bluuebunny/crossref_metadata_2025 huggingface dataset:
Linear polymers of some vinyl monomers containing a terminal acetylenic group
Authors: D'Alelio G. F. , Evers R. C.
Published: April 2003

The synthesis and polymerization of representative acrylic‐type esters containing a terminal acetylene group, CH2C(R)COO(CHR′)mCCH, where R and R′ are H and CH3 and m = 1 or 2, by anionic initiation to linear polymers are described. In contrast, crosslinked polymers were formed when radical and cationic initiators were used. Crosslinked polymers were also obtained with organolithium compounds but not with sodium naphthalene and sodium benzalaniline; this observation is discussed and compared to the behavior of the acetylenic acrylic esters which do not contain a terminal acetylenic hydrogen. The unpolymerized acetylenic bonds in the resulting linear polymers were shown to be present by infrared spectroscopic methods and by the following post‐reactions of these bonds: (1) the heat‐ and radical‐initiated crosslinking of the polymers through the acetylenic bonds; (2) the post‐bromination of the acetylenic bonds; and (3) the reaction of decaborane with the acetylenic bonds. The anionic copolymerization of acrylonitrile and styrene with these acetylenic monomers were performed and compared to the copolymerizations with 1‐acryloxy‐2‐butyne and 1‐methacryloxy‐2‐butyne. Dibromination of the linear polymers affords self‐extinguishing polymers, while decaboronation yields soluble polymers which do not soften up to 300°C. The linear polymers may be classified as “self‐reactive” polymers which yield thermosetting polymers.
Solid‐state polymerization of 1,2,3,4‐diepoxybutane initiated by cobalt‐60 γ‐radiation
Authors: Parrish C. F. , Harmer D. E.
Published: April 2003

The solid‐state polymerization of 1,2,3,4‐diepoxybutane appears to proceed “insource” by an ionic mechanism and has an overall activation energy of 0.4 kcal./mole with an intensity dependency of 0.99. There is a rapid increase in the rate of polymerization just prior to the melting point and a very low rate for the liquid‐phase reaction. Limiting conversions of 5% polymer are observed at −196°C. for irradiation in vacuo. No limiting conversion was observed when the monomer was polymerized in the presence of air or in vacuo at −78°C. Under all polymerization conditions the reactions were characterized by the absence of an induction period.
Copolymerization of styrene. II. Emulsion copolymerization with styrene derivatives containing nitrile groups in the side chain
Authors: Narkis Moshe , Kohn David H.
Published: April 2003

Copolymers of styrene with cinnamonitrile, ethyl benzylidenecyanoacetate, and benzylidenemalononitrile were prepared in emulsion with the use of the redox system potassium persulfate–sodium bisulfite. The kinetics of copolymerization as a function of the composition of monomers, of the concentration of emulsifier and initiators, and of temperature was studied. Copolymers of high molecular weight were obtained in good yields.
Copolymerization of styrene. III. Physical and mechanical properties of copolymers with styrene derivatives containing nitrile groups in the side chain
Authors: Narkis Moshe , Kohn David H.
Published: April 2003

Copolymers of styrene with cinnamonitrile (I), ethyl benzylidenecyanoacetate (II), and benzylidenemalononitrile (III) were prepared in bulk, in suspension, and in emulsion up to high conversion. Their softening points, flexural properties, impact resistance, hardness, and volumetric shrinkage due to polymerization were studied. All three copolymers show improved thermal resistance in comparison to polystyrene, but whereas copolymers styrene–I and styrene–III are inferior to polystyrene in flexural strength and the impact resistance, the copolymer styrene–II is about equal to polystyrene in its flexural properties and impact resistance.
Mechanism of initiation in the γ‐radiation‐induced polymerization of ethylene
Authors: Mitsui Hiroshi , Machi Sueo , Hagiwara Miyuki , Kagiya Tsutomu
Published: April 2003

The relation between the gaseous products and the reaction conditions such as pressure, temperature, and dose rate in the γ‐radiation‐induced polymerization of ethylene was studied. The main gaseous products were hydrogen and acetylene, and the amounts of these products increased linearly with reaction time, monomer density, and dose rate, while they were independent of reaction temperature. The ratio of rate of formation of hydrogen to acetylene was about one‐half. Further, it was found that the number of moles of polymer chain formed was almost equal to that of acetylene at room temperature. An initiation mechanism in which both hydrogen and acetylene are formed is proposed. The equation which is derived on the basis of the initiation mechanism is shown to be in good accordance with the experimental results.
Applications of limiting conversion free‐radical polymerizations. I. tert‐butyl hydroperoxide‐initiated polymerization of styrene in benzene
Authors: Indictor N. , Linder C.
Published: April 2003

Data for the tert‐butyl hydroperoxide‐initiated polymerization of styrene in dilute benzene solution at 126°C. are presented. These data are discussed in terms of Tobolsky's limiting conversion kinetics. Several rate laws are considered. Simple unimolecular decomposition of the peroxide appears to be unimportant under these conditions, as does solvent interaction.
Studies on poly(vinyl chloride). III. The role of the precipitated polymer in the kinetics of polymerization of vinyl chloride
Authors: Cotman John D. , Gonzalez Margaret F. , Claver George C.
Published: April 2003

In polymerization of vinyl chloride monomer, free radicals precipitate on or within aggregates of partially swollen dead polymer. Polymerization on the solid polymer is characterized by autoaccelerating rates due to a progressive reduction in termination rate. This reduction in termination rate is due to the fact that as the reaction progresses and more polymer accumulates there is a decrease in probability that chain transfer of polymer radicals to monomer will generate a mobile radical, which can readily terminate an occluded or stuck free radical. From the appearance of the particles of solid polymer in the system, it has been concluded that free radicals precipitate both on polymer particle surface and inside the open structure of polymer particles.
Linear polymers of vinyl aryl monomers containing another unsaturated group
Authors: D'Alelio G. F. , Hoffend T. R.
Published: April 2003

The synthesis and the anionic polymerization of representative substituted styrenes, CH2CHC6H4R′, where R′ is an ethylenic or acetylenic group attached directly or indirectly to the benzene ring, to linear polymers is described. In contrast, crosslinked polymers were obtained when radical and cationic initiators were used. The unpolymerized, unsaturated bonds in R′ in the resulting linear polymers were shown to be present by infrared spectroscopic methods and by the following post‐reactions of these bonds: (1) the thermal‐ and radical‐initiated crosslinking of the linear polymers through the unsaturated bonds in R′; (2) the post‐bromination of these unsaturated bonds; (3) the post‐copolymerization of these unsaturated bonds with vinyl monomers; and (4) the reaction of decaborane with the acetylenic bonds. The anionic copolymerizations of methyl methacrylate, acrylonitrile, and styrene with these monomers were performed and confirmed their behavior as substituted styrenes. Block copolymerizations with styrene and methyl methacrylate were also performed and the expected results obtained. Post‐bromination of the linear polymers afforded self‐extinguishing polymers. The linear polymers and copolymers may be classified as “self‐reactive” polymers which yield thermosetting polystyrenes.
Preparation and characterization of some cellulose graft copolymers. Part IV. Some properties of isolated cellulose acetate–styrene graft copolymers
Authors: Wellons J. D. , Williams J. L. , Stannett V.
Published: April 2003

A series of purified graft copolymers of cellulose acetate and polystyrene, which were prepared and characterized during the course of an earlier investigation, have been used for some initial property studies. Grafts with high molecular weight backbones and low molecular weight side chains and vice versa, and with both side chains and backbones of high and low molecular weights, were prepared. The graft polymers were found to be insoluble in most solvents but soluble in dimethylformamide and pyridine and in mixtures of solvents for each component. Films cast from mixtures of the grafts and homopolymers showed that the grafts were compatible with the homopolymer of the component with a higher molecular weight. A graft copolymer with high molecular weight backbone and side chains was found to be compatible with both homopolymers separately and with a mixture of both across a wide range of compositions. A blend of the high and low molecular weight grafts was also found to be highly compatible with both homopolymers. The permeability, diffusion, and sorption of gases and water vapor in the grafts and in the corresponding homopolymers was also studied. In the case of water vapor, the sorption in cellulose acetate was much higher than in polystyrene whereas the diffusion was much lower. It was found that the graft polymers showed both diffusion and solution behavior closer to that of cellulose acetate, whereas the permeability constants were more intermediate between those of the two homopolymers. The gas permeability and diffusion constants were found to be intermediate between the values obtained with the two homopolymers.
Polymerization of methyl methacrylate with butyllithium–diethylzinc complex
Authors: L'Abbe G. , Smets G.
Published: April 2003

The low‐temperature polymerization of methyl methacrylate initiated with butyllithium–diethylzinc has been studied in toluene and in toluene–tetrahydrofuran and toluene–dioxane mixtures in various proportions. The polymerization process is typically anionic; it is characterized by a very rapid initiation reaction, and the absence of termination and chain transfer reactions, the molecular weight increasing proportionally with the degree of conversion. With toluene as a solvent, the polymer chains are associated, as is shown by viscometric measurements; moreover the polymers produced are highly polydisperse (Mv/Mn = 5.4). The kinetics are very complicated and vary with the range of the catalyst and monomer concentrations. In pure toluene in the presence of the organometallic complex, butyllithium–diethylzinc, the monomer addition is more stereospecific than when butyllithium alone is used as catalyst. By adding tetrahydrofuran to the reaction mixture, the polymer chain association disappears; concomitantly the stereochemical structure of the polymer changes from an isotactic to a mainly syndiotactic configuration. In toluene–tetrahydrofuran mixtures containing from 1 to 10 vol.‐% tetrahydrofuran, the kinetics of polymerization can easily be interpreted by assuming the presence of two propagating reactive species which are in equilibrium with each other: the ion pair and the THF‐solvated ion pair. The energy of activation of propagation for the free ion pair is equal to 7.5 kcal./mole; for the solvated ion pair a value of 5.5 kcal./mole was found, including the solvation enthalpy of the organometal with tetrahydrofuran. The existence of any relation between the reactivity of the propagating species and the tactic incorporation of the monomeric units has been discussed. The polymerization in mixtures of toluene–dioxane is intermediate between that in pure toluene and that in toluene–HF mixtures; the reaction mechanism however cannot be interpreted with the usual kinetic scheme. The experimental data concerning the rate dependence on catalyst and monomer concentrations are briefly summarized.
Method of calibrating gel permeation chromatography with whole polymers
Authors: Cantow Manfred J. R. , Porter Roger S. , Johnson Julian F.
Published: April 2003

Column systems for gel permeation chromatography are usually calibrated by eluting a series of sharp polymer fractions of known molecular weights and by correlating their elution volumes with molecular size or weight. A different method for calibration is proposed in which only one polymer sample, with a broad, well‐characterized molecular weight distribution, is used. The cumulative distribution and the integrated, normalized GPC chromatogram are successively superimposed, and molecular weights and corresponding elution volumes are correlated. It is found that calibration curves obtained in this manner show a definite curvature. A possible explanation and correction for this behavior is given, based on the concentration dependence of elution volumes.
High‐resolution NMR of crosslinked polymers: Effects of crosslinked density and solvent interaction
Authors: Liu Kang‐Jen , Burlant William
Published: April 2003

Measurements have been made of the dependence of nuclear magnetic resonance bandwidths of polymers on the degree of crosslinking. Poly(methyl methacrylates) and poly(hexadecyl acrylates) were studied. Three regions of behavior are apparent: (1) in lightly crosslinked materials, bandwidths are quite insensitive to the degree of crosslinking, and the networks behave almost as linear polymers in solution; (2) in moderately crosslinked material, bandwidths are significantly affected by the degree of crosslinking; and (3) in highly crosslinked materials, bandwidths are extremely sensitive to crosslink density, and the polymer peaks become so broad that they disappear almost completely. These results indicate that segmental motion of a polymer in solution is not a function solely of its molecular weight, and that a certain degree of crosslinking is required to restrict polymer motion at the segmental level. The solvent (benzene) peak is always a singlet in swollen poly(methyl methacrylate) systems with swelling ratios up to 6.4 (regions 1 and 2, above) but as the swelling ratio further decreases to 3.5 (region 3), the solvent peak splits into a doublet; this phenomenon may indicate the existence of two different arrangements of solvent molecules in the swollen network, for which interchange is not sufficiently rapid to produce a single line.
Cyclocopolymerization of dicyclic dienes and maleic anhydride to fused ring systems
Authors: Meyersen Klaus , Wang Jean Y. C.
Published: April 2003

The cyclocopolymerization of maleic anhydride and four 1,5‐ and 1,6‐dienes (bicyclopentene, bicyclohexene, dicyclopentenyl ether, and dicyclohexenyl ether) and one tetraene (quartercyclopentene) is described. Soluble, low molecular weight copolymers were obtained from all five compounds. Their compositions approach 2:1 copolymer ratios. Fused ring structures are proposed as the main repeating units. Among the compounds listed, bicyclopentene copolymerized most easily and gave good conversions for monomer ratios of 2:1. Quartercyclopentene and dicyclopentyl ether, the other five‐membered ring compounds, also polymerized to good‐to‐fair yields. However, a monomer ratio of about 4:1 was required to obtain conversions comparable to a 2:1 maleic anhydride—bicyclopentene polymerization. The six‐membered systems, bicyclopentene and dicyclopentenyl ether, gave consistently low conversions, even with a 4:1 monomer ratio. The influence of the initiator system, initiator concentration, and reaction medium was studied on copolymerizations of bicyclopentene. Best results were obtained in acetic anhydride with azobisisobutyronitrile as the initiator.
Polyoxazolidones
Authors: Iwakura Yoshio , Nabeya Aiko , Hayano Fusakazu , Kurita Keisuke
Published: April 2003

Polyurethans with chloromethyl side chains were prepared by the polyaddition reaction of bischlorohydrins and diisocyanates. The polyurethans had inherent viscosities in a range of 0.22–0.60 and gave transparent films by solution casting. These polyurethans were easily converted to the polyoxazolidones by treatment with sodium methoxide. The polyoxazolidones had inherent viscosities up to 0.51, and gave transparent films by solution casting.
Effects of metal salts on polymerization. Part IV. Polymerization of N‐vinylcarbazole initiated by oxidizing metal nitrates
Authors: Tazuke Shigeo , Tjoa Tjin Bu , Okamura Seizo
Published: April 2003

The polymerization of N‐vinylcarbazole (VCZ) in ethylene dichloride, acetone, benzene, and dioxane with cupric nitrate, ferric nitrate, and ceric ammonium nitrate as catalyst was studied. In all cases the polymerization seemed to be of a cationic nature, judged by copolymerization with styrene. Electron spin resonance (ESR) spectroscopy was made for the polymerization system and also for a system containing N‐ethylcarbazole instead of VCZ. Singlet ESR spectra were observed for all systems containing ceric salt and for some systems containing ferric salt but not for systems containing cupric salt. The ESR spectra indicated the formation of an ion radical by electron transfer between the oxidizing metal salt and the carbazole derivatives. Mechanisms of initiation other than electron transfer were less likely, and it was concluded that the initiation process was most likely to be of the electron transfer type.
Copolymerization of trioxane with styrene catalyzed by BF3·O(C2H5)2
Authors: Higashimura T. , Tanaka A. , Miki T. , Okamura S.
Published: April 2003

It was determined whether trioxane, a cyclic formal, can copolymerize with styrene, a vinyl monomer, in the presence of BF3·O(C2H5)2 catalyst at 30°C. The methanol‐in‐soluble fraction after extraction with benzene was found to contain the copolymer of styrene and trioxane, thus demonstrating that trioxane can copolymerize with styrene In this case the amount of the methanol‐insoluble polymer was less than that of the total monomer consumed, as determined by gas chromatography. This was found to be caused partly by the formation of the cyclic oligomer, 4‐phenyl‐1,3‐dioxane. The relative reactivity of styrene was qualitatively found to be larger than that of trioxane, not only from the rate of monomer consumption but also from the composition of the methanol‐insoluble polymer obtained. In a nonpolar solvent the reactivity of trioxane increased, and the difference in reactivity between the two monomers decreased. Indeed, an apparent monomer reactivity ratio might be obtained from the relationship between the monomer composition and the monomer consumption rate or the composition of the methanol‐insoluble polymer, but it did not have a quantitative meaning because of the complexity of the copolymerization reaction.
Synthesis of 5(6)‐vinylbenzimidazole and of 2‐vinylbenzimidazole
Authors: Overberger C. G. , Kösters B. , St. Pierre T.
Published: April 2003

The syntheses of 2‐ and 5(6)‐vinylbenzimidazole are described. These compounds were characterized by appropriate chemical reactions and physical properties. Incidental to this work, 3,4‐diaminostyrene was also prepared.
Analysis of polyethylenimine by spectrophotometry of its copper chelate
Authors: Perrine T. D. , Landis W. R.
Published: April 2003

Polyethylenimine (PEI) forms a copper chelate with a N/Cu ratio of about 5 and with extinction coefficients of about 175 at 6350 A. and 4250 at 2694 A. Solutions of PEI‐copper chelate obey Lambert's and Beer's laws and show increased optical density in the presence of chloride ion. Above pH 4.25, hydrogen ion has little effect. A comparison with the copper chelate of polyvinylamine suggests that PEI has a highly, branched structure. Analysis of PEI via its copper chelate is described.
Studies on the polymerization of ethyl acrylate. I. Kinetic studies
Authors: Raghuram P. V. T. , Nandi U. S.
Published: April 2003

Kinetic studies on the polymerization of ethyl acrylate have been carried out and the various rate constants and their corresponding activation energies determined.
Preparation and polymerization of a sugar dithiol
Authors: Whistler Roy L. , Hoffman Daniel J.
Published: April 2003

2,4‐O‐Benzylidene‐1,6‐dithiol‐D‐glucitol is prepared by nucleophilic displacement of tosyloxy groups from 3,5‐di‐O‐acetyl‐2,4‐O‐benzylidene‐1,6‐di‐O‐tosyl‐D‐glucitol with thioacetate in N,N‐dimethylformamide and deacetylation of the product. Oxidative polymerization with oxygen and selenium dioxide produces film‐forming disulfide polymers with intrinsic viscosities up to 0.41. Other oxidizing agents produce polymers of lower viscosity. Condensation of the dithiol with benzaldehyde also gives polymers of low viscosity.
On the thermal behavior of 4‐(o‐carboranyl)‐1‐butylmethyl siloxane–dimethyl siloxane copolymers
Authors: Delman A. D. , Kelly J. J. , Stein A. A. , Simms B. B.
Published: April 2003

Polysiloxanes containing carboranylbutyl and methyl pendant groups were investigated, to determine their resistance to thermal decomposition when heated in air. Results indicate that the copolymers degrade through SiC as well as SiO bond rupture. At 300°C. thermooxidative scission of pendant groups was the predominant reaction. whereas SiO and SiC bond rupture occurred at 500°C. Variations in the behavior of the copolymers studied suggest that the carborane nucleus provides some inhibiting influence on their thermal decomposition. This is mainly attributed to steric hindrance effects rather than polarity factors. Chain extension with tin octoate caused a reduction of thermal stability, probably because of the addition of SnO bonds to the molecules.
Acid‐catalyzed methanolysis of tri‐O‐methylamylose and tri‐O‐methylcellulose
Authors: BeMiller J. N. , Allen Earle E.
Published: April 2003

Past experimental evidence has indicated that the acid‐catalyzed hydrolysis of polysaccharides does not proceed randomly, and it has been suggested that hydrolysis is more rapid for the glycosidic bonds by which the nonreducing endgroups are attached. To test this hypothesis, amylose and cellulose were permethylated and subjected to methanolysis. It was found that in both the methanolysis of tri‐O‐methylamylose and tri‐O‐methylcellulose the production of methyl 2,3,4,6‐tetra‐O‐methyl‐α,β‐D‐glucopyranoside was complete before the production of methyl 2,3,6‐tri‐O‐methyl‐α,β‐D‐glucoside was finished. Since the former compound could only come from the original nonreducing end units and the latter from all other units, these results were interpreted as giving support to the idea of a preferential scission of the bonds at the nonreducing ends, even though the release of original end units was not complete until 70–85% of the glycosidic bonds had been cleaved. It was concluded that methanolysis proceeds by a modification of the hydrolysis mechanism and that methanolysis is therefore a poor model for hydrolysis.
Differential permeation and absorption of water vapor in polyacrylamide film
Authors: Kishimoto Akira , Kitahara Takeru
Published: April 2003

An investigation has been made of successive differential absorption and differential permeation of water vapor in polyacrylamide a t 30°C. The successive differential ab sorptions showed two types of non‐Fickian anomalies: sigmoid type and two‐stage type curves. The experimental data have been analyzed in terms of the Fick diffusion equation assuming a time‐dependent approach of the surface concentration. The calculated family of absorption curves agreed with the experimental results. The permeation curves in the region of high and low pressure increments were apparently normal, but at medium pressures they showed anomalous behavior. It was found that in the differential type of permeation experiment the stress effect induced by a concentration gradient between the surfaces of the film was eliminated. By assuming the time‐dependent approach of the equilibrium surface concentration, we calculated the time lag as a function of film thickness and applied the theory to the data for permeation through polyacrylamide film with different film thicknesses a t relatively small pressure intervals. The rate parameter calculated from permeation data was found to be in good agreement with that from successive differential absorption data.
Stereoregularity of poly(methyl acrylate)
Authors: Matsuzaki Kei , Uryu Toshiyuki , Ishida Akira , Ohki Tatsumi , Takeuchi Makoto
Published: April 2003

The stereoregularity of poly(methyl acrylate) and poly(methyl acrylate‐αd) was determined from the NMR spectra. A method of quantitative determination of stereoregularity of poly(methyl acrylate) proposed in this paper is based on the fact that in the 100 Mc./sec. NMR spectrum the absorption peaks due to methylene protons in syndiotactic configurations overlap absorptions due to only one of two methylene protons in isotactic configurations. The stereostructure of poly(methy1 acrylates) polymerized with anionic catalysts such as Grignard reagents, n‐butyllithium, and LiAlH4 is generally richer in isotactic diads than in syndiotactic diads. For example, poly(methyl acrylate) polymerized with phenylmagnesium bromide as catalyst at −20°C. consists of 99% isotactic and 1% syndiotactic diads. In radical polymerization, the isotacticity of poly(methyl acrylate) is independent of polymerization temperature. Poly(methyl acrylates) polymerized with a Ziegler‐Natta catalyst consisting of Al(C2H5)2Cl and VCl4 have configurations similar to those polymerized by radical initiators. The stereoregularity of poly(methyl acrylate‐α‐d) resembled that of poly(methyl acrylate) polymerized under the same conditions.
Polyethers. I. Polymerization of 2‐methyl‐2‐butene oxide
Authors: Field N. D. , Kieras J. A. , Borcherts A. E.
Published: April 2003

2‐Methyl‐2‐butene oxide (2,3‐epoxy‐2‐methylbutane) was polymerized with modified alkylaluminum initiators a t low temperatures to a high‐melting, crystalline, film‐forming polymer. High yields and comparatively high molecular weights were obtained with Al(i‐Bu)3−xH2O initiators in inert diluents. When such initiators were modified with acetylacetone they became ineffective. Ammonia could be substituted for water in formulating an active initiator. Attempts to prepare an active initiator in the presence of the monomer were unsuccessful indicsting competition with the water for Al(i‐Bu)3. Thermal decomposition of the polymer produced methyl isopropyl ketone with some pivaldehyde.
Mechanism of thermal stabilizers for poly(vinyl chloride). II. Synergistic effect of combination of metal soaps
Authors: Onozuka Mitsuo
Published: April 2003

The esterification of metal soaps, in the combination of zinc and calcium soaps, on poly(vinyl chloride) (PVC) has been carried out both in liquid and solid phase to determine why the reactivity of zinc soap decreases on addition of calcium soap, improving the long‐run heat stability of PVC and causing the well‐known synergism. It is suggested as the mechanism of synergism that metal soaps having low ionization‐potential values, such as calcium soap, act as ester‐exchangers of metal chlorides, such as zinc chloride, which is generated after the stabilization of PVC, and also decrease the reactivity of the zinc soap by forming a complex, as that of zinc soap—calcium soap. If a third material, such as organic ester silane, reacting as ester‐exchanger on zinc chloride and preventing the formation of a zinc—calcium soap complex, is added to the system, these compounds have an excellent synergistic effect.
Aromatic polyhydantoins from bisiminoacetate and diiscyanates
Authors: Imai Yoshio
Published: April 2003

Aromatic polyhydantoins of high molecular weight have been prepared by a polyaddition—cyclocondensation reaction of diethyl m‐phenylenebisiminoacetate with aromatic diisocyanates in m‐cresol. The polyhydantoin obtained from methylenebis(4‐phenyl isocyanate) showed good thermal stability up to 400°C. in air. A transparent and tough film could be cast from a m‐cresol solution of the polymer.
Stereoregular polymerization of 1‐vinylnaphthalene, 2‐vinylnaphthalene, and 4‐vinylbiphenyl
Authors: Heller Jorge , Miller Donald B.
Published: April 2003

1‐Vinylnaphthalene, 2‐vinylnaphthalene, 4‐vinylbiphenyl, and styrene were polymerized with Et3Al–TiCl4, Et2AlCl–TiCl3, and Et3Al–TiCl3 catalyst systems. The latter catalyst system gave polymers in 75–95% conversion which were at least 90% isotactic. Extraction with 2‐butanone (MEK) separated the atactic from the isotactic fractions. The polymers were characterized by infrared and nuclear magnetic resonance spectroscopy.
Cyclopolycondensations. VI. Fully aromatic polybenzoxazinones from aromatic poly(amic acids)
Authors: Yoda Naoya , Ikeda Kojuro , Kurihara Masaru , Tohyama Shunroku , Nakanishi Ryoji
Published: April 2003

New high temperature aromatic polybenzoxazinones of high molecular weight have been prepared by the cyclopolycondensation of 4,4′‐diaminobiphenyl‐3,3′‐dicarboxylic acid (I) with aromatic dicarboxylic acid halides (II). The low temperature solution polymerization techniques afforded poly(amic acid) (III) of high molecular weight in the first step. An open‐chain precursor subsequently underwent thermal cyclodehydration along the polymer chain at 200–350°C. in the second step, to give in quantitative yield a fully aromatic polybenzoxazinone (IV) of outstanding heat stability both in nitrogen and in air. The poly(amic acid) is soluble in N‐methyl‐2‐pyrrolidone, and tough, transparent films can be cast from solution. Insoluble aromatic polybenzoxazinone films which possess excellent oxidative and thermal stability were obtained by the heat treatment of the polyamic acid. A detailed account of polymerization conditions in the low temperature solution polymerization of polybenzoxazinones is given, and the reaction mechanisms of cyclopolycondensation of poly(amic acids) and the formation of polybenzoxazinones are discussed.
The formylation of cellulose
Authors: Heath J. E. , Jeffries R.
Published: April 2003

The reaction between formic acid and disordered cellulose is described. It is shown that a degree of substitution as high as 2.5 can be readily obtained without any catalyst. There is no evidence of any difference between the formylation behavior of this cellulose up to the monoformate level and that beyond this level. Formic acid produces ordered, inaccessible regions in disordered cellulose; this behavior reduces the value of the latter material as a calibration standard in formylation studies and also throws doubt on the basic value of formylation as a method of measuring disorder in cellulose. There is evidence that native celluloses formylate less rapidly per unit amount of hydrogenbond‐disordered material than do regenerated celluloses; this may be associated with the fibrillar nature of the native celluloses.
Solid‐state polymerization studies. I. 2‐vinylnaphthalene post‐polymerization initiated by 60Co γ‐irradiation
Authors: Parrish C. F. , Trinler W. A. , Burton C. K.
Published: April 2003

60Co γ‐irradiated 2‐vinylnaphthalene was obsreved to post‐polymerize in the solid phase. Plots of conversion versus time indicated a 14% limiting conversion of monomer to polymer. The post‐polymerization was found to be first‐order in monomer with an Arrhenius activation energy of 19.0 kcal./mole.
Radical copolymerization of crotonyl compounds with styrene
Authors: Minoura Yuji , Tadokoro Toshio , Suzuki Yasuyuki
Published: April 2003

The monomer reactivity ratios for the radical copolymerization of crotononitrile (CN), methyl crotonate (MC), and n‐propenyl methyl ketone (PMK) with styrene (St) were measured at 60°C. in benzene and little penultimate unit effect was shown for these systems. The values obtained were: St–CN, r1 = 24.0, r2 = 0; St–MC, r1 = 26.0, r2 = 0.01; St–PMK, r1 = 13.7, r2 = 0.01. The rate of copolymerization and the viscosity of the copolymer decreased markedly as the molar fraction of the crotonyl compound in the monomer mixture increased. The Q–e values were also calculated to be as follows: CN, e = 1.13, Q = 0.009; MC, e = 0.36, Q = 0.015; PMK, e = 0.61, Q = 0.024. A linear relationship was obtained between the e values of the crotonyl compounds and their Hammett constants σm.
Graft polymers: Chain transfer and branching
Authors: Rao S. Prabhakara , Santappa M.
Published: April 2003

The vinyl monomers, methyl methacrylate, ethyl methacrylate, and methyl acrylate were polymerized in the presence of chlorinated rubber or poly(vinyl chloride) in homogeneous solution with benzoyl peroxide as catalyst. A graft polymer was formed by a chain‐transfer reaction involving the growing polymer radicals to the backbone of chlorinated rubber or poly(vinyl chloride), in addition to homopolymer from the monomer. The homopolymer was isolated from the polymer mixture by fractional precipitation from methyl ethyl ketone solution with methanol as precipitant. The chain‐transfer constants for the branching reactions were evaluated. The ratios kp/(kt)1/2 for the grafting reactions were obtained by a correlation of chain‐transfer constants with the extent of branching. The chain‐transfer data were correlated on the basis of an extension of the Q–e scheme of Alfrey and Price to polymer–polymer transfer reactions. Specific effects due to the backbone are found to have considerable influence on the course of the chaintransfer reactions and kp/(kt)1/2 of the grafting reactions.
α,ω‐diols from polymerization of ethylene
Authors: Anderson W. S.
Published: April 2003

Polyethylene is prepared in silver perchlorate solution by initiation with dialkyl peroxydicarbonates at 0–40°C. Saponification of the polymer endgroups yields a product rich in α,ω‐diols. Well‐known reactions convert the hydroxyl groups to other functional groups. The diol may be condensed with phosgene so as to increase its molecular weight severalfold or crosslinked with silicon tetrachloride to form a network.
Synthesis of polyurethanes from fluorinated diisocyanates
Authors: Hollander Jerome , Trischler Floyd D. , Gosnell Rex B.
Published: April 2003

A number of polyurethanes based on fluorinated aliphatic diisocyanates, perfluorinated aromatic diisocyanates, and chlorinated aromatic diisocyanates have been prepared. The polyurethane prepared from perfluorotrimethylene diisocyanate and hexafluoropentanediol was a rubbery solid which hydrolyzed readily in air to a liquid or sticky solid but was stable if protected from moisture. The products of hydrolysis were isolated and identified. Polyurethanes based on hexafluoropentamethylene diisocyanate were synthesized by reaction of hexafluoropentanediamine with hexafluoropentamethylene bischloroformate and with tetrafluoro‐p‐phenylene bischloroformate. Polyurethanes were synthesized by reaction of tetrafluoro‐p‐phenylene diisocyanate with hexafluoropentanediol and pentanediol. Other perfluoroaryl diisocyanate‐based polyurethanes were synthesized by reaction of tetrafluoro‐m‐phenylene diisocyanate with hexafluoropentanediol and with tetrafluoro‐p‐hydroquinone. Polyurethanes were also synthesized by reaction of tetrachloro‐p‐phenylene diisocyanate and 2,3,5,6‐tetrachloro‐p‐xylylene‐α,α′‐diisocyanate with hexafluoropentanediol.
Gel permeation chromatography: Effect of pore‐size distribution
Authors: Cantow Manfred J. R. , Johnson Julian F.
Published: April 2003

The pore‐size distributions of various grades of porous glass were determined by gas desorption and mercury porosimeter measurements. This allowed the calculation of elution volumes as a function of pore diameters. The coil sizes of polystyrenes in toluene were obtained for a series of molecular weights from hydrodynamic theory and matched with pore diameters. In this manner, expected calibration curves for gel permeation chromatography could be calculated. Good agreement was found with experimental data.
Homopolymers and vinyl chloride copolymers of vinyl esters of chlorinated fatty acids from umbelliferae and limnanthes douglasii
Authors: Liepins R. , Marvel C. S. , Magne F. C.
Published: April 2003

Homopolymers and copolymers of vinyl esters of chlorinated C18, C20, and C22 fatty acids with vinyl chloride have been prepared and evaluated. The incorporation of the vinyl ester of chlorinated C18, C20, and C22 acids as comonomers with vinyl chloride produced more flexible copolymers than have other comonomers, yet none have imparted the plasticization that can be obtained by an equal amount of external plasticizer.
Organometallic polymers. I. Synthesis of ferrocene‐containing poly(phosphine oxides) and poly(phosphine sulfides)
Authors: Pittman Charles U.
Published: April 2003

Poly(phosphine oxides) and poly(phosphine sulfides) of ferrocene were synthesized in the melt phase. The resulting ferrocene polymers, linked by phosphorus bridges, were thermally stable and infusible solids, of low molecular weight (M̄n < 4000). Phenyldichlorophosphine, phenyldichlorophosphonate, and phenylphosphonothioic dichloride were copolymerized with ferrocene in the melt phase (80–110°C.) with ZnCl2 as a catalyst. As the polymerization temperature was raised, cleavage of cyclopentadiene rings from iron became more pronounced, and cyclopentane‐bridged polymers of ferrocene were produced in competition with the ferrocene–phosphorus polymers. The cleavage‐polymerization process became predominant at 140°C. The structures of poly(phosphine oxides) (and sulfides) of ferrocene were verified by infrared and nuclear magnetic resonance spectroscopy.
Di‐isotacticity of poly(methyl propenyl ether) and double‐bond opening of methyl propenyl ether in cationic polymerization
Authors: Ohsumi Y. , Higashimura T. , Okamura S. , Chujo R. , Kuroda T.
Published: April 2003

The di‐isotacticity of poly(methylpropenyl ether) obtained by the cationic polymerization has been studied by NMR spectra. The NMR spectra of β‐methyl protons of the polymer are decoupled from the β‐methine proton spectra to determine the di‐isotactic fraction in a polymer. The signals of β‐methyl protons at 8.78 and 8.89 τ are estimated as spectra based on threo‐ and erythro‐di‐isotactic diads, respectively. With BF3·O(C2H5)2 as a catalyst, the trans monomer yields a crystalline polymer and its structure is threo‐di‐isotactic. Otherwise, cis monomer produces an amorphous polymer, and it is a mixture of threo‐ and erythro‐di‐isotactic structure. From these results, it is concluded that the double bond in trans monomer is opened exclusively in the cis type, and in cis monomer cis‐ and trans‐openings take place at almost the same rate.
Kinetics of bulk polymerization of trimeric phosphonitrilic chloride
Authors: MacCallum J. R. , Werninck A.
Published: April 2003

The kinetics of the pure bulk polymerization of trimeric phosphonitrilic chloride were investigated in the temperature range 240–255°C. The reaction was found to be secondorder with an activation energy of 57 kcal./mole. Polymerization catalyzed by benzoic acid was first‐order, and the reactivities of benzoic acid and sodium benzoate at 235°C. were found to be about similar. The volatile decomposition products for the benzoic acid reaction were identified. Mechanisms are postulated for the catalyzed and uncatalyzed reactions.
Polymer reactions. V. Kinetics of autoxidation of polypropylene
Authors: Chien James C. W. , Boss C. R.
Published: April 2003

The rate constants for the autoxidation of polypropylene were determined by a combined ESR, volumetric, and chemical method. The values of ki, kp, and kt at 110°C. are 3 × 10−4 sec.−1, 1.9 l./mole‐sec., and 3 × 106 l./mole‐sec., respectively. The values of ki and its activation energy are the same as those for the decomposition of polypropylene hydroperoxide, thus identifying the latter as the principal initiation process. The values of the temperature‐independent kt suggest that secondary peroxy radicals are the terminating species. The rate constants are compared with rate constant ratios for initiated autoxidations of squalane and other related systems.
Retardation of spontaneous polymerization of formaldehyde by acidic substances
Authors: Yokota Hisao , Kondo Masatsune , Kagiya Tsutomu , Fukui Kenichi
Published: April 2003

The stability of liquid formaldehyde produced by pyrolysis of α‐polyoxymethylene was studied in connection with the presence of impurities in the monomer. Liquid monomer was divided into several fractions by means of the distillation. The stability of each fraction for polymerization is dependent on the order of fraction, that is, the monomer obtained in the early fractions of distillation was much more stable with regard to polymerization than later distillate. Analyses of the monomer fractions indicated that various impurities such as carbon dioxide, water, methanol, and methyl formate were present in the early monomer distillates. From the influence of these impurities on the stability of liquid formaldehyde, it was found that small amounts of carbon dioxide and hydrogen cyanide noticeably depressed the polymerization, and that with acetic acid and maleic anhydride the rate of polymerization decreased with small amounts of these compounds but increased with an excess of additive. On the other hand, the addition of these acidic substances did not affect the molecular weight of the polymer produced. From the fact that the acidic substance retards only the initiation of polymerization, it has been concluded that the spontaneous polymerization of formaldehyde in bulk or in toluene solution is initiated by an anionic species.
Depolarized light and differential thermal analyses of some polyolefin transitions
Authors: Barrall Edward M. , Gallegos Emilio J.
Published: April 2003

The depolarized light intensity (DLI) technique detec's transitions in birefringent materials by simultaneously measuring sample temperature and intensity of polarized light roatated by the sample. Most polyolefins in the solid state rotate 30–40% of the polarized light. At any temperature at which the sample exhibits an ordered state, some rotation occurs. Temperatures of transitions and changes in refractive index can be determined in this way. Many of these transitions can also be followed by the well‐known method of differential thermal analysis (DTA). A comparison of DLI and DTA curves of polyethylene, polypropylene, mixtures of these polymers, and block copolymers of ethylene and propylene shows the two techniques to be complementary and of use in determining the physical behavior of these polymers. Instrumentation and system variables of the DLI technique are discussed.
Effect of temperature on the ozone cracking of butyl rubbers
Authors: Gent A. N. , Hirakawa H.
Published: April 2003

The rates of growth of single ozone cracks have been measured for vulcanizates of two butyl rubbers over the temperature range of 20–160°C. Over most of this range the rates are quantitatively related to the segmental mobility of the polymer and depend upon temperature in accord with the appropriate from of the WLF relation. The rates are also proportional to the concentration of ozone. It is therefore concluded that diffusion of ozone into the polymer before reaction is the rate‐controlling step. This is contrasted with the behavior of butadiene–styrene copolymers, for which the rates of crack growth are also quantitatively related to the segmental mobility, but the rates are somewhat larger at equivalent mobilities and the dependence upon ozone concentration is smaller. The difference is attributed to different penetration distances before reaction in polymers containing low and high densities of reactive sites.
Dielectric relaxation in the paracrystalline phase in polyacrylonitrile
Authors: Hayakawa Reinosuke , Nishi Toshio , Arisawa Kunio , Wada Yasaku
Published: April 2003

Thermal expansion and dielectric relaxation of polyacrylonitrile were measured in the temperature range from −75 to 152°C. at frequencies from 30 cps to 3 Mc./sec. The thermal expansion curve and the temperature dependence of logarithmic relaxation time both show an inflection at 85°C. An x‐ray study by Bohn reveals that this inflection comes from the thermal expansion of the paracrystalline phase of this polymer, and consequently the transition at 85°C. and the associated relaxation are ascribed to molecular motion in the paracrystalline phase. The relaxation strength increases with increasing temperature above this point. The transition is caused by freezing of the bending vibration of chains whereas the relaxation results from rotational vibration. The length of segments in this phase is roughly estimated to be ca. 100 A. by comparing the observed relaxation strength with the theory developed on the basis of the above considerations.
Frequency dependence of intrinsic viscosity of macromolecules with finite internal viscosity
Authors: Peterlin A.
Published: April 2003

In order to explain the observed nonvanishing limiting value of dynamic intrinsic viscosity of polymer solutions at ω = ∞ one has considered the necklace model with finite resistance to the rate of coil deformation introduced long ago by Cerf for the study of gradient dependence of intrinsic viscosity and streaming birefringence. The calculation need not take into account change of hydrodynamic interaction as a consequence of coil deformation because the experimental data are always either obtained at very low gradient or extrapolated to zero gradient so that in the experiment the macromolecule has the same conformation as in the solution at rest. The model indeed yields a finite [η]′ω = ∞ in good agreement with experiments on polystyrene in Aroclor. According to the theory [η]′ω = ∞/[η]0 decreases with increasing molecular weight as M−1 and M−1/2 for the free‐draining and impermeable coil, respectively. The absolute limiting value [η]∞′, therefore turns out to be nearly independent of M, at least for small values of internal viscosity. From the observed value [η]∞′/[η0] one can obtain the coefficient of internal viscosity of the macromolecule. The value for polystyrene in Aroclor calculated from dynamic experiments on rather concentrated solutions is close to that derived by Cerf from streaming birefringence observations of polystyrene in a series of solvents of widely differing viscosity.
Dynamic mechanical properties of a gel of cellulose nitrate in diethyl phthalate: Reduced variable analysis in terms of amorphous and crystalline phases
Authors: Ninomiya Kazuhiko , Ferry John D.
Published: April 2003

A phenomenological theory is presented to extend the method of reduced variables for the effects of both temperature and changing degree of crystallinity on the linear viscoelastic properties of solutions of crystalline polymers. The vertical and the horizontal shift factors, which are both obtainable in the course of analysis of the experimental data, are correlated with the concentration of the solution and the volume fraction of the crystalline phase, and the fractional free volume of the system, respectively. Dynamic mechanical properties of a gel of cellulose nitrate (nitrogen content, 12.6%) in diethyl phthalate with a nominal concentration of 18% by weight were obtained in the transition region from glasslike to rubberlike consistency and also in the rubbery plateau region by employing the Fitzgerald apparatus and a freely oscillating torsion pendulum over the temperature range from −49 to 65°C. Application of the new reduction method to the experimental data was found to be quite successful, and it was shown that in general the degree of crystallinity in the system (and hence also the concentration of polymer in the amorphous phase) can depend on both temperature and thermal history. The dynamic mechanical data of a gel of different nominal concentration (23% by weight) previously obtained by Plazek were reanalyzed in terms of the method herein given.