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Copyright of Industria Textila is the property of Institutul National de Cercetare-Dezvoltare pentru Textile si Pielarie and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Self-crimp side-by-side bicomponent filaments (SBSBFs) were prepared via melt spinning using two kinds of polyethylene terephthalate (PET) with great disparity of intrinsic viscosity. The influence of the volume ratio on the surface morphology, crystallinity, crimping properties, mechanical properties and shrinkage properties of the bicomponent filaments was investigated using wide-angle X-ray diffraction, a differential scanning calorimetry (DSC), scanning electron microscope, etc. As the proportion of the low-viscosity component increases, the shrinkage in boiling water or hot air, as well as the shrinkage force and the sonic orientation factor of the bicomponent filaments decrease, and the DSC heating curves change from double peaks to a single peak. These phenomena should be ascribed to the high orientation and low crystallinity of the high-viscosity PET component and low orientation and high crystallinity of the low-viscosity PET component. Moreover, the crimp property of the bicomponent filament with a volume ratio of 50:50 is superior to those with other volume ratios. [ABSTRACT FROM AUTHOR]

Prediction of Thickening Efficiency of VII and Kinematic Viscosity @ 40 and 100 °C of Blended Base Oils. Olefin Copolymers as Viscosity Index Improver for Lubricants. [Display omitted] • Excellent correlations between intrinsic viscosity of olefin copolymer with its Thickening Efficiency and Kinematic viscosities, Viscosity index of OCP Blended base oils. • Fairly high i.e. above 99% Accuracy and very low i.e. less than 0.04 Standard error in all the above predicted measurements. • Prediction of performance of an olefin copolymer in blended base oils based on an easily and quickly measurable intrinsic viscosity parameter, leading to faster screening of large number of olefin copolymers for their utility as Viscosity Modifiers in lubricants. The engine oil contains various performance additives along with polymer-based viscosity index improver, which are made from special types of flexible long chain polymers whose functionality is derived from their thickening efficiency, viscosity-temperature relationship, and shear stability. Olefin copolymers of the type ethylene/propylene copolymer are extensively used as viscosity index improver for engine oil formulations whose performance is a function of their composition, co-monomer sequence distribution and molar mass. Polymer coils interact with base oil and make it increasingly resistant to flow which accounts for substantial changes in viscosity parameters i.e. kinematic viscosities and viscosity index of blended base oils. Intrinsic viscosity of a polymeric solution is an important "dilute solution viscosity" parameter, which is easily measurable using Ubbelohde viscometer. In the present work, intrinsic viscosity of twenty samples of laboratory synthesized olefin copolymer in cyclohexane at 30 °C were correlated with their thickening efficiencies, kinematic viscosities of the olefin copolymer blended base oils at 40 °C and 100 °C. These correlation studies enable prediction of performance of olefin copolymer in blended base oil based on an easily and quickly measurable intrinsic viscosity parameter, leading to faster screening of large number of olefin copolymers for their utility as viscosity index improver in lubricants, in a short span of time with limited resources. [ABSTRACT FROM AUTHOR]

The development of non-toxic, glycidol-free chain extenders is essential for enabling the recycling and reuse of both bottle-grade PET (PET-B) and thermoform PET (PET-T) in the packaging industry without the need for separation, thereby addressing the health concerns associated with commercial glycidol-based extenders. Herein, two novel series of novel glycidol-free chain extenders for bottle-grade recycled polyethylene terephthalate (PET-B) and thermoform-grade PET (PET-T) blends are reported. Blends of PET-B with up to 20 wt% of PET-T were incorporated into novel epoxy acrylate chain extenders with terminal (PEAT-BA) and internal (PEAI-BA) epoxy groups. These chain extenders are glycidol-free and improve the mechanical, rheological, and thermal properties of the PET-B/PET-T blends, offering better performance enhancements than are provided by commercial chain extender Joncryl ADR (J). The results showed significant improvements in intrinsic viscosity and mechanical properties by around 10 and 15 %, respectively, without affecting thermal properties. These findings can play a role in enabling the recycling and re-use of PET-B and PET-T blends without requiring separation while offering glycidol-free solutions. [Display omitted] [ABSTRACT FROM AUTHOR]

Copyright of Polimery is the property of Industrial Chemistry Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Poly(L-lactic acid) (PLLA), a biodegradable polymer from plant sources, is widely employed in biomedical applications for its biocompatibility and versatile mechanical properties. However, comprehending its phase behavior in various solvents poses a challenge for broader applications. In this study, the phase behavior of the polymer was investigated in various solvent and cosolvent media and combinations at a wide range of temperatures and pressures to gain insight into the polymer properties. PLLA of varying intrinsic viscosity (IV): [0.15 dl/g, with an estimated weight average molecular weight (M w) range of approximately: 1600 to 2400 g/mol; 1.0 dl/g (M w): 100,000 g/mol); and 1.8 dl/g (M w): 80,000 to 100,000 g/mol] was employed for this study. The phase behavior of the polymer across different compositions of PLLA and solvent (CH 2 F 2 , CHF 3 , CO 2 , DME, F-22) in a wide range of temperatures from 333 to 425 K and high pressure 1.55 to 172 MPa was investigated. Miscibility of PLLA in DME and F-22 is predicted to be higher with increasing in concentration than the other cosolvents. Furthermore, in the case of the supercritical solvent CHF 3 and DME the phase transition pressure curve of PLLA was observed to exhibit a lower critical solution temperature (LCST) type with a positive gradient with increasing temperature. However, lower phase transition pressure was noticed for lower molecular weight PLLA in supercritical solvent CHF 3 and DME, i.e., of the order IV 0.15 dl/g

The viscoelastic properties of cellulose fibers play an important role in chemical recycling of textiles. Here we discriminated the intrinsic viscosity of cotton roll towels and bed linens using near-infrared imaging spectroscopy and supervised pattern recognition. The classification results showed training and test set accuracies of 84–97% and indicated that the relevant spectral features were related to water, cellulose, and cellulose crystallinity. We hypothesized that the decreasing intrinsic viscosity of cotton was associated with changes in cellulose crystallinity and water adsorption, which was supported by additional X-ray and sorption measurements. These results are important as they indicate the potential to non-invasively estimate the degree of polymerization and the suitability of different cotton materials for chemical recycling. We propose that changes in the degree of polymerization and cellulose crystallinity could be used as an indicator of the chemical quality of cellulose fibers, which would have wider impacts for textile recycling. [Display omitted] [ABSTRACT FROM AUTHOR]

Enzymatic recovery of glucose and polyester from cotton / polyester textile blends was investigated. Grinding to a fibre length of 0.5 mm increased cellulose recovery from 53.6 to 85.4%. Subsequent steam explosion combined with alkaline pre-treatment led to complete hydrolysis of cotton while sonication and solvent pre-treatments were less effective. Comparison of weight loss and HPLC analysis indicated the presence of cellu-oligomers besides glucose. Recovery of enzymes via ultrafiltration only caused less than 5% in activity loss when used in five subsequent hydrolysis cycles. Similar bioethanol yields were determined for the hydrolysate and commercial glucose as carbon source for S. cerevisiae. The absence of peaks at 3600 cm−1 and 3000 cm−1 in FT-IR analysis and differential scanning calorimetry (DSC) analysis indicated no cellulose present in the polyester fraction. Re -granulation led to an intrinsic viscosity of 0.6 dl g −1 suitable for fibre spinning and production of towels thereby closing the cycle. [Display omitted] [ABSTRACT FROM AUTHOR]

Ethylene–vinyl acetate (EVA) copolymers were chosen for this work because they show different characteristics depending on their vinyl acetate (VA) percentage. EVA has a wide range of applications, including coating of photovoltaic cells and covering of tires and cables, as a consequence of the different varieties of the material depending on the VA percentage. To date, no study has been conducted yet to determine the relationship between VA percentage and the flow ability response of an emulsion. Previous studies commonly highlighted the effect of particle size and emulsifier concentration on the emulsion process, but none of these studies directly discussed the effect of VA percentage of an EVA copolymer on the flow ability response of an emulsion. In this study, correlation between polymer-interaction was studied through measurement of intrinsic viscosity [ABSTRACT FROM AUTHOR]

Copyright of Kobunshi Ronbunshu is the property of Society of Polymer Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In conventional viscometry studies an additional treatment of data is necessary in order to obtain the expected linear dependence of the reduced viscosity on concentration in extremely diluted polymer solutions. This work reports on the direct measurements of this dependence using a new Couette-type viscometer. The values of intrinsic viscosity and Huggins coefficient of the studied poly(N-vinyl-2-pyrrolidone) (PVP) water solution notably differ from the previous results obtained by the traditional capillary viscometers. From the obtained data the parameters used in the bead-spring theories of polymer universal behavior, such as the gyration radius and the longest relaxation time are calculated. [ABSTRACT FROM AUTHOR]

The kappa number, intrinsic viscosity, and yield of Southern Pine pulps were determined after oxygen delignification at different alkali concentrations, temperatures, oxygen pressures, and treatment time in a Berty throughflow reactor. It was found that the highest delignification-cellulose degradation selectivity is achieved at low alkali concentrations and temperatures of about 100°C or less. Oxygen pressure has little effect on selectivity. Carbohydrate yield loss is proportional to kappa number loss up to kappa reduction of 60%. At higher delignification, the carbohydrate yield loss increases more strongly than delignification. However, carbohydrate yield loss is linearly correlated with cellulose degradation at all degrees of delignification. Hexenuronic acids are not removed during conventional oxygen delignification. To increase delignification of softwood pulp beyond about 60%, oxygen system design should be changed so that alkali concentration and charge are decoupled, as is similarly done in modern cooking systems. [ABSTRACT FROM AUTHOR]

The oxygen delignification of unbleached kraft pulps produced from industrial hemp stalks and hemp 'wood' was studied, as well as the susceptibility of such pulps to bleaching. Hemp stalk and wood pulp showed comparable susceptibility to delignification with oxygen in alkaline media and good bleachability in the elemental chlorine free (ECF) and the total chlorine free (TCF) bleaching processes. Good bleachabili3ty was also shown by hemp bast fibre pulp. The final yield and intrinsic viscosity of bleached pulps produced from industrial hemp were also determined and compared with the properties of pulps produced from tree wood. It was found that the final yield of bleached hemp stalk pulp was higher than that of conventional bleached birch- and pine papermaking pulps. However, the retention of high intrinsic viscosity in hemp pulps can be achieved by varying the conditions of the oxygen delignification and bleaching processes. [ABSTRACT FROM AUTHOR]

Aqueous solution properties of poly (N-isopropylacrylamide) (PNIPA) samples synthesized by radical and living anionic polymerizations were examined in detail. It is found that the cloud points in aqueous solutions of PNIPA samples synthesized by radical polymerization with azobis (isobutyronitrile) as an initiator are appreciably different from each other if the solvents used for the polymerization are different, even though the samples have the same weight-average molecular weight Mw and stereochemical composition specified by the fraction fr of racemo diads. From analyses of the mean-square radius of gyration, second virial coefficient, and intrinsic viscosity for those samples in methanol at 25.0°C, it is found that the PNIPA samples synthesized by radical polymerization have branched structure and that the number of branch points depends on the kind of solvent used for the radical polymerization. As for linear PNIPA samples synthesized by living anionic polymerization, it is shown that the cloud point in their aqueous solutions decreases remarkably with decreasing Mw in the range of 5 x 10³ Mw ≲ 7 x 104 due to effects of hydrophobic chain end groups of the samples. The transmittance of light passing through an aqueous solution of a linear PNIPA sample synthesized by living anionic polymerization was examined in detail in the vicinity of its cloud point. It is found that the transmittance approaches a constant value even at a temperature slightly higher than the cloud point, indicating that macroscopic phase separation does not take place at the cloud point in the solution and therefore the cloud-point curve does not correspond to the binodal. Static and dynamic light scattering measurements were then carried out for aqueous solutions of the linear PNIPA sample and one synthesized by radical polymerization at some temperatures considerably lower than the cloud point. It is shown that both PNIPA aqueous solutions contain aggregates even at such temperatures, and the number, size, and density profile of the aggregates depend on the kind of chain end group and also on the primary structure. [ABSTRACT FROM AUTHOR]

Intrinsic viscosities [η] were determined for five polystyrene samples ranging in molecular weight Mw from 9.0 x 104 to 1.2 x 106 in toluene-supercritical carbon dioxide mixtures with different weight fractions of CO2 (denoted as w(CO2)) at 40 °C in a pressure range P = 7.0-10.0 MPa using a rolling-ball viscometer. For every sample [η] was a gradually increasing function of P, indicating that the polystyrene coil expands with increasing P. At fixed P and w(CO2), the molecular weight dependence of [η] was expressed in the form [η] α Mwa. The exponent a remarkably changed with w(CO2) at constant P; for example, it decreased from 0.68 (a good solvent value) to 0.42 (a poor solvent value below the theta point where a = 0.5) with an increase in w(CO2) from 15 to 31% at P = 7.0MPa. The solvent goodness was quantified in terms of the binary-cluster integral determined by analyzing the [η] data according to the two-parameter theory. [ABSTRACT FROM AUTHOR]

The second virial coefficient A2 and intrinsic viscosity [n] were determined in methanol at 25.0°C for poly(Nisopropylacrylamide) (PNIPA) samples synthesized by living anionic polymerization in the range of weight-average molecular weight Mw from 4.91 x 10³ to 7.23 x 104, which are called L samples, and also for those by radical polymerization in ten-butanol and benzene by the use of azobis(isobutyronitrile) as an initiator in the range of Mw from 1.23 x 104 to 7.83 x 104, which are called T and B samples, respectively. It is found for both A2 and [n] that their values for the three kinds of samples agree well with each other in the range of Mw <∼ 3 x 104 but deviate from each other as Mw is increased from 3 x 104, the value for the L sample being the largest and that for the B sample the smallest. The result is consistent with the fact that the average chain dimension is the largest for the L sample having no branch point and the smallest for the B sample having the largest number of branch points. From a simultaneous analysis of A2 and [n] for the L samples on the basis of the Kratky-Porod wormlike chain with excluded volume, the stiffness parameter λ-1 is estimated to be 18 Å, which is almost the same as those determined for typical flexible polymers. For the L samples, the cloud point was also determined in their aqueous solutions in the range of the weight fraction w of PNIPA from ca. 0.5 to ca. 10%. It is found that the cloud point in the range of w >∼ 2% decreases from ca. 32°C to ca. 18°C as Mw is decreased from 7.23 x 104 to 5.47 x 10³. Such behavior may be regarded as arising from effects of hydrophobic chain end groups of the L samples. [ABSTRACT FROM AUTHOR]

Light and small-angle X-ray scattering, sedimentation equilibrium, viscosity, circular dichroism, and infrared absorption measurements have been made on 1,4-dioxane (DIOX) and 2-ethoxyethanol (2EE) solutions of seven amylose tris(phenylcarbamate) samples ranging in molecular weight from 2 × 104 to 3 × 106. Analyses of gyration radius, scattering function, and intrinsic viscosity data in terms of the wormlike chain model yield Kuhn segment lengths of 22 ± 2 nm and 16 ± 2 nm in DIOX and 2EE, respectively, and a contour length per residue of 0.33 ± 0.02 nm in both, showing that the amylose derivative chain has high stiffness and a contour length slightly shorter than the known value 0.37-0.40 nm for amylosetriesters in the crystalline state. These results are consistent with the intramolecular hydrogen bonding between the C=O and NH groups of the neighbor repeating units detected by infrared absorption and also with the locally regular (or helical) conformation indicated by circular dichroism. [ABSTRACT FROM AUTHOR]

It is demonstrated that wormlike micelles of nonionic surfactants polyoxyethylene alkyl ethers H(CH2)i(OCH2CH2)jOH (CiEj) have been successfully characterized by static (SLS) and dynamic light scattering (DLS) measurements and viscometry with the aid of the theories developed so far in the field of polymer solution studies, i.e., a molecular thermodynamic theory for light scattering, chain statistical and hydrodynamic theories for semi-flexible polymers. The results for the excess Rayleigh ratio, radius of gyration, hydrodynamic radius, and intrinsic viscosity have been shown to be well represented by the theories based on a wormlike spherocylinder model. Some salient features found for the micelles of CiEj with various i or j, their binary mixtures, and the micelles including n-alcohol and n-alkane are discussed. [ABSTRACT FROM AUTHOR]

The intrinsic viscosity [η] was determined for 13 samples of poly(diisopropyl fumarate), each with the fraction of racemo diads fr=0.22, in the range of weight-average molecular weight Mw from 4.02×104 to 8.59×105 in tetrahydrofuran at 30.0 °C. The translational diffusion coefficient D was also determined from dynamic light scattering measurements for 12 of them in the range of Mw from 4.95×104 to 8.59×105 under the same solvent condition. The data so obtained were analyzed on the basis of the corresponding transport theories for the unperturbed Kratky—Porod (KP) wormlike cylinder model combined with the quasi-two-parameter theory for the intramolecular excluded-volume effect. It is shown that the experimental values are in quantitative agreement with the perturbed KP theory ones by the use of the model parameter values consistent with those determined previously from analyses of the mean-square radius of gyration and second virial coefficient A2. An examination was also made of behavior of the Flory—Fox factor Φ and reduced hydrodynamic radius ρ-1 as functions of Mw. [ABSTRACT FROM AUTHOR]

The mean-square radius of gyration (S2), second virial coefficient A2, and intrinsic viscosity [η] were determined in methanol at 25.0°C for two kinds of poly(N-isopropylacrylamide) (PNIPA) synthesized by radical polymerization in tert-butanol and benzene by the use of azobis(isobutyronitrile) as an initiator. In all cases of the three quantities, it is found that the value is smaller for the PNIPA synthesized in benzene than for that synthesized in tert-butanol and the difference between the two kinds of PNIPA increases with increasing the weight-average molecular weight Mw. The average chain dimension of the former PNIPA should then be smaller than that of the latter. Since the two kinds of PNIPA were shown to have the same stereochemical composition (and also the same chain end group), the difference in the average chain dimension may be regarded as arising from the difference in the primary structure, i.e., the number of branch points. Considering the fact that the average dimension of a given polymer chain in general decreases with increasing the number of branch points, it may be concluded that the number is larger in the former PNIPA than in the latter. The behavior of the interpenetration function Ψ and the Flory-Fox factor Φ as functions of Mw is also examined, confirming the conclusion. [ABSTRACT FROM AUTHOR]

The ratio gη of the intrinsic viscosity of the Kratky-Porod (KP) wormlike regular three-arm star touched-bead model to that of the KP linear one, both having the same (reduced) total contour length L and (reduced) bead diameter db, is numerically evaluated in the Kirkwood-Riseman (KR) approximation. Prior to the evaluation of gη, an interpolation formula for the mean reciprocal of the end-to-end distance of the once-broken KP chain, which is necessary for the theoretical calculation in the KR approximation, is constructed on the basis of the asymptotic forms derived by the use of the Daniels method near the random-coil limit and the ∈ method near the rod limit and also on the basis of the Monte Carlo results. From an examination of the behavior of gη as a function of L and db, it is found that the ratio of gη/gη0 of gη to the rod-limiting value gη0 of gη monotonically increases from 1 to 2.03 with increasing L and is almost independent of db for db ≲ 0.2, although the behavior of gη itself as a function of L remarkably depends on db. An empirical interpolation formula is then constructed for gη/gη0 as a function of L, which is considered to be useful for practical purposes. [ABSTRACT FROM AUTHOR]

Static and dynamic light scattering and viscosity measurements were made on 12 samples of polymacromonomer F110 consisting of polystyrene with 113 styrene units in each side chain to determine the z-average mean-square radius of gyration, the hydrodynamic radius, and the intrinsic viscosity in cyclohexane at 34.5 °C (the theta temperature) and toluene at 15.0 °C as functions of weight-average molecular weight Mw. Small-angle X-ray scattenng experiment was also performed for one sample in the two solvents. The dependence of the three measured properties on Mw in the range 1.9 x 105-1.3 x 107 studied were consistently explained by available theories for the wormlike chain with ML (the molar mass per unit contour length) = 45500nm-1, λ-1 (the stiffness parameter) = 80nm (in cyclohexane) or 155 nm (in toluene), and d (the chain diameter) = 16-26 nm (depending on the kind of solvent and measured property) when the end effect arising from side chains near the main-chain ends was taken into account. The side-chain length dependence of/λ-1, examined with the aid of previous data for three polystyrene polymacromonomers with shorter side chains of 15, 33, and 65 styrene units, was found to be almost quantitatively explained by the theory of Nakamura and Norisuye [Polym J., 33, 874 (2001)]. That of d was also discussed in relation to the end-to-end distance of a wormlike side chain [ABSTRACT FROM AUTHOR]

A Monte Carlo (MC) study is made of the intrinsic viscosity [η] and also of the mean-square radius of gyration (S²) for regular three-arm star freely rotating chains of bond angles θ = 109°, 165°, and 175° and with the Lennard-Jones 6-12 potentials between beads having the parameter values corresponding to the η temperature, in the range of the total number n of bonds in the chain from 60 to 300. Three kinds of approximate values of [η] are calculated by the use of the Kirkwood-Riseman (KR) approximation, the Zimm rigid-body ensemble approximation which gives an upper bound [η](U) to [η], and by the Fixman method which gives a lower bound [η](L), the KR value of [η] being designated [η](KR). On the basis of the three kinds of MC values of [η] so obtained, the behavior of the ratio gη of [η] for the star chain to that for the linear one, both having the same n, is examined as a function of the reduced contour length ηL as defined as the total contour length L of the corresponding Kratky-Porod (KP) wormlike chain divided by its stiffness parameter η-1, the values of ηL having been determined from an analysis of the present and previous MC data for (S²) on the basis of the KP chain. It is found that the KR value gη(KR) of gη as defined by [η](KR)(star)/[η]KR(linear) lies between the values of an upper bound gη(U) and a lower one gηL which are defined by [η](U)(star)/[η](L)(linear) and [η](L)(star)/[η](U)(linear), respectively, irrespective of the values of ηL. Further, the difference between the two bounds becomes very small for small ηL. [ABSTRACT FROM AUTHOR]

The behavior of poly(vinyl pyrrolidone) (PVP) in methanol was examined using several independent methods. The hydrodynamic radius (Rh) of individual samples, over a range of molecular weights (10,000-360,000), was determined using dynamic light scattering (DLS) measurements. Dynamic Light Scattering (DLS) techniques directly probe such dynamics by monitoring and analyzing the pattern of fluctuations of the light scattered from polymer molecules. Some viscosity measurements were also performed to complete the DLS measurements and to provide more information on the particle structure. The results obtained with PVP-methanol system showed that plotting the variation of intrinsic viscosity versus the logarithm of the molecular mass of this polymer, we observe one crossover point. This crossover point appears when we reach the Θ-solvent behavior and delimit two molecular mass regions. The second order least-squares regression was used as an approach and was in excellent agreement with viscometric experimental results. [ABSTRACT FROM AUTHOR]

The temperature and molecular weight dependencies of the intrinsic viscosity [η] were investigated for cellulose tris(phenyl carbamate) (CTC) in tetrahydrofuran (THF). By the analysis of the [η] data in terms of the wormlike cylinder model, the persistence length q of CTC was determined as a function of the temperature. With decreasing the temperature from 25 to -20°C, q increases from 10.5 to 13.7 nm. This temperature dependence of q was successfully explained by the broken wormlike chain model, where each glucose residue in the cellulosic chain is assumed to take left-handed 3/1 or 2/1 helical state and occasionally a kink state generated by a glucosidic bridge angle fluctuation. While the torsional fluctuation in each glucosidic bond is considerably small, there are two energetically favored helical (3/1 and 2/1) states, so that the cellulosic chain may not be regarded as a regular helix in solution. [ABSTRACT FROM AUTHOR]

The intrinsic viscosity [η] of a poly(acrylic acid) (PAA) ,sample with a molecular weight of 4 x 106 in aqueous salt solution drastically increased by adding isopropyl amine (A-1). At the infinitely high concentration of the hydrochloric salt of A-1, where the electrostatic interaction is completely screened out, [η] was enlarged by 40 times as the degree of complexation fc increases from ca. zero to 0.6. Here fc was determined by potentiometric and NMR titrations. Furthermore, [η] at infinite ionic strength for PAA complexed with a bulkier and room hydrophobic amine, (R)-(+)-1-(phenyl)ethylamine (A-2), was higher than that for the complex of PAA and A-1 at the same ft. The drastic expansion of the PAA chain by the complexation with the amines A-I and A-2 may arise from the chain stiffening and enhanced excluded volume effect. [ABSTRACT FROM AUTHOR]

Micelles of pentaoxyethylene C12E5, hexaoxyethylene C12E6, hepatoxyethylene dodecyl ethers C12E7, and heptaoxyethylene tetradecyl ether C14E7 in dilute aqueous solutions were characterized by viscometry. The intrinsic viscosity [η] of the micelles whose size are concentration-dependent were able to be determined at finite concentrations by applying an equation derived by combining the Huggins and Fuoss-Mead equations. The results of [η] as a function of the molar mass of the micelle were successfully analyzed by the hydrodynamic theory for wormlike polymers formulated with the touched bead model, indicating that the micelles assume a flexible cylindrical shape. The values of the cross-sectional diameter d have suggested that the surfactant molecules take a randomly coiled form in the micelles. [ABSTRACT FROM AUTHOR]

Thin film composite membranes of poly(ether-block-amide) copolymer Pebax® 3533 were prepared for the first time on asymmetric polysulfone supports by a phase inversion method. The casting solution concentration and the number of layers were varied to study their influence on the selective layer thickness and the gas separation performance. The casting solution concentrations of polymer dissolved in the 1-propanol/1-butanol mixture were 0.25, 0.5, 1.0 and 1.5 wt%. These conditions produced membranes with selective skin layers with thicknesses from 0.2 to 1.8 µm. All the membranes were characterized by scanning electron microscopy, thermogravimetric analysis and infrared spectroscopy. Furthermore, the intrinsic viscosity of all the casting solutions was studied to understand the effect of the polymer concentration on the homogeneity and the gas separation properties of the obtained membranes. In general, lower viscosity of casting solutions rendered to more defective skin layers, resulting in a higher number of layers required to obtain selective membranes. The gas separation performance was tested for the post-combustion 15/85 CO 2 /N 2 mixture at 25–50 °C and under a feed pressure of 3 bar. The best separation performance was achieved with the 0.5 wt% casting solution membranes after the deposition of four polymer layers, obtaining a CO 2 permeance of 127 GPU and a CO 2 /N 2 selectivity of 21.4 at 35 °C, the same selectivity of the corresponding dense membrane but with much higher permeance. [Display omitted] • Thin film Pebax®3533/PSF membranes were fabricated for the first time by a phase inversion method. • The effect of the viscosity of casting solutions on the deposition of Pebax® layer was studied. • With diluted casting solutions, a minimum of four Pebax® layers were required. • Selective skin layer thicknesses of Pebax ranged from 0.2 to 1.8 µm. • The effect of casting solution concentration and number of polymer layers on the CO 2 /N 2 separation was studied. [ABSTRACT FROM AUTHOR]