Copolymers viscosity-molecular weight relationship

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. 

Intrinsic viscosity—molecular weight relationships have been obtained for copolymers in methyl ethyl ketone. The value for a 15 wt % ethyl acrylate (EA) copolymer is [77] = 2.88 x 10 . ... 

There are relatively few data available for the synthetic polyamides. From the studies of Schaefgen and Flory (224) on 6-Nylon in sulfuric acid and those of Howard (127) on 66-Nylon in formic acid-sodium formate we derive identical values of A and of isomeric polymers is also shown in the work of Batzer and Moschle (32 f), who found that both of these Nylons and their copolymers obeyed the same viscosity-molecular weight relationship. 

In contrast, an unfractionated equimolar styrene-MA copolymer has the following viscosity-molecular weight relationship ... 

The molecular weight of SAN can be easily determined by either intrinsic viscosity or size-exclusion chromatography (sec). Relationships for both multipoint and single point viscosity methods are available (18,19). Two intrinsic viscosity and molecular weight relationships for azeotropic copolymers have been given (20,21) ... 

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 ... 

A similar variety of samples was tested for thermal stability by capillary rheometry and TGA. Figure 6.3 shows the viscosity-shear rate dependence for PCTFE homopolymers and one copolymer (Alcon 3000). All materials, save one, showed virtually identical viscosity relationships despite large changes in inherent viscosity. Only the polymers from runs initiated by fluorochemical peroxides (FCP) showed a dependence of molecular weight (as measured by inherent viscosity) upon melt viscosity. 

Molecular Weight. The viscosity average molecular wei t of the homopolymer and copolymers was determined from single point determinations of viscosity of a 0.25% solution in Fisher purified cyclohexane at 30.0 + 0.01° C. The molecular wei t is calculated from the intrinsic viscosity, [q], using the relationship ( ... 

Anomalous relationship of melt viscosity to molecular weight. The melt viscosity of a block polymer is significantly higher than that of the corresponding random copolymer of the same molecular weight, and this deviation itself Increases with molecular weight of the blocks. 

The relationship between molecular weight and intrinsic viscosity for each copolymer composition was not established. An approximate value for Mv was obtained from Eq. (1) derived for polyisobutylene (19) ... 

PG, PL, and PLG copolymers are characterized by first determining their inherent viscosity ( 7inh) and/or intrinsic viscosity, [ ], in a suitable solvent (benzene, toluene, chloroform or HFIP). A method is given in ASTM D-2857. Intrinsic viscosity is also a convenient means of determining the molecular weight of the homopolymers using the Mark-Houwink relationship between intrinsic viscosity [ ] and molecular weight. 

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