bluuebunny/crossref_metadata_2025 huggingface dataset:
Coordinated radical polymerization and redox polymerization of acrylamide by ceric ammonium nitrate
Authors: Takahashi Toru , Hori Yasuhiko , Sato Ichiro
Published: April 2003

The ceric salt‐initiated polymerization on acrylamide and graft copolymerization of acrylamide onto cellulose were studied. The mechanism of the ceric salt‐initiated polymerization of acrylamide in the homopolymerization system can be explained by a radical mechanism based upon Ce4+‐coordinated acrylamide, and the mechanism of the ceric salt‐initiated graft copolymerization of acrylamide onto cellulose can be explained in two ways: a free‐radical mechanism with the ceric—cerous redox system, and a radical mechanism based upon Ce4+‐coordinated acrylamide. The velocities of initiation, propagation, and termination in the redox mechanism are quite different from those in the coordinated radical mechanism. From the infrared absorption and nuclear magnetic resonance spectra measurements it is concluded that the structure of the ceric‐coordinated acrylamide is the π‐complex.
Thermal stability of silicon‐containing amide benzimidazole, hydrazide, and oxadiazole polymers
Authors: Delman Alvin D. , Kovacs Hanna Nagy , Simms Bernard B.
Published: April 2003

Studies were undertaken to ascertain the thermal stability of several types of silicon‐containing polymers. Results of thermal analysis investigations indicate that all of the polymers are unusually heat‐resistant when heated in air at elevated temperatures. Solution‐cast films of the polymers on aluminum showed excellent flexibility and adhesion characteristics after being heated in air for 100 hr. at 300°C. and then for 3.5 hr. at 400°C. Visual examination of the films after the heating sequence indicated that the silicon‐containing polyamides and polybenzimidazole had darkened slightly, while the polyoxadiazole appeared to be unaffected in this respect. Infrared spectroscopy studies showed that all of the polymers underwent only very minor structural changes during the prolonged heating process.
Polymerization of α‐piperidone with M–AlEt3, MAlEt4, or KAlEt3(piperidone) as catalysts and N‐acetyl‐α‐piperidone as initiator
Authors: Tani Hisaya , Konomi Tuyoshi
Published: April 2003

Low‐temperature polymerization of α‐piperidone was carried out by using MAlEt4, KAlEt3(piperidone), and M–AlEt3 (where M is Li, Na, or K) as catalysts and N‐acetyl‐α‐piperidone as initiator. The behavior in polymerization of these catalysts was superior to alkali metal or aluminum triethyl, and a polymer having an intrinsic viscosity of 0.8 dl./g. was obtained. Polymerization results and infrared analyses of the metal salts of lactams suggest that a complex, the structure of which was analogous to the one formed from M–AlEt3, is formed in the case of the alkali metal piperidonate–ethyl aluminum dipiperidonate catalyst system and that it is changed to another complex having a different composition and lower catalytic activity by heat treatment. The infrared absorption band of the metal salts of lactams and of KAlEt3(piperidone) at 1570–1590 cm.−1, which is attributable to the CN group in enolate form, may be considered to be related to the catalytic activities of alkali metals and the polymerizabilities of lactams. Such special catalysts as MAlEt4, alkali metal–AlEt3, or KAlEt3(piperidone) are supposed to suppress the consumption, by alkali metal, of N‐acyl‐α‐piperidone group of growing polymer end. A prolonged polymerization required for obtaining a high molecular weight polymer, even when such catalysts are used, is ascribable to a greater difficulty in re‐forming lactam anion from α‐piperidone, the basicity of which is higher than that of the other lactams.
Polymerization of 2,5‐dimethyl‐3,4‐dihydro‐2H‐pyran‐2‐carboxyaldehyde (methacrolein dimer). Part II
Authors: Kitahama Yoshiharu
Published: April 2003

2,5‐Dimethyl‐3,4‐dihydro‐2H‐pyran‐2‐carboxyaldehyde (methacrolein dimer) gave a polymer consisting of only recurring bicyclic structure of 1,4‐dimethyl‐6,8‐dioxa‐bicyclo‐[3,2,1] octane with the use of Lewis acid and protonic acid as catalyst at room temperature. On the other hand, the polymer obtained by using BF3·(C2H5)2O under −78°C. was found to have the structures produced by the aldehyde group polymerization as well as the bicyclic ones. The polymer obtained at −40°C. had a low decomposition temperature (164°C.) owing to the presence of polyacetal group, whereas the fully saturated bicyclic polymer had a considerably high one (346°C.). The main factors affecting the polymerization were polymerization temperature and catalyst. Lowering temperature increased the polymerization of the aldehyde group. Anionic catalysts and weak cationic catalyst such as Al(C2H5)3H2O, which were active catalysts for acrolein dimer, did not initiate the polymerization of methacrolein dimer. The fact that the relative viscosity of the polymer increased with polymerization time shows the polymerization of this monomer is a successive reaction.
Reactions of trifluoroacetic acid with poly(vinyl alcohol) and its model compounds. Effect of neighboring hydroxyl groups on the reaction
Authors: Fujii K. , Brownstein S. , Eastham A. M.
Published: April 2003

Reactions of trifluoroacetic acid with poly(vinyl alcohol) and various model alcohols were investigated by observing the fluorine and the proton magnetic resonance spectra of the reaction mixtures. At equilibrium the degree of conversion to ester under given conditions decreased in the order isopropanol, pentane‐2,4‐diol, heptane‐2,4,6‐triol and poly(vinyl alcohol). Therefore the equilibrium constant for esterfication of a hydroxyl group is depressed by the presence of neighboring hydroxyl groups. It was observed that the steric structures of the models and polymers also affect the equilibrium position of the reaction and this is mainly ascribable to the fact that meso (isotactic) molecules react more slowly with the acid than do racemic (syndiotactic) molecules. In acid‐catalyzed acetylation of the model alcohols with acetic acid no similar dependence on the steric configuration was found. Therefore trifluoroacetylation seems to be specific in this respect.
Salt effect in the base‐catalyzed polymerization of unsaturated amide compounds. III. Nature of the polymerization system
Authors: Asahara Tomohiko , Ikeda Kojuro , Yoda Naoya
Published: April 2003

Coordination complexes of lithium chloride with polar solvents and monomers were isolated, and their physical properties were studied. The parallel between stabilities of isolated complexes and coordination function in the polymerization system is discussed. The increase of the Q and e values of p‐vinylbenzamide (VBA) supports the mechanism of vinyl‐type polymerization of VBA in the presence of the salt. The specific solvent effect of dimethyl sulfoxide was determined by measurement of electrical conductivity of a model system.
Relative reactivities of cyclic ethers in cationic copolymerizations: Effects of ring strain and basicity
Authors: Aoki Shuzo , Harita Yoshiyuki , Tanaka Yoshiaki , Mandai Hiroshi , Otsu Takayuki
Published: April 2003

The relative reactivities of α‐monosubstituted cyclic ethers having rings of three to six members toward a cation were estimated from their copolymerizations with 3,3‐bis‐(chloromethyl)oxetane (M1) catalyzed by boron trifluoride etherate in methylene chloride at 0°C. It was found that the reactivity of these cyclic ethers was dominated by both the ring strain and the basicity. The following empirical equation was derived to represent the relative reactivity of cyclic ethers: log (1/r1) = −0.086ΔRS − 0.31ΔB + 0.57, where ΔRS and ΔB are constants, characteristic of ring strain and basicity of the cyclic ethers and determined from the differences in free energy of polymerization of the corresponding cycloalkanes and in basicity between M1 and M2 monomers, respectively. A good linear correlation was observed between the reactivities calculated from this equation and those obtained from the experiments.
Electron‐transfer polymers. XXIX. Copolymerizability of vinylhydroquinone derivatives
Authors: Uno Keikichi , Ohara Mutsuko , Cassidy Harold G.
Published: April 2003

Ten vinylhydroquinone and one vinyl resorcinol derivatives are compared, particularly with respect to NMR spectra and copolymerizability with styrene. They are vinylhydroquinone dimethyl ether (I), vinyl‐O,O′‐bis(1‐ethoxyethyl)hydroquinone (II), vinylhydroquinone di(2‐pentyl)ether (III), 4‐vinyl resorcinol bismethoxymethyl ether (IV), 2‐vinyl‐5‐methylhydroquinone dimethyl ether (V), 2‐vinyl‐5‐methyl‐O,O′‐bis(1‐ethoxyethyl)hydroquinone (VI), 2‐vinyl‐6‐methylhydroquinone dimethyl ether (VII), 2‐vinyl‐5‐tert‐butylhydroquinone dimethyl ether (VIII), 2‐vinyl‐5‐chlorohydroquinone dimethyl ether (IX), 2‐vinyl‐3,6‐dimethylhydroquinone dimethyl ether (X), and 2‐vinyl‐3,5,6‐trimethylhydroquinone dimethyl ether (XI). All the vinyl protons have almost the same coupling constants. Though subtle distinctions are found among all the spectra, they can in general be put into two groups on the basis of the chemical shifts. Let the hydrogen on carbon‐1 of the vinyl group be A, the hydrogen cis to A be B the hydrogen trans to A be C, then in the first group, (I) through (IX), the chemical shifts (τ) are (A) 3.02 ± 0.08, (C) 4.41 ± 0.05, and (B) 4.87 ± 0.07, and in the second group, (X) and (XI), they are (A) 3.30 ± 0.03, (C) 4.49 ± 0.01, and (B) 4.59 ± 0.03. It is supposed that in (X) and (XI) the vinyl group is out of the plane of the ring, because of the two ortho substituents, and this conformation is reflected in the NMR data. Ultraviolet spectra are consonant with this interpretation, since the λmax of (X) and (XI) correspond closely with those of nonvinyl reference compounds, while those of (II), (V), and (VIII) are shifted to longer wavelengths. When these compounds are copolymerized separately with styrene, the behaviors are classifiable into the following three groups, where r1 and r2 are monomer reactivity ratios with styrene as the first monomer: (i) r1 < 1 and r2 < 1 for compounds (II) and (III) and the reference compound O,O′‐dibenzoylvinylhydroquinone, (ii) r1 < 1 and r2 > 1 for compounds (I), (V), (VII), (VIII), (IX), and (iii) r1 > 1 and r2 = 0 for compounds (X) and (XI). These behaviors are correlated with the effect of electronegativity of groups on the stability of the radical at the growing end of the chain and with the simultaneous effects of steric hindrance.
Optically active imidazole‐containing polymers
Authors: Overberger C. G. , Cho Iwhan
Published: April 2003

In order to investigate the stereospecificity of enzyme‐catalyzed reactions, an optically active copolymer of 4(5)‐vinylimidazole and 2,5(S)‐dimethyl‐1‐hepten‐3‐one was synthesized, and its effects on the solvolytic rates, in ethanol‐water, of the p‐nitrophenyl and 4‐carboxy‐2‐nitrophenyl esters of 3(R)‐ and 3(S)‐methylpentanoic acid and of the commercially available N‐carbobenzoxy‐(R)‐ and (S)‐phenylalanine p‐nitrophenyl esters were investigated. The optically active comonomer was prepared by thermal decomposition of solid (+)‐1‐piperidino‐2,5(S)‐dimethylheptan‐3‐one hydrochloride, which was obtained from the reaction of 2(S)‐methylbutyllithium with 3‐piperidino‐2‐methylpropionitrile. The 3(R)‐methylpentanoic acid was prepared in 92% optical purity from L‐alloisoleucine via diazotization in concentrated hydrobromic acid and subsequent reductive debromination with zinc amalgam in dilute hydrochloric acid. In the optically active copolymer‐catalyzed solvolyses of the optically active esters performed at pH values of 6–8 no significant differences between the solvolytic rates of (R) and (S) isomers of substrates were observed. Poly‐L‐histidine was also employed as a catalyst for the solvolyses of these substrates. At pH 6.0 in ethanol–water the latter catalyst also failed to exhibit specificity towards (R) and (S) substrates.
Photodegradation of polyethylene film
Authors: Heacock James F. , Mallory Frank B. , Gay Frank P.
Published: April 2003

A structure occurs in radical‐polymerized polyethylene which leads to formation of a triene on ultraviolet radiation. An inhibition of oxidative processes is observed while the triene or its precursor are being consumed. Subsequent formation of oxygenated products—hydroxyl, carbonyl, and carboxyl—is well behaved and arises from short wavelenght light. A crosslinking reaction is initiated by light of ∼4000 Å wavelength.
Syntheses and properties of photochromic polymers of the azobenzene and thiazine series
Authors: Kamogawa Hiroyoshi , Kato Masao , Sugiyama Hiroko
Published: April 2003

Photochromic polymers of the azobenzene and thiazine series were synthesized via two routes: (1) synthesis of vinyl photochromic monomers and subsequent polymerization and (2) chemical reactions of the substrate polymers with photochromic components. Polyvinylaminoazobenzenes, polyvinylhydroxyazobenzenes, polyacrylamidomethylaminoazobenzenes, and polyacrylamidomethylthionine were thus prepared and their photochromic behavior investigated. In the case of azobenzene polymers, irradiations from a 100‐W projection lamp are enough to induced reversible changes in absorption spectra both in benzene solutions and film states, their absorption maxima being located around 400 mμ in the dark. Better results are obtained for some polymers as compared with the corresponding low molecular weight compounds; in the case of the thionine polymer (absorption maximum, ca. 600 mμ), the presence of ferrous ion remarkably enhances the photosensitivity in aqueous solutions, but incorporation of some polymers containing hydroxyl groups, such as poly(vinyl alcohol), are preferable for film states.
Cationic polymerization of α,β‐disubstituted olefins. VI. Steric structure of poly(methyl propenyl ether) obtained by cationic catalysts
Authors: Ohsumi Y. , Higashimura T. , Okamura S. , Chûjô R. , Kuroda T.
Published: April 2003

The steric structure of poly(methyl propenyl ether) obtained by cationic polymerization was studied by NMR spectra. From the analysis of β‐methyl and α‐methoxyal spectra, it was found that the tacticities of the α‐carbon were different from those of the β‐carbon in all polymers obtained. In the crystalline polymers obtained from the trans isomer by homogeneous catalysts, BF3·O(C2H5)2 or Al(C2H5)Cl2, and from the cis isomer by a heterogeneous catalyst, Al2(SO4)3–H2SO4 complex, the structure of polymers was threo‐di‐isotactic. Though the configurations of all α‐carbons were isotactic, a small amount of syndiotactic structure was observed in the β‐carbon. On the other hand, in the amorphous polymer obtained from cis isomer by the homogeneous catalyst, the configuration of the α‐carbon was isotactic, but that of the β‐carbon was atactic. These facts suggest that the type of opening of a monomeric double bond is complicated, or that carbon–carbon double bond in an incoming monomer rotates in the transition state. From these experimental results, a probability treatment was proposed from the diad tacticity of α,β‐disubstituted polymers. It shows that the tacticity is decided by a polymerization mechanism different from that proposed by Bovey.
Solution polymerization of trioxane catalyzed by stannic chloride
Authors: Miki T. , Higashimura T. , Okamura S.
Published: April 2003

The polymerization of trioxane catalyzed by stannic chloride (SnCl4) in ethylene dichloride was studied and compared with the results obtained with boron trifluoride etherate, BF3·O(C2H5)2, as catalyst. Under the same conditions, the polymerization rate was larger with SnCl4 than with BF3·O(C2H5)2, while at a fixed polymer yield the molecular weight of the polymer obtained by SnCl4 was lower than with the BF3·O(C2H5)2 catalyzed reaction. The overall activation energy of trioxane polymerization with SnCl4 was 11.0 ± 0.8 kcal/mole. The kinetic orders of catalyst and monomer were determined to be close to 2 and 4, respectively. A certain amount of tetraoxane was also produced in an early stage of the polymerization with SnCl4 similar to BF3·O(C2H5)2‐catalyzed reaction. However, the maximum amount of tetraoxane produced at 30°C was larger with SnCl4 than with BF3·O(C2H5)2. In addition, a ten‐membered ring compound (pentoxane) was isolated in the solution polymerization of trioxane catalyzed by both SnCl4 and BF3·O(C2H5)2. The confirmation of pentoxane formation is strong evidence for the back‐biting reaction mechanism.
Preparation of poly(diphenyl phosphazene)
Authors: MacCallum J. R. , Tanner J.
Published: April 2003

The preparation of substituted polyphosphazenes has been briefly surveyed. A method of synthesis of a fully substituted poly(diphenyl phosphazene) has been investigated. The product has been characterized and thermogravimetric analysis carried out. The volative products of pyrolysis have been identified and the hydrolytic stability of the polymer tested.
Preparation and properties of poly(phosphonatoalanes)
Authors: Schmidt Donald L. , Flagg Edward E.
Published: April 2003

Two general types of poly(phosphonatoalanes), [Al(X)OP(O)(R)O]n (X = Cl or F, R = alkyl or aryl) and [Al(OP(O)R2)OP(O)(R′)O]n, were prepared and studied. Poly[chloro(phosphonato)alanes] are influsible and have low molecular weights (n = 4–11). Polyfluoro(phosphonato)alanes are fusible and also have low molecular weights, but under certain conditions grow to higher polymers (n = 30–45). Poly[phosphinato(phosphonato)alanes] are fusible and are prepared with high molecular weights (n = 83–340).
Modification of poly(vinyl chloride). X. Crosslinking of poly(vinyl chloride) with a soft segment of an elastomer containing thiol groups
Authors: Nakamura Yoshiro , Mori Kunio
Published: April 2003

To obtain poly(vinyl chloride) (PVC) of excellent toughness, a new method of crosslinking PVC is proposed in which PVC is crosslinked with the soft segment in an elastomer such as liquid Thiokol. The reaction can be accomplished by immersing PVC–Thiokol blends in liquid ammonia at 20–30°C. A similar reaction occurs in aqueous ammonia when hexamethylphosphoramide is used as an activator. Characteristics of the crosslinked PVC thus obtained and of the controls of a similar uncrosslinked composition (PVC–Thiokol LP‐8, 100:5 by weight) were as follows: tensile strength, 7.3 and 4.8 kg/mm2; elongation at break, 30 and 2.5%; Young's modulus, 3.5 × 104 and 2.9 × 104 kg/cm2; tensile impact, 88 and 15 kg‐cm/cm3, respectively. The crosslinked PVC as plasticized with dioctyl phthalate (DOP) and the control blend (PVC–Thiokol LP‐8–DOP, 100:10:10 by weight), respectively, showed tensile strengths of 5.9 and 4.8 kg/mm2, elongations at break of 44 and 24%, Young's moduli of 2.5 × 104 and 1.6 × 104 kg/cm2, and tensile impact strengths of 62 and 120 kg‐cm/cm3. As the crosslinkage through the soft segments increases up to about 5%, the elongation at break, Young's modulus, and tensile impact, in addition to the tensile strength, are improved. This is different from the results so far observed with the crosslinked amorphous polymers and is characteristic of the products of crosslinking through the soft segment. The experimental results are discussed in this paper.
Polyhydrazides. III. N‐methylated polyhydrazides by ring‐opening of poly‐p‐phenylene‐1,3,4‐oxadiazole
Authors: Iwakura Yoshio , Uno Keikichi , Hara Shigeyoshi , Kurosawa Shigeru
Published: April 2003

A new ring‐opening reaction of 1,3,4‐oxadiazole by methylating reagents was developed in fuming sulfuric acid or polyphosphoric acid and then, by applying this reaction to poly‐p‐phenylene‐1,3,4‐oxadiazole, a high molecular weight poly‐N‐methylterephthalylhydrazide was obtained. Various methylating reagents were investigated as ring‐opening reagents. The degrees of ring‐opening in polymers were estimated and related to the properties of the polymers.
Transition temperatures and crystallinity in polyoctadecene‐1
Authors: Aubrey D. W. , Barnatt A.
Published: April 2003

Polyoctadecene‐1, as isolated from a Ziegler‐type polymerization, was examined by density and refractive index measurements and by differential thermal analysis. Two main transitions were observed, their sharpness suggesting that they are both first‐order. Extraction with n‐hexane at 25°C. separated the polymer into two almost equal fractions, each showing essentially one of these transitions. Transition temperatures were compared with those of certain other polymers having long n‐alkyl side chains. From this comparison, and from the findings of other workers, it was concluded that the polymer of lower transition temperature is atactic polyoctadecene, in which the side chains only participate in crystallization, whereas the polymer of higher transition temperature is tactic polyoctadecene, in which crystallization involves both the main chain and side chains.
Determination of orientation of the crystalline and amorphous phases in polyethylene by X‐ray diffraction
Authors: Wilchinsky Zigmond W.
Published: April 2003

For polyethylene fibers, orientation parameters of the form 〈cos2 ϕ〉 were calculated from traces obtained with an x‐ray diffractometer equipped with an orientation integrator. The angle ϕ is that which a crystal or molecular axis makes with the fiber axis. Traces over a continuous range of diffraction angle were obtained for (2/π)Iav, and also the weighted averages (2/π)Iav 〈cos2ϕ〉 and (2/π)Iav 〈sin2ϕ〉, where Iav is the intensity averaged over all orientations. The orientation for the crystal a, b, and c axes were determined from area measurements of the {110} and {200} lines, and the orientation parameter for the molecular axis in the amorphous phase was determined from area measurements of the amorphous halos. An undrawn fiber showed a slight a and c axis orientation along the fiber axis, and a slight transverse orientation of the b axis and the molecular axis. For a highly drawn fiber the orientation parameter for the c axis was 0.98 and for the molecular axis 0.65. The degree of crystallinity, measured from the (2/π)Iav versus 2θ traces, were 66.1% and 73.3% for the undrawn and drawn fiber, respectively.
Polymer fractionation. I. The preparative problem
Authors: Koningsveld R. , Staverman A. J.
Published: April 2003

The molecular weight distributions of the fractions in the two liquid phases which, in preparative fractionation, form upon a change in temperature, have been calculated for various initial concentrations and model distributions differing widely in shape and width. It was found that the normally recommended conditions do not always lead to the result desired, i.e., to a fraction with a narrow distribution. Under these conditions (dilute solution; large phase‐volume ratio; small fraction, i.e., little polymer in the concentrated phase) it may even happen that the fraction has a relatively wider distribution than the parent polymer. Treatment of a single‐peaked distribution will then be liable to yield a two‐peak fraction distribution. These unwanted phenomena do not occur in Staverman and Overbeek's variant of the extraction fractionation method. Here, the bulk of the polymer goes into the concentrated phase, and the macromolecules left in the dilute phase constitute the fraction to be isolated. In this way, relatively narrow distributions can be obtained in one step, even at high concentrations. Moreover, the method is very well suited for use in large‐scale fractionation. Fraction distribution wider than the initial distribution were found experimentally in the systems polyethylene–diphenyl ether and polystyrene–cyclohexane.
Polymer fractionation. II. The analytical problem
Authors: Koningsveld R. , Staverman A. J.
Published: April 2003

Complete fractionations into 5, 10, and 20 fractions were calculated by a numerical method based on the Flory‐Huggins theory in order to evaluate various procedures for determining the molecular weight distribution from fractionation data. If the initial distributions are wide, the differential distribution cannot be accurately reconstructed, not even if each fraction is characterized by two average molecular weights (instead of one, as is customary). In addition to this inadequacy in the evaluation procedure there are the experimental errors which further detract from the accuracy of the result. The integral distribution can, in some cases, be approximated fairly well by means of the Schulz method, provided that the polymer is separated into many fractions with narrow distributions. However, the integral distribution thus obtained does not reflect details in the differential distribution. Polymer fractionation does not appear to be a suitable procedure for accurate determination of the differential distribution. From the assembled material, a thermodynamic method has been derived which seems to hold out better prospects. It should enable the differential distribution to be directly determined from a detailed analysis of the liquid–liquid phase relationships, provided the free energy of mixing function of the system is known.
Low‐temperature dispersion related to methylene units of a polymer main chain
Authors: Dammont F. R. , Kwei T. K.
Published: April 2003

Polymers containing dynamically isolated polymethylene segments of various lengths were obtained from the reaction of bisphenol‐A‐diglycidyl ether with α,ω‐diamines. On the basis of the mechanical damping data of these polymers, it was established that the shortest polymethylene segment to show the −125°C. γ dispersion, characteristic of polyethylene, must consist of at least five carbon atoms.
Viscoelastic properties of polybutadienes—linear and lightly crosslinked near the gel point
Authors: Valentine Robert H. , Ferry John D. , Homma Terutake , Ninomiya Kazuhiko
Published: April 2003

Viscoelastic properties of four linear and three very lightly crosslinked polybutadienes (microstructure about 50% trans) were studied. Of the latter, two had not reached the gel point, and their molecular weight distributions were determined by sedimentation velocity analysis; the third was crosslinked just past the gel point, with only 32% gel fraction present. The crosslinking agent was sulfur. Complex shear compliances were measured over a frequency range from 0.1 to 1000 cps at temperatures from −70 to 30°C. with a Fitzgerald transducer and a Plazek torsion pendulum; and torsional creep measurements were made over time periods up to about three days. The creep data were converted to the corresponding dynamic viscoelastic functions at very low frequencies by conventional approximation methods. All data were reduced to 25°C. by shift factors calculated from a previously adopted equation of the WLF form. In the transition zone, the viscoelastic properties of linear samples were almost independent of molecular weight. The entanglement spacing, derived from the minimum in the loss tangent and the inflection in the storage compliance, was 130 to 160 chain atoms. The maximum in the retardation spectrum attributable to motions of individual network strands was closely similar to the corresponding maxima for more highly crosslinked vulcanizates previously studied, showing that even in the latter it is associated with entanglement network strands rather than strands between chemical crosslinks. For a linear sample with molecular weight 180,000, the retardation processes disappear at times beyond about 10 sec. at 25°C. With crosslinking short of the gel point (i.e., branching) the slow retardation processes are enormously increased and prolonged to longer times. With further crosslinking through the gel point and beyond, the slow retardation processes decrease progressively in magnitude. Qualitatively, this behavior resembles the sharp maximum in content of highly branched and aggregated molecular species which is predicted at the gel point by crosslinking statistics; but the slow processes (or low‐frequency losses) persist farther past the gel point than would be expected on this basis. The steady‐state compliances of the linear samples were smaller, but for a sample crosslinked short of the gel point were much larger, than the prediction of the Rouse theory modified for molecular weight distribution.
Multiple‐order light scattering from ringed spherulites
Authors: Clough Stuart B. , Stein Richard S.
Published: April 2003

Light scattering from polymer films containing ringed spherulites may show multiple‐order intensity maxima directly related to the period of the banded structure. Calculations based on spherulite models where the angle of twist of lamellae ω varies linearly with radial distance predict only first‐order peaks. If the variation of ω is nonlinear, even though the ring spacing remains constant, higher‐order intensity maxima will result. Other sources of multiple‐order scattering are considered. It is concluded that for polyethylene the presence of multiple‐order scattering is due to non‐uniform twisting of the lamellae.
Structure–property relations of polyimide films
Authors: Wallach M. L.
Published: April 2003

A series of well‐characterized polyamic acids from pyromellitic dianhydride and 4,4′‐diaminodiphenyl ether of systematically varied molecular weight and known molecular weight distribution were chemically converted to polyimide films under regulated conditions. The films were essentially noncrystalline, of moderate orientation, and soluble in concentrated sulfuric acid. The mechanical properties of the films varied sigmoidally with the solution properties of the precursor. Molecular weights were derived for the onset of mechanical strength and limiting property values are given. The relations between film properties and molecular structural parameters suggest that cyclization probably occurs here with little contribution from crosslinking, degradation, or other side reactions which would appreciably alter molecular weight and molecular weight distribution.
Morphology of cold‐drawn nylon 66
Authors: Crystal Richard G. , Hansen David
Published: April 2003

A nylon 66 composed of uniformly sized spherulites approximately 50 μ in diameter was examined before and after cold drawing by light and electron microscopy of thin sections and by low‐angle x‐ray diffraction. Spherulites retained their identity through drawing, but the spherulites elongated less than the bulk specimen indicating that relative motion of spherulities must have occurred. The observation of dilations (0.3 μ long) at interspherulitic boundaries support this contention. The thin‐section electron micrographs indicated that the spherulites were composed of radiating lamellae approximately 95 A. thick. After drawing, the lamellae were preferentially oriented both parallel and perpendicular to the draw direction. Lamellae parallel to draw had thinned to approximately 70 A. While lamellae perpendicular to the draw had apparently thickened to 150 A. Three low‐angle x‐ray diffraction patterns yielded quantitative agreement with the electron‐micrograph data. The pattern form the undrawn nylon was a diffuse ring corresponding to a 95 A. spacing. On the drawn specimen, with the beam parallel to draw, a ring corresponding to the 150 A. spacing was obtained, while with the beam perpendicular to draw two arcs were recorded at spacings of 70 and 150 A. The drawing was done at room temperature and proceeded by neck formation and propagation, yielding a 4:1 draw ratio.
Upturn effect in the Non‐Newtonian intrinsic viscosity of polymer solutions. II. Polyisobutylene in polybutene oil
Authors: Bianchi U. , Peterlin A.
Published: April 2003

With an increasing gradient, the intrinsic viscosity of a high molecular weight polyisobutylene (M̄n = 7 × 106) in polybutene oil L.100 (ηs = 5 poise) first drops to a minimum and then rises again. The minimum occurs at β = M[η]0ηsG/NkT = 240, which is about ten times the value predicted by the dumbbell model. Such a shift to larger gradient is in good agreement with the more realistic necklace model of macromolecules in a good solvent. The increase of intrinsic viscosity after the minimum is nearly linear with the gradient and continues beyond the value at zero gradient. Experiments with capillaries of different length‐to‐diameter ratios yield identical flow curves so that one may exclude the possibility that the observed upturn is an artifact caused by end effects or time dependence of viscosity.
Depolymerization studies on polyacetaldehyde
Authors: Graessley W. W. , Nagasubramanian K. , Advani R. , Huetter D. F.
Published: April 2003

Depolymerization of amorphous polyacetaldehyde has been studied by measurements of weight loss versus time for thin films of the polymer in vacuum. Temperatures ranged from 40 to 80°C. The samples were prepared by freezing or melting the monomer in contact with treated glass surfaces. Light scattering, osmometry, and intrinsic viscosity measurements were used to characterize the polymers. Depolymerization rates were between second and third order with respect to the unvolatilized fraction, and the activation energy was 26.3 kcal. Much of the evidence points toward a slow unzipping reaction at the chain ends, but the analysis seems to be complicated by structural variations among the samples.
Annealing experiments on drawn nylon 66 fibers
Authors: Dumbleton J. H. , Buchanan D. R.
Published: April 2003

Drawn, nylon 66 yarns have been annealed in oil under relaxed conditions. Shrinkage and tensile modulus were measured and the yarns were examined by wide‐ and small‐ angle x‐ray diffraction. The results are similar to those obtained by Dismore and Statton, but there are significant differences. The data indicate a model for a drawn nylon 66 fiber in which substantial amounts of folds remain.
Development of gel permeation chromatography for polymer characterization. I. Operational variables
Authors: Boni K. A. , Sliemers F. A. , Stickney P. B.
Published: April 2003

The effects of operational variables on calibration of GPC are reported. Variables examined include (1) temperature and solvent changes, (2) sample concentration, (3) injection time, and (4) flow rate. Each of these variables significantly affected molecular weight averages calculated from GPC data. The causes and methods of minimizing the effects produced by the individual variables are discussed.
Crystallization kinetics of isotactic polystyrene. II. Influence of thermal history on number of nuclei
Authors: Boon J. , Challa G. , van Krevelen D. W.
Published: April 2003

The influence of various thermal pretreatments on the nucleation of isotactic polystyrene has been studied quantitatively by dilatometry. A distinction can be made between nuclei still present above the melting point (“resistant” nuclei) and nuclei created by severe supercooling (“induced” nuclei). The number of spherulites formed has been determined for different combinations of supercooling and crystallization temperatures. The results are interpreted in a satisfactory manner by assuming that in severe supercooling induced nuclei are created, which may grow into effective nuclei at higher temperatures. The crystallization of a severely supercooled polymer is completely governed by these induced nuclei, because they outnumber the resistant nuclei by some orders of magnitude. The number of induced nuclei can be decreased by purifying the polymer (removing catalyst residues). When cooled polymer is heated to temperatures just above the melting point, the induced nuclei are destroyed (“reversible melting”), so that only the resistant nuclei, which are few in number, remain. These resistant nuclei govern the crystallization behavior of a polymer which has not previously been cooled. Their number decreases on heating to temperatures far above the melting point.
Determination of melt viscosity as a function of hydrostatic pressure in an extrusion rheometer
Authors: Choi S. Y.
Published: April 2003

Polymer melt viscosity was determined as a function of hydrostatic pressure in an extrusion rheometer. An extrusion rheometer consisting of a barrel and a capillary can be looked upon as two capillaries in series. The barrel itself was used as the main viscometer and several different capillaries having length/diameter ratios of 3.5–100 were used as pressure boosters. For a Phillips type polyethylene of 0.95 g/cc density and 0.4 melt index, the apparent viscosity at 190°C and 7.12 sec−1 was increased nearly fourfold as the average pressure in the barrel was raised from atmospheric to 24000 psi. With colored layers of polyethylene as tracers the flow pattern in the barrel was examined. The velocity profiles in the barrel were well developed and parabolic, and thus indicated regular laminar flow under these conditions.
Steady‐state distribution of water in cellulose acetate membrane
Authors: Rosenbaum S. , Cotton O.
Published: April 2003

The effect of hydrostatic pressure applied to a solution on one side of a membrane on the steady‐state concentration distribution of permeating solvent inside the membrane has been examined with a view to distinguishing between different mechanisms of permeation in reverse osmosis. The concentration gradients found experimentally in stacks of cellulose acetate films support the view that permeation takes place by diffusion in a nonporous membrane.
γ‐Ray‐induced copolymerization of carbon monoxide with cyclic ethers
Authors: Kagiya Tsutomu , Kondo Masatsune , Fukui Kenichi , Yokota Hisao
Published: April 2003

The γ‐ray copolymerization of carbon monoxide with cyclic ethers, such as ethylene oxide, phenyl glycidyl ether, 1,3‐dioxolane, 2‐vinyl‐1,3‐dioxolane, terahydrofuran, 1,4‐dioxane, and acetaldehyde was studied. A yellowish or brownish powdery copolymer was obtained in most of the cases examined. The infrared spectra showed that copolymers containing the ester structural unit were produced in the copolymerization with cyclic ethers which have no vinyl groups, and that a copolymer containing a ketone structure was produced from cyclic ether having vinyl group. It was found that the copolymer with ethylene oxide also had a β‐propiolactone ring structure at the chain end or the side chain. The copolymers were confirmed to be partially crystalline from the x‐ray diffraction diagrams. Further, a ring‐opening polymerizability of the cyclic ether by γ‐radiation was discussed. And it was found that as the bond dissociation energy between the carbon–oxygen linkage of the cyclic ether is small, the polymer yield both in the homopolymerization and copolymerization with carbon monoxide is high. A mechanism for the copolymerization is proposed on the basis of the results.
Effects of iron(III) chloro complexes on the polymerization of styrene
Authors: Dass N. N. , George M. H.
Published: April 2003

The polymerization of styrene initiated by 2,2′‐azobisisobutyronitrile has been studied in N,N‐dimethylformamide solution at 60°C in the presence of hexakis(N,N‐dimethylformamide) iron(III) tetrafluoroborate alone, and also in the presence of added lithium chloride. The presence of Fe(DMF)63+ ions in the polymerizing systems caused retardation, but iron(III) chloro complexes produced well defined inhibition periods. Velocity constants at 60°C for polystyryl radicals towards Fe(DMF)63+, Fe(DMF)5Cl2+, Fe(DMF)4Cl2+, and FeCl4− ions were calculated to be 847, 4.15 × 104, 6.55 × 104, and 3.14 × 104 l./mole‐sec, respectively. Values of the initiator efficiency f for most systems investigated ranged from 0.59 to 0.62.
Metal‐containing initiator systems. VI. Polymerization of butadiene with metal–organic halide systems
Authors: Otsu Takayuki , Yamaguchi Masami
Published: April 2003

The polymerization of butadiene with binary initiator systems consisting of some activated metals and organic halides was investigated at 60°C. From the results obtained, it was found that systems of reduced nickel and methyltrichlorosilane or dimethyldichlorosilane were most effective for the polymerization, and those of reduced nickel and carbon tetrachloride, benzyl chloride, benzyl bromide and benzoyl chloride, showed moderate activity. The polybutadienes obtained with these systems were observed to contain product of more than 80% cis‐1,4 microstructure. From detailed studies on the reduced nickel–methyltrichlorosilane system, these polymerization mechanisms were explained by the hypothesis that the initiation occurred through the reaction of the dissociated transition state complex with the monomer or with a trace amount of water, and then the propagation proceeded via a coordinated cationic mechanism. These systems did not show a good activity for the cis‐1,4 polymerization of isoprene.
Reactivity ratios for copolymerization of vinyl chloride with 2‐methylpentyl vinyl brassylate by computerized linearization
Authors: Chang Shu‐Pei , Miwa Thomas K. , Tallent William H.
Published: April 2003

A computerized version of the Fineman‐Ross linearization procedure was used to determine reactivity ratios for copolymerization of vinyl chloride (monomer 1) and 2‐methylpentyl vinyl brassylate (monomer 2). From differential refractometry data for the products of low‐conversion copolymerization, the procedure gave r1 = 1.06 and r2 = 0.234. The ratios computed from chlorine contents of the same products were r1 = 1.10 and r2 = 0.239. The polarity factor (e2) and general monomer reactivity (Q2) calculated for monomer 2 from these ratios were, respectively, −0.95 to −0.98 and 0.032–0.033. The interquartile range for the copolymerization of a mixture of 60% monomer 1 and 40% monomer 2 was 1.4%. These values suggest that from suitable proportions of reactants, sufficiently homogeneous distribution of monomers can be achieved in copolymers of vinyl chloride and 2‐methylpentyl vinyl brassylate to offer the possibility of effective internal plasticization.
Polyimides having pendant hydroxy and acetoxy groups. II. Polyimides derived from bisaminoalcohols
Authors: Iwakura Yoshio , Kurita Keisuke , Hayano Fusakazu
Published: April 2003

Polyamic acids were prepared from bisaminoalcohols and pyromellitic dianhydride. They were converted to polyimides having pendant hydroxy groups by heating them in toluene or xylene (ηinh = 0.22–0.34 dl/g). Treatment of these polyamic acids with a mixture of pyridine and acetic anhydride gave polyimides having pendant acetoxy groups (ηinh = 0.22–1.04 dl/g). These acetoxypolyimides were converted to hydroxypolyimides (ηinh = 0.20–0.81 dl/g) by an ester‐exchange reaction. Furthermore, the hydroxypolyimides were easily acetylated to give acetoxypolyimides.
Polymerization of acrylonitrile by V5+–lactic acid system in aqueous sulfuric acid
Authors: Saccubai S. , Santappa M.
Published: April 2003

Kinetics of polymerization of acrylonitrile by the redox system V5+–lactic acid in sulfuric acid at 20–35°C was studied. Oxidation of lactic acid by V5+ in the absence of monomer was also carried out under identical conditions. The rates of polymerization, V5+ disappearance and the chainlengths of polyacrylonitrile were measured. From the results it is concluded that the polymerization reaction is initiated by an organic free radical arising from the V5+–lactic acid reaction with termination by V5+ ions. Mutual termination of active polymer radicals does not appear to operate under the conditions studied. The various rate parameters were evaluated.
Salt effect in the base‐catalyzed polymerization of unsaturated amide compounds. IV. Polymerization of p‐vinylbenzamide in the presence of LiCl/N,N,N′,N′‐tetramethylethylenediamine
Authors: Asahara Tomohiko
Published: April 2003

In the presence of lithium chloride and N,N,N′,N′‐tetramethylethylenediamine, p‐vinylbenzamide was polymerized in basic media to form a polymer with structure consisting of units due to both proton transfer and vinyl type polymerization, whereas in the presence of the salt alone the monomer underwent exclusively vinyl type of polymerization to give a polystyrene derivative:
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Novel preparation of pure β‐TiCl3 and its use in isoprene polymerization
Authors: Smith G. H. , Perry D. C.
Published: April 2003

Treatment of the reaction product of TiCl4, Al, AlCl3, and an aromatic compound with an ether and subsequently with TiCl4 yields very pure β‐TiCl3. This material, when treated with small amounts of aluminum trialkyls, is a very active catalyst for the stereospecific polymerization of isoprene. If the above reaction is stopped after the ether addition, before the addition of TiCl4, the product so obtained is largely TiCl2. Reaction variables in the preparation of TiCl3 are described as is the effect of various organoaluminum compounds as cocatalysts for polymerization.
Effects of metal salts on polymerization. VI. Photo and thermally catalyzed polymerization of N‐vinylimidazole in the presence of metal salts
Authors: Tazuke Shigeo , Okamura Seizo
Published: April 2003

Polymerization of 2‐methyl‐1‐vinylimidazole (MVI) and 2‐ethyl‐1‐vinylimidazole (EVI) was found to be markedly photosensitized in the presence of oxidizing metal salts such as UO2(NO3)2, Ce(NH4)2(NO3)6, Hg(CH3COO)2, AgNO3; non‐oxidizing metal salts such as ZnII did not act as photosensitizers. The interaction of monomer with a metal salt is discussed on the basis of infrared and electronic spectroscopy. This photopolymerization is very specific with respect to the kind of monomer. The polymerization of noncomplexing monomer (styrene) is not photosensitized by these metal salts. Consequently, photosensitized electron transfer between monomer and metal salt via complex formation is considered to be the most probable initiation mechanism. Cupric acetate and sodium chlorolaurate, which have been reported as efficient initiators for the polymerization of vinylpyridine and N‐vinylcarbazole, respectively, act as linear terminators of growing radicals. The radical polymerizability of the zinc complex of MVI was studied by means of copolymerization with styrene. The reduction of the reactivity of MVI on complexing was explained by correlating with the spectroscopic observations. Because the polymerization system is heterogeneous, a detailed discussion was not possible.
Polybis(phosphinato)fluoroalanes
Authors: Schmidt Donald L. , Flagg Edward E.
Published: April 2003

A new class of coordination polymers, polybis(phosphinato)fluoroalanes, [Al(F) (OPRR′O)2n], where R,R′ are alkyl, phenyl, or benzyl, was prepared and studied. The properties of these polymers are influenced by the phosphinate (R) substituents; polymers having n‐alkyl groups with more than five carbons are flexible and exhibit unusual hydrolytic stability. A polymer was obtained with a degree of polymerization of 104 by incorporating a 2:1 ratio of benzyl(n‐heptyl) and di‐n‐octyl phosphinate groups. The properties of the flexible materials are consistent with linear rather than highly crosslinked or network systems. Feasible structures are proposed for the polymers.
Autoxidation of polystyrene catalyzed by cobalt salt and sodium bromide in chlorobenzene–acetic acid
Authors: Le‐Khac‐Bi  , Kamiya Yoshio
Published: April 2003

In the oxidation of atactic polystyrene initiated by azobisisobutyronitrile, the kinetic chain length was obtained as 1.5. In the presence of cobalt salt and bromide ion, the rate of oxidation is first order with respect to the concentration of polymer and second order with respect to the concentration of cobalt. In addition, this rate is dependent on the molar ratio of NaBr to cobalt, independent of the partial pressure of oxygen and the molecular weight of polystyrene. The overall energy of activation is 22.5 kcal/mole. The molecular weight decreased from 152000 to 10 800 under the present conditions of oxidation. Carbon monoxide and carbon dioxide are the only significant volatile products. The primary product of oxidation is hydroperoxide. Benzaldehyde, acetophenone, and phenol were found as final products. The acetophenone‐type structure and methyl endgroups were observed. The formation of phenol presented a large selfinhibiting effect in the oxidation of polystyrene. The oxidation of isotactic polystyrene gave a maximum rate of oxidation twofold higher than that of atactic polystyrene and a value of 17.0 kcal/mole for the overall energy of activation.
Polymerization of vinyl chloride
Authors: Enomoto S.
Published: April 2003

Polymerization of vinyl chloride (VC) was studied. natural evolution of HCl from VC occurred in the polymerization. VC, VC‐αd1, VC‐β,βd2 and VC‐d3 were used to study the reactivities of the hydrogen atoms in the polymerization and the β‐hydrogen atoms contributed to the chain transfer. Chemical and physical methods were used to observe irregular structures, such as branching, double bonds, and head‐to‐head or tail‐to‐tail addition, and also to confirm the relation between conversion and the irregular structures.