Showing papers in "Polymer Journal in 1972"
TL;DR: In this article, an alternately-deflected molecular structure was proposed to release steric hindrance between the fluorine atoms along the chain, and a satistically disordered packing of such deflected chains satisfies the observed fiber period and improves appreciably the structure factor agreement.
Abstract: The crystal structures of three forms of poly(vinylidene fluoride) were studied by X-ray diffraction method. Although the structure of form I has been determined to be a fully extended planar zigzag by Lando, et al. [orthorhombic; a=8.58 A, b=4.91 A, and c(fiber axis)=2.56 A; space group Cm2m(C2v14)], an alternately-deflected molecular structure was postulated in order to release the steric hindrance between the fluorine atoms along the chain. A satistically disordered packing of such deflected chains satisfies the observed fiber period and improves appreciably the structure factor agreement. Form II is monoclinic [pseudo-orthorhombic; a=4.96 A, b=9.64 A, c(fiber axis)=4.62 A, and β=90°; space group P21/c(C2h5)], and its cell contains two molecular chains. The molecular conformation is essentially the TGTG type (internal rotation angles, 179° and 45°), and the glide plane of the molecular chain coincides with the c glide plane of the lattice. It is suggested that form III is monoclinic [a=8.66 A, b=4.93 A, c(fiber axis)=2.58 A, and β=97°; space group C121(C23)], and the structural features similar to that of form I.
718 citations
TL;DR: In this article, the formation of three crystalline forms of polyvinylidene fluoride was studied in detail by using an apparatus for heat treatments under high pressure up to 5000 atm.
Abstract: The formation of three crystalline forms of poly(vinylidene fluoride) was studied in detail by using an apparatus for heat treatments under high pressure up to 5000 atm. Form II consisting of TGTG-type molecular chains was the most stable under atmospheric pressure, and form I, composed of planar zigzag-type chains, was formed under special conditions, such as tension, high pressure, etc. Form III may be an intermediate modification between I and II. Based upon these experimental facts, as well as the potential energy calculations of the intra- and intermolecular interactions in the crystal lattices due to the van der Waals and electrostatic forces, the relation between the conditions of formation of the three forms and their structures was examined. The planar zigzag-type conformation (in forms I and III) is considered to be less stable than the TGTG type (form II) because of the steric hindrances and electrostatic dipole interactions. In spite of the difference in the intramolecular potential energy between these two molecular conformations, the stabilities of the three crystalline forms are not so very different because of the more favorable intermolecular interaction in form I.
228 citations
TL;DR: The Melting Temperature of Thermally Reversible Gel: as discussed by the authors The Melting temperature of reversible gel is the temperature at which the gel degrades to polyvinyl chloride.
Abstract: The Melting Temperature of Thermally Reversible Gel. I. Poly(vinyl chloride)–Organic Solvent Gels
63 citations
TL;DR: In this article, a white powder was found to be poly(N-formylethyleneimine, which was shown to be a crystalline polyethyleneimine by X-ray diffraction diagram (mp ca. 210°C).
Abstract: Pure unsubstituted 2-oxazoline (OXZ) was first prepared in good yields by modifying Wenker’s method.1 OXZ was found to polymerize by cationic catalyst in an aprotic polar solvent to give a solid polymer. The polymerization of OXZ in less-polar solvents gave polymer in much decreased yields. Lewis acids such as BF3OEt2 and SbF5, sulfonates, sulfate esters, mineral acids, and alkyl iodide were effective as the polymerization catalyst. But metal chlorides such as SnCl4 and SbCl5 were ineffective. The polymer was a white powder, which was soluble in water and insoluble in most organic solvents. The polymer was shown to be crystalline by X-ray diffraction diagram (mp ca. 210°C). The molecular structure of the polymer proved to be poly(N-formylethyleneimine) by NMR and IR spectra. Alkaline hydrolysis of poly-OXZ gave crystalline polyethyleneimine (mp 58.5°C).
60 citations
TL;DR: In this article, a sample of styrene and 1,4-divinyl-2,3,5,6-tetrachlorobenzene was prepared and fractionated using fractionated copolymers, and the effects of chain branching on the intrinsic viscosity and sedimentation coefficient were studied experimentally.
Abstract: A sample of copolymer of styrene and 1,4-divinyl-2,3,5,6-tetrachlorobenzene was prepared and fractionated. Using the fractionated copolymers, effects of chain branching on the intrinsic viscosity and sedimentation coefficient were studied experimentally. It was found that in both theta and good solvents, the intrinsic viscosity of the branched polymers obeyed a new semiempirical relationship, [η]b=g0.6[η]1. Here [η]1 is the intrinsic viscosity of a linear polymer having the same molecular weight as the branched one and g is the contraction factor which is defined as the ratio of the mean-square radii of gyration between the branched and linear polymers, i.e., g=‹S2›b/‹S2›1. It was also found that the sedimentation coefficient in theta solvent agreed with the theoretical value obtained by Kurata and Fukatsu. The degree of branching estimated from the intrinsic viscosity or sedimentation coefficient was in close agreement with the value estimated from consideration of the copolymerization kinetics.
47 citations
TL;DR: In this article, the authors examined the solution properties of nearly equimolar AB-diblock and BAB-triblock copolymers, wherein A is polystyrene (PST) and B poly(methyl methacrylate) (PMMA), in various selective solvents.
Abstract: Solution properties of nearly equimolar AB-diblock and BAB-triblock copolymers, wherein A is polystyrene (PST) and B poly(methyl methacrylate) (PMMA), were examined in various selective solvents. In either type of selective solvents the diblock copolymers usually underwent intermolecular association and formed micelles, in which domains of PST- and PMMA-subchains were presumably segragated (intramolecular phase separation). The stability and size of such micelles depended on their molecular weight and composition as well as on the nature of solvents. The behavior of the triblock copolymers appeared to be more critically influenced by the solubility of the PMMA than that of the PST. In selective solvents having preferential solvency towards PMMA rather than PST, their behavior was more or less similar to that of the diblock copolymers whilst in selective solvents preferential to PST, they were usually unstable and liable to precipitate. In the transition region between the stable solution and precipitation states, the individual triblock copolymer chains often showed conformational anomalies without forming micelles, as shown by the intrinsic viscosity anomaly in p-xylene at 30°C. The possibility of intramolecular association of two PMMA subchains within a single triblock copolymer molecule was suggested as a hypothesis. However the hydrodynamic properties alone cannot provide decisive evidence for this possibility.
47 citations
TL;DR: In this article, a modified Walden's rule was proposed to determine the ratio of critical hole size for ionic charge transport to that for the segmental motion in terms of the WLF and the Ferry-Stratton (FS) equations.
Abstract: Temperature and pressure dependences of the ionic d.c. conductivity σ(∞σ) and the segmental mobility (∞τ−1) were analysed in terms of the WLF and the Ferry–Stratton(FS) equations, respectively, where τ is the dielectric relaxation time for the segmental motion above the glass transition. The WLF parameter C2 for σ is nearly equal to that for τ−1, and the FS parameter b2 for σ is also nearly equal to that for τ−1 in some cases. In the other cases, however, this does not hold. If τ−1 and the ionic mobility μ are assumed to be described by the same C2, the former cases correspond to a constant carrier density and the latter to variable carrier density. In the case of constant carrier density, the relation σ(T, P) [τ(T, P)]m=const. is derived from experimental results. This is designated as a “modified Walden’s rule.” The exponent m is given by the ratio C1(σ)/C1(τ−1) or b1(σ)/b1(τ−1). The physical meaning of m is the ratio of critical hole size for ionic charge transport to that for the segmental motion.
45 citations
TL;DR: In this paper, the authors reported that the plots of the reaction based on the simple second-order rate equation form smooth curves showing no distinction for steps involved, and a kind of conversion limit exists when hydrolysis is about 60% complete.
Abstract: The alkaline hydrolysis of poly(acrylamide) was followed by determining the residual amount of unreacted amide groupContrary to the report of Moens and Smets, the plots of the reaction based on the simple second-order rate equation form smooth curves showing no distinction for steps involved, and a kind of conversion limit exists when hydrolysis is about 60% completeTheoretical calculations based on the assumption that the reactivity of each amide group depends upon whether zero, one, or two of its nearest neighbors have reacted were compared with the experimental data Under the ionic strength of about 05, the actual progress of the reaction is in satisfactory accord with the theoretical figure
45 citations
TL;DR: Structural studies on polyurethane Fibers I Crystal and Molecular Structures of Aliphatic Polyurethanes from Hexamethylene Diisocyanate and Some Linear Glycols as mentioned in this paper.
Abstract: Structural Studies on Polyurethane Fibers I Crystal and Molecular Structures of Aliphatic Polyurethanes from Hexamethylene Diisocyanate and Some Linear Glycols
43 citations
TL;DR: In this paper, the applicability of multiple-pulse NMR techniques for the analysis of heterogeneous polymer systems is discussed from the view point of principles of wide-line NMR and system recovery time of pulsed NMR.
Abstract: The difficulties of wide line NMR or conventional pulsed NMR techniques for the analysis of heterogeneous polymer systems are discussed from the view point of principles of wide-line NMR and system recovery time of pulsed NMR. They are clarified in the case of a simple two-phase model, and the distinguishability of the two phases for both techniques is calculated. In order to overcome these difficulties the applicability of multiple-pulse NMR techniques are studied i.e., the applicability of solid echo for T2 (spin–spin relaxation time) and of solid echo train for T1ρ* (spin–lattice relaxation time in rotating frame). Solid echo and solid echo train techniques are applied to Nylon 6, low-density and high-density polyethylenes. There are obtained T2, T1ρ* and the fraction of the crystalline, intermediate and amorphous phases of Nylon 6, high-density and low-density polyethylenes. In the case of low-density polyethylene, the temperature dependence of T2, T1ρ* and the fraction of the three phases between −120°C to 100°C are obtained.
43 citations
TL;DR: Theory of light scattering by an Isotropic System Composed of Anisotropic Units with Application to the Porod-Kratky Chain was proposed in this article, where anisotropic units were used for light scattering.
Abstract: Theory of Light Scattering by an Isotropic System Composed of Anisotropic Units with Application to the Porod–Kratky Chain
TL;DR: In this paper, a statistical model of the effects of the active component on the transition of polypeptides was developed on the assumption that the active solvent exists in the form of a dimer and that the dimerized molecules react with pairs of CO and NH groups of randomly coiled peptide units.
Abstract: A number of synthetic polypeptides are known to undergo “inverse” thermal helix–coil transitions in solvent mixtures containing an “active” solvent such as dichloroacetic acid (DCA). A statistical mechanical theory of the effects of the active component on the transition is developed here on the assumption that the active solvent exists in the form of a dimer and that the dimerized molecules react with pairs of CO and NH groups of randomly coiled peptide units. Expressions are derived for the equilibrium constant, u, of helix formation and the cooperativity parameter, σ, and they are used to analyze data obtained for poly(γ-benzyl-L-glutamate) and poly(β-benzyl-L-aspartate) in mixtures of DCA and ethylene dichloride as functions of temperature and solvent composition. The values of the transition parameters so determined make it possible to understand not only why and how the observed values of transition enthalphy ΔH and cooperativity parameter σ depend on temperature and solvent composition, but also the general features of inverse transitions in quantitative terms. An important conclusion is that σ is profoundly affected by the binding of the active solvent on the polypeptide chain.
TL;DR: In this article, the crystal transformation from modification 2 to modification 1 in unstrained polybutene-1 films was observed by the infrared absorption and refractive index methods and was also observed by means of the infrared dichroism method developed by us.
Abstract: The crystal transformation from modification 2 to modification 1 in unstrained polybutene-1 films was observed by the infrared absorption and refractive index methods. The crystal transformation and orientation during stress-strain measurements were also observed by means of the infrared dichroism method developed by us. The crystal transformation in a fresh sample begins at about 30 min after the sample preparation, and the degree of transformation increases with increasing time until it reaches about 0.9 at 50 hr and 1.0 about 3 weeks after the sample preparation. The rate of crystal transformation could be expressed by an equation of the same form as that for the one-dimensional crystallization rate.Stress-strain curves, degree of crystal transformation vs. strain curves as well as infrared dichroic ratio vs. strain curves for film specimens having different initial degrees of crystal transformation differ remarkably. On the basis of these experimental results, the deformation and crystal transformation processes during stree-strain measurements under constant rate of elongation are discussed.
TL;DR: In this article, a folded-type single crystal of hexagonal shape was obtained from dilute solution of p-xylene and that of irregular shape has been obtained from the melt of dispersion powder.
Abstract: Crystallizations of poly(chlorotrifluoroethylene)(PCTFE) from dilute solution and from the melt of dispersion powder at atmospheric pressure and from the melt of the bulk material under high pressure have been carried out and examined by electron microscope. A folded-type single crystal of hexagonal shape has been obtained from dilute solution of p-xylene and that of irregular shape has been obtained from the melt of dispersion powder.To determine the optimum crystallization temperature under high pressure, DTA measurements have been carried out and the melting and recrystallization curves have been obtained. Remarkable increase of Tm with respect to pressure (dTm/dP=60°C/1000 kg/cm2) has been observed. Experiments on the crystallization have been performed on the basis of these data. The fracture surface of the bulk sample crystallized under high pressure shows a completely developed band structure. In this polymer this structure has been obtained easily by the application of pressure of only a few hundred kg/cm2. From the examination of X-ray fibre pattern of stretched film crystallized under high pressure, a 17 monomer 1 turn helix configuration has been determined.
TL;DR: Viscoelastic properties of Concentrated Solutions of Poly(methyl methacrylate) in Diethyl Phthalate as discussed by the authors were studied in the context of polymeric solutions.
Abstract: Viscoelastic Properties of Concentrated Solutions of Poly(methyl methacrylate) in Diethyl Phthalate
TL;DR: In this paper, a light-scattering analysis of conformational anomalies in p -Xylene Solution is presented, along with thermodynamic and conformational properties of styrene-methyl methacrylate block copolymers in dilute solution.
Abstract: Thermodynamic and Conformational Properties of Styrene–Methyl Methacrylate Block Copolymers in Dilute Solution. V. Light-Scattering Analysis of Conformational Anomalies in p -Xylene Solution
TL;DR: In this article, the propagating species and the mechanism of the cationic polymerization of 2-oxazoline(OXZ) were investigated, and the reaction of OXZ with CH3I at 80°C was detected, but N-(β-iodoethyl)-N-methylformamide 3 was isolated.
Abstract: The propagating species and the mechanism of the cationic polymerization of 2-oxazoline(OXZ) were investigated. Equimolar reactions of OXZ with polymerization catalysts were directly followed by NMR spectra. In the polymerization with methyl tosylate(MeOTs) catalyst, the propagating species was shown to be an oxazolinium ion. In the reaction of OXZ with BF3OEt2 in acetonitrile at 40°C, the BF3–OXZ complex was isolated in a quantitative yield. On the other hand, in the reaction of OXZ with CH3I at 80°C, no oxazolinium ion was detected, but N-(β-iodoethyl)-N-methylformamide 3 was isolated. 3 was taken to have been derived from the ring-opening reaction of unstable oxazolinium iodide which was transiently formed by the reaction of OXZ with CH3I. In addition, 3 itself caused the OXZ polymerization and gave a similar polymer yield to that of the polymerization by CH3I. Thus, the propagating species of the OXZ polymerization by CH3I was assumed to be N(CHO)CH2CH2N(CHO)CH2CH2I. The initiating behavior of alkyl halides and the effect of solvents upon the OXZ polymerization demonstrated a close-relationship between the OXZ polymerization by alkyl halide catalyst and the Menschutkin reaction.
TL;DR: In this article, the natural abundance 13C-1H high-resolution nuclear magnetic resonance spectra were measured for polyacrylonitrile polymers and it was concluded that the nuclear Overhauser effect due to total proton decoupling did not affect the relative intensities of the resonances of carbons which differ only in stereochemical configurations.
Abstract: The natural abundance 13C–{1H} high-resolution nuclear magnetic resonance spectra were measured for polyacrylonitrile. The sample used were three tactically different polymers. The spectra of carbons of methine and cyano groups clearly split into three peaks. These splittings were assigned to triad configurations.It was concluded that the nuclear Overhauser effect due to total proton decoupling did not affect the relative intensities of the resonances of carbons which differ only in stereochemical configurations. The spectra of methylene carbon was rather broad but with a single peak.
TL;DR: Selective Polymerization of 2-Isopropenyl-2-oxazoline and cross-linking reaction of the polymers this paper was used in this paper.
Abstract: Selective Polymerization of 2-Isopropenyl-2-oxazoline and Cross-linking Reaction of the Polymers
TL;DR: In this paper, the mean square displacements of carbon atoms from their average locations were represented by the symmetric tensor U having four independent elements, Uaa, Ubb, Ucc, and Uab.
Abstract: X-Ray scattering intensities of bulk crystallized polyethylene were measured at temperatures from −165°C to 120°C. Mean square displacements of carbon atoms from their average locations were represented by the symmetric tensor U having four independent elements, Uaa, Ubb, Ucc, and Uab. These elements and the atomic coordinates were determined as a function of temperature by the least square method. The displacement of the carbon atom was a maximum in the direction perpendicular to the skeletal zigzag plane. The minimum displacement was found in the direction along the the molecular axis. The mean square displacements of atoms were separated into contributions from the molecular vibration and the lattice imperfection by extrapolating the elements of tensor U to the temperature of absolute zero. The amplitudes of molecular vibration obtained by X-ray measurements agreed fairly well with the theoretical values calculated on the assumption of the harmonic oscillator model by Kitagawa and Miyazawa at the temperatures below 0°C. The atomic coordinates did not change below 0°C. The skeletal plane of polyethylene molecule tended to deflect slightly toward the a axis above 0°C with increasing temperature.
TL;DR: Monomer reactivity ratios r12 and r22 were obtained for acrylonitrile (M1)–methyl methacrylate (M2) system based on the values of mole fraction of three kinds of triad, namely, 121, 122 (and 221), and 222, which were evaluated from the relative intensities among corresponding three OCH3 peaks in its NMR spectrum.
Abstract: Determination of Monomer Reactivity Ratios in Copolymerization from a Single Sample and Its Application to the Acrylonitrile–Methyl Methacrylate System
TL;DR: In this article, an iterative computer method was proposed for estimating the degree of branching and molecular weight distribution simultaneously from a pair of measurements on intrinsic viscosity and gel-permeation chromatography.
Abstract: An iterative computer method was proposed for estimating the degree of branching and molecular weight distribution simultaneously from a pair of measurements on intrinsic viscosity and gel-permeation chromatography. The validity of the method as applied to randomly branched polymers was tested by using both fractionated and unfractionated samples of branched polystyrenes. It was experimentally concluded that the average number of branch points per unit molecular weight, λ, can be determined by this method with an accuracy of about 15%, and the weight-average molecular weight with accuracy of about 10%.
TL;DR: In this paper, the solubilities of poly(p-chlorostyrene) (PPCS) were examined for about ninety solvents, including aliphatic, aromatic and chlorinated hydrocarbons, ethers, esters, ketones, alcohols, and others.
Abstract: The solubilities of poly(p-chlorostyrene) (PPCS) were examined for about ninety solvents. The solvents employed were aliphatic, aromatic and chlorinated hydrocarbons, ethers, esters, ketones, alcohols, and others. The solubilities were successfully interpreted by the three dimensional plots according to Crowley, Teague, and Lowe, in which the solubility parameter, dipole moment, and hydrogen bonding parameter were used as three components, and to Hansen, who devided the solubility parameter into dispersion, polar and hydrogen bonding components. It can be seen that the soluble region is found to be inside the closed surface in the three-dimensional plots. The present systems involve some with either LCST or UCST. The difference between the PPCS–solvent system with LCST and that with UCST is reflected in the relative contribution of the three components rather than in the structure of the solvent. Furthermore, the phase relationships of PPCS were investigated. The eleven theta solvents found in this work contain both the four theta solvent with LCST, i.e., isopropyl acetate (θ=75.7°C), t-butyl acetate (θ=65.4°C), ethylcarbitol (θ=27.8°C) and n-butylcarbitol (θ=50.1°C), and the seven theta solvents with UCST, i.e., ethylbenzene (θ=−14.7°C), isopropylbenzene (θ=59.0°C), carbon tetrachloride (θ=50.7°C), tetrachloroethylene (θ=44.4°C), methyl chloroacetate (θ=64.6°C), ethyl chloroacetate (θ=−1.8°C), and isopropyl chloroacetate (θ=−8.2°C). It is considered from these phase relationships and from calorimetric measurements in the corresponding monomer solutions for esters that the theta solvent with LCST corresponds to an exothermic solvent and that characterized by UCST to an endothermic one.
TL;DR: In this paper, the solid-state transition in styrene-methacrylic acid copolymer was studied by infrared method in the range of 23-170°C from the temperature dependence of the peak absorbances of 1700- and 1745 cm−1 bands, transition at 120°C was detected, and its mechanism was presumed to be associated with the association-dissociation process of intermolecular force between chains.
Abstract: Recently, infrared spectrophotometry has been applied as a useful tool for the investigation of polymer transitions The solid-state transition in styrene–methacrylic acid copolymer was studied by infrared method in the range of 23–170°C From the temperature dependence of the peak absorbances of 1700- and 1745 cm−1 bands, transition at 120°C was detected, and its mechanism was presumed to be associated with the association-dissociation process of intermolecular force between chains, namely with the breakdown of intermolecular hydrogen bonding These results are in good agreement with Andrews’ definition for polymer transitions (or Tg) Thus the transition at 120°C was interpreted by the normal thermodynamic equilibrium consideration
TL;DR: Copolymerization of Ethylene with Propylene of a Soluble Catalytic System (C 5 H 5 ) 2 TiCl 2 Al(C 2 H 5 ] 2 Cl in an Ethyl Chloride.
Abstract: Copolymerization of Ethylene with Propylene of a Soluble Catalytic System (C 5 H 5 ) 2 TiCl 2 –Al(C 2 H 5 ) 2 Cl in an Ethyl Chloride
TL;DR: In this article, an alternating copolymer of N -Vinyl carbazole and Fumaronitrile was formed by charge transfer polymerization, which is a charge transfer polymerization technique.
Abstract: Mechanism of Charge-Transfer Polymerization: Formation of an Alternating Copolymer of N -Vinylcarbazole and Fumaronitrile
TL;DR: In this paper, nuclear magnetic resonance spectroscopy of poly(vinyl chloride) and its model compounds is described and compared to the model of the model used in this paper.
Abstract: 13 C–{ 1 H} Nuclear Magnetic Resonance Spectroscopy of Poly (vinyl chloride) and its Model Compounds