Showing papers on "Intrinsic viscosity published in 1975"

Viscosity and molecular weight of hyaluronic acids.

Abstract: The intrinsic viscosity ([eta]) and the molecular weight (M) by sedimentation equilibrium were determined for hyaluronic acids of low (M=104--7.2X10(4)) and high (M=3.1X10(5)--1.5X10(6)) molecular weights. Double logarithmic plot of [eta] against M gave different lines for the two groups. The relationship between [eta] and M was [eta]=3.0X10(6)XM1,20 for the former and [eta]=5.7X10(-4)XM0.46 for the latter group. The molecular weight at the point of intersection of the two lines was about 1.5X10(5). The rheological behavior of the hyaluronic acids below M=2.1X10(4), for which the value of reduced viscosity was independent of concentration, was different from that of the hyaluronic acids above M=5.1X10(4), for which the value of reduced viscosity increased with concentration.

Dynamics of chain molecules. I. Solutions to the hydrodynamic equation and intrinsic viscosity

Abstract: An exact numerical solution to the equation of motion for a flexible macromolecule in solution is given for the bead and spring model incorporating the preaveraged Oseen hydrodynamic interaction. The limits to be imposed on the strength of the interaction are confirmed and discussed. The data obtained for the eigenvalues λK, the eigenvectors QjK, and the quantities μK show that the hydrodynamic interaction affects the relaxation times and the shapes, the mean square length of the modes remaining practically unchanged with respect to the free‐draining results. By comparison with the intrinsic viscosity experimental data, the values of r/b (hydrodynamic interaction strength) and b (mean dimension of the subchain) may be obtained. The method has been applied to PS and PDMS. Defined and reasonable values of r/b and b have been obtained. The range of r/b of major interest (0.2–0.3) gives small draining effects over a large molecular weight range; this makes the intrinsic viscosity depend approximately on M0.5,...

Dilute Solution of Bisphenol A Polycarbonate

Abstract: Narrow-distribution fractions of bisphenol A polycarbonate in tetrahydrofuran (THF) and chloroform were studied by light-scattering, sedimentation velocity, and viscosity measurements over the range of molecular weights from 4×103 to 5×105. The asymptotic values of a dimensionless quantity A2Mw/[η] and the interpenetration function Ψ Where significantly lower than those usually expected for flexible polymers, suggesting a certain stiffness of the polycarbonate chain. Here A2 is the second virial coefficient, Mw is the weight-average molecular weight, and [η] is the intrinsic viscosity. Data for statistical radii ‹S2›1/2, sedimentation coefficients SO, and [η] in THF were analyzed in terms of the wormlike chain model. First, the three parameters q, ML, and d characterizing the wormlike cylinder were estimated by using a recent theory of SO by Yamakawa and Fujii and assuming that the hydrodynamic volume per gram is equal to the partial specific volume of the polymer. Here q is the persistence length, ML is the shift factor defined as the molar weight per contour length, and d is the diameter of the cylinder. The results were q=18 A, ML=26 daltons/A, and d=6.6 A. It was then shown that these molecular parameters and small expansion factors for the excluded volume allowed a consistent interpretation of the experimental data for SO, ‹S2›, and [η]. The consistency between the intra- and inter-molecular excluded-volume effects were also examined by use of the perturbation theories for αs (expansion factor for ‹S2›) and for A2 of the wormlike beads. An important finding from the present study is that, while αs of the polycarbonate in THF is rather small, the binary cluster integral between a pair of monomers is quite large (about 170×10−24cm3).

Studies on hyaluronic acid. V. Relationship between the protein content and viscosity of rooster comb dermis hyaluronic acid.

Abstract: Protein accounted for an average of 8.7% w/w of the hyaluronic acid obtained from rooster comb dermis extracts and three types of peptide constituents appeared to be present. A few collagen-like fibers were closely associated with the hyaluronic acid when samples were examined in the electron microscope and collagenase treatment decreased the intrinsic viscosity from 7000-5000 ml/g to 3900-2700 ml/g. The quantities of collagen present, however, were too small to detect chemically with the methods employed. The major peptide consituent was readily separated from the hyaluronic acid by fractionation in a cesium chloride gradient or by treatment with pronase. The viscosity was decreased by the density gradient procedure but not by the pronase digestion. Repeated fractionation in a cesium chloride gradient decreased the intrinsic viscosity still further and a small peptide constituent with a high glycine and serine content remained associated with a hyaluronic acid. The data suggest that an interaction or entanglement with collagen fibers is responsible for the high viscosity of hyaluronic acid in this tissue extract and that the viscosity of purified hyaluronic acid preparations is dependent upon interactions between adjacent polysaccharide chains. Interactions between the major peptide constituent and polysaccharide chains or the small residual peptide component remaining with hyaluronic acid after extensive purification procedures, however, appear to be involved in some organized structure because the presence of the major peptide constituent minimized the decrease in viscosity that occurred when hyaluronic acid samples were lyophilized.

Correlation function formula for the intrinsic viscosity of dilute polymer solutions

Abstract: The correlation function formalism for the intrinsic viscosity of polymers is studied. A controversy concerning the correct force to use in the momentum flux is resolved. It is shown that when the diffusion equation is used in the full configuration space of polymer segments the forces entering the momentum flux are purely mechanical and there is no entropic contribution. A comparison is made with Kirkwood’s theory of viscoelastic behavior. The correlation function expression we advocate is shown to yield the correct high frequency limiting behavior for the case of elastic dumbbells.

Frictional properties of dilute polymer solutions IV. Intrinsic viscosity

Abstract: In the framework of our generalization of the Debye-Bueche theory for the frictional properties of dilute polymer solutions we study the intrinsic viscosity. A careful definition of the intrinsic viscosity for polymers with spherically symmetric density distribution is given. The equations are solved explicity for uniform spheres and spherical shells. For the general case a perturbation method is applied and a variational principle of minimum energy dissipation is formulated which is suitable for numerical work.

Some Physical and Chemical Properties of Nuclease P1

Abstract: Some physico-chemical properties of nuclease P1 (isoelectric point, 4.5) from Penicillium citrinum were studied. The extinction coefficient at 280 nm, , was 18.4. The partial specific volume , the intrinsic viscosity ([η]), the sedimentation coefficient () and the diffusion coefficient (D20,w) were 0.712 ml/g, 4.17 × 10−2 ml/g, 3.55 S and 7.4 × l0−7 cm2/sec, respectively.The molecular weight was estimated to be 42,000~50,000 by several methods including sedimentation velocity, sedimentation equilibrium, gel filtration and SDS-acrylamide gel electrophoresis. The amino acid composition of the enzyme was characterized by the high content of hydrophobic amino acids, especially tyrosine and tryptophan. The enzyme was found to be a zinc metalloenzyme which contained 3 gram atoms of zinc per mole based upon the molecular weight of 44,000. The enzyme also contained about 17.4% carbohydrates, consisting of mannose, galactose and glucosamine in a molar ratio of 6: 2: 1. The enzyme exhibited a high affinity for conc...

Estimation of the zero shear rate viscosity for dilute solutions of rigid macromolecules with complex configurations

Abstract: A method for estimating the zero shear rate viscosity for dilute solutions of rigid macromolecules with complex configurations is proposed; this method is based on the macromolecular kinetic theory of Curtiss, Bird, and Hassager. Macromolecular models constructed from a collection of spheres, cylindrical rods, circular discs, and parallelepipeds with arbitrary dimensions and relative orientations can be easily handled by this method. Comparison with available experimental data for several biopolymers shows excellent agreement. As an application to this method, we investigate the effect of surface roughness on the intrinsic viscosity of spherical particles.

The interaction of glutaraldehyde with poly(α,L-lysine), n-butylamine, and collagen. II. Hydrodynamic, electron microscopic, and optical investigations on the reaction products

Abstract: Interactions of glutaraldehyde with either n-butylamine, poly(α,L-lysine), or collagen resulted in a fast release of protons in dilute aqueous solutions at various pH values, followed by much slower changes. The latter reactions, which extended over hours and days, were followed spectrophotometrically and revealed the formation of distinct absorption bands in the visible and near-ultraviolet regions in all the above systems. The visible-range bands disappeared upon treatment with sodium borohydride. A qualitative relationship between oxygen uptake by the system n-butylamine–glutaraldehyde and the slow formation of colored products has been established, while the chemical nature of the reaction products has not been determined. Sedimentation velocity, viscosity, and optical rotation measurements on the products of interaction between poly(L-lysine) and glutaraldehyde in aqueous solution indicated large conformational changes in the polyamino acid present in excess (in residues) over the dialdehyde. In particular, the intrinsic viscosity dropped considerably after interaction, indicating intramolecular crosslinking. At molar ratios of 1:1 between polylsine residues and aldehyde groups, intermolecular crosslinking of polylysine was obtained at pH 8.6. Electron microscopic examinations of collagen samples treated by glutaraldehyde at various pH values indicated changes from unordered to more ordered structures upon treatment with glutaraldehyde, in particular at pH 10. The present structural and optical investigations are considered to be relevant to tanning processes of hides and to fixation procedures.

High molecular weight polycondensates from solid phase condensation

Abstract: Polyester precondensates are catalytically polycondensed in solid phase at a constant temperature with a linear increase (during polycondensation) in intrinsic viscosity. The linear increase makes possible an accurate advance determination of reaction time required to produce thermoplastic polycondensate of the desired intrinsic viscosity.

The intrinsic viscosity of dilute solutions of stiff polymers

Abstract: The intrinsic viscosity of a dilute polymer solution is studied for a polymer model with rigid constraints on some quantities, such as bond lengths and bond angles. The constraints are introduced via a harmonic constraining potential; the strength of this potential is taken to infinity at the end of the calculation. Expressions for the frequency dependent intrinsic viscosity are obtained with the correlation function formalism. The limiting form for the case in which the constraints become rigid is obtained via a systematic expansion procedure. In the limit we obtain a contracted description in terms of the unconstrained variables only. We discuss the form of the polymer diffusion equation and various expressions for the stress tensor that may be used in the context of such a contracted description, as well as expressions for both the frequency dependent and the frequency independent part of the intrinsic viscosity. We compare our results with those of other authors. Complete agreement is found with the r...

The application of the gel permeation chromatography-intrinsic viscosity method to the determination of long-chain branching in polychloroprene

Abstract: We report the preparation of a low-temperature (—20°C), low-conversion (4.5%) emulsion polymer of 2-chlorobutadiene-1,3 which has been employed as a “linear” standard trans-1,4-polychloroprene. This “linear” standard was fractionated, and the fractions characterized by light scattering, viscometry, and gel permeation chromatography (GPC). The Mark-Houwink constants, K and a, were determined in tetrahydrofuran at 30°C and found to be 4.18 × 10−5 dl/g and 0.83, respectively. Furthermore, polychloroprene was found to adhere to the concept of universal calibration. The GPC-intrinsic viscosity method for the determination of long-chain branching has been applied to polychloroprene polymers prepared at 40°C as a function of conversion. The degree of branching increases with conversion in a manner consistent with the accepted mechanism of free radical diene polymerization.

Block and graft copolymers by selective cationic initiation. II. Synthesis and characterization of styrene‐isobutylene block copolymers by use of chlorobrominated alkanes

Abstract: The synthesis and characterization of a new block copolymer, poly(styrene-b-isobutylene) (PSt-b-PIB), is described. The synthesis involves the initiation of an isobutylene polymerization by a polystyrene molecule containing a terminal tertiary bromine (PSt-Br), in conjunction with diethylaluminum chloride coinitiator. The species PSt-Br is in turn synthesized by initiating the polymerization of styrene selectively by the tertiary chlorine of the 2-bromo-6-chloro-2,6-dimethylheptane/Et3Al initiator system in the absence of chain transfer. The conditions conducive for selective initiation by tertiary chlorine have been worked out. The pure block copolymer, PSt-b-PIB, is obtained by selective extraction and some of its properties were determined, e.g., solubility and film behavior, Tg, and intrinsic viscosity versus temperature. The intrinsic viscosity (in toluene) exhibits a maximum and a minimum in the temperature range from 15 to 55°C.

Process for producing chemically crosslinked polyethylene-polybutadiene

Abstract: A process for producing a chemically crosslinked polyethylene foam, which comprises heating a polyethylene composition consisting essentially of 97 to 50 % by weight of polyethylene, 3 to 50 % by weight of polybutadiene having a 1,2-addition unit content of at least 70 %, an intrinsic viscosity [η] of at least 0.7 dl/g (as measured in toluene at 30° C), at least one blowing agent and at least one crosslinking agent to foam and crosslink said polyethylene composition. The above process can be carried out with a smaller amount of crosslinking agents without expensive crosslinking equipment, and the foam obtained by this process has improved physical properties.

Unperturbed dimensions of linear chain polymers in pure and in mixed solvents

Abstract: The unperturbed dimensions of poly (p-tert-butylphenylmethacrylate) and of poly (p-tert-butylcyclohexyl-methacrylate) have been determined from intrinsic viscosity in pure and mixture of solvents by using the semiempirical equation ofStockmayer andFixman.

Dielectric Study on Globule-Coil Transition in Polymer Solution

Abstract: Dielectric transition similar to that found in poly(vinyl acetate) solution was also observed in dioxane solution of poly(vinyl chloride) and poly ( p -chlorostyrene) in carbon tetrachloride. It is shown that the dielectric dispersion observed above the transition temperature is attributed to a rotational motion only of a few monomeric units between two bonds undergoing rotation. On the other hand, below the transition temperature, the chain motion is subject to restriction caused by some intrachain interaction and a large number of the monomeric units must move together because of that interaction. Measurements of the intrinsic viscosity on poly(vinyl acetate) in carbon tetrachloride and poly(vinyl chloride) in dioxane show that the transition is a conformational transition from a loosely coiled chain molecule to a compact chain molecule. It is shown that the transition is a kind of globule-coil transition suggested theoretically by some authors.

Screening regimes for the viscosity of concentrated polymer solutions

Abstract: Our previous theory of the concentration dependence of the viscosity of polymer solutions is generalized to treat gaussian chains in the intermediate draining case It is shown that the high concentration polymer viscosity displays two distinct screening regimes with an intermediate transition zone The low concentration regime is characterized by a screening constant and a specific polymer viscosity which is proportional to the polymer concentration c The high concentration regime sets in for concentrations approaching bulk values and has a Debye-like screening constant ∝c½ and a concentration independent specific polymer viscosity Throughout the screening regime, the polymer viscosity has a Rouse-like molecular weight dependence, despite the full inclusion of hydrodynamic interactions

Unperturbed dimensions of poly(9‐vinyladenine)

Abstract: The effect of base stacking interactions on the conformation of poly(9-vinyladenine) (PVAd) was investigated by osmometry, intrinsic viscosity, and light-scattering measurements. At neutral pH, ideal solution behavior (θ conditions) for this polymer was observed at 26 and 40°C. Intrinsic viscosity measurements revealed a conformational transition on heating from 26 to 40°C, while the ultraviolet absorbance of the solution was insensitive to the change. The transition was accompanied by an inversion in sign of the entropy parameter from negative to positive and an increase in the partial specific volume. At 40°, the variation of intrinsic viscosity with molecular weight corresponded to a random coil conformation, but the characteristic ratio, r02/nl2 = 8.6 ± 0.2 indicated that the unperturbed dimensions were smaller than usually observed for comparable vinyl polymers. At 26°, a rare macromolecular phenomenon was found, the intrinsic viscosity–molecular weight relation and the estimated r02/nl2 of 6.0–6.8 suggested that the PVAd was in a very highly compacted coil conformation, approaching a semirigid sphere. It is proposed that this effect be named the introversion phenomenon. Unlike polyadenylic acid, whose unperturbed dimensions increase with decreasing temperature due to nearest-neighbor base stacking, the results reported here suggest that both nearest-neighbor and long-range intramolecular base stacking occur in PVAd. The different stereochemical arrangements of bases in PVAd and Poly A are probably responsible for the opposite behavior observed.

Excluded volume study of a sulfonate‐containing polyelectrolyte in salt solutions

Abstract: Chain characteristics of a linear sulfonate-containing homopolymer, sodium poly(3-methacryloyloxypropane-1-sulfonate), in aqueous salt solutions (ionic strength, Cs = 0.01N to 5N NaCl) have been investigated by light scattering and intrinsic viscosity. The molecular weight (Mw)–viscosity relation can be well described by the Mark–Houwink and the Stockmayer–Fixman equations. The coil is highly expanded even in the most concentrated NaCl solution (6N), and no 1:1 electrolyte was found to precipitate this polymer. A linear relation was observed between the viscosity expansion factor, α3η, and (Mw/Cs)1/2. Examination of the data in terms of theories for excluded volume and hydrodynamic interaction suggests that the coil experiences dominant hydrodynamic interaction, corresponding to a nondraining coil, and the second virial coefficient and coil expansion at high Cs can be correlated by the Flory–Krigbaum–Orofino equation. Results for this polymer are compared with those for other polyelectrolytes, and are discussed in terms of chain structure, flexibility, and hydrophobicity.

Solution Properties of Phycocyanin. II. Studies of the Molecular Shape and Size by Using the Shell Model

Abstract: The number-average molecular weight and intrinsic viscosity of phycocyanin, isolated from Porphyra tenera, have been determined by osmotic pressure and viscosity measurements at various values of pH and ionic strength. The molecular shape and size for phycocyanin aggregates were also discussed by comparing the experimental values of sedimentation coefficient and intrinsic viscosity with the calculated results obtained by using the shell model theory. It is shown that the aggregate of phycocyanin at pH 5.4 is a hexamer of molecular weight 256000 and the structure consists of six juxtaposed monomers. The monomer is a prolate ellipsoid of 35 A in diameter and 105 A length. This structure for the hexamer is consistent with the model proposed by Jennings. At pH 6.8, it is shown that the number-average molecular weight of phycocyanin depends on the ionic strength in solution.

Some further comments on correlation‐function formulas for polymer intrinsic viscosity

Abstract: A correlation‐function formalism for the intrinsic viscosity of polymers is reinvestigated. It is shown that the nonprojected part of the total momentum flux for the solution may be neglected for long enough chains and that the diffusion‐force term does not appear in the flux for the polymer in the diffusion limit.