Intrinsic viscosity copolymer

SAN resins show considerable resistance to solvents and are insoluble in carbon tetrachloride, ethyl alcohol, gasoline, and hydrocarbon solvents. They are swelled by solvents such as ben2ene, ether, and toluene. Polar solvents such as acetone, chloroform, dioxane, methyl ethyl ketone, and pyridine will dissolve SAN (14). The interactions of various solvents and SAN copolymers containing up to 52% acrylonitrile have been studied along with their thermodynamic parameters, ie, the second virial coefficient, free-energy parameter, expansion factor, and intrinsic viscosity (15). 

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 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 . ... 

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 ... 

Figure 12 were superimposable on those for detector 2. Therefore, when the plot shown in Figure 14 is linear over the range of compositions involved in the sample, then (according to equations (1-4) ) the composition of the sample is the same at each retention volume. If the variation with retention volume is negligible the copolymer can then possibly be treated as is a homopolymer in GPC interpretation. In particular, intrinsic viscosity measurements could then lead to estimates of molecular weight via the universal calibration curve. 

Along with spectroscopic techniques, the presence of — Sn... 0=C in the copolymers studied was confirmed by viscosimetric data 2). /Ns-The dependence of intrinsic viscosity on concentration has a non-linear character, which is probably due to the conformational changew caused by the destruction of... 

Viscosimetric studies of organotin copolymer solutions allow the changes in the shape of the macromolecules to be followed as a function of the electrostatic charge. From the plot of the intrinsic viscosity of copolymers in DMFA solution against the degree of dilution it is seen that increasing dilution results in a rise of viscosity, probably due to an extension of macromolecular chains accompanied by conformational transformations. Naturally, this rise in viscosity with dilution cannot proceed infinitely since a coiled chain cannot be extended more than a completely extended chain conformation, due to intramolecular repulsion. 

All copolymers were prepared by solution polymerization, under adiabatic conditions, giving at least 99.9% conversions. The polymer gels were granulated and then dried at 90 °C to a residual water content of 10 to 12%. The active polymer content of each sample was calculated from the initial weight of the comonomers and the weight of the dried gel. Hydrolysis of the polymers was determined by conductometric titration to be less than 0.2% of the acrylamide charge. The molecular weight of the polymers was 8-10 million as determined by intrinsic viscosity measurements. 

We have recently performed systematical measurements of the intrinsic viscosity of acrylamide-acrylic acid copolymers for large ranges of r and a, in the presence of CaCl2(26). Our results show that the empirical relation (14) can be extended to the case of divalent cations by using the value of 7 given in relation (15). It should then possible to predict the variation of intrinsic viscosity at infinite dilution, but at finite concentration the formation of aggregates makes difficult the determination of the Huggins constant. 

Comparison of the limiting viscosity numbers determined in deionized water with those determined in 1 molar sodium nitrate shows a 20 per cent decrease in copolymer intrinsic viscosity in the saline solution. These results are consistent with previous studies using aqueous saline solutions as theta solvents for 2-propenamide polymers(47) Degree of hydrolysis controls the value of limiting viscosity number for the hydrolyzed copolymers in distilled water. 

Table 1. Statistical copolymers of FOA with vinyl monomers. Polymerizations were conducted at 59.4 +0.1°C and 345 + 0.5 bar for 48 hours in C02. Intrinsic viscosities were determined in 1,1,2-trifluorotrichloroethane (Freon-113) at 30 °C [23]...

Copolymer Feed Ratio Incorporated Intrinsic Viscosity (dL/g)... 

Schulze and Crouch [7] observed that the viscosity of the soluble fraction of copolymers from butadiene and styrene decreased sharply with the conversion after an initial increase up to the point of gelation. This decrease could not be solely attributed to a selective incorporation of higher molecular mass fractions in the gel, thus leaving fractions of low molecular mass in solution. Cragg and Manson [8] reported a similar relationship between the intrinsic viscosity and the fraction of the crosslinking DVB in the ECP with styrene. Within the concentration range up to 0.1 mass % of DVB no gel was formed. Therefore, a selective removal of species with a high molecular mass could not have taken place to explain the decrease in the intrinsic viscosity observed after its increase at lower concentrations of DVB. 

Figure 20.1 The chemical structures of the materials used in this study, i.e. the liquid crystal copolymer (PHB-PET), PEN and PET IV, intrinsic viscosity...

In addition, the molar mass (which is proportional to the intrinsic viscosity, [t]]. Tab. 6.17) of the copolymer decreases with increasing potential in the silent system, whereas in the sonicated case it is effectively constant. Overall ultrasound also appears to produce a more uniform reaction system in that in the silent system the reactivity ratio (determined by infra red spectroscopy) increases with electrode potential, whilst under sonication it remains fairly constant. 

Table 2 contains the characteristics of the amic ester-aryl ether copolymers including coblock type, composition, and intrinsic viscosity. Three series of copolymers were prepared in which the aryl ether phenylquinoxaline [44], aryl ether benzoxazole [47], or aryl ether ether ketone oligomers [57-59] were co-re-acted with various compositions of ODA and PMDA diethyl ester diacyl chloride samples (2a-k). The aryl ether compositions varied from approximately 20 to 50 wt% (denoted 2a-d) so as to vary the structure of the microphase-separated morphology of the copolymer. The composition of aryl ether coblock in the copolymers, as determined by NMR, was similar to that calculated from the charge of the aryl ether coblock (Table 2). The viscosity measurements, also shown in Table 2, were high and comparable to that of a high molecular weight poly(amic ethyl ester) homopolymer. In some cases, a chloroform solvent rinse was required to remove aryl ether homopolymer contamination. It should also be pointed out that both the powder and solution forms of the poly(amic ethyl ester) copolymers are stable and do not undergo transamidization reactions or viscosity loss with time, unlike their poly(amic acid) analogs.

Keywords. Dendrimers, Hyperbranched macromolecules. Block copolymers. Surface functionalization, Solvatochromism, Intrinsic viscosity... 

This study addresses two questions 1) Is polymer aggregation in solutions directly related to solvent quality 2) If not, does solvent quality exert an effect on the viscosity of semidilute solutions separate from the effect of aggregation The copolymer poly(vinylbutyral) (PVB) was chosen for this investigation. PVB is known to aggregate in several solvents (IS). Light scattering and intrinsic viscosity measurements were used to assess solvent quality. Viscosities were measured at one concentration in three solvents and temperatures from 25 to 55 C. 

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