction witli surrounding molecules is similar to tliat found for low-molecular-weight compounds. The second important parameter tliat controls polymer properties is tire molecular weight. Contrary to tire situation for low-molecular-weight compounds, it plays a fimdamental role in polymer behaviour. It detennines tire slow-mode dynamics and tire viscosity of polymers in solutions and in tire melt. These properties are of utmost importance in polymer rheology and condition tlieir processability. The mechanical properties, solubility and miscibility of different polymers also depend on tlieir molecular weights. 

We shall be interested in determining the effect of electrolytes of low molecular weight on the osmotic properties of these polymer solutions. To further simplify the discussion, we shall not attempt to formulate the relationships of this section in general terms for electrolytes of different charge types-2 l, 2 2, 3 1, 3 2, and so on-but shall consider the added electrolyte to be of the 1 1 type. We also assume that these electrolytes have no effect on the state of charge of the polymer itself that is, for a polymer such as, say, poly (vinyl pyridine) in aqueous HCl or NaOH, the state of charge would depend on the pH through the water equilibrium and the reaction... 

The dilute solution properties of copolymers are similar to those of the homopolymer. The intrinsic viscosity—molecular weight relationship for a VDC—AN copolymer (9 wt % AN) is [77] = 1.06 x 10 (83). The characteristic ratio is 8.8 for this copolymer. 

The analysis of the main properties of aqueous solutions of polyacrylamide and copolymers of acrylamide has been reviewed [4,5]. The main characteristics of aqueous solutions of polyacrylamide is viscosity. The viscosity of aqueous solutions increases with concentration and molecular weight of polyacrylamide and decreases with increasing temperature. The relationship between the intrinsic viscosity [q]) in cmVg and the molecular weight for polyacrylamide follows the Mark-Houwink equations ... 

Dilute and concentrated solution properties of PBZT and PBZO have been studied [30] in detail by Berry et al. Their research has provided important relationships for the solutions of these polymers such as the response of the viscosity to temperature, shear, polymer concentration, polymer molecular weight and solvent composition. The relationship of intrinsic viscosity to molecular weight has been determined for both PBZT and PBZO [31]. 

The size of a polysaccharide molecule is an indeterminate property molecular weight, for example, depends on the analytical method. Electroviscosity and solute-solvent and solute-solute interactions affect the volume-gram relationship (density) and conformational dimensions. The degree of polymerization is not affected and is therefore a constant, reliable indicator of the molar mass. 

Robinson, G., Ross-Murphy, S. B., and Morris, E. R. (1982). Viscosity-molecular weight relationships, intrinsic chain flexibility, and dynamic solution properties of guar galactomannan. Carbohydr. Res. 107 17-32. 

It should be pointed out that the characteristics of polymer structure (e.g., porosity, tortuosity, steric hindrance, mesh size, etc.) should be determined in order to calculate the diffusion coefficient of a specific molecule in a particular polymer. For cross-linked polymers, additional polymer properties should be characterized. Even though there are methods to determine these properties, a simple mathematical relationship between the diffusion coefficient of a solute and its molecular weight has been used due to the complexity of the experiment ... 

These chemical tests on papermaking pulps can serve as general indicators of fiber quality. It has been well established that permanence of papers is enhanced if the solubility in alkaline solutions and the content of functional groups are low and the molecular weight or degree of polymerization (DP) is high. The relationships, however, cannot be stated except in general terms it is not possible at the present time to establish specifications for these properties which will ensure permanence... 

Theories of the frictional properties of polymer solutions, from which the relationship between viscosity and molecular weight must ultimately be derived, can proceed in various ways, but we will mention just two models. In the first, it is assumed that the velocity of the solvent is barely affected by the presence of the polymer, so that it streams or freely drains through the coil in a largely unperturbed fashion (Figure 12-31). 

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