bluuebunny/crossref_metadata_2025 huggingface dataset:
Extrapolation procedures for intrinsic viscosity and for Huggins constant k′
Authors: Sakai Tsukasa
Published: April 2003

Conventional extrapolation procedures for the calculation of intrinsic viscosities and the Huggins constant k′ have been critically examined. A condition which must be satisfied by the basic equation for viscosity–concentration relations of dilute solutions of nonelectrolytic polymers has been clarified. On the basis of the comparison of the curvatures for empirical equations and for the basic equation, it is proposed to use arithmetic averages of the values calculated from a Huggins plot and those from a Martin plot for good‐solvent systems, and to employ the averages of values from the former and those from a Schulz‐Blaschke plot for poor‐solvent systems as approximations to the correct values. Failure to confine approximations in the usual statistical treatment of experimental points to the given range of the variables as well as neglect of the fact that curvatures for the empirical and basic equations do not necessarily coincide are the usual sources of error in the conventional extrapolation procedures.
Shearing of oriented polyethylene and polypropylene
Authors: Robertson Richard E. , Joynson Catherine W.
Published: April 2003

To learn more about the out‐of‐plane deformation of polymer lamellae during drawing, we have measured the resistance to shear along various planes in uniaxially oriented polyethylene and polypropylene. Fissures parallel to the orientation axis in oriented materials always cause too small an experimental value for the resistance of crystal glide parallel to the chain axes, but a rough estimate for the resistance to crystal glide is obtained using the elastic anisotropy. Also, the results suggest that kinking can be easier than glide when glide is inhibited by tie molecules.
High‐temperature mechanical behavior of unplasticized poly(vinyl chloride)
Authors: Crugnola A. , Pegoraro M. , Danusso F.
Published: April 2003

We studied the high‐temperature mechanical behavior of unplasticized poly(vinyl chloride) by stress relaxation experiments covering a temperature range of 100–180°C and a time interval of 0.01–3600 sec at an elongation of 40%. The polymer was observed to respond elastomerically within these set temperature limits. The molecular basis for this behavior is linked to the partial crystalline nature of this material. The crystalline phase is postulated to be the seat of the relaxation process taking place in the rubbery response region, and evidence is presented supporting this point of view. A comparison is made between free volume variations arising from thermal expansion and those originating instead from uniaxial straining. It is also pointed out that, following linear viscoelastic theory, the viscosity is a time‐dependent quantity, and it is shown that for this polymer its variation with temperature at short times is ninefold less than the corresponding variations in its limiting value. Finally it is noted that the measured high‐temperature tensile strength corresponds to a chain bond strength approximately 1/300 of the theoretical value.
Crystallization kinetics of isotactic polystyrene. I. Spherulitic growth rate
Authors: Boon J. , Challa G. , Van Krevelen D. W.
Published: April 2003

The spherulitic growth rate of isotactic polystyrene has been measured in a wide range of temperature by means of a polarizing microscope provided with a hot stage. It was possible to fit the experimental data to theory by choosing a value of 75 for the constant C2 of the WLF equation. The growth rate parameters were compared with those of polyethylene and polychlorotrifluoroethylene. The slowness of crystallization of isotactic polystyrene is mainly a consequence of the lower mobility of the molecules caused by the bulky phenyl groups.
Basic gel permeation chromatography studies. III. Mathematical analysis of peak spreading
Authors: Hendrickson J. G.
Published: April 2003

Peak spreading in gel permeation chromatography has been studied with a range of gels including those whose permeation limit corresponded to about 103, 106, 108, and 109 molecular weight polystyrene. Peak spreading conformed to the equation YV2 = YM2 + YA2 + YI2 + YD2 + YS2, where YV is the peak width of a normal chromatogram, YM is the contribution due to the true molecular weight of the sample, YA is due to peak spreading in the apparatus, YI is spreading in the interstitial volume, YD is diffusional spreading due to time spent in the gel, and YS is due to sorption. Evaluating the appropriate parts of the equation leads to measures of the true molecular weight distribution and the contribution due to diffusion into and out of the gel. The data also allowed estimates as to the diffusional spreading with small molecules. With polystyrene having 100 000 molecular weight, diffusional spreading accounts for 80% of YV,2 but with small molecules the contribution due to diffusion was not detected.
Flow birefringence of short‐chain molecules: Cellulose tricarbanilates in benzophenone
Authors: Janeschitz‐Kriegl H. , Burchard W.
Published: April 2003

Measurements of flow birefringence of cellulose tricarbanilates were carried out on nine fractions (0.27 × 105 < M ≤ 12 × 105) in a temperature range of 55–110°C, with benzophenone as a matching solvent (dn/dc = 0). The ratio of Maxwell constant to intrinsic viscosity, which has been found to be independent of molecular weight for the limiting case of Gaussian molecules, is successfully interpreted as a function of molecular weight in terms of the recent theory of Gotlib and Svetlov (based on the wormlike chain model of Kratky and Porod). From the measurements at 55°C a number of 36.6 monomer units per random link is deduced. This is in accord with results of small‐angle x‐ray scattering. For the extinction angle curves a clear transition is observed from rodlike to statistical molecules when the molecular weight is increased. At high molecular weights the master curves obtained for anionic polystyrenes and cellulose tricarbanilates coincide. Implications of this observation on the kinetic stiffness of the cellulose tricarbanilate chain are discussed. The intrinsic viscosity‐molecular weight relationship is considered. From a comparison with the results of the theory of Eizner and Ptitsyn it is concluded that the cellulose tricarbanilate chain must be highly solvated in benzophenone.
Normal stress effect of molten polyethylene
Authors: Sakamoto Kunisuke , Ishida Nobuhiro , Fukasawa Yoshiaki
Published: April 2003

A brief description is given of a new parallel‐plate rheogoniometer for normal stress measurements on polymer melts as functions of the rate of shear. A wire‐resistance strain gauge is used as the pressure gauge. Measurements are reported on high‐density polyethylene. It is found that the time‐temperature superposition principle is applicable to the normal stress data as well as to shear stress in steady flow.
Microstructure of ethylene–vinyl chloride copolymers. I. Direct verification of terminal radical effects on copolymerization by a simplified NMR approach
Authors: Wilkes Charles E. , Westfahl J. C. , Backderf Richard H.
Published: April 2003

The sequence distributions of monomer units in a series of high‐pressure, bulk ethylene–vinyl chloride copolymers have been determined by high‐resolution NMR spectroscopy. The concentrations of EE, VV, and EV (VE) monomer pairs or diads were used with NMR‐determined compositions to calculate, in addition to the sequence distribution parameters, the reactivity ratio product for the system. Inclusion of feed data allowed the calculation of individual reactivity ratios. Well within experimental error, the reactivity ratio product (r1r2 = 0.7) determined from microstructure analysis—independent of monomer feed data—was equal to that determined by the standard Fineman‐Ross technique. Terminal monomer unit effects on the copolymerization were observed. The nonrandom structures result from a copolymerization described by first‐order Markoffian statistics.
Studies in some new initiator systems for vinyl polymerization. III. Amine–halogen systems as redox initiators
Authors: Pramanick Dinabandhu , Palit Santi R.
Published: April 2003

Amine–halogen redox systems are very efficient initiators of polymerization of a number of vinyl monomers in benzene media and are rather inefficient initiators in aqueous media. A large number of aliphatic amines and a few aromatic amines have been used. Among the halogens, chlorine and bromine are very effective. Iodine initiates with a few amines only. Endgroups incorporated are halogen and amine totalling an average of nearly one per chain in the case of polymerization in benzene media and 0.5–0.7 per chain in polymerization in aqueous media. In the light of endgroup results, a mechanism of initiation through halogen and amine radicals has been suggested.
Unit cell dimensions of isotactic polyvinylcyclopropane
Authors: Noether H. D. , Overberger C. G. , Halek G.
Published: April 2003

The unit cell dimensions of isotactic polyvinylcyclopropane were determined, based on crystalline, oriented fiber and film samples. Two structures were found: (1) a hexagonal structure with a = 13.6 Å, c = 6.48 Å, 31 helix, space group P31 and P32, ρ(calc) = 0.9805 g/cm3, ρ(obs) = 0.975 g/cm3; (2) a tetragonal structure with a = 15.21 Å, c = 20.85 Å, 103 helix, space group I4, ρ(calc) = 0.926 g/cm3.
Photo‐oxidation of the 2,4‐dichloropentanes and PVC
Authors: Kwei Kwei‐Ping Shen
Published: April 2003

The photo‐oxidation of PVC and its model compounds, the dl‐ and meso‐2,4‐dichloropentanes, were studied by high‐resolution NMR spectroscopy. The structure, CHClCH2COCH2 was found to be present in PVC after photo‐oxidation. Two peaks, which corresponded to the CHCl and CH2 groups next to the carbonyl group, were observed in carbon disulfide–acetone‐d5 mixture, at 6.15 and 7.25τ, respectively. From the NMR spectra, the ratio of the CH2 to CHCl protons in PVC and the model compounds were found to increase linearly with the time of photo‐oxidation after induction periods. The initial rates of the model compounds were comparable with that of PVC; i.e., 1.6 × 10−2 hr−1, at 30°C. Since similar gaseous products were also detected by mass spectrometry in the initial stage, their photo‐oxidation probably assumed the same rate‐determining step. According to the results that the dl‐2,4‐dichloropentane was photo‐oxidized 1.5 times faster than the meso‐compound, it would be likely that the syndiotactic sequences in PVC might be more easily photo‐oxidized than the isotactic sequences.
Aromatic polyimide‐co‐amides. I
Authors: Wrasidlo W. , Augl J. M.
Published: April 2003

A series of aromatic polyimide‐co‐amides of high thermal stability were synthesized. Low‐temperature solution condensation involving aromatic diamines of varying basicity and bifunctional carboxylic acid chlorides containing performed imide rings was empolyed. This approach offers several advantages over the conventional polyamic acid route. The final polymers obtained are linear, soluble, and of high molecular weight. Solution of the final polymers are stable in contrast to polyamic acid solutions, which depolymerize hydrolytically due to the neighboring‐group effect. Tough, flexible films were cast from solution and required no heat cure. The properties of one polymer made by the preformed ring approach were compared to its structurally related amide and imide homologs.
Cationic graft copolymerization of polystyrene onto poly‐2,6‐dimethoxystyrene by the termination reaction
Authors: Overberger C. G. , Burns C. M.
Published: April 2003

Poly‐2,6‐dimethoxystyrene (P26) was used as the polymeric backbone and was obtained by a new synthetic route involving the Wittig reaction. The grafting reaction was studied by polymerizing styrene with stannic chloride as catalyst in the presence of various concentrations of preformed P26 in solution with carbon tetrachloride and nitrobenzene at 60, 45, 30, and 0°C. The product was fractionated with cyclohexane and the fractions were analyzed by ultraviolet absorption spectroscopy and density‐gradient ultracentrifugation. The molecular termination constant of P26 at 30°C was 0.106 much larger than the value of 0.016 which had been obtained for poly‐p‐methoxystyrene at 0°C. The amount of grafting and grafting efficiency generally increased with increasing temperature, contrary to results using the cationic initiation reaction. Anomalous results were obtained at 0°C as the product was no longer completely soluble. The ratio of grafted to ungrafted polystyrene chains was proportional to the concentration of P26 and generally increased with temperature. The grafting reaction was competitive with the normal termination reaction, and the energy of activation of the grafting reaction was estimated to be larger by ca. 7 kcal/mole.
Contributions au fractionnement des copolymères. II. Copolymères ternaires acrylonitrile–acétate de vinyle–α‐méthylstyréne
Authors: Feldman Dorel , Uglea Constantin , Simionescu Natalia
Published: April 2003

Acrylonitrile, vinyl acetate, and α‐methyl styrene copolymers, were synthesized in aqueous solution, and the resulted products were studied viscometrically by fractionation and by cloud‐point titration. The values of the intrinsic viscosities of the polymers in DMF at 20°C are not influenced by the overall composition of the copolymers and the distribution mode of the comonomers. The solubility of the products is directly dependent on the composition, namely, it increases as the acrylonitrile content decreases. The differential fractionation curves are influenced by the chemical composition and by the mode of distribution of the monomers along the macromolecular chain. The successive precipitation method for the fractionation of the ternary copolymers is recommended.
Alkyllithium and alkali metal tert‐butoxide as polymerization initiator
Authors: Hsieh H. L. , Wofford C. F.
Published: April 2003

We have shown that the presence of other alkali metal alkoxides in the alkyllithium‐initiated polymerization drastically increases the rate of polymerization and vinyl unsaturation in polybutadiene. Mechanistically, the propagating center is the dynamic equilibriums between carbon–metal bonds and oxygen–metal bonds. With potassium, rubidium, and cesium salts it reaches a limiting anionic behavior.
Polymerization and copolymerization of some epoxides by potassium tert‐butoxide in DMSO
Authors: Price Charles C. , Atarashi Yuji , Yamamoto Ryuzo
Published: April 2003

Copolymerization of tritiated PGE with analogs and with propylene oxide by potassium tert‐butoxide in DMSO shows that this anionic polymerization is favored by electron‐withdrawing groups. The homopolymerization of PGE and its p‐chloro and p‐methoxy analogs gives polymer with molecular weight limited by chain transfer. For PGE, where this limit is about 7000, some of the polymer is insoluble, crystalline isotactic material.
Direct metalation of poly(2,6‐dimethyl‐1,4‐phenylene ether)
Authors: Chalk A. J. , Hay A. S.
Published: April 2003

Poly(2,6‐dimethyl‐1,4‐phenylene ether) (I) was metalated with butyllithium in tetrahydrofuran and with the N,N,N′,N′‐tetramethylethylenediamine complex of butyllithium in a variety of solvents. In these cases, metalation occurred at both the ring and side chain positions, the former being preferred initially. Subsequently, there was an isomerization in favor of the side chain.

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At 25°C, there is no significant amount of polymer scission or crosslinking during metalation, but some crosslinking occurs on derivatizing with dimethyl sulfate and trimethylchlorosilane for high extents of ring metalation. With sodium and potassium alkyls, only side‐chain metalation was observed. The metalated polymer reacts as a typical organometallic, allowing polymer modification by a wide variety of reactions.
Thermal decomposition products of polyisobutylene
Authors: Tsuchiya Yoshio , Sumi Kikuo
Published: April 2003

Polyisobutylene was decomposed at 325, 345, and 365°C under vacuum, and the volatile products were trapped by using liquid nitrogen. The products, C1–C24 hydrocarbons, were analyzed by gas chromatography. The formation of the main products is discussed on the basis of a free‐radical mechanism. Intramolecular radical transfer can account for the production of most fragments including dimers, trimers, tetramers, and so on, of isobutylene.
Relationship between structures and activities of silver salt–organic halide catalyst systems for styrene polymerization
Authors: Kagiya Tsutomu , Izu Masatsugu , Maruyama Hitoshi , Fukui Kenichi
Published: April 2003

The rate of bulk polymerization of styrene initiated by silver salt–organic halide systems was measured at 0°C. Neither of the catalyst components initiated the polymerization when used alone, while combined catalysts containing both components initiated the polymerization in the case that the components reacted with each other with precipitation of silver halide. The rate in the early stage of the polymerization increased with an increase in reaction time. Plots of yield against the second power of time gave a linear relation in the early stage of the polymerization. The slope of the line was taken as a measure of catalytic activity. The catalytic activity was markedly influenced by the kinds of the components. The activities of silver perchlorate–organic halide systems increased in the following order of halides: chloride < bromide < iodide in most cases. The activities of silver perchlorate–organic chloride systems increased with a decrease in ionization potentials of the organic groups of the chlorides. The activities of silver salt–benzyl bromide systems increased with a decrease in the pKa values of conjugate acids of silver salts. From these results, it was concluded that the facility of ionic dissociation of the catalyst components determined the activities.
Polymerization of β‐cyanopropionaldehyde. III. Polymerization by organoaluminum and by organoaluminum–titanium chloride complexes
Authors: Kobayashi Kazukiyo , Sumitomo Hiroshi
Published: April 2003

The mechanism of formation and stereoregularity of poly(cyanoethyl)oxymethylene have been studied. The polymerization was carried out at −78°C with use of aluminum compounds [Al(C2H5)3, Al(C2H5)2Cl, Al(C2H5)Cl2, and AlCl3] and complex catalysts [Al(C2H5)3–TiCl4, Al(C2H5)3–TiCl3, and Al(C2H5)2Cl–TiCl3] as initiators. The stereoregularity of poly(cyanoethyl)oxymethylene was estimated from the optical density ratio, D1258/D1270, in the infrared absorption spectrum. Polymer yields were observed to depend upon the aluminum compound used as initiators, while the stereoregularity of the polymer was nearly independent of the particular aluminum compound used. As the catalyst ratio of titanium chloride to aluminum compound increased, the polymer yield was found to increase to a maximum and then to decrease with further increase of the ratio. It is supposed that titanium chlorides themselves increase the acid strength of aluminum compounds through chlorination, resulting in the change of the polymer yield. The highest stereoregularity of poly(cyanoethyl)oxymethylene was attained by increasing the molar ratio of titanium trichloride to aluminum and by treating β‐cyanopropionaldehyde (CPA) with titanium trichloride prior to the polymerization. Complex formation of the nitrile group of CPA with titanium is considered responsible for the increase in stereoregularity. A propagation mechanism is also proposed.
Poly‐as‐triazines
Authors: Hergenrother P. M.
Published: April 2003

Two high molecular weight (ηinh > 1.0) soluble poly‐as‐triazines have been prepared by the solution polycondensation in m‐cresol of 2,6‐pyridinediyl dihydrazidine with p,p′‐oxybis(phenyleneglyoxal hydrate) and with p,p′‐oxydibenzil. Thermal characterization of the poly‐as‐triazines by TGA showed polymer decomposition temperatures of ∼400°C after a 300°C cure in argon. Poly‐as‐triazines exhibited weight losses <8% after aging in static air at 316°C for 200 hr. Clear yellow films cast for m‐cresol solutions exhibited good flexibility and toughness even after aging at 316°C for 200 hr in air and after refluxing in 10% aqueous potassium hydroxide solution for 24 hr.
Polymers containing carbohydrate residues
Authors: Overberger C. G. , Takekoshi Tohru
Published: April 2003

2,3,4,6‐Tetra‐O‐methyl‐D‐glucosyl methacrylate and acrylate were prepared and subsequently polymerized by radical initiation. The optical rotatory dispersions of the polymers in tetrahydrofuran and in chloroform obeyed a first‐order Drude equation.
Relationships for determining the rate constant of the polymerization growth reaction by means of the emulsion polymerization method
Authors: Hrabák František , Hynková Vlasta , Bezděk Milan
Published: April 2003

Some simple equations for the emulsion polymerization system were derived on the basis of the Smith‐Ewart theory. These are used in calculating the molar monomer concentration and rate of polymerization in units of moles per liter per second for the zero‐order region with respect to the monomer as well as in calculating the rate constant of the growth reaction.
Mechanism of cyclopolymerization. Conformational analysis of cis‐1,3‐diisocyanatocyclohexane
Authors: Corfield G. C. , Crawshaw A.
Published: April 2003

In 1,3‐disubstitued cyclohexanes, in general, the diaxial conformation of the cis isomer is, energetically, the least favored conformation. An interspacial electronic interaction in the ground state of a cis‐1,3‐disubstituted cyclohexane would be expected to increase the proportion of this conformer in the equilibrium mixture. Such an interaction would provide an energetically favorable pathway for cyclopolymerization. From nuclear magnetic resonance studies on cis‐and trans‐1,3‐diisocyanatocyclohexane the conformational equilibrium in the cis isomer was determined. It is shown that cis‐1,3‐diisocyanatocyclohexane exists in the diequatorial conformation; this is taken as evidence that a ground‐state interaction between isocyanato groups in this monomer, which readily cyclopolymerizes, is not a significant factor in the cyclopolymerization mechanism. The value of the free energy barrier, ΔG‡, for trans‐1,3‐diisocyanatocyclohexane was calculated as 11.1 kcal/mole.
Selective reactivities and accessibilities of the hydroxyl groups in cotton cellulose based on equilibrium data from a reversible chemical reaction
Authors: Cirino V. O. , Bullock A. L. , Rowland S. P.
Published: April 2003

In order to determine the relative equilibrium constants for reactions of the hydroxyl groups at C2, C3, and C6 of the D‐glucopyranosyl units, methyl vinyl sulfone was reacted with cellulose dissolved in benzyltrimethylammonium hydroxide. The reaction was carried to constancy in distribution of substituents between the 2–0– and 6–0–positions. The distributions of substituents in the D‐glucopyranosyl units were measured by gas‐liquid chromatographic analysis of the products from hydrolysis of the modified cellulose. Relative equilibrium constants were then evaluated, assuming complete accessibility of all three types of hydroxyl groups of the cellulose in solution. For determination of the relative accessibilities of the individual types of hydroxyl groups in heterogeneous reactions of cotton cellulose with methyl vinyl sulfone, the reactions were carried to equilibrium distributions in media of various normalities of sodium hydroxide (i.e., media of various swelling strength). The distributions of substituents in the D‐glucopyranosyl units were measured. From these values and the ratio of equilibrium constants, the relative accessibilities of the hydroxyl groups at C2 versus those at C6 were calculated. Apparent accessibilities of the hydroxyl groups at C2 are approximately double those at C6 when the reaction is carried out in 1N sodium hydroxide and about triple those at C6 when the reaction is carried out in 0.5N sodium hydroxide.
Electron‐transfer polymers. XXXIX. Redox polymers based on duroquinonyl glycol
Authors: Nakabayashi Nobuo , Wegner Gerhard , Cassidy Harold G.
Published: April 2003

Redox polyurethanes, polyesters, and alternate copolyurethanes and copolycarbonates from two kinds of benzoquinonyl glycol were prepared based on 2‐(duroquinonyl)‐propan‐1,3‐diol. The oxidized polymer is stable. When the fully reduced polymer in solution is exposed to air the durohydroquinonyl residues are oxidized to the quinone form while the less substituted hydroquinonyl glycol residues remain stable in the reduced form. There is thus prepared polymer with oxidized and reduced groups alternating along the chain.
Effects of substituents on chain‐transfer reactivities of p‐substituted cumenes in radical polymerization of p‐substituted styrenes
Authors: Yamamoto Tadahiro , Otsu Takayuki
Published: April 2003

In order to study the effects of the substituents in both substrate and attacking radical on the chain‐transfer reactivities of nuclear‐substituted cumenes toward substituted polystyryl radicals, the polymerizations of p‐substituted styrenes in the presence of p‐substituted cumenes were carried out with α,α′‐azobisisobutyronitrile as an initiator at 60°C, and their chain‐transfer constants were determined. The relative chain transfer reactivities of p‐substituted cumenes toward given p‐substituted polystyryl radicals did not follow the Hammett equation, but were correlated with the modified Hammett equation, log(k/k0) = pρ + γER, which was proposed by the present authors for evaluating the substituent effects in radical reactions. On the other hand, the relative reactivities of poly‐(p‐substituted styrene) radicals toward given p‐substituted cumenes were correlated by the Hammett equation. Thus, it was concluded that the effects of the substituents in substrate cumene depended upon the contributions of both polar and resonance factors, while those in attacking polystyryl radical depended upon only a polar factor.
Polymerization of β‐cyanopropionaldehyde. IV. Polymerization by the adducts of β‐cyanopropionaldehyde with triethylaluminum
Authors: Kobayashi Kazukiyo , Sumitomo Hiroshi
Published: April 2003

Adducts (X, Y, and Z) between triethylaluminum and β‐cyanopropionaldehyde (CPA) have been prepared and characterized. It was found that an equimolar amount of triethylaluminum undergoes Grignard type addition reaction with aldehyde group of CPA to give aluminum alkoxide and that another equimolar quantity of triethylaluminum undergoes coordination with the nitrile group of CPA (adduct X, in which the molar ratio of CPA to aluminum is 1:2). The coordinated triethylaluminum in adduct X may be changed to aluminum alkoxide by the addition of further equimolar amount of CPA (adduct Y, molar ratio = 1:1); on the other hand, heating at 130°C affords mixtures of aluminum aldimine and aluminum ketenimine structures (adduct Z, molar ratio = 1:2). From the cryoscopic measurement, adduct Z may be regarded as a coordinated polymer joined through bridged structures I and II.
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In the polymerization of CPA at −78°C, the stereoregularity of the resulting poly‐(cyanoethyl)oxymethylene was found to increase in the order: X < triethylaluminum < Y < Z. The polymerizations with triethylaluminum, X, and Y are considered to be initiated by NCCH2CH2CH(C2H5)OAl(C2H5)2. The degree of association of the species may influence the stereoregularity of the polymer.
Syntheses and reactions of functional polymers. XLII. Preparation and use of polymers having N‐hydroxy‐succinimide unit in the chain
Authors: Akiyama Masayasu , Narita Mitsuaki , Okawara Makoto
Published: April 2003

Styrene‐maleic anhydride alternating copolymer was converted to N‐hydroxymaleimide‐styrene copolymer by reaction with hydroxylamine in pyridine at room temperature. The conversion was more than 90%. From this copolymer, N‐acetoxy‐ or N‐benzoyloxymaleimide‐styrene copolymers were derived by action of acetic anhydride or benzoyl chloride in dimethylformamide at room temperature. Acylation of several primary amines was carried out effectively by use of these N‐acyloxyimide‐styrene copolymers. The reaction of the acetylated copolymer with diethylamine at room temperature afforded N‐hydroxyimide copolymer.
Polymerization of β‐cyanopropionaldehyde. V. Anionic polymerization initiated by benzophenone–alkali metal complexes
Authors: Sumitomo Hiroshi , Hashimoto Kazuhiko
Published: April 2003

Anionic polymerization of β‐cyanopropionaldehyde was studied with use of benzophenone‐monosodium, ‐disodium, and ‐dilithium complexes as initiators. The resulting poly(cyanoethyl)oxymethylene was compared with that obtained by cationic and coordinated initiators previously reported. Polymer of higher stereoregularity but lower molecular weight was formed in the present system. The marked influence of the initiator concentration on the polymer yield and stereoregularity is explained on the basis of the difference in the degree of association of the alcoholate ion pair, i.e., the associated ion pair may form stereoregular polymer and the nonassociated or less‐associated ion pair may form a large amount of amorphous atactic polymer. The initiation with benzophenone‐dialkali metal complex was found to be bond‐formation type. Chain transfer with active hydrogen of β‐cyanopropionaldehyde frequently occurs.
Graft polymerization of styrene on lithiated poly(2,6‐dimethyl‐1,4‐phenylene ether)
Authors: Chalk A. J. , Hoogeboom T. J.
Published: April 2003

Styrene has been grafted onto poly(2,6‐dimethyl‐1,4‐phenylene ether) (I) with the use of lithiated I as an initiator. In benzene solution, solvent metalation resulted in some polystyrene homopolymer. In tetrahydrofuran, however, only graft copolymer was formed. By forming a derivative with trimethylchlorosilane and examining by NMR, it was possible to establish the proportion of lithium scavenged by impurities, the amount of polymeric lithium which reacted with styrene, and the amount which did not. The chain length of the grafted polystyrene was also calculated. No crosslinking was found, except where a high ratio of lithium to styrene resulted in some unreacted ring‐metalated polymer. In this case only, reaction with trimethylchlorosilane causes some crosslinking.
Photodegradation of copolymers of methyl methacrylate and methyl acrylate at elevated temperatures
Authors: Grassie N. , Torrance B. J. D. , Colford J. B.
Published: April 2003

Four methyl methacrylate—methyl acrylate copolymers with molar ratios, MMA/MA, of 112/1, 26/1, 7·7/1, and 2/1 have been photodegraded at 170°C by 2537 Å radiation. The changes which occur in the molecular weight of the copolymers are typical of a random scission process and from these and volatilization data the extent of chain scission during the course of the reaction has been calculated. The pattern of volatile products is the same as that previously obtained in the thermal reaction at 300°C although there are a number of differences in detail. For example, only one in ten of the methyl acrylate units is liberated as monomer compared with one in four in the thermal reaction and the ratio CO2/chain scissions is considerably greater than the strict 1/1 ratio observed in the thermal reaction. Zip lengths are also very much greater in the photo reaction. These minor differences between the two reactions have been accounted for in terms of the mechanism previously presented to account for the thermal reaction, bearing in mind the differences in the temperature (170 and 300°C) at which the two investigations were carried out.
Relationship between reduction of ceric ion with poly(vinyl alcohol) and graft copolymerization
Authors: Ogiwara Yoshitaka , Uchiyama Masahiro
Published: April 2003

Various poly(vinyl alcohol) samples were preliminarily subjected to oxidation treatment with sodium hypochlorite, and the reduction of ceric ion and subsequently initiation in the graft copolymerization in the system containing methyl methacrylate were investigated. The reduction behavior of ceric ion could be subdivided into three parts, each of different reaction rate. In the initial stage of the reaction, there was observed rapid cleavage of the backbone chain of poly(vinyl alcohol) with ceric salts. The amount A of cleavage was proportional to the amount of ceric ion reduced at the initial fastest rate for various samples of different extents of oxidation; cleavage of 1 mole required ca. 10 moles of reduction of ceric ion. Higher carbonyl contents of the sample caused increased A. Graft polymerization was carried out in the same system with the addition of the monomer. The amounts of grafted chains produced were determined, and approximately one mole of grafted chains was obtained for per mole of cleavage. The copolymer is concluded to be blocklike in structure. The contribution of the carbonyl groups in poly(vinyl alcohol) sample to the initiation of the polymerization should be emphasized.
High‐pressure studies of polymerization in sulfur
Authors: Vezzoli Gary C. , Dachille Frank , Roy Rustum
Published: April 2003

By x‐ray and optical studies of thermally quenched products and by differential thermal analysis under pressure the effect of high pressure on the melting and polymerization of sulfur has been investigated to 31 kb and 500°C. At least four different liquid fields have been identified. DTA experiments indicate that pressure shifts the 159°C polymerization transition first toward higher temperatures and then toward lower temperatures until it finally coincides with the melting point at a pressure of about 0.7 kb. The depolymerization temperature was found by the same technique to increase with increasing pressure up to 0.4 kb. A liquid P—T boundary that may constitute the higher‐pressure extension to the depolymerization transition has been traced up to 7.5 kb and 480°C. A very sharp, practically temperature‐independent reaction in the liquid state has been located at about 9 kb extending from the liquidus to at least the limits of the apparatus at about 450°C. Evidence has been found for a possible second‐order phase transformation extending from about 10 kb at 400°C to the liquidus at approximately 360°C.
Alternating copolymerization of polar vinyl monomers in the presence of zinc chloride. I. Propagation and initiation of the copolymerization of acrylonitrile with styrene copolymer
Authors: Yabumoto Shigeru , Ishii Kiyoshi , Arita Koichiro
Published: April 2003

Copolymerization of acrylonitrile with styrene spontaneously occurred on addition of zinc chloride without addition of any other radical initiator. The composition of the copolymer approached that of strictly alternating copolymer as zinc chloride added to the copolymerization system increased. The significance of the apparent monomer reactivity ratios of this copolymerization system was studied from a kinetic point of view, and it was shown that the monomer sequence distribution is indicated by the apparent monomer reactivity ratios. Further, equations which represent the relation between the apparent monomer reactivity ratios and Q,e values at a given salt concentration were derived. These equations reasonably accounted for the decrease of the apparent monomer reactivity ratios of the copolymerization of acrylonitrile with styrene in the presence of zinc chloride and the behavior of the other acrylonitrile copolymerization systems in the presence of zinc chloride. The initiation step of the spontaneous radical copolymerization of acrylonitrile with styrene in the presence of zinc chloride was explained by a cross‐initiation mechanism.
Radiation‐induced solid‐state polymerization of derivatives of methacrylic acid. II. Postirradiation polymerization of octadecyl methacrylate
Authors: Bowden M. J. , O'Donnell J. H.
Published: April 2003

Octadecyl methacrylate (mpc ≈ 12°C.) polymerized readily in the solid state in the temperature range −30 to +12°C. after gamma irradiation at −196°C. The initial rate of polymerization and the “limiting” conversion increased with radiation dose and temperature. The temperature dependence of the rate corresponded to an “apparent” activation energy of 20 kcal./mole. Difficulties were experienced with polymerization during separation of the polymer from residual monomer, but these were minimized by using low radiation doses and a hot, selective solvent. The maximum conversion achieved was 70%. The polymer was crosslinked, even at low conversions.
Dehydration kinetics and glass transition of poly(acrylic acid)
Authors: Eisenberg A. , Yokoyama T. , Sambalido Emma
Published: April 2003

The kinetics of dehydration and decarboxylation as well as the glass transition temperature as a function of anhydride content were measured for poly(acry1ic acid). It was found that the glass transition of PAA is of the order of 103°C and increases with increasing anhydride content, reaching an extrapolated value of 140°C for the pure linear anhydride. Anhydride formation is a firstsrder reaction, as is also decarboxylation, the latter being much slower than the former. The rate constants are for dehydration, ka = 2.5 × 109 exp {−26000/RT}; for decarboxylation, kd = 2.9 × 108 exp {−27000/RT}. Anhydride formation occurs primarily by an intramolecular process.
Properties of swollen block copolymer elastomers
Authors: Cooper Stuart L.
Published: April 2003

The linear polyester—urethane block copolymer Estane is soluble in solutions having a solubility parameter of about 10.5. In benzene—methanol mixtures having solubility parameters sufficiently above and below 10.5, it is possible to swell this polymer to a quasi‐equilibrium state. For samples swollen to the same swelling ratio, those in the more polar swelling medium display lower tensile properties. This indicates that, although swelling involves solvation of both the associated rubbery polyester and aromatic urethane segments, the aromatic segments function primarily as quasi‐crosslinks which lead to enhanced physical properties. This is in agreement with previous observations on the mechanical properties of the unswollen elastomer.
Anionic graft polymerization of methacrylonitrile on potassium starch alkoxide
Authors: Tahan Menashe , Zilkha Albert
Published: April 2003

The anionic graft polymerization of methacrylonitrile on potassium starch alkoxide in dimethyl sulfoxide was studied. Factors affecting the graft polymerization such as monomer and alkoxide concentrations as well as temperature were investigated. The yield of the graft polymers was found to increase with alkoxide concentration, and it was possible to incorporate all the starch into graft polymer. On increasing the monomer concentration the graft polymer yield increased to a flat maximum. At the higher monomer concentrations, the efficiency of monomer in giving graft polymer decreased due to increased homopolymer formation. The composition of the graft polymers varied with increasing monomer concentration, graft polymers having about 40–65% of grafted starch were obtained. With increasing temperature (10 to 60°C), the yield of graft polymer decreased, there was more homopolymerization, but the amount of starch incorporated in the graft remained constant. The structure of the graft polymers was deduced from hydrolysis of the starch backbone of the graft polymers by dilute mineral acid and the determination of the molecular weights of the grafted side chains, and from oxidation by periodic acid, which showed the extent of grafting at the secondary hydroxyl groups. These results have shown that by anionic graft polymerization it is possible to obtain graft polymers having more densely packed grafted side chains of relatively low molecular weights than those obtained previously by free‐radical graft polymerization.
Dilute solution studies of nitrogen‐substituted polyurethanes
Authors: Beachell H. C. , Buck Jean C. Peterson
Published: April 2003

A high molecular weight linear polyurethane was prepared by the polyaddition of equimolar amounts of ethylene glycol and methylene bis(4‐phenyl isocyanate). Varying amounts of the labile carbamate protons of the polyurethane backbone were substituted by a number of groups of varying length and composition. The resultant grafted or nitrogen‐substituted polyurethanes were then studied viscometrically in both polymer solvent and in a polymer solvent—nonsolvent mixture. The configuration of the nitrogen‐substituted polyurethane was found to be dependent upon the number and length of pendent branches.
Anionic graft polymerization of methyl methacrylate on starch and dextrin
Authors: Cohen Eliahu , Zilkha Albert
Published: April 2003

The anionic graft polymerization of methyl methacrylate on the potassium alkoxide derivative of starch or dextrin in DMSO was studied. The effects of monomer and alkoxide concentrations as well as temperature were investigated. The yield of graft polymer increased with increasing alkoxide concentration. With increasing monomer concentration and with increasing temperature the extent of homopolymer formation increased. The composition of the graft polymers was found to depend on the reaction conditions. Graft polymers having about 10–40% poly(methyl methacrylate) were obtained. There were quantitative differences in yield of isolated graft polymer between starch and dextrin and these were ascribed to differences in the solubility properties of the carbohydrates. Evidence on the structure of the graft polymers and on the mechanism of the graft polymerization was obtained from acid hydrolysis of the graft polymers and determination of the molecular weights of the cleaved side chains.
Properties of PVC. I. Properties of PVC films prepared by casting and by precipitation
Authors: Maláč Jiří , Šimu̇nková Eva , Zelinger Jiří
Published: April 2003

This investigation compares the properties of PVC films prepared both by casting from tetrahydrofuran solution and from samples obtained by precipitation with properties of samples from the original PVC. The differences in properties are explained on the basis of solvent residues remaining in the samples even after tempering at higher temperatures and after extremely long times of drying. Attention was given to the difficulties caused by this fact, namely, in observing the influence of molecular weight and of distribution of molecular weights of fractions on PVC properties. Reasons were given for the retention of the tetrahydrofuran by PVC.
Sulfur modification of polyethylene surfaces. II. Modification of polyethylene surfaces with fuming sulfuric acid
Authors: Olsen Douglas A. , Osteraas A. Jean
Published: April 2003

Previous work has shown that atomic sulfur irreversibility modifies polyethylene, presumably through an insertion reaction into carbon—hydrogen bonds with formation of surface thiol groups. The thiol groups were then oxidized to sulfonic acid surface groups, which were further reacted chemically as shown by wettability measurements. In this work the thiol group was bypassed and the surface sulfonic acid groups were obtained by exposing the polyethylene surface directly to fuming sulfuric acid. The sulfonic acid groups were reacted further. Critical surface tension values identical with those in the previous work with atomic sulfur were obtained, thus substantiating the previous work.
Silyl celluloses: A new class of soluble cellulose derivatives
Authors: Klebe J. F. , Finkbeiner H. L.
Published: April 2003

Two general methods for the silylation of cellulose have been developed. Silyl amides undergo silyl—proton exchange reactions with cellulose in polar solvents leading to displacement of 80–90% of the hydroxyl protons by silyl groups. The same products are obtained by reaction of the corresponding chlorosilanes with cellulose in pyridine; however, di‐ and trifunctional impurities present in commercial chlorosilanes have to be removed by scavenging with a carbohydrate in order to avoid crosslinking. Cellulose derivatives with trimethylsilyl, dimethylphenylsilyl, methyldiphenylsilyl, and γ‐cyanopropyldimethylsilyl substituents have been prepared by both methods. The properties of the new soluble polymers are largely dependent on the nature of the silyl substituents. The silyl celluloses exhibit a relatively high degree of hydrolytic stability; methyldiphenylsilyl cellulose is hydrolytically stable even under severe conditions.
Anionic polymerization of cyanoacetylene (propiolnitrile)
Authors: Wallach J. , Manassen J.
Published: April 2003

Cyanoacetylene can be polymerized into linear polymers at low temperatures by anionic initiators. The polymers are brown to black amorphous powders, soluble in polar organic solvents. Their molecular weights are of the order of several thousands and the presence of the acidic acetylenic hydrogen does not seem to be an inhibiting factor in polymerization. Some general features of the polymerization and the products obtained are discussed. It is possible to synthesize copolymers with acrylonitrile, which show spectral and solution properties intermediate between those of the two homopolymers. The difference in structure between the materials obtained after pyrolysis of polyacrylonitrile and polycyanoacetylene is discussed.
Studies on the biaxial stretching of polypropylene film. III. Electron microscopic observation of the one‐step biaxial stretching of isotactic polypropylene spherulites
Authors: Tanaka Hiroshi , Masuko Toru , Homma Keisuke , Okajima Saburo
Published: April 2003

Polypropylene films of various isotacticities and crystallinities were stretched biaxially in one step in air at 140–152°C or polyaxially in poly(ethylene glycol) at 130–160°C, and the morphological changes were studied by electron microscopy (replica). In the initial stage of stretching, with vA = 1.4, the spherulites of one of the films used for the experiment were broken both from the centers and boundaries, and those of another film were broken mainly from the center. This difference in the deformation behavior seems to be characteristic of the film properties and independent of the method of stretching, although the factors involved are still unknown. On further stretching (vA = 22), well annealed spherulites were broken into many small blocklike fragments with unfolded fibrils running among them, particularly at the low stretching temperature (140°C), and fibrillation proceeded at the expense of the residual fragments. In the case of quenched or slightly crystallized material, the fragments were dendritic and divided into finer and finer fibrils on stretching. At elevated temperature, however, even for well annealed spherulites, the deformation behavior resembles that of the quenched material, and at a high degree of stretching the spherulites take on the fibrillar net structure in every case. In films containing a high amount of atactic fraction, radial, tangential, and boundary cracking occurred more easily, and broad fibrils were observed across the cracks.
Grafting acrylic acid monomer to poly‐(vinyl alcohol) and methyl cellulose by ceric ion
Authors: Mukhopadhyay Sailes , Mitra Bhairab Chandra , Palit Santi R.
Published: April 2003

A graft copolymer of acrylic acid on poly(vinyl alcohol) was prepared by use of the ceric ion–polyol redox system in aqueous medium. The graft copolymer obtained was water‐soluble under the specified experimental conditions. The efficiency of grafting was determined by measuring carboxyl group content (as expected from acrylic acid unit) in the copolymer by applying the newly developed reverse dye‐partition technique. The graft copolymer was also characterized by viscosity and solubility measurements. The effect of varying concentration of catalyst, monomer, and grafting time has also been determined.