Molecular Weight Mark-Houwink-Sakurada constants

The Mark-Houwink-Sakurada constants for PMMA resin are o = 0.73 and K = 1. X 10 Table 3.3 contains solvent viscosity versus concentration data. Find the intrinsic viscosity using both the specific and relative viscosities and the viscosity average molecular weight. 

Mark-Houwink-Sakurada constant Mass transfer coefficient around gel Fractional reduction in diffusivity within gel pores resulting from frictional effects Solute distribution coefficient Solvent viscosity nth central moment Peak skewness nth leading moment Viscosity average molecular weight Number of theoretical plates Dimensionless number... 

Benoit and co-workers [18] proposed that the hydrodynamic volume, Vr which is proportional to the product of [17] and M, where [17] is the intrinsic viscosity of the polymer in the SEC eluent, may be used as the universal calibration parameter (Fig. 18.3). For linear polymers, interpretation in terms of molecular weight is straightforward. If the Mark-Houwink-Sakurada constants K and a are known, log [t7]M can be written log M1+ + log K, and VT can be directly related to M. The size-average molecular weight, Mz, is defined by this process ... 

B. Assume that the GPC curve of Polymer A is that of a polydisperse linear poly-chloroprene with Mark-Houwink-Sakurada constants in THF at 30°C of K = 4.18 x 10 5 dl/g and a - 0.83. Calculate the weight and number molecular weight averages, the polydispersity and the intrinsic viscosity of this polychloroprene. 

Beer M. U., Wood P. J., Weisz J. 1999. A simple and rapid method for evaluation of Mark-Houwink-Sakurada constants of linear random coil polysaccharides using molecular weight and intrinsic viscosity determined by high performance size exclusion chromatography Application to guar galactomannan. Carbohvdr. Polymers. 39, 377-380. 

Condition Ar atmosphere [21]/[BF3-OEt2] =40 solvent, CH2CI2 [21] =0.5mol " The weight average molecular weight Mw,sec-malls, polydispersity Mw,sEC-MALLs/ fn,SEC-MALLS, intrinsic viscosity [rj], and Mark-Houwink-Sakurada constant a ([ ] = KMw,sec-malls ) were determined by SEC in THF equipped with MALLS and viscosity detectors. 

Viscosity molecular weight is calculated using the Mark-Houwink-Sakurada (MHS) equation of [rj] = Km Mv, where 7] is intrinsic viscosity, Mv is viscosity molecular weight, a is the MHS exponential factor (material and system-specific, between 0.9 and 1.0 for metal complex-based solvents), and Km is a constant. Moiecuiar weight distributions resuit from GPC experiments. 

Also, according to Mark-Houwink-Sakurada (MHS) equation (3.183) with the assumption that the constants K and a are independent of molecular weight, one can write... 

The logarithms of intrinsic viscosities of fractionated samples are plotted against log or log Mn. The constants a and K of the Mark-Houwink-Sakurada equation are the intercept and the slope, respectively, of that plot. Except for the lower molecular weight samples, the plots are linear for linear polymers. Many values of K and a for different linear polymers can be found in the literature [66]. 

Mark-Houwink equation n. Also referred to as Kuhn-Mark-Houwink-Sakurada equation allows prediction of the viscosity average molecular weight M for a specific polymer in a dilute solution of solvent by [77] = KM, where K is a constant for the respective material and a is a branching coefficient K and a (sometimes a ) can be determined by a plot of log [77] versus logM" and the slope is a and intercept on the Y-axis is K. Kamide K, Dobashi T (2000) Physical chemistry of polymer solutions. Elsevier, New York. Mark JE (ed) (1996) Physical properties of polymers handbook. Springer-Verlag, New York. Ehas HG (1977) Macromolecules, vols 1-2. Plenum Press, New York. 

Calculated from the values of Ko (Mark-Houwink-Sakurada prefactor imder conditions) and o (viscosity constant) found in Ref. (21), using the relationship y = ( X ) , where Mq is the monomer molecular weight (71 g/mol), and b is the monomer length (0.25 nm). 

On the other hand, using molecular weights measured by GPC, the constants of the Mark-Houwink-Sakurada equation for poly(3-hexylthiophene) were determined in tetrahydrofiiran at 25°C [78] ... 

The Mark-Houwink-Sakurada (MHS) equation (eqn (5.5)) offers a convenient means of determining the molecular weight of a polymer which is soluble in a solvent. It has been experimentally confirmed that the parameters Km and a in the MHS equation are constant over a wide range of molecular weights under the constraints of zero shear rate at given temperature for a... 

---