bluuebunny/crossref_metadata_2025 huggingface dataset:
Crosslinking of gelatin by aqueous peroxydisulfate
Authors: Needles H. L.
Published: April 2003

Aqueous gelatin (5%) is crosslinked in the presence of 0.040–0.020M peroxydisulfate at 70°C., but in 0.40M peroxydisulfate, gelatin initially is crosslinked and then redissolves to give a solution of reduced viscosity. The rate of crosslinking depends on the concentration of peroxydisulfate, the nature of peroxydisulfate's cation, and the pH range of the solution during crosslinking. Addition of silver ion to gelatin–peroxydisulfate solutions increases the rate of crosslinking, whereas addition of hydroquinone inhibits crosslinking. Further, induced decomposition of peroxydisulfate is observed in the presence of gelatin. Acetylated and esterified gelatins are crosslinked by aqueous peroxydisulfate, but the ability of deaminated gelatin to crosslink is greatly reduced. Crosslinking is believed to proceed via sulfate and hydroxyl free‐radical attack of gelatin, with in situ generation of reactive intermediates that crosslink with other reactive sites in gelatin. Possible sites of crosslinking in gelatin have been suggested in light of viscosity data, chemical and amino acid analyses, and peroxydisulfate's known mode of decomposition.
Synthesis of polyamides by the polyaddition of bissuccinimides with diamines
Authors: Kagiya Tsutomu , Izu Masatsugu , Matsuda Takehisa , Fukui Kenichi
Published: April 2003

Polyamides which contain succinamide units, NHCO(CH2)2CONH were prepared by the ring‐opening polyaddition of bissuccinimides with diamines at 200°C. in bulk. Nylon 24 and nylon 64 were prepared by the reaction of N,N′‐ethylenedisuccinimide with ethylenediamine and of N,N′‐hexamethylenedisuccinimide with hexamethylenediamine, respectively. It was suggested that the transamidation reaction by aminolysis influenced the detailed structures of the polymers prepared from N,N′‐ethylenedisuccinimide and hexamethylenediamine and from N,N′‐hexamethylenedisuccinimide and ethylenediamine. The detailed structures of the polymers are discussed on the basis of their melting points and x‐ray diagrams. It is concluded that the polymers contain a crystalline portion of \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--}[{\rm NH \hbox{--} (CH}_2 {\rm)}_{\rm 2} {\rm \hbox{--} NHCO \hbox{--}}({\rm CH}_2)_2 {\rm \hbox{--} CONH \hbox{--}}({\rm CH}_2)_6 {\rm \hbox{--} NHCO \hbox{--}}({\rm CH}_2)_2 {\rm \hbox{--} CO\rlap{---}]} $\end{document} sequences.
Isotactic sequence lengths by ozonation of poly(propylene oxide)
Authors: Price Charles C. , Tumolo Anthony L.
Published: April 2003

Ozonation followed by lithium aluminum hydride reduction cleaved high molecular weight isotactic poly(propylene oxide) to crystalline polyglycols. From the melting point and molecular weight of the latter, the molar freezing point depression produced by end groups is found to be ca. 18°C./mole, as compared to that estimated for poly(ethylene glycols), Kf = 12°C./mole, from earlier data. By assuming syndiotactic placements (or other irregularities) would produce the same molar depression, the melting point of isotactic poly(propylene oxides) produced by various catalysts has been used to estimate the isotactic sequence lengths.
The initiation process in the polymerization of tetrahydrofuran with carbonium ion salts
Authors: Kuntz Irving
Published: April 2003

The initiation process for the polymerization of tetrahydrofuran with (C6H5)3C+SbCl6− has been studied. Two mechanisms have been considered: a cation‐addition process, and a process in which tetrahydrofuran donates a hydride ion to the cation of the initiator to form triphenylmethane. The biscarbonium salt [(C6H5)2C+C6H4CH2]2(SbCl6−)2 has been synthesized and used to initiate the polymerization of tetrahydrofuran. The results are consistent with the hydride‐ion mechanism but may be inconclusive because of chain transfer. NMR experiments with 0.05–0.2M solutions of initiator in tetrahydrofuran show that triphenylmethane is rapidly produced in an amount equal to the molar amount of initiator originally present. Some NMR evidence for the presence of an acetal end group in the polymer has been obtained. It is concluded that the initiation process in this system definitely involves the formation of triphenylmethane, although a detailed, unique mechanism cannot be selected at this time.
Influence of preparative conditions on molecular weight and stereoregularity distributions of polypropylene
Authors: Combs R. L. , Slonaker D. F. , Joyner F. B. , Coover H. W.
Published: April 2003

The influence of preparative conditions on the molecular weight and stereoregularity distributions of polypropylene was investigated. The stereoregularity distribution is narrowed by using a highly stereospecific catalyst, by decreasing the polymerization temperature, and for the three‐component catalyst by keeping the mole proportion of the electron‐donating third component at 0.5. The molecular weight distribution can be narrowed by using a highly stereospecific catalyst, a high monomer concentration, and a high polymerization temperature, and by having a lower conversion, particularly at low monomer concentration. The possibility of long‐chain branching in polypropylene was indicated by data from the fractionation of tritium‐labeled polymers.
Course of the terpolymerization of ethylene, propylene, and dicyclopentadiene. II. Two‐step addition of dicyclopentadiene
Authors: Cunningham Robert E.
Published: April 2003

Terpolymerizations of ethylene, propylene, and dicyclopentadiene were carried out in which the dicyclopentadiene was added to the reaction system in two equal portions at the beginning and midpoint of each run, while the monoolefins were added continuously. In the resultant elastomers, unsaturation remains much more constant throughout the course of the polymerization than for terpolymers obtained when all dicyclopentadiene is added at the start of the reaction. Yield and molecular weight of the terpolymers produced by either technique are quite comparable, however. With VCl4 catalyst (with Al2Et3Cl3 cocatalyst) in heptane solvent, the two‐step addition of the diene gave terpolymers with little gel, in contrast to the high gel in terpolymers formed with the single initial addition of the diene. This system also produced terpolymer with the highest final unsaturation and molecular weight. Catalysts of VCl4, VOCl3, or V(C5H7O2)3 in benzene gave terpolymers of moderate unsaturations and molecular weights.
Electron spin resonance study of irradiated monomer and polymer of 3,3‐bis(chloromethyl)oxetane
Authors: Tsuji Kozo , Iwamoto Takeo , Hayashi Koichiro , Yoshida Hiroshi
Published: April 2003

ESR spectra were studied for irradiated 3,3‐bis(chloromethyl)oxetane (BCMO) single crystals and poly‐BCMO obtained by polymerizing BCMO single crystals in solid state. In both cases, the spectra consist of the superposition of two‐line and threeline components at −196°C. On warming the sample, only the former survived. From the examination of hyperfine coupling tensors, it is concluded that the two‐line spectrum is due to the free radicals
magnified image
for the monomer and C(CH2Cl)2ĊHO for the polymer sample, respectively. The orientation of the free radicals gives information about the mode of ring opening in the solid‐state polymerization of BCMO.
Preparation and polymerization of some vinyl monomers containing the 1,3‐dioxolane group
Authors: D'Alelio G. F. , Caiola R. J.
Published: April 2003

The synthesis and structure determinations of (2,2‐dimethyl‐1,3‐dioxolan‐4‐yl)‐methyl acrylate, 4‐(2,2‐dimethyl‐1,3‐dioxolan‐4‐yl)methyl itaconate, and [(2,2‐dimethyl‐1,3‐dioxolan‐4‐yl)methyl] methyl fumarate are described. Reactivity ratios in the copolymerization of these monomers with other comonomers are reported and the Alfrey‐Price Q and e values calculated. The post‐polymerization study of the effects of ultraviolet light and heat on these polymers and copolymers is presented. The 1,3‐dioxolane group when appended to the polymer chain performs as an internal ultraviolet sensitizer. A mechanism is offered to explain the crosslinking behavior of these polymers when treated with ultraviolet light.
Linear polymers of allyl acrylate and allyl methacrylate
Authors: D'Alelio G. F. , Hoffend T. R.
Published: April 2003

Allyl acrylate and allyl methacrylate were polymerized by anionic initiators to soluble linear polymers containing allyl groups in the pendant side chains. The pendant unpolymerized allyl groups of the resulting linear poly(allyl acrylates) were shown to be present by: (1) the disappearance of the acrylyl and methacrylyl double bond absorptions in the infrared spectra in the conversions of monomers to polymers; (2) postbromination of the allyl bonds in the linear polymer; (3) the disappearance of the allyl groups absorptions in the infrared spectra of the brominated linear polymers; and (4) the thermal‐ and radical‐initiated crosslinking of the linear polymers through the allyl groups. Allyl acrylate and allyl methacrylate show great reluctance to copolymerize with styrene under anionic initiation, but copolymerize readily with methyl methacrylate and acrylonitrile. Block copolymers were prepared by reacting allyl methacrylate with preformed polystyrene and poly(methyl methacrylate) anions. The linear polymers and copolymers of allyl acrylate may be classified as “self‐reactive” polymers which yield thermosetting polymers. Bromination of the linear polymers offers a convenient method of producing self‐extinguishing polymers.
Synthesis of an arylene/alkylene polyether from diphenolic acid and rosenmund reduction to the polyether aldehyde
Authors: Fitch Robert M. , Chow Carl Da
Published: April 2003

The Williamson ether synthesis has been applied to the formation of an arylene/alkylene polyether with pendant carboxyl groups from 4,4‐bis(p‐hydroxyphenyl)pentanoic acid and 1,4‐dichlorobutane. The polymer was found to have a viscosity—molecular weight relationship following the equation, [η] = 1.30 × 10−4M0.94, in dimethylformamide at 25°C. Hydrogenolysis of the derived polyether acid chloride was found to proceed smoothly at atmospheric pressure in the presence of Pd–BaSO4 catalyst without poisoning of the catalyst by multiple absorption of polymer. The resulting polyether aldehyde undergoes typical aldehyde reactions. The infrared spectra of the polymers are also examined.
Photolysis of poly(ethylene terephthalate)
Authors: Marcotte F. B. , Campbell D. , Cleaveland J. A. , Turner D. T.
Published: April 2003

The photolysis of poly(ethylene terephthalate) films was studied in vacuo with light of wavelengths 2537 and 3130 A. A very stable filter system which cuts out the 3025 A. line was developed to isolate 3130 A. from a mercury spectrum. Despite the fact that the penetration of 2537 A. light was limited to a depth of a ca. 103 A. whereas 3130 A. light was more uniformly absorbed it was possible to demonstrate that the quantum yields for CO and CO2 formation were in agreement for the two wavelengths. Quantum yields for fractures and crosslinks were estimated by sol‐gel analysis. An absorption maximum which develops near 13 μ after exposure of poly(ethylene terephthalate) to light or γ‐rays was attributed to the formation of groups formed by elimination of CO and CO2. ESR spectra for trapped radicals were tentatively assigned to the components p‐C6H3· and ·OCH2CH2. It is suggested that the former radicals combine to form crosslinks. Quantum yields (× 104) with 3130 A. light are: CO, 6; CO2, 2; crosslinks, 5.5; trapped radicals, 1.5; With 2537 A. light, quantum yields are: CO, 6–9; CO2, 2–3; the network formed was not characterized as to crosslinks and fractures; trapped radicals were observed to exist but not determined.
Cyclo‐ and cyclized diene polymers. XIII. γ‐Ray‐initiated polymerization of 1,3‐dienes
Authors: S̆těpán Václav , Vodehnal Josef , Kössler Ivo , Gaylord Norman G.
Published: April 2003

The γ‐ray‐initiated polymerization of butadiene, isoprene, and 2,3‐dimethylbutadiene‐1,3 was carried out at temperatures of 20°C. and −78°C. Polymers of butadiene and isoprene with mixed linear and cyclic structure were proved to result from the polymerization at −78°C. A monocyclic structure was found for the 2,3‐dimethylbutadiene‐1,3 polymers initiated either at −78°C. or in the thiourea canal complex at 20°C.
Synthesis and evaluation of a series of regular polyampholytes
Authors: Neufeld C. H. H. , Marvel C. S.
Published: April 2003

A series of three true polyampholytes with unequivocally alternating acidic and basic groups attached directly to the skeletal backbone of the polymer chain have been prepared. This was accomplished by copolymerizing 3,6‐diallyl‐2‐piperidone with the α,ω‐dithiols containing 2‐, 4‐, and 6‐methylene groups. The polymerization was carried out in an emulsion system initiated by 2,2′‐azobisisobutyronitrile (AIBN), yielding soluble piperidone‐containing polymers with molecular weights in the 20,000–30,000 range. The piperidone rings in the polymers were hydrolyzed by dilute sulfuric acid to yield the desired polyampholytes. Fibers were prepared by wet‐spinning formic acid solutions of the polyampholyte into saturated salt solution or by melt‐spinning. These fibers were quite elastic. We were unsuccessful in demonstrating that mechanical energy could be attained by the effect of pH on the fibers. Similarly, no pH effect could be elicited in Instron tests. The stress‐relaxation curve showed a marked positive force–temperature effect characteristic of rubberlike materials with few crosslinks. In a check of transition temperatures, it was noted that on repeated runs the second‐order transition temperature rose markedly, suggesting an irreversible change. Viscometric studies clearly demonstrated polyelectrolyte behavior. X‐ray diffraction studies of the polyampholytes showed that maximum crystallinity and orientation occurred in the polymer containing as part of the repeating unit the 1,4‐butane dithiol moiety.
Aromatic polysulfonamides
Authors: Arnold F. E. , Cantor S. , Marvel C. S.
Published: April 2003

Aromatic polysulfonamides have been prepared by solution polycondensation of aromatic disulfonyl chlorides and aromatic diamines with a suitable acid acceptor in such solvents as N,N‐dimethylacetamide and tetramethylenesulfone. The highest molecular weight polymers were obtained by using 2,6‐dimethylpyridine as the acid acceptor in tetramethylenesulfone as the solvent. Clear, translucent, brittle films of the polysulfonamides may be formed from solution or from melt.
Stereospecific polymerization of methacrylonitrile. I. Characterization of crystalline polymethacrylonitrile
Authors: Joh Yasushi , Kotake Yahide , Yoshihara Toshio , Ide Fumio , Nakatsuka Kazuo
Published: April 2003

Methacrylonitrile (MAN) was polymerized with diethylmagnesium. Acetone‐insoluble portions of the polymers are found to be crystalline. Highly crystalline portions can be isolated by further extraction of the acetone‐insoluble parts with dimethylformamide (DMF). A film of DMF‐insoluble fraction can be oriented uniaxially by hot‐press rolling. The crystalline PMAN is insoluble in the usual solvents for amorphous PMAN because of their crystallinity and is easily soluble in CF3COOH or Cl2CHCOOH. The viscosity–molecular weight relationship was determined in Cl2CHCOOH at 30°C. as [η] = 3.24 × 10−3M0.520. We found several crystalline bands in the infrared spectra, for example, at 1192 and 885 cm.−1. Formation of the carbonyl group in the polymer is discussed, and it is concluded that it may be formed by the hydrolysis of conjugated cyclic imine or hydrolysis of the nitrile group in the polymer to acid amide.
Uranyl ion‐sensitized polymerization of acrylamide and methacrylamide in aqueous solution
Authors: Venkatarao K. , Santappa M.
Published: April 2003

The kinetics of polymerization of the vinyl monomers, acrylamide and methacrylamide, photosensitized by uranyl ions in homogeneous aqueous acid medium was studied systematically. Monochromatic radiation of wavelengths 365, 405, and 436 mμ was used for irradiation. Uranyl perchlorate in aqueous perchloric acid (pH = 0–2) was used as the sensitizer to ensure that only uncomplexed UO22+ ions existed in the solution. Polymerization was found to proceed without any induction period, the steady state being attained in about 10–20 min., and was followed by the measurement of the rate of monomer disappearance by bromine addition method. The chain lengths of the polymers were determined by viscometry. It was observed that there was no change in the initiator concentration, [UO22+], during polymerization. The dependence of the rate of polymerization on variables like light intensity, light absorption fraction by the active species, wavelength, monomer concentration, hydrogen ion concentration, temperature, nature of the acid used (HClO4 and H2SO4), viscosity of the medium etc., were studied. A kinetic reaction scheme is proposed and discussed in the light of the experimental results. Certain rate parameters were calculated. The mechanism of photosensitization by uranyl ions with specific reference to primary photochemical act, initiation of polymerization etc., are discussed.
Conformation of polyesters adsorbed on solid surfaces
Authors: Peyser Paul , Tutas Daniel J. , Stromberg Robert R.
Published: April 2003

The conformation of a polyester, poly(ethylene o‐phthalate), of relatively low molecular weight was studied after adsorption. The extension of the adsorbed molecule in a poor solvent on several planar metal surfaces was studied by ellipsometry and the fraction p of attached groups on colloidal silica particles in a good solvent was determined by the shift in the infrared absorption frequency between free and adsorbed carbonyl groups. In contrast to previously reported results for polystyrene, the extension normal to the surface remained constant (∼70 A.) while the concentration of polymer in the adsorbed film increased during the adsorption period. The value of p (0.34 for MW = 5400) is relatively high and was independent of surface population for the range of solution concentrations measured. Differences between these results and those for polystyrene are interpreted as resulting from differences in interaction energy and chain stiffness.
Synthesis of polyaryloxysilanes by melt‐polymerizing dianilino‐ and diphenoxysilanes with aromatic diols
Authors: Dunnavant W. R. , Markle R. A. , Stickney P. B. , Curry J. E. , Byrd J. D.
Published: April 2003

A series of polyaryloxysilanes was prepared from aromatic diols and dianilino‐ and diphenoxysilanes. High molecular weight polymers were obtained at temperatures of 200°C. or higher by using melt‐polymerization procedures. The polymers, which combine the structures of silicones and polyaromatics, possessed high thermal stabilities and were obtained as materials which (1) failed to melt or soften at 350°C., (2) were gumlike at elevated temperatures, or (3) were soluble, film‐ and fiber‐forming polymers capable of being processed as conventional thermoplastics and having potentially useful mechanical properties. The preparation of monomers, general polymerization procedures, and certain structure‐property relationships for the thermoplastic polyaryloxysilanes are considered.
Chemical modifications of polycyclopentadiene
Authors: Meyersen Klaus , Wang Jean Y. C.
Published: April 2003

Polycyclopentadiene, which is known to undergo extremely fast autoxidation resulting in insoluble products, was chemically modified, leading to derivatives no longer sensitive to oxygen. Soluble and stable products can be obtained in high conversions by Diels‐Alder addition of hexachlorocyclopentadiene (96.5 mole‐%), by epoxidation (93.5 mole‐%), and by addition of thioglycolic acid (97.9 mole‐%). A prerequisite is an efficient purification of polycyclopentadiene via reprecipitations in an oxygen‐free atmosphere. Other attempted alterations of the double bond were the hydroxyformylation and the free‐radical addition of haloalkanes, which, however, resulted in completely insoluble products. Typical addition reactions were carried out with the epoxy derivative of polycyclopentadiene, e.g., additions of hydrogen chloride, monochloracetic acid, chlorophenol, thiophenol, piperidine, hydrolysis to glycols. Easily initiated polymerization of the epoxy group is believed to be a conversion‐limiting side reaction in certain addition reactions, such as addition of hydrochloric acid or hydrolysis to glycols.
Role of heterogeneous Cr(AcAc)3–AlEt3 catalyst system in isoprene polymerization
Authors: Deshpande A. B. , Subramanian R. V. , Kapur S. L.
Published: April 2003

Polymerization of isoprene in presence of a heterogeneous Ziegler‐type catalyst system, Cr(AcAc)3–AlEt3, has been studied in benzene medium. The rate of polymerization is first‐order with respect to catalyst as well as monomer concentration. The rate studies, activation energy, and polymer microstructures are reported in order to follow the probable mechanism of polymerization.
Effect of temperature and solvents on stereospecific polymerization of vinyl alkyl ethers catalyzed by aluminum sulfate–sulfuric acid complex
Authors: Lal Joginder , McGrath James E. , Trick G. S.
Published: April 2003

The effect of polymerization temperature and solvents was determined on the crystallinity of polymers of vinyl isobutyl ether and of vinyl n‐butyl ether prepared with aluminum sulfate–sulfuric acid complex catalyst. Principally, the methyl ethyl ketone (MEK)‐insoluble fractions of these polymers were used for characterization. Density, per cent crystallinity by x‐ray diffraction, infrared ratio, and dilatometric volume contraction of these polymer fractions were used as criteria of crystallinity. The MEK‐insoluble fractions of poly(vinyl n‐butyl ethers) prepared in carbon disulfide in the temperature range of −30 to +25°C did not show any significant difference in the values of the above crystallinity parameters. The polymer obtained at 50°C. was less crystalline than the rest of the polymers. The MEK‐insoluble fractions of poly(vinyl isobutyl ethers) prepared at 0–50°C. in carbon disulfide and n‐heptane solvents also did not significantly differ in their degree of crystallinity. They were, however, decidedly less crystalline than the MEK‐insoluble fractions of the corresponding polymers obtained at −20°C. These data a indicate that on increasing the temperature of polymerization the crystallinity of the polymers was either unchanged or decreased slightly. The polymerizations of vinyl n‐butyl ether and vinyl isobutyl ethers were also carried out in binary mixtures of carbon disulfide with n‐heptane, chlorobenzene, and MEK. Generally, increasing the concentration of carbon disulfide increased the inherent viscosities of polymers as well as the weight percentage of their MEK‐insoluble fractions. The MEK‐insoluble fraction of poly(vinyl isobutyl ether) prepared in carbon disulfide‐MEK mixture (volume ratio 2:1) was isotactic and highly crystalline. Likewise, the MEK‐insoluble fractions of two polymers of vinyl n‐butyl ether prepared in MEK itself were also isotactic and highly crystalline. Compared to poly(tetramethylene oxide), these latter fractions exhibited less dependence of rate of crystallization upon temperature. Consequently, at low degrees of supercooling they crystallize much more rapidly than does poly(tetramethylene oxide).
NMR studies on the stereospecific polymerization of methyl vinyl ether. Part I. Polymerization by metal halides: Penultimate effect
Authors: Ohsumi Y. , Higashimura T. , Okamura S.
Published: April 2003

Methyl vinyl ether (MVE) was polymerized under various conditions by BF3·O(C2H5)2 and SnCl4·CCl3CO2H catalysts. The effect of polymerization conditions on the steric structure of poly(methyl vinyl ether) (PMVE) was studied by NMR spectra. It was found that the triad isotacticity of PMVE decreased and the syndiotacticity and heterotacticity increased with increasing polarity of the solvent and increasing polymerization temperature. This result coincided with the qualitative conclusion estimated from softening point and infrared spectra. However, the variation of tacticity by the change of the polarity of a solvent was not so large as expected. There was no large difference between the behavior of BF3·O(C2H5)2 and SnCl4·CCl3CO2H as catalysts. From the relation between the difference of free energy of monomer addition due to the steric structure of the polymer and the polymerization temperature, it was concluded that the penultimate effect really existed and was due to only the difference in enthalpy in the MVE–BF3. O(C2H5)2 or MVE–SnCl4·CCl3CO2H systems. The penultimate effect was not greatly changed by the polymerization conditions in these systems.
NMR studies on the stereospecific polymerization of methyl vinyl ether. Part II. Polymerization by sulfuric acid–aluminum sulfate complex: Enantiomorphic catalyst sites model
Authors: Higashimura T. , Ohsumi Y. , Kuroda K. , Okamura S.
Published: April 2003

Highly crystalline poly(methyl vinyl ether) (PMVE) was produced in toluene in a temperature range of 0 to −20°C. with the use of sulfuric acid–aluminum sulfate complex (SA catalyst). It was found from the NMR spectra that these polymers contained more than 50% of the triad isotactic fraction and the melting point of the unfractionated polymer was about 130°C. However, PMVE containing a large amount of the isotactic fraction was insoluble in nitromethane, so the triad tacticity of highly crystalline PMVE could not be quantitatively determined. The molecular weight of PMVE increased with increasing conversion and increasing polymerization temperature. This behavior is different from that in metal halide catalysts. Also, the stereoregularity of PMVE decreased with increasing monomer concentration. However, addition of a polar solvent and increasing the polymerization temperature had little effect on the stereoregularity of the polymer. The increase in the isotactic fraction at high catalyst concentration and the difference in the monomer composition in the copolymerization of methyl vinyl ether with 2‐chloroethyl vinyl ether by SA catalyst from that obtained by BF3·O(C2H5)2 suggest that the absorption of MVE on a catalyst surface is an important step in the propagation step by SA catalyst. The fraction of the triad tacticity calculated from the enantiomorphic catalyst sites model8 coincided with the experimental results. This fact shows that the steric structure of the adding monomer is determined only by the nature of the catalyst irrespective of the nature of a growing chain end. It is concluded, on considering also the results of the previous paper, that completely different factors can control the steric structure of a polymer even for the same monomer when different catalysts are used.
Pulse radiolysis studies of styrene
Authors: Metz D. J. , Potter R. C. , Thomas J. K.
Published: April 2003

We have applied the pulse radiolysis technique of studying short‐lived, radiation‐produced intermediates to a study of pure, dry liquid styrene. We have observed at least three distinct species. The most rapidly decaying species (τ1/2 = 4 μsec., λmax ≈ 370 mμ) exhibits an apparent first‐order decay which is slowed down in the presence of dry oxygen, occurs too rapidly to be measured in the presence of water, and has a temperature coefficient of approximately 1 kcal./mole between 25 and 45°C. We have tentatively identified the species as the styryl anion with a G value for formation of approximately 0.15. A second species (τ1/2 = 220 μsec. λmax ≈ 320–330 mμ) exhibits a first‐order decay which appears to be independent of oxygen and water. From its spectrum, we have tentatively identified it as the styryl radical. The third species (λmax ≈ 310 and 320 mμ) is relatively stable in the dark, but is radily photolyzed by the analyzing light of the usual experimental set‐up for pulse radiolysis studies. The formation of this species appears to be independent of the water and oxygen content of the styrene.
Polymerization of β‐isovalerolactone
Authors: Ciaperoni A. , Gechele G. B. , Mariani L.
Published: April 2003

The polymerization of β,β′‐dimethyl‐β‐propiolactone with various catalysts was investigated. A detailed study on the heterogeneous polymerization initiated by triethyl aluminum was carried out. A reaction mechanism is suggested on the basis of chemical analysis of the polymer.
Polymerization of aromatic nuclei. XII. Oligomerization of halobenzenes by aluminum chloride‐cupric chloride
Authors: Kovacic Peter , Uchic John T. , Hsu Li‐Chen
Published: April 2003

Polymerization of chloro‐ and fluorobenzene by aluminum chloride‐cupric chloride produced highly colored oligomers. Chlorobenzene reacted under the standard conditions, i.e., 6/1/0.5 (molar ratio) of aromatic/catalyst/oxidant at 60°C. for 1 hr., to give a red solid in 14% yield. Evidence concerning the structure was obtained from elemental analyses, infrared and ultraviolet spectra, dechlorination, oxidation, solubility, molecular weight, and color. The data indicate that the backbone chain consists of an o‐polyphenyl structure with chlorine atoms situated at the 4‐positions. Polynuclear regions presumably comprise part of the structure. Molecular weight data pointed to an average of 10–12 units per chain. The coupled product from fluorobenzene was very similar to the chlorobenzene oligomer in most respects. In contrast to the chlorobenzene case, there was evidence of propagation occurring to some extent by attack ortho to the fluorine. Bromobenzene produced brominated p‐polyphenyl apparently by disproportionation to benzene which then functioned as the monomer. An oxidative cationic mechanism (σ polymerization) is proposed for the nuclear coupling.
Polybenzimidazoles. VI. Polybenzimidazoles containing aryl sulfone linkages
Authors: Narayan T. V. Lakshmi , Marvel C. S.
Published: April 2003

Four new polybenzimidazoles with aryl sulfone linkages between the recurring units have been prepared in order to study their thermal stability and solubility properties. The polymers prepared were high molecular weight materials with good thermal stability.
Synthesis of polyamides by the polyaddition of bisimidazoline with dicarboxylic acids
Authors: Kagiya Tsutomu , Izu Masatsugu , Hatta Masakazu , Matsuda Takehisa , Fukui Kenichi
Published: April 2003

N,N′‐Dipropionylethylenediamine was synthesized by the ring‐opening addition reaction of 2‐ethyl‐2‐imidazoline with propionic acid at 220°C. By applying this reaction to polymerization, polyamides were synthesized by the ring‐opening polyaddition reaction at 220°C. of 1,4‐bis(imidazoline‐2‐yl)butane with adipic acid, succinic acid, sebacic acid, and terephthalic acid. The reaction product of 1,4‐bis(imidazoline‐2‐yl)butane with adipic acid, which was proposed to be nylon 26, was compared with an authentic sample of nylon 26 and shown to possess a very similar infrared spectrum and melting point.
Xylene‐stream method for obtaining thin polyethylene specimens for electron microscopy
Authors: Kubota Katsuya
Published: April 2003

A new technique is described for obtaining thin specimens from melt‐crystallized polyethylene surface for studying the lamellar structure with the electron microscope. The specimen was first backed with carbon–gelatin backing and then the polyethylene side was exposed to a temperature‐controlled xylene stream. After dissolving most of the specimen, a very thin layer of polyethylene which shows certain aspects of the original lamellar structure was obtained. Stereoscopic micrographs revealed the structure of polyethylene consisting of curved layers, concave, convex and other forms. These curved layers were identified by analysis of the Bragg fringes to be the crystalline lamellae. A special pattern resembling a spider in shape caused by a spherical crystal was investigated.
Low molecular weight by‐products in the Ziegler polymerization of higher terminal olefins
Authors: Aubrey D. W. , Barnatt A.
Published: April 2003

For the polymerization of n‐octadecene‐1 with catalysts derived from titanium tetrachloride and triethylaluminum, it has been shown that, in addition to polymerization of the olefin, the formation of isomerized olefin occurs. The latter is predominantly trans‐n‐octadecene‐2 and its formation is favored by increase in Al:Ti mole ratio, in catalyst concentration, and in reaction temperature. It has also been shown that 1,1‐disubstituted ethylene is present in the nonpolymeric reaction products. The influence of added trans‐n‐octadecene‐2 or trans‐n‐octadecene‐7 on the polymerization of n‐octadecene‐1 has been studied, and it is shown that the 2‐isomer has the more pronounced effect on polymer yield and intrinsic viscosity. It has also been shown that no significant copolymerization of terminal with nonterminal octenes or octadecenes occurs under these conditions. Results indicate that, in polymerizations of this kind, the interaction of catalyst with isomerized monomer is probably an important factor in determining polymer yield and molecular weight. The isomerization reaction is also of interest as a general preparative method for trans‐2‐olefins.
Some new polymeric semiconductors
Authors: Paushkin Ya. M. , Vishnyakova T. P. , Nisova S. A. , Lunin A. F. , Omarov O. Yu , Markov Yu. Ya , Machus F. F. , Golubeva I. A. , Polak L. S. , Patalakh I. I. , Stychenko V. A. , Sokolinskaya T. A.
Published: April 2003

This paper deals with some new methods for synthesis of the polymeric semiconductors by conjugated reactions and also with electrophysical properties of the polymers. Elimination of hydrogen halides from α,β‐dihalo derivatives by bases (calcium oxide or tertiary amines) yields polymers with conjugated bonds. The reaction proceeds at 200–300°C. under atmospheric or elevated pressures, acetylenes being the intermediates. α,β‐Dihalo compounds with calcium carbide above 150°C. produce polyacetylenic copolymers by elimination of two moles of hydrogen halide, also by generating acetylene from calcium carbide. The identical reaction (elimination of water) was observed between carbonyl compounds and calcium carbide. Elimination of water from monoand bifunctional phenols in the presence of zinc chloride under pressure above 200°C. yields polyphenylenes and polyhydroxyphenylenes, dehydrobenzene (benzyne) and hydroxybenzyne being intermediates. The polyhydroxyphenylenes prepared have a degree of polymerization from 4–5 to several thousand and are of interest as intermediates for thermostable resins, inhibitors etc. Linear polycyanamide and polycyanic acid were first prepared by polycondensation of urea with ammonium bicarbonate in the presence of zinc chloride. Analogous polymers were obtained from the ring‐opening polymerization of melamine and cyanuric acid. The polymers show good semiconductor and ion‐exchange properties. Polycondensation of ketones with ammonium bicarbonate also gave conjugated polymers. Thus, organometallic polymers were prepared from acetyl‐ and diacetyl ferrocene. We have also studied electrophysical, magnetic, and catalytic properties of the conjugated polymers prepared by the new methods. The electrical conductivity of the best specimens ranged from 10−3 to 10−6 ohm−1 cm.−1; the number of electrons unpaired was 1018–1019 spins/g.
Studies in cyclocopolymerization. III. Copolymerization of divinyl ether with certain nitrogen‐containing alkenes
Authors: Butler George B. , Vanhaeren Gerard , Ramadier Marie Francoise
Published: April 2003

The copolymerization of divinyl ether with fumaronitrile (A), tetracyanoethylene (B), and 4‐vinylpyridine (C) has been studied, azobisisobutyronitrile being used as initiator. The compositions of the copolymers were calculated from their nitrogen and unsaturation content. Over a wide range of initial monomer composition, the mole fraction of A in the copolymers lies in the range 0.55–0.63, and the copolymers contained only 2–3% unsaturation, indicating a high degree of cyclization. The composition of the copolymers of B indicated that cyclization occurred to only a small extent, as the copolymers contained rather high unsaturation content. The values of r1 = 0.23 and r2 = 0.12 were obtained. The mole fraction of C in the copolymers lies between 0.85 and 0.998. If the assumption is made that r1 ⋍ rc ⋍ 0 and there is predominant cyclization, r2 = 32.0 in this case. The difference in the composition of the copolymers is attributed to the difference between the electron density of the double bonds in A, B, and C.
Synthesis of 1,4,5,6,7,7‐hexachloro‐ and hexabromobicyclo‐[2,2,1]‐5‐heptene‐2‐carboxylic acid vinyl esters and copolymerization with acrylonitrile
Authors: Kovacs J. , Marvel C. S.
Published: April 2003

1,4,5,6,7,7‐Hexachloro‐ and hexabromobicyclo‐[2,2,1]‐5‐heptene‐2‐carboxylic acid vinyl esters have been prepared by esterification of the Diels‐Alder addition products of hexachloro‐ and hexabromocyclopentadiene with acrylic acid. These monomers have been copolymerized with acrylonitrile to yield flame‐retardant polymers. Copolymers having a chlorine content up to 18.35% or a bromine content up to 6.35% burn, but copolymers containing 25.0% or more of chlorine or 9.83% or more of bromine do not support combustion.
Grafting of polyacrylonitrile to granular corn starch
Authors: Brockway C. E. , Seaberg P. A.
Published: April 2003

Acrylonitrile grafts readily to granular corn starch in aqueous slurry when initiated by hydrogen peroxide plus activator. Prime evidence for grafting lies in the ease of separating PAN from starch in high yield when the initiator is azobisisobutyronitrile rather than peroxide. Grafting efficiencies are determined by extraction with appropriate solvents: dimethylformamide for homo‐PAN, and boiling water for ungrafted starch. Grafting efficiencies of PAN range from 78 to 95%, M̄n values for grafted PAN are 4,000 to 90,000, and frequency of attachment of side chains range from 300 to 1100 glucose units per chain. Increasing the monomer level, at fixed initiator concentration, tends to result in longer rather than more frequent side chains. AN behaves much as has been previously found for MMA, but the somewhat more efficient grafting at more frequent intervals and the more nearly uniform distribution of polymer in the starch granule suggest that AN penetrates the starch granule more readily than MMA.
Some considerations of the kinetics of the acid hydrolysis of poly‐ and oligosaccharides. Part III. The disaccharides 2‐O‐(α‐D‐glucopyranosyluronic acid)‐D‐xylose, 2‐O‐(4‐O‐methyl‐α‐D‐glucopyrano‐syluronic acid)‐D‐xylose, and 2‐O‐(4‐O‐methyl‐α‐D‐glucopyranosyl)‐D‐xylitol
Authors: Meller Alexander
Published: April 2003

Rate equations have been formulated for the formation and depletion of the hydrolysis product(s) of the title disaccharides. They are based on the assumptions that (1) the rate of acid hydrolysis of the disaccharides is according to first order, and (2) the rate of depletion of the hydrolysis product(s) is constant in the early periods while it approaches first order in the more advanced stages of the reactions. By using experimental rate data from the literature the rate constants of the hydrolysis of the disaccharides and of the depletion of the hydrolysis product(s) have been computed. The validity of the assumptions underlying the rate equations advanced has been confirmed by (a) the agreement between experimental and calculated values and (b) the similar values for the rate constant of the depletion of xylose formed in the hydrolysis of the two biouronic acids. Also discussed are some implications arising from the magnitude of the hydrolysis rate constant of methylaldobiouronic acid and of the depletion rate constant of xylose in relation to complete hydrolysis of polysaccharides.
α,ω‐Glycols from copolymers of isobutylene and 2,5‐dimethyl‐2,4‐hexadiene
Authors: Hecht J. K. , Marvel C. S. , Campbell T. W.
Published: April 2003

Isobutylene has been copolymerized with 2,5‐dimethyl‐2,4‐hexadiene using a boron trifluoride catalyst in petroleum ether solution. Ozonization of the products followed by reduction with lithium aluminum hydride has furnished polyisobutylene glycols in good yield.
Cyclocopolymerization of bicyclopentene and other dicyclic dienes with sulfur dioxide to fused ring systems
Authors: Meyersen Klaus , Wang Jean Y. C.
Published: April 2003

The synthesis and cyclocopolymerization with sulfur dioxide of four 1,5‐ and 1,6‐dienes (bicyclopentene, bicyclohexene, dicyclopentenyl ether, and dicyclohexenyl ether) and one tetraene (quartercyclopentene) is described. Under optimum conditions, completely soluble copolymers are obtained from bicyclopentene in high conversions at temperatures down to −39°C. Bicyclohexene also gave soluble copolymers, but in a by far slower reaction and in low conversion. Quartercyclopentene does copolymerize, but as expected, gives only insoluble polymers. The two compounds with 1,6‐diallyl ether structure, dicyclopentenyl ether and dicyclohexenyl ether, failed to polymerize. The influence of initiator, temperature, reaction medium, diene concentration, etc., on the properties of the polymers was studied in detail for copolymerizations of bicyclopentene. Only a very limited number of peroxides in unusual large quantities was found to be effective in initiating this copolymerization. The reaction is further limited to a narrow choice of solvents, e.g,. diethyl ether and tetrahydrofuran, in order to obtain soluble products. Polymerization could not be achieved in ethanol, benzene, methylene chloride, dimethyl sulfoxide, and tetramethylene sulfone; excess sulfur dioxide yields only dark and insoluble products. Diene concentrations of below 0.3 wt.‐% are normally required to obtain poly(bicyclopentene sulfones) which are soluble in dimethyl sulfoxide, tetramethylene sulfone, or sulfuric acid. Polymerization can be carried out from room temperatures down to −39°C.; optimum results are generally obtained around 0°C. Inherent viscosities of 1.72 (0.5 g./100 ml. dimethyl sulfoxide) have been measured. X‐ray diffractions are those of amorphous polymers.
Kinetics of the solution polymerization of dioxolane in the presence of water
Authors: Kučra Miloslav , Hladký Eduard , Majerová Karla
Published: April 2003

Water acts as a cocatalyst in the polymerization of dioxolane initiated by the ion pair ∼Si⊕HSO4⊖. The dependence of the reaction rate on the water concentration exhibits a maximum, the width of which strongly depends on the concentration of dioxolane. The change of the coordinates of the maximum and its shape with the decrease of the monomer concentration causes the reaction rate to decrease with increasing conversion. The point at which the slope of the conversion curve changes is a function of initial concentration of water. There is a very fast decrease of the concentration of free water in the polymerizing system. The consumption of water is associated with some peculiarities. The amount of free water which remains in the system is a function of the concentration of the original initiator. The ratio [H2O]∞/[initiator] is constant over a rather broad range of initial concentration of water.
Radiation‐induced solid‐state polymerization in binary systems. IV. Solid‐state polymerization in the glassy phase
Authors: Kaetsu Isao , Tsuji Kozo , Hayashi Koichiro , Okamura Seizo
Published: April 2003

The radiation‐induced polymerization of glass‐forming systems containing monomers has been investigated. It was found that irradiation below the second‐order transition temperature Tg of the systems causes no in‐source polymerization but causes a rapid postpolymerization on warming above the Tg after initial irradiation below the Tg. The post‐polymerization was followed by differential thermal analysis and ESR spectra. It is caused above the Tg by the release of peroxy radicals trapped below the Tg, and its rate is proportional to the irradiation dose to some extent, often is explosively high, and brings about a remarkably large temperature rise by accumulation of polymerization heat. Irradiation above the Tg causes rapid in‐source polymerization which is accelerated by the high viscosity of the monomeric system between Tg and Ts (WLF temperature) compared to crystal or ordinary solution polymerization. The temperature dependence of the in‐source polymerization of glassy systems shows a peak between the Tg and Ts which may be the result of competing effects of the rate increase by the decreased termination near Ts and the rate decrease by the decreased propagation caused by the diffusion prevented near the Tg. The degree of polymerization was also investigated. The temperature dependence of the degree of polymerization of the polymers obtained by in‐source polymerization shows a peak similar to that of the temperature dependence of conversion. Unusually large values of the Huggins constant k' are noted between Tg and Ts. The degree of polymerization of the polymer obtained by post‐polymerized increases with the increase of irradiation dose and the polymerization rate; this may be the result of decreased chain transfer to nonpolymerizable components.
Effect of reaction medium on copolymerization of acrylonitrile and methyl acrylate
Authors: Izumi Zenzi , Kitagawa Hideji
Published: April 2003

The copolymerization of acrylonitrile (AN) with methyl acrylate (MEA) has been investigated in three types of polymerization, i.e., emulsion polymerization in water with a water‐soluble initiator, suspension polymerization in water with an oil‐soluble and water‐insoluble initiator, and solution polymerization in dimethyl sulfoxide (DMSO). Monomer reactivity ratios at 50°C. for AN and MEA are found to be r1 = 0.78 ± 0.02, r2 = 1.04 ± 0.02 in emulsion polymerization; r1 = 1.02 ± 0.02, r2 = 0.70 ± 0.02 in DMSO solution polymerization; r1 = 0.75 ± 0.05, r2 = 1.54 ± 0.05 in suspension polymerization. The large differences found in the reactivity ratios may be attributed to the different ratio of concentration of two monomers in the loci of polymerization. Chemically, AN is somewhat more reactive than MEA as shown by the reactivity ratios in DMSO. In the case of the suspension polymerization, the MEA/AN ratio in the polymer particles in which polymerization occurs may be higher than that in the total phase. Experimental results of the emulsion polymerization show that the emulsion polymerization of AN occurs both in the particles and in water. In addition, rates of the copolymerization of AN with MEA have also been investigated.
Reactivity of ester groups on insoluble polymer supports
Authors: Letsinger R. L. , Jerina D. M.
Published: April 2003

A study was made of the comparative rates of reaction of active ester functional groups (p‐nitrophenyl and 2,4‐dinitrophenyl esters) situated on three types of insoluble support polymers and on small, soluble analogs of the polymer molecules. The supports consisted of a styrene—divinylbenzene bead‐type polymer (2% DVB), a styrene—divinylbenzene popcorn polymer (0.2% DVB), and a popcorn polymer with 2,3‐dimethylbutadiene and substituted styrene units in the chain. p‐Nitrophenyl benzoate and 2,4‐dinitrophenyl p‐isopropylbenzoate were used as soluble analogs. Rates of aminolysis by small molecules (2‐aminoethanol and n‐tetradecylamine) in pyridine and of solvolysis in alcohols catalyzed by both small (N‐methylimidazole) and large (polyvinylimidazole) molecules were determined. With the small amines, finely divided particles of popcorn and bead type styrene polymers reacted at about the same rate, which was approximately 1/5 the rate of reaction of the homogeneous analogs. With a high molecular weight reagent, polyvinylimidazole, the heterogeneous reactions were much slower and the popcorn polymer reacted faster than the bead polymer. In catalyzed solvolyses, the styrene popcorn derivative reacted faster in benzyl alcohol and slower in 1‐hexanol than the dimethylbutadiene popcorn polymer derivatives.