bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultimate properties of lightly crosslinked polymer networks in the long‐time region
Authors: Janáček J. , Raab M.
Published: April 2003

It was found that the strain‐at‐break plotted against strain rate of poly(2‐hydroxyethyl methacrylate) networks crosslinked to a low degree suggests in the region of low reduced speeds of deformation the presence of a maximum.

This effect was related to the secondary maximum in loss compliance, J″, and explained by the long relaxation times of untrapped entanglements.
Depolarization thermocurrents in amorphous polymers
Authors: Lacabanne C. , Chatain D.
Published: April 2003

The depolarization thermocurrent (DTC) method gives the dependence of the dielectric relaxation time on temperature. It has been used for investigations of relaxations obeying an Arrhenius‐like law in crystalline polymers. The analysis of this method shows it is possible to study mechanisms described by the Williams‐Landel‐Ferry (WLF) equation. The critical temperature appearing in the free‐volume theory of Cohen and Turnbull and also in the statistical thermodynamic theory of Adam and Gibbs can then be measured with good accuracy. The thermal coefficient of expansion of the free‐volume and the WLF coefficient for any reference temperature can also be obtained. Since analysis of the experimental DTC spectrum is particularly simple, this method seems to be a very useful tool for examination of relaxation transitions in amorphous polymers. As an example, results obtained for poly(methyl methacrylate) are presented; they are consistent with published data.
High‐resolution gel‐permeation chromatography
Authors: Kato Yoshio , Kido Shiro , Hashimoto Tsutomu
Published: April 2003

The resolution attainable in gel‐permeation chromatography (GPC) was investigated by using columns packed with polystyrene gel particles of about 5 μ diameter and mixtures of two monodisperse poly‐α‐methylstyrene samples studied previously. The resolution of GPC was found comparable to that of the sedimentation velocity method and slightly better than that of precipitation chromatography. Standard polystyrene samples obtained from Pressure Chemical Co. also were measured with the same columns. It was found that weight‐average to number‐average molecular weight ratios (M̄w/M̄n) of these samples with molecular weight in the range 97,000–411,000 are smaller than 1.006. For samples with molecular weight of 10,000–51,000 and 498,000–860,000, M̄w/M̄n is larger than 1.006, and the width of molecular weight distributions of these samples differed. In particular, molecular weight distributions of samples with molecular weights 19,800 and 51,000 were shown to be bimodal. It is therefore concluded that GPC is useful for samples of very narrow molecular weight distribution if high‐resolution columns are used.
Sinusoidal normal stress measurements with the Weissenberg rheogoniometer
Authors: Kajiura Hirokazu , Endo Hiroshi , Nagasawa Mitsura
Published: April 2003

In measuring sinusoidal normal stress difference of concentrated polymer solutions in a Weissenberg rheogoniometer, the resistance to motion of the upper platen due to the sample between the cone and plate should be taken into account. Correction terms are derived. The theoretical predictions of Lodge and others concerning the relationship between oscillatory normal stress difference and oscillatory shear stress are found to agree with experimental data if these corrections are applied.
Phase transition and paracrystalline order in solution‐crystallized solid n‐paraffins
Authors: Phaovibul O. , Čačković H. , Loboda‐Čačković J. , Hosemann R.
Published: April 2003

Solution‐crystallized single crystals of various paraffins were investigated at room temperature by nuclear magnetic resonance and by small‐angle and wide‐angle x‐ray scattering. The samples were crystallized from various solvents and annealed 2, 5, 6, and 12°C below the melting point. The NMR spectra are separated into three components (α, β1 and γ) of different chain‐segment mobility. On combining these results with x‐ray measurements and with results on polyethylene, enough information is obtained to propose a model of the paracrystalline superlattice built up by at least 30 paraffin lamellae and to find where the chains of various conformation are located in the structure. The phase transition of C44H90 in the solid state gives further hints for this allocation. For instance, the β1 component of intermediate mobility increases anomalously from 3% before to 10% after the phase transition. The paracrystalline g value of the macrolattice of the orthorhombic phase is 1.5% and the gap between the lamellae is 2.2 Å. At the beginning of the phase transition, the chains incline stepwise to the lamella surface retaining the orthorhombic macrolattice distance P0 = 58 A and enlarging the gap to 8.8 Å without changing the g value of 1.5%. The growing monoclinic phase, on the other hand, has a constant g value of 3.5% from the beginning with Pm = 52 Å and has gaps of only 3 Å between adjacent lamellae. This explains the large β1 (ca. 10%) of these two new phases, because the mobile chain ends consist of approxiamately 1 CH3 and 1 CH2 group on the average. The γ component of highest micro‐Brownian mobility corresponds to the γ component in polyethylene with a line width of ca. 0.07 gauss. Unlike the case of polyethylene it is produced by only a small amount (0.02–0.13) of free CH3 groups per chain. Another fraction of the CH3 groups belongs to the rigid component α of the crystalline phase. They are located where adjacent lamellae touch each other in crystalline‐like order. Because of these contacts, stacks of lamellae about 1000 Å thick scatter coherently, and the long period Po of the orthorhombic phase remains undestroyed by annealing until the monoclinic domains collapse to the smaller period Pm of the monoclinic phase.
Local mode relaxation in polychlorotrifluoroethylene
Authors: Sasabe Hiroyuki
Published: April 2003

The effects of temperature and pressure on the dielectric relaxation time τ, relaxation strength Δε, distribution of relaxation time β, and shape of absorption curve of the local mode relaxation in polychlorotrifluoroethylene are discussed from the viewpoint of intermolecular interaction. Changes of τ and Δε with temperature and pressure are explainable in terms of changes in intermolecular distance. The temperature and pressure dependences of the dielectric retardation spectrum for the local mode relaxation are different from each other.
Relevance of cage recombination in the plastic deformation of polymers
Authors: Davis L. A. , Baughman R. H. , Pampillo C. A.
Published: April 2003

For a polymer in which permanent rupture of individual molecules is the rate‐limiting process for plastic deformation, the kinetics of chain‐end diffusion and secondary radical reactions should be compared with the kinetics of caged radical recombination in the calculation of activation parameters for plastic deformation. If mechanisms of cage escape are slower than those for cage recombination, the activation parameters for plastic deformation will differ from those for the initial bond‐breaking process. For the case of polyethylene deformed in the vicinity of 250°K, the critical thermally activated event appears to involve scission of the polymer molecule near the site of an abstracted hydrogen atom. For this system the dominant cage‐escape mechanism is diffusion, which is faster than either hydrogen abstraction or unzipping to the monomer. However, at low stresses the rate of cage recombination is expected to be higher than the rate of cage escape, so that the activation parameters for deformation should be the sum of those for chain scission and diffusion. The contribution of diffusion (ca. 15 kcal/mole) to the activation energy for deformation (E*, extrapolated to zero stress conditions) is relatively modest. However, the calculated molar activation volume for deformation V* increases by almost an order of magnitude, i.e., from ca. 10 to ca. 76 cm3/mole when diffusion is required. Consideration of experimental values of E* and V* for high molecular weight polyethylene indicates that, in the regime examined, chain scission plus chain‐end diffusion is required to effect plastic deformation.
Negative thermal expansion of a polydiacetylene single crystal
Authors: Baughman R. H. , Turi E. A.
Published: April 2003

Macroscopic thermal expansion in the chain direction has been measured for the first time on organic polymeric single crystals. Negative linear thermal expansion coefficients αM are reported and related to chain torsional motion and equilibrium point‐defect formation for a solid‐state polymerized phase of 2,4‐hexadiyne‐1,6‐diol bisphenylurethane (HDU) which contains crystallographically located interstitial dioxane and for a dioxanefree phase obtained by thermal annealing. Data for as‐polymerized single crystals (which are probably of extended chain morphology) between −50 and 100°C give αM = −(1.686 ± 0.039) × 10−5 − (1.35 ± 0.18) × 10−7 t with t in °C. During volatilization of 11.7 ± 1.0 wt‐% interstitial dioxane and a resulting crystal structure change, the as‐polymerized fibers fibrillate and shrink irreversibly by 0.16 ± 0.04%. Although dichroism and diffraction measurements indicate both a high degree of crystallinity and chain alignment for the dioxane‐free phase, the average thermal expansion coefficient, (−3.0 ± 1.0) × 10−6 °C−1 between −50 and 150°C, is about an order of magnitude less than for the as‐polymerized single crystals.
Diffusion into and adsorption of polyethylenimine on porous silica gel
Authors: Hostetler Ronald E. , Swanson John W.
Published: April 2003

The polyethyleneimine (PEI)–water–silica gel absorption system was used as a model system to investigate the relationship between diffusion into the porous structure, adsorption rate, and molecular weight of the polymer. Three silica gels, Porasil A, B, and and C having a range of characteristic porosity were used as adsorbents. Adsorption of PEI on Porasil C, which has the majority of its pores much larger than the dimensions of the adsorbate molecule, increased initially with increased molecular weight but became nearly constant at higher molecular weight. Little increase in adsorption occurred for this silica gel with increased ionic strength or with increased pH between 9.5 and 10.8. In contrast, adsorption increased sharply with increased ionic strength and for the same pH range on Porasil A. Molecular weight dependence was reversed. Adsorption decreased with increased molecular weight on Porasil A. In this case, the molecular size of PEI investigated was the same as the majority of pore apertures in the adsorbent. Solution environments (i.e., pH and ionic strength) that decrease the size of the PEI molecule and its affinity for the anionic silica gel surface, thus enabling it to more readily diffuse into the smaller porous regions of the adsorbent, are the apparent causes of the very large adsorption increase. Electrostatic repulsion between PEI molecules do not appear greatly to affect adsorption. Similar adsorption behavior has been reported in the literature for the PEI–cellulosic fiber adsorption system. Maximum adsorption on Porasil A occurred at pH 10.8, the same maximum generally reported for adsorption of PEI on cellulosic fibers. In this case, the silica gel (Porasil A) was found to have a pore size distribution and specific surface area of the same magnitude as cellulosic fibers prepared in the expanded state.
Radiation‐induced emulsion polymerization of ethylene. I. Effect of reaction conditions on the polymerization
Authors: Senrui Shiro , Suwa Takeshi , Konishi Kunio , Takehisa Masaaki
Published: April 2003

The effect of reaction conditions on the rate of radiation‐induced emulsion polymerization of ethylene was studied by use of a 500‐ml autoclave. Among various kinds of emulsifiers, a series of potassium salts of fatty acids gave high rates of the polymerization. The polymerization was inhibited by the presence of oxygen, but the rate of polymerization followed by the induction period was not influenced by the initial presence of oxygen. Stirring rate and the monomer: water ratio did not affect the rate of polymerization. The rate of polymerization was maximum at about 80°C, and number‐average molecular weight was influenced by the temperature in a similar manner as the rate of polymerization. This suggests that the change of mobility of propagating radical in the polymer particle changes the rate of termination reaction. The rate of polymerization was proportional to the 1.7 power of the reaction pressure.
Copolymerization of carbon dioxide with propyleneimine
Authors: Soga Kazuo , Chiang Wen‐Yen , Ikeda Sakuji
Published: April 2003

Carbon dioxide and propyleneimine were allowed to copolymerize without using any catalyst to give a polyurethane with a carbon dioxide content of 10–35 mole‐%. The polymer yield, the specific viscosity, and the content of carbon dioxide in the copolymer increased with increasing polymerization temperature. The infrared spectrum of the copolymer showed the characteristic peak assignable to a cyclic urethane(4‐methyl‐oxazolidone‐2) at 1750 cm−1 as well as the peak characteristic of the urethane linkage at 1700 cm−1. The relative intensity ratio of the former absorption to the latter decreased markedly with increasing polymerization temperature. Propyleneimine did not polymerize at all in the absence of carbon dioxide. Polymerizations were also carried out with the use of various solvents. On the basis of these results, a probable reaction scheme of the copolymerization was proposed.
Imidization during polymerization of acrylamide
Authors: Minsk L. M. , Kotlarchik C. , Meyer G. N. , Kenyon W. O.
Published: April 2003

The spontaneous imidization of acrylamide during polymerization has been studied in three media: benzene, diglyme, and water. The data indicate that neither medium, time, nor temperatures below 140°C cause imidization to occur. The ascription of the low nitrogen found in polyacrylamide by some investigators to imide formation appears to be in error. The low nitrogen is due rather to retained solvent and/or water, for which polyacrylamide has a strong affinity. Imidization may be brought about by strong acids. The solubility of an imidized polyacrylamide decreases with increasing imide content.
Anionic polymerization of phenyl vinyl ketone initiated with a model compound possessing the same structure as the growing chain end
Authors: Tsushima Rikio , Tsuruta Teiji
Published: April 2003

Anionic polymerization of phenyl vinyl ketone (PVK) was carried out in toluene at 0°C by use of an initiator, ethylzinc 1,3‐diphenyl‐1‐pentene‐1‐olate (I), which possesses the same structure as the growing chain end of PVK in the diethylzinc (ZnEt2)‐initiated polymerization. A unimodal molecular weight distribution was found in the obtained polymer. The polymerization system exhibited a “living characteristic” with the initiator efficiency being 1.0.
Temperature dependence on the binding of butyl orange by bovine serum albumin
Authors: Takagishi Toru , Takami Katsushige , Kuroki Nobuhiko
Published: April 2003

The binding of 4′‐dibutylaminoazobenzene‐4‐sulfonate anion (butyl orange) by bovine serum albumin has been examined quantitatively by an equilibrium dialysis method at 5, 10, 15, 20, 25, and 35°C. The first binding constants and the thermodynamic parameters for the formation of the first dye anion‐protein complex have been calculated. The peculiar temperature dependence of the first binding constant could be observed. That is, the value of the first binding constant increases with increasing temperature until it reaches a maximum value at approximately 18°C and then decreases with raising temperature. Accordingly, this binding process is exothermic above 18°C and is endothermic below 18°C. Near 18°C the process exhibits athermal reaction. From the thermodynamic data obtained, it is evident that the favorable free energy of the binding is accompanied by an entropy gain and that the enthalpies of the binding vary from a positive (unfavorable) value below 18°C to a negative (favorable) one above 18°C. Furthermore an apparent temperature dependence of the thermodynamic functions was observed. That is, ΔF° becomes larger in absolute magnitude as the temperature increases. The positive quantity of ΔS° tends to decrease with increasing temperature. All these facts can be interpreted satisfactorily in terms of hydrophobic interactions between hydrophobic portions of the dye and nonpolar parts of the albumin.
Studies on the photooxidation mechanism of polymers. II. The role of quinones as sensitizers in the photooxidative degradation of polystyrene
Authors: Rabek Jan F. , Rånby Bengt
Published: April 2003

During the quinone‐sensitized photooxidative degradation of polystyrene film and its solution in benzene, an initial rapid decrease of average molecular weight has been observed by GPC and viscosity measurements. The reaction rates are strongly increased by quinones such as p‐quinone, duroquinone, anthraquinone, and chloranil. It has been suggested that this photosensitized degradation of polystyrene occurs by a singlet oxygen reaction which might be related to an energy transfer mechanism from excited triplet states of quinones to molecular oxygen. The photooxidative degradation of polystyrene in solution can be diminished by addition of typical singlet oxygen quenchers such as 1,3‐cyclohexadiene or β‐carotene.
Preparation and properties of polymers with biphenyl units in the chain: Syntheses of solvent‐soluble substituted polyphenylenes
Authors: Hayama Shigeru , Niino Shogo
Published: April 2003

Benzidinetetrazonium chloride (BTC)–CuCl and BTC–FeCl2 complexes were thermally converted to benzene‐soluble poly‐4,4′‐biphenylene plus small amounts of insoluble material. The soluble fraction was more stable than the insoluble fraction when heated at 300–500°C, although the solubility decreased. BTC in water was converted to an insoluble material by addition of alkali or cuprous ammonia solution. The C/(H + Cl) ratio indicated the existence of three to five side groups for each twenty phenyl groups of the insoluble fraction, while that of the soluble fraction showed few such groups. The number increased to one or more side groups for each phenyl nucleus as both soluble and insoluble fractions were heated to 500°C. A thin film of soluble fraction deposited on a copper plate showed an electrical conductivity in the range 10−2–10−3 ohm−1 cm−1 at 25°C and an energy gap (ΔEg) of 0.2–0.3 eV. However, a compressed specimen of the same soluble fraction showed little conductivity. Solventsoluble samples of substituted poly‐4,4,‐biphenylene were prepared by the same procedure. These materials cracked on processing, and accurate conductivity measurements could not be made.
Kinetics of radiation‐induced bulk polymerization of vinyl chloride in the temperature range of −50 to 90°c
Authors: Tavan M. , Palma G. , Carenza M. , Brugnaro S.
Published: April 2003

Kinetic investigations on the bulk polymerization of vinyl chloride initiated by exposure to 60Co γ‐rays were carried out in the temperature range of −50 to 90°C at dose rates varying from 0.15 to 50 rad/c. Some polymerization runs were also carried out in a centrifugal field. As generally reported for this polymerization system, in which the polymer is insoluble in the monomer, the polymerization rate was found to change as a function of the amount of the polymer formed in a special fashion. This particular function has been shown to be greatly influenced by the polymerization temperature and to be independent of the rate of initiation, or, more rigorously, of the dose rate. Thus, at any given temperature the equation of the polymerization conversion rate could be written in the form of the product of two separate functions, one for the polymerization conversion and the other for the dose rate. While for the latter the results gave an essentially square‐root dependence on dose rate as is normally found for homogeneous polymerization, the former has been discussed in the terms of recently advanced kinetic schemes, based on a two‐phase polymerization model. The kinetic parameters found in this work are in agreement with previous authors' data.
Synthesis and characterization of polyaryloxyphosphazenes
Authors: Singler R. E. , Hagnauer G. L. , Schneider N. S. , Laliberte B. R. , Sacher R. E. , Matton R. W.
Published: April 2003

The synthesis, dilute solution characterization, and thermal analysis of seven polyaryloxyphosphazenes are described. Synthesis is accomplished by the ring‐opening polymerization of hexachlorocyclotriphosphazene at 245°C, followed by reaction of polydichlorophosphazene with sodium aryloxide salts in solution at 115°C. Polymers prepared and characterized have the general structure [(ArO)2PN]n, with Ar = C6H5, m‐ and p‐CH3C6H4, m‐ and p‐ClC6H4, p‐C2H5C6H4, or p‐CH3OC6H4. Elemental and infrared analyses show these polymers are essentially free of reactive chlorine sites. All the polymers displayed high intrinsic viscosities [η] > 1 dl/g, in tetrahydrofuran or chloroform. Closer examination of the dilute solution properties of two polyaryloxyphosphazenes revealed high molecular weights (M̄w> 6 × 105) and broad molecular weight distributions (M̄w/M̄n > 4.7). The experimental values for the Z‐average radii of gyration, 〈S2〉z1/2, characterized at near theta conditions, are larger than the calculated values for a freely rotating chain, which suggests that these polymers are relatively linear and not highly branched. Thermal analysis revealed second‐order glass transitions between −37 and +13°C and first‐order endothermic transitions between 43 and 160°C for the different polymers. Although crystalline structure can persist above this first‐order transition, this temperature can be regarded as a melting temperature or softening temperature at which films can be molded. Decomposition temperatures, measured in argon and oxygen, ranged from 250°C to 400°C.
Availability and disposition of hydroxyl groups on surfaces of crystalline cellulose II
Authors: Rowland Stanley P. , Roberts Earl J. , French Alfred D.
Published: April 2003

The relative availabilities of hydroxyl groups at C(2), C(3), and C(6) on the D‐glucopyranosyl units of a particular, highly ordered hydrocellulose II have been studied by means of the reaction of N,N‐diethylaziridinium chloride, which introduces 2‐(diethyl‐amino)ethyl substituents. The hydrocellulose II was formed by hydrolysis of fibrous cotton cellulose II during 40 min reflux in 2.5M hydrochloric acid and is designated EHC‐II (exemplar hydrocellulose II) because it represents the most highly ordered (crystalline) particles in a series of hydrocelluloses. The deviation in the distribution of substituents among the 2‐O‐, 3‐O‐, and 6‐O‐ positions of the D‐glucopyranosyl units in EHC‐II from that in a disordered cellulose, in which the three types of hydroxyl groups are equally available, is the basis for estimated availabilities of the three types of hydroxyl groups on the surfaces of elementary fibrils in EHC‐II. The experimental values of relative availabilities of O(2)H:O(3)H:O(6)H for EHC‐II were 1.0:0.26:0.72 compared to estimated values of 1.0:0.0:.075 for surfaces of elementary fibrils of an idealized, perfectly ordered cellulose II, a model that is based on intensities of x‐ray diffraction peaks.
Modification and characterization of polystyrene surfaces used for cell culture
Authors: Matsuda Takehisa , Litt Morton H.
Published: April 2003

Surfaces of polystyrene Petri dishes used for cell culture were chemically modified by 5% fuming sulfuric acid. The sulfonation was performed at room temperature for various times. Formation of polar groups takes place essentially on the surface of the polymer. Wettability and ionic character of the modified surfaces were determined by contact angle measurements and surface conductivity measurements, respectively. Radioactive calcium (45Ca) adsorption at these surfaces was investigated by means of radiotracer techniques. The chemical composition (concentration of polar sites produced) of these modified polystyrene surfaces was thus determined. It was found that the wettability of these surfaces is directly related to the concentration of sulfonate groups. The cation‐exchange capacity of treated surfaces with inorganic cations (Na+, Mg2+, Ca2+, and Al3+) were determined by the radiotracer technique.
Metal compounds in free‐radical processes. II. Interaction of copper (II) chelates of N‐alkylnorephedrines with peroxides and 2,2′‐diphenyl‐1‐picrylhydrazyl
Authors: Horanská V. , Bartoň J.
Published: April 2003

The reactions of the copper (II) chelates of norephedrine (I), N‐methylnorephedrine (II), N‐ethylnorephedrine (III), and N‐n‐butylnorephedrine (IV) with benzoyl peroxide, cumene hydroperoxide, and 2,2′‐diphenyl‐1‐picrylhydrazyl have been studied. Only the chelates of N‐alkyl‐substituted norephedrines enter into the reactions with free radicals, while their reactivity increases with the length of the alkyl substituent in the amino group of the ligand. The decomposition of cumene hydroperoxide was catalyzed by all four chelates; the catalytic efficiency increases in the order I<II<III < IV.
High temperature polymers. I.—Sulfone ether diamines as intermediates for tractable high temperature polymers
Authors: Kawakami James H. , Kwiatkowski George T. , Brode George L. , Bedwin Albert W.
Published: April 2003

A useful synthesis of a series of new aromatic sulfone ether diamines, H2NC6H4O\documentclass{article}\pagestyle{empty}\begin{document}$\hbox{---}\hskip-5pt[\ {\rm C}_{\rm 2} {\rm H}_{\rm 4} {\rm SO}_{\rm 2} {\rm C}_{\rm 6} {\rm H}_{\rm 4} \hbox{--} {\rm ORO}\hbox{---}\hskip-5pt ]_n {\rm OC}_{\rm 6} {\rm H}_{\rm 4} {\rm SO}_{\rm 2} {\rm C}_{\rm 6} {\rm H}_{\rm 4} \hbox{---} {\rm OC}_{\rm 6} {\rm H}_{\rm 4} {\rm NH}_{\rm 2} $\end{document}, where n = 0, 1, 2…, which increases the tractability of polyimides, polyamide‐imides, and polyamides, was developed. These diamines were prepared by condensing various proportions of sodium p‐aminophenate, sodium bisphenates, and dichlorodiphenyl sulfone. The synthetic procedures are now refined to the point where simply coagulating these diamines into water yields high purity polymer‐grade sulfone ether diamines. The latter have good tractability; and in some cases, it is possible to extrude and injection‐mold these high temperature polymers.
Interaction of polyvinylpyrrolidone and iodine
Authors: Cournoyer Robert F. , Siggia Sidney
Published: April 2003

A nonsolvent preparation of the polyvinylpyrrolidone (PVP) complex provides new insight into the nature of the polymer‐iodine interaction. The preparation is obtained by simply mixing PVP with crystalline iodine and is of interest because it provides a system in which no interfering ions are present and only one type of iodine is initially present. The iodine is shown to undergo hydrolysis with moisture in the polymer to give iodide and hypoiodite. The ionic forms of iodine appear to associate with the molecular iodine, resulting in the final stable PVP‐iodine complex.
Electron spin resonance studies of propagating radicals in polymerization. II. Acrylate propagating radicals
Authors: Harris James A. , Hinojosa Oscar , Arthur Jett C.
Published: April 2003

Ferric chloride‐photosensitized free‐radical initiation was used to generate propagating radicals in polymerization of acrylic acid (AA), methyl acrylate (MA), ethyl acrylate (EA), butyl acrylate (BA), acrylamide (A), and diacetone acrylamide (DAA) in rigid glasses of methanol, ethanol, n‐propanol, isopropanol, or acetone at near liquid nitrogen temperatures. When the temperatures of the glasses were increased, primary radicals derived from the solvents reacted with the monomers to yield propagating radicals. Formation and conformational changes of the propagating radicals at different temperatures were studied by electron spin resonance (ESR) spectroscopy. It was concluded that one type of propagating radical was formed in all cases. However, when the temperature of the rigid glass was increased, the structural conformation of the radical that initially allowed the near‐equivalent interaction of the α‐hydrogen and one of the β‐hydrogens with the unpaired electron generated a three‐line spectrum.
Epoxy/modifier block copolymers
Authors: Noshay A. , Robeson L. M.
Published: April 2003

The curing of epoxy resins with anhydrides in the presence of dihydroxyl‐terminated polyester or polyether modifiers produces block copolymer structures in which one “block” is the crosslinked epoxy/anhydride network and the other block is the linear modifier segment. The morphology of the cured system is dependent upon modifier molecular weight. The critical molecular weight of polycaprolactone and poly(propylene oxide) is 3000–5000. Below this level, single morphological phase systems are obtained, but two‐microphase systems result above this level. This behavior is displayed by several epoxy resins. Two‐phase systems display a superior balance of heat distortion temperature and impact strength, thus providing tough systems with greater elevated temperature capabilities than are obtained with single‐phase systems.
Synthesis of polyamides from pseudo dibenzoylphthaloyl chlorides and aliphatic diamines
Authors: Ueda Mitsuru , Ohkura Masatsugu , Imai Yoshio
Published: April 2003

New pseudo dibenzoylphthaloyl chlorides, namely, 2,5‐dibenzoylterephthaloyl, 4,6‐dibenzoylisophthaloyl, and 4,6‐di(p‐toluyl)isophthaloyl chlorides, were synthesized as monomers. The ring‐opening polyaddition reaction of the pseudo dibenzoylphthaloyl chlorides with aliphatic diamines in N‐methyl‐2‐pyrrolidone afforded a new class of polyamides having inherent viscosities of 0.2 ∼ 0.6 in quantitative yield. The solution polymerization was almost completed within 30 min at room temperature. All of the polyamides were soluble in a wide range of solvents including tetrahydrofuran. These polymers began to decompose at around 300°C both in air and under nitrogen as determined by differential thermal analysis (DTA) and thermogravimetric analysis (TGA).
Copolymerization of carbon dioxide and N‐phenylethylenimine
Authors: Soga Kazuo , Hosoda Satoru , Ikeda Sakuji
Published: April 2003

Copolymerizations of carbon dioxide and N‐phenylethylenimine were carried out with the use of various catalysts and solvents. The infrared spectrum of the polymer produced showed the characteristic absorption peak at 1730–1735 cm−1 based on the urethane linkage.

The content of the urethane linkage decreased in the following order: Mn(acac)2 ≈ MnCl24H2O > Al(OBu)3 > Ti(OBu)4 > ZnCl2 ≫ BF3OEt2 = VCl3 = Mn(acac)3 = FeCl3 = CrCl3 · 6H2O = 0. The manganase (bivalent) catalyst in combination with n‐hexane solvent was found to be the best system for the copolymerization, and this system received detailed study. Generally speaking, both the polymer yield and the content of the urethane linkage increased with increasing content of carbon dioxide in the feed as well as with increasing polymerization temperature. From the fractionation of polymer in methanol, it was found that the produced polymer is composed of both homopolymer of N‐phenylethylenimine and copolymer of N‐phenylethylenimine and carbon dioxide. The content of the urethane linkage of the copolymer thus fractionated was as high as about 80%.
Investigations on poly(vinyl chloride). I. Evolution of aromatics on pyrolysis of poly(vinyl chloride) and its mechanism
Authors: Iida Takeo , Nakanishi Motoharu , Gotō Kunio
Published: April 2003

Poly(vinyl chloride) (PVC) alone or mixed with 10 wt‐% and 50 wt‐% TiO2, SnO2, ZnO, and Al2O3 were pyrolyzed by using a pyrolysis gas chromatograph. Benzene, toluene, ethylbenzene, o‐xylene, styrene, naphthalene, and various chlorobenzenes were identified. No hydrocarbons could be detected in pyrolysis products of any samples at 200°C. More aromatic hydrocarbons than aliphatic hydrocarbons are released from the PVC–TiO2 system and in preheated PVC. The contrary result is observed in the PVC–ZnO and PVC–SnO2 systems. Aromatics having methyl endgroups are easily released from the PVC–ZnO and PVC–SnO2 systems and at elevated pyrolysis temperature, because methylene groups are easily isolated along the chain by ZnO, SnO2 and the heating. The release of ethylbenzene o‐xylene, and chlorobenzenes suggests a repeated dehydrochlorination and recombination of HCl and Cl2 to double bonds along the chain. Possible decomposition mechanisms of PVC are discussed.
Radical polymerizability of fumaramide derivatives
Authors: Azuma C. , Ogata N.
Published: April 2003

Various N‐cycloalkyl fumaramides having different characters of N‐cycloalkyl groups such as piperidine, morpholine, or pyrrolidone were synthesized and homopolymerized or copolymerized with styrene by use of a radical initiator and ultraviolet irradiation, respectively. N,N′‐Dipiperidinyl or ‐dimorpholyl fumaramides copolymerized with styrene to form a random copolymer, while N,N′‐fumaroyl dipyrrolidone tended to form an alternating copolymer with styrene, indicating that the electron distribution of the N‐cycloalkyl group affects the polymerizability of fumaramide derivatives. Photopolymerizability of these fumaramides was not as great as that of α,β‐unsaturated esters.
Binding of methyl orange and its homologs by polycations containing apolar pendant groups
Authors: Takagishi Toru , Nakata Yoshiro , Kuroki Nobuhiko
Published: April 2003

The binding of methyl orange, ethyl orange, and propyl orange by polycations involving various apolar pendant groups such as methyl, ethyl, benzyl, or dodecylbenzyl groups has been examined quantitatively by an equilibrium dialysis method at 5, 15, 25, and 35°C. The first binding constants and the thermodynamic parameters in the course of the binding have been calculated. The favorable free energy of the binding is accompanied by an entropy gain and an exothermic enthalpy change. The shorter the alkyl chain of the dyes or the polymers, the more negative is the enthalpy change and hence the smaller is the entropy change. Furthermore, an increase in binding affinity can be created in the polycation upon introduction of hydrophobic groups. In particular, the binding ability of the polycation containing a dodecylbenzyl group for methyl orange is almost 300‐fold that of bovine serum albumin. Therefore it is clear that hydrophobic interactions, as well as electrostatic ones, are involved in the binding.
Polymerization and reaction rate studies on substituted phenylmethylbis(dimethylamino)silanes
Authors: McManus Samuel P. , Patterson William J. , Pittman Charles U.
Published: April 2003

The synthesis of seven para‐ or meta‐substituted phenylmethylbis(dimethylamino)‐silane monomers has been carried out. These silanes were polymerized with 1,4‐bis(hydroxydimethylsilyl)benzene in tetrahydrofuran at 30°C, and the polymerization kinetics were followed by monitoring dimethylamine evolution for 200 min. The polymers were quenched by precipitation in methanol and molecular weight data were obtained. The polymerizations followed second‐order kinetics in every case as evidenced by the linear plots of 1/(a − x) versus time. The molecular weight data generally correlated with the specific reaction rate constant k2 to show an increasing polymer molecular weight with increasing polymerization rate, although the range of k2 values obtained for the substituted aminosilanes was relatively small (2.50 × 10−5–6.67 × 10−5 l./mole‐sec). The value of k2 increased in the following order: p‐OCH3, p‐F, m‐CH3, H, m‐OCH3, p‐CF3, 3,5‐di(CF3). The logarithms of the rate constants correlated with the σ constants for the substituents, with a reaction constant, ρ of 0.391. The displacement at silicon in these reactions is discussed in terms of bimolecular mechanisms in which a four‐center transition state may participate.
Influence of copolymeric poly(diethylene glycol) terephthalate on the thermal stability of poly(ethylene terephthalate)
Authors: Hergenrother W. L.
Published: April 2003

Copolymers of poly(ethylene terephthalate) (PET) containing 1–24% poly(diethylene glycol)terephthalate (PDEGT) were prepared and characterized by infrared spectra. The energy and entropy of activation for the thermal degradation were measured for these copolymers and for the PDEGT. These activation energies and energies and entropies were found to decrease steadily with increasing diethylene glycol content. From these measurements the mechanism of degradation of PDEGT was found to be different from that of PET. Fibers prepared from seven different copolymeric compositions were heat‐aged at 121°C and 204°C for 24 hr. From the changes observed in intrinsic viscosity, per cent ether, hydroxyl and carboxyl endgroups during heat aging it became apparent that the mechanisms for decomposition are operative below melt temperatures and can rapidly destroy such copolymers.
Polyurethane–polyacrylate interpenetrating polymer networks. I
Authors: Frisch K. C. , Klempner D. , Migdal S. , Frisch H. L.
Published: April 2003

Two‐component topologically interpenetrating polymer networks (IPN) of the SIN type (simultaneous interpenetrating networks) composed of a melamine‐cured polyacrylate and five different polyether‐based polyurethanes were made. The linear polymers and prepolymers were combined in solution, together with the necessary crosslinking agents and catalysts; films were cast, chain‐extended, and crosslinked in situ. Infrared spectroscopy indicated that little or no reaction between the different networks occurred. In all cases, except for one IPN which was made from a very highly crosslinked polyurethane, maxima in tensile strength, significantly higher than the tensile strengths of the components, occurred. This was explained by an increase in crosslink density resulting from interpenetration. Some enhancement in other physical properties (impact strength and thermal resistance) was also noted.
Preparation of new reactive methylene monomers
Authors: Ponticello I. , Furman R. L.
Published: April 2003

Acryloylacetone, methacryloylacetone, and related monomers have been synthesized by using cyclopentadiene as a blocking agent during the Claisen condensation.
Molecular chain conformation and crystallite structure of cellulose. I. Fine structure of rayon fibers
Authors: Watanabe Sadayoshi , Hayashi Jisuke , Akahori Tadayoshi
Published: April 2003

A most reasonable folded‐chain model for the fine structure of rayons (cellulose II) has been developed through experimental work on a theoretical basis. All the materials uniformly gave a levelling‐off DP of about 40, equivalent to a length around 200 Å, for cellulose molecule segments at the early stage of heterogeneous acid hydrolysis when the first minor fraction is scarcely dissolved. Measurements by small‐angle and wide‐angle x‐ray scattering put the crystallite length from various rayon fibers at about 200 Å, without exception. A family of GPC chromatograms, furthermore, on the hydrolyzed cellulose exhibited a single peak considered to represent monodispersed materials. These data suggest that clearly divided sections exist within the microfibril along its axis in a regular manner at an interval of about 200 Å. This cannot be explained in terms of the fringed micelle model. On the other hand, the possibility that cellulose II may have a folded‐chain conformation has been demonstrated. A single cellulose molecule is essentially folded back and forth in the (101) plane to form a sheetlike structure. Such a structure is the basic unit that can fit perfectly into the unit cell of cellulose II. The cellulose molecule can achieve a fairly sharp U‐turn in the (101) plane, with only one glucose unit of in the half‐boat conformation. A crystallite consists of a number of sheets held together by secondary forces in the (101) plane. Accordingly, crystallographically, the crystallites are closely packed at the surface of each fold at its longitudinal edges to make up the cellulose microfibril. According to our model, the oxygen atom of the glucosidic link in the fold, where acid hydrolysis would have to take place, protrudes partially from the surface of the crystallite; a pair of atoms at the folds are then facing each other and are therefore, accessible for hydrolysis. This would explain chain scission of cellulose II at these sites in hydrolysis. This folded‐chain model is supported further by other experimental evidence.
Gel‐permeation chromatography: X. Molecular weight detection by low‐angle laser light scattering
Authors: Ouano A. C. , Kaye Wilbur
Published: April 2003

Effluent from a gel‐permeation chromatographic column has been simultaneously and continuously monitored with a differential refractometer and a low‐angle laser light‐scattering (LALLS) photometer. This provides a true and direct determination of molecular weight distribution rather than through a calibration method as obtained by conventional GPC techniques. Computer assisted data reduction provides a rapid determination of M̄w, M̄n, M̄z, M̄w/M̄n, as well as a plot of molecular weight distribution. Samples of very narrow molecular weight distribution (MWD) polystyrene from Pressure Chemicals Co. and relatively wide MWD samples of poly(methyl methacrylate) in chloroform have been characterized.
Identification of the principal high molecular weight fragments in the thermal degradation of poly(methyl acrylate)
Authors: Haken J. K. , Ho D. K. M. , Houghton E.
Published: April 2003

The pyrolysis of poly(methyl acrylate) has been studied with identification of the major pyrolysis products. The degradation mechanism of Cameron and Kane involving random homolytic scission of the polymer chain followed by a series of intermolecular and intramolecular transfer reactions is extended and confirmed, and it is apparent that a series of saturated and unsaturated oligomers of methyl acrylate are produced.
Kinetics and mechanism of stereospecific polymerization of methyl methacrylate with VOCl3–AlEt2Cl catalyst system
Authors: Gandhi V. G. , Deshpande A. B. , Kapur S. L.
Published: April 2003

Methyl methacrylate was polymerized at 40°C with VOCl3–AlEt2Cl catalyst system in n‐hexane. The rate of polymerization was proportional to catalyst and monomer concentration at Al/V ratio of 2 and overall activation energy of 9.25 kcal/mole support a coordinate anionic mechanism of polymerization. The catalytic activity and stereospecificity of this catalyst system is discussed in comparison with that of VOCl3–AlEt3 catalyst system.
Ethylene–propylene terpolymers based on methylcyclopentadienyl‐5‐norborn‐2‐enylmethane derivatives
Authors: Cesca S. , Duranti P. V. , Roggero A. , Santi G. , Bruzzone M.
Published: April 2003

The terpolymerization of ethylene, propylene, and methylcyclopentadienyl‐5‐endonorborn‐2‐enylmethane (III) by means of different vanadium‐based coordination catalysts was investigated. The structure of III and its isomeric composition was studied by using vapor‐phase chromatography, mass spectrometry, and NMR, infrared, and ultraviolet spectroscopy. The catalyst system V Acac3–Et2AlCl was used under different conditions, and the influence of several variables regulating the terpolymerization process were related to the properties of the resulting terpolymers (EPTM). The insertion of III into EPTM chains takes place randomly and does not influence the random distribution of comonomers. The selective opening of the norbornene double bond of III has been demonstrated by use of 2,3‐dihydro‐III as model compound. Tritiated III gave a radiochemical titer of unsaturation in excellent agreement with the value deduced from ultraviolet measurements. The influence of Lewis bases added to VAcac3–Et2AlCl catalyst is discussed.
Phosphorescence from nylon polymers: Effects of thermal and photochemical oxidation
Authors: Allen N. S. , McKellar J. F. , Phillips G. O.
Published: April 2003

The phosphorescence from the nylon polymers 6, 66, 11, and 12 has been studied from the aspects of excitation and emission wavelength location and of emission lifetime. In contrast to the other nylons, the 66 polymer exhibits two distinct phosphorescence bands, both of which are sensitive to thermal and photochemical oxidation of the polymer. The species responsible for these emissions are concluded to be carbonyl in nature and their role in the complex reactions that occur during thermal and photochemical oxidation of the polymer is discussed.
Effect of primary radical termination on chain length and initiator efficiency
Authors: Ito Katsukiyo
Published: April 2003

In polymerization with primary radical termination, when reaction between primary radicals, which escape from solvent cage, is not negligible, a relation between chain length and polymerization rate is found regardless of tractable approximate procedures. Such a relation is applied to the kinetic data obtained in the polymerizations of methyl methacrylate (MMA) and vinyl acetate (VA) initiated by 2,2′‐azobis(2,4‐valeronitrile) at 50.0°C. Further, when the primary radical termination is high, an initiator efficiency can not be approximated to a ratio of the primary radicals escaping from the cage to the total primary radicals formed in the cage. In the polymerization of MMA, after the primary radicals escapes from the cage, they immediately react with the monomer. Thus, the reaction between the primary radicals is not significant. However, in the polymerization of VA, the rate of reaction between the primary radical and the monomer might be comparable to the rate of reaction between the primary radicals when the initiator concentration is quite high.
Effects of mercaptides on anionic polymerization. III. Polymerization of methyl methacrylate by thiophenoxides in polar aprotic solvents
Authors: Hirahara Takuji , Minoura Yuji
Published: April 2003

Sodium thiophenoxide initiated the polymerization of methyl methacrylate in polar aprotic solvents (DMF, DMSO, HMPA). The active species that initiated the polymerization of the monomer was found by spectrophotometric measurements and by the sodium fusion method to be sodium thiophenoxide itself. The activation energy for the polymerization of the monomer in DMF solvent obtained was E = 3.4 kcal/mole below 30°C, and E = −3.3 kcal/mole above the temperature. The phenomena were reasoned as the result of the formation of two active species: a solvent‐separated ion pair and a contact ion pair. The effects of counterions on the reactivity of thiophenoxide increased with increasing electropositivity of the metals: Li < Na < K. Sodium phenoxide, the oxygen analog of thiophenoxide, was also found to initiate the polymerization of the monomer in the solvents. The relative reactivity of thiophenoxide to phenoxide for the monomer in HMPA at 30°C was thus determined: phenyl‐SNa > phenyl‐ONa. The relative effect of the polar aprotic solvents on the reactivity of thiophenoxide was also as follows: HMPA > DMF > DMSO. The kinetic studies were made by the graphical evaluation of rate constants. The following results were obtained for the monomer at 20°C in DMF solvent: Kp = 3.5 × 102 1./mole‐hr and Kt = 9.8 × 10−2/hr.
Thermal decomposition of poly(tert‐butyl N‐vinylcarbamate)
Authors: Schulz Gerald O. , Harwood H. James
Published: April 2003

Pyrolysis of poly(tert‐butyl N‐vinylcarbamate) at 185–200°C in bulk yields a rigid foam containing cyclic urea units, primary amine units, and a small amount of urea crosslinks. The yield of primary amine units (ca. 13%) and the yields of carbon dioxide (ca. 57%), isobutylene (ca. 57%), and tert‐butanol formed in this reaction indicate that it involves pairwise decomposition of adjacent carbamate units to form cyclic urea units, tert‐butanol, carbon dioxide, and isobutylene. The vinyl amine units are formed from carbamate units that become flanked by urea units. The amounts of amine units and residual carbamate units were determined as a function of degree of pyrolysis by an ion‐exchange technique and agreed with values expected for a random cyclization process. The pyrolyzed polymers are useful as ion‐exchange resins and as rigid foams having good thermal stability.