bluuebunny/crossref_metadata_2025 huggingface dataset:
Statistics of substitution polymers
Authors: Frensdorff H. K. , Ekiner O.
Published: April 2003

Equations are developed for predicting the distributions of degree of substitution and block length in substitution copolymers which result when homopolymers are subjected to substitution reactions. Several different cases are treated differing in complexity from entirely random substitution to substitution affected by substituents already present on the same and on the neighboring repeat units. The equations are then applied to chlorinated polyethylene as an example of their use.
Nuclear magnetic resonance studies of polymer solutions. I. Poly(methyl methacrylates)
Authors: Liu Kang‐Jen
Published: April 2003

The microscopic interactions of solvent with the diastereoisomeric units of isotactic and syndiotactic poly(methyl methacrylate) have been studied by high‐resolution nuclear magnetic resonance. The changes in chemical shifts in various solvents were compared with those of low molecular weight analogs, methyl acetate, and methyl propionate. These changes are caused mainly by the ring‐current effect, which has been found to be larger for the low molecular weight analogs than for the polymer. This is especially true when the protons on the polymer backbone are compared with the corresponding ones in the low molecular weight compounds. As one changes from a chloroform solvent to an aromatic solvent, the displacements of the chemical shifts of the polymer can be expressed as percentages of the corresponding shifts of methyl acetate. For syndiotactic poly(methyl methacrylate) in chlorobenzene, benzene, and α‐chloronaphthalene, respectively, the percentages are 82, 93, 75 for ester protons; 35, 29, 17 for the backbone methylene protons; and 18, 6.7, 0 for the backbone α‐methyl protons. For isotactic poly(methyl methacrylate) in chlorobenzene and benzene, respectively, the percentages are 71, 76 for the ester protons; 41, 38 for the backbone methylene protons; and 41, 32 for the backbone α‐methyl protons. These results are discussed in terms of the local stereochemistry of the polymer systems. The exploitation of procedures of this sort in revealing details of polymer behavior in solution indicates dramatic possibilities for future investigations.
Theory of polymer fractionation efficiency
Authors: Huggins Maurice L.
Published: April 2003

The theory of the equilibrium distribution of a mixture of different size species of a polymer between two liquid phases is reviewed and used as a basis for the calculation of the dependence of fractionation efficiency on overall concentration, interaction coefficient (hence, choice of solvent and temperature), average molecular weight, and the spread of the molecular weight distribution in the polymer. The special case of a single type of polymer in a single solvent, for which the polymer–solvent interaction coefficient is independent of concentration, is dealt with quantitatively. The ultimate aim is to make it possible to determine systematically the optimum solvent (or mixture of solvents), temperature, and overall concentration for fractionation of a given type of polymer, having a given average molecular weight and molecular weight distribution, considering practical limitations, e. g., the total volume which can conveniently be handled and the time required to achieve a sufficiently close approach to equilibrium.
New initiator for the low‐temperature polymerization of vinyl chloride
Authors: Borsini Giancarlo , Nicora Carlo
Published: April 2003

The polymerization of vinyl chloride initiated by a mixture of tetraethyllead and ammonium ceric nitrate has been studied at low temperatures. As (NH4)2Ce(NO3)6 was insoluble in vinyl chloride, methanol was added. Methanol was found to be not only a solvent for the catalyst but also to affect the polymerization reaction by complexing the ceric ions. A reaction order of −0.4 with respect to methanol was calculated. Rate curves were shown to decrease fairly rapidly with time, suggesting a decrease of the rate of production of radicals during the polymerization. The apparent activation energy obtained from polymerizations carried out at different temperatures was 7.4 kcal./mole. A maximum in average polymerization rate on changing the ceric salt concentration was attributed to reactions of radicals with ceric ions. Orders of 1.2 with respect to (NH4)2Ce(NO3)6 and 0.9 with respect to Pb(C2H5)4 were obtained. An increase in molecular weight was observed during the polymerization; this could be accounted for by the decreasing rate of production of radicals and by the transfer process involving one component of the initiator system. The results indicate that the mechanism of formation of radicals is described by the equation:
Vinyl polymerization. 178. Copolymerizations of p‐substituted phenyl vinyl sulfides
Authors: Tsuda Kazuichi , Kobayashi Shigeru , Otsu Takayuki
Published: April 2003

The copolymerizations of p‐substituted phenyl vinyl sulfides (M2) having OCH3, CH3, H, Cl, and Br substituents with styrene and methyl methacrylate (M1) and their intercopolymerizations at 60°C. were studied. From the results of copolymerizations with styrene and methyl methacrylate, the monomer reactivity ratios and the Q2e2 values were determined. For example, the Q and e values for unsubstituted phenyl vinyl sulfide were 0.45 and −1.26 in the copolymerization with methyl methacrylate. This result indicated the importance of the 3d orbital resonance between the sulfur atom and the adjacent carbon atom in the transition state of copolymerizations. The relative reactivities of these monomers toward the polymer radicals were found to be correlated with the Hammett σ constants of the substituents. In the intercopolymerizations of these monomers, it was also found that the relative reactivities followed the Hammett equation approximately.
Statistische methoden zur ermittlung der verteilung der molekülgrössen in hochpolymeren systemen aus experimentalergebnissen der fraktionierten fällung. IV. Berücksichtigung der polydispersität der fraktionen
Authors: Hosemann R. , Schramek W.
Published: April 2003

The relation between the most important statistical parameters of the number frequency h(P) determining the kinetics of polymerization and the molecular weight distribution H(P) is explained. The polydispersity gw of H corresponds to the non‐uniformity of H(= U). For calculating gw, a correction formula (22) is derived which takes into account the averaged polydispersity α of the fractions. By this means, the asymmetry of h is also calculated. As explained in an earlier investigation, it is possible to determine the type of distribution function in the SWN step diagram. If this type is known, it is furthermore possible to calculate the correction quantity α according to the equilibrium theory of G. V. Schulz. The α unequivocally depends on the distribution function, the volume quotient φ of the sol and the gel, and on the parameter k of the function type, if the number X of the fractions lies between 5 and 20 and the single fractions show approximately the same mass. As an example, it is shown that then the quantity k, which is characteristic for the type of the reaction, can be calculated from the experimental data with an error of only a few per cent, and α2 has a value below 0.1. Although, with a fractionation column, α2 generally shows lower values, in favorable cases even down to 0.03, the uncertainty in the determination of the parameter k is, for many practical reasons, generally not lower compared with the uncertainty observed in precipitation fractionations using our new method.
Polymer reactions. III. Structure of polypropylene hydroperoxide
Authors: Chien James C. W. , Vandenberg E. J. , Jabloner H.
Published: April 2003

Oxidation of polypropylene introduces hydroperoxide groups into the polymer. Infrared spectroscopy has determined that more than 90% of these groups are intramolecularly hydrogen bonded. The sequential lengths and sequence distributions of these neighboring hydroperoxides were estimated from the electronic spectra of the polyenes derived from the polypropylene hydroperoxide by two methods: (1) reduction, acetylation, and pyrolysis, and (2) reduction and dehydration. The results indicate that all the hydroperoxide groups are present in sequences of length two and greater. Intramolecular hydrogen abstraction during oxidation could account for the formation of these neighboring hydroperoxides.
Thermal decomposition products of polyethylene
Authors: Tsuchiya Yoshio , Sumi Kikuo
Published: April 2003

Decomposition products of polymers have been determined by many investigators, but the results are often conflicting because of difficulties in analyzing a large number of products. A comprehensive analysis of the volatile thermal decomposition products of high‐density polyethylene has been made with the latest techniques in gas chromatography. The formation of products is explained on the basis of free‐radical mechanism. The predominant process in the formation of volatiles appears to be intramolecular transfer of radicals, in which isomerization by a coiling mechanism plays an important role in determining the relative quantities of each product.
Cationic polymerization of formaldehyde in liquid carbon dioxide. Part I
Authors: Yokota Hisao , Kondo Masatsune , Kagiya Tsutomu , Fukui Kenichi
Published: April 2003

A cationic polymerization of formaldehyde which gave a high molecular weight polymer was studied in liquid carbon dioxide at 20–50°C. In the polymerization without any catalyst both the rate of polymerization and the molecular weight of the resulting polymer increased rapidly with a decrease in the loading density of the monomer solution to the reaction vessel, and also increased with an increase in the initial monomer concentration. From these results it was concluded that the initiating species could be ascribed to an impurity contained in the monomer solution. Both the rate of polymerization and the degree of polymerization of the polymer also increased with rising temperature. The carboxylic acid added acted as a catalyst in the polymerization because of increase in the polymer yield, the molecular weight of polymer formed, and the number of moles of polymer chain with increasing dissociation constant of acid used. It was concluded that the polymerization in liquid carbon dioxide proceeded by a cationic mechanism. Methyl formate had no influence on the polymerization, but methanol and water acted as a chain‐transfer agent.
Infrared spectroscopic studies of polystyrene emulsion polymers: Effect of oxidation during polymerization
Authors: Shaw J. N. , Marshall M. C.
Published: April 2003

Infrared spectroscopy was empolyed to study the nature of the structural changes which occurred through oxidation during the emulsion polymerization of styrene. Aliphatic carboxylic, amino, and phosphate emulsifiers and hydrogen peroxide and potassium persulfate initiators were empolyed for polymer preparation. In addition, a polystyrene dispersion prepared in the absence of any emulsifier or stabilizer was examined. Irrespective of the nature of the initiator–emulsifier combination employed, all of the polymer spectra revealed bands at 1705 and 1770 cm.−1. The band at 1705 cm.−1 was assigned in part to the carbonyl stretching mode of dimertic carboxylic acid, formed by oxidation, in the polystyrene chains. Absorption at 1770 cm.−1, which was very weak, was tentatively attributed to the carbonyl stretching mode of the monomeric form of this acid. The structure of the acid endgroup was not established, but the results obtained suggest that it was possibly a phenylacetic acid residue or a residue with a similar structure.
Effects of mercaptides on the butyllithium‐initiated polymerization of methyl methacrylate
Authors: Hirahara Takuji , Nakano Toyotoshi , Minoura Yuji
Published: April 2003

The effect of mercaptides on the butyllithium‐initiated polymerization of methyl methacrylate in toluene were investigated. The rates of polymerization were decreased by the addition of mercaptides, possibly owing to the formation of a relatively stabilized complex between the mercaptides and the active center of the polymerizing monomer. The stereoregularity was also affected by the addition of mercaptides. The effects increased in the order of increase in the bulk of the alkyl group of the mercaptides: n‐propyl < isopropyl < tert‐butyl < phenyl. The effects of mercaptides on the stereoregularity were larger than those of the analogous oxygen compounds. The concentrations of butyllithium and monomer had no effect on the stereoregularity.
Vinyl polymerization initiated by ceric ion reducing agent systems in sulfuric acid medium
Authors: Subramanian S. V. , Santappa M.
Published: April 2003

Polymerization of the monomers, methyl acrylate (MA) and methyl methacrylate (MMA) was carried out in sulfuric acid medium at 15°C. With the redox initiator system, ceric ammonium sulfate–malonic acid. There was no induction period, and a steady state was attained in a short time. There was found to be no polymerization even after 1 hr. in the absence of the reducing agent R. The initiation was by the radical produced from the Ce4+–malonic acid reaction. The rate of monomer disappearance was proportional to [M]1.5, [R]0.5, and [Ce4+]0.3–0.5, and the rate of ceric disappearance was directly proportional to [R] and [Ce4+]. Chain lengths of the polymers were directly proportional to [M] and inversely to [R]1/2 and [Ce4+]1/2. The experimental results were explained by a kinetic scheme involving the following steps: (a) oxidation of the substrate to give the primary radical which reacts with Ce4+ to give the products, (b) initiation by the primary radical, (c) propagation, and (d) termination of the growing polymer radicals by the mutual type. For the polymerization of acrylonitrile (AN) by the redox system, ceric ammonium sulfate–cyclohexanone (CH), in sulfuric acid at 15°C., the scheme was modified to include linear type of termination by Ce4+, along with the mutual termination to explain the results especially under conditions with [Ce4+] ≥ [CH].
Polytetrazoles and polyaminotetrazoles
Authors: Dyer Elizabeth , Christie Peter A.
Published: April 2003

Polyaminotetrazoles were obtained by the action of hydrazoic acid on solutions of polycarbodimides prepared from methylenebis(4‐phenyl isocyanate), toluene 2,4‐diisocyanate, 3,3′‐dimethoxy‐4,4′‐biphenylene diisocyanate, mesitylene diisocyanate, and hexamethylene diisocyanate. The polyaminotetrazoles, which were soluble only in concentrated sulfuric acid, had inherent viscosities of 0.12–0.78. Polymerization of the disodium salts of bistetrazoles with α,ω‐dihalides gave polytetrazoles without the secondary amine linkage in the chain. The bistetrazoles, used were methylenebis(5‐tetrazole) and 5,5′‐p‐phenylenebistetrazole, and the dihalides were α,α′‐dichloro‐p‐xylene, 1,2‐dibromoethane, and 1,4‐dibromobutane. The polytetrazoles were soluble in concentrated sulfuric acid and had low inherent viscosities, 0.08–0.17. Thermogravimetric analyses showed that marked degradation of both classes of polymers occured at 250–300°C.
Crystalline titanium dichloride—an active catalyst in ethylene polymerization. II. Polymer structure, polymerization variables, and scope
Authors: Benning C. J. , Wszolek W. R. , Werber F. X.
Published: April 2003

Polymerization of ethylene with ball‐milled titanium dichloride leads to a completely linear polymer with terminal unsaturation corresponding to approximately one carbon–carbon double bond per molecule. Polymerization rate is first‐order in both monomer and catalyst concentration at 140°C. Due to a thermal deactivation of the catalyst, the polymerization rate falls sharply with temperature above 180°C. Propylene and butene‐1 will copolymerization with ethylene in this system, propylene more efficiently than butene‐1. Evidence for copolymerization of trans‐2‐butene, but not of the cis‐isomer or of isobutene, in trace concentrations is presented. Propylene is homopolymerized to a product low in isotactic content. The significance of the structural and (limited) kinetic data in terms of the mechanism of polymerization are discussed.
Effect of polymer structure on ease of hydrogen abstraction by cumyloxy radicals
Authors: Lal Joginder , McGrath James E. , Board Robert D.
Published: April 2003

Vulcanizates of five elastomers having different chemical structures were prepared with recipes comprising dicumyl peroxide. Cumyl alcohol/acetophenone molar ratios were determined by gas–liquid chromatography (GLC) on acetone extracts of vulcanizates. Diphenyl ether was used as the internal standard. The ease of hydrogen abstraction by cumyloxy radicals, reflected by the cumyl alcohol/acetophenone ratio, decreases in the following order: cis‐1,4‐polyisoprene > poly(propylene oxide) > poly(vinyl n‐butyl ether) > poly‐1‐heptene ≅ EPR. This order is in qualitative agreement with the order based on calculated relative rates of hydrogen abstraction by methyl and tert‐butoxy radicals and literature data on oxygen absorption of some of these polymers as a result of hydrogen abstraction by peroxy radicals.
Reactions of living polystyrene with difunctional nitriles to produce specifically placed grafting sites
Authors: Gervasi J. A. , Gosnell A. B. , Woods D. K. , Stannett V.
Published: April 2003

Graft polymers have been synthesized with two equal length branches and one or two branches of a different length or composition. The first step was a coupling reaction of living polystyrene with a difunctional nitrile. The product was hydrolyzed to form a ketone‐containing backbone. Subsequently another sample of living polystyrene or of poly‐2‐vinylpyridine was added to the backbone to form the graft. Anionic polymerization was used for the synthesis of backbone and side chains, so all of the products are well defined. The products and reaction sequences also serve as models for a general synthesis of well‐defined comb‐shaped polymers, in which the length of the backbone, and the number, length, and spacing of the side chains may be controlled.
Polycondensation rate of poly(ethylene terephthalate). I. Polycondensation catalyzed by antimony trioxide in presence of reserve reaction
Authors: Stevenson R. W. , Nettleton H. R.
Published: April 2003

The technique of G. Challa was employed for following the reaction of oligomeric poly(ethylene terephthalate) in the presence of antimony trioxide. This technique is based on determining the changes in glycol and bishydroxyethyl terephthalate concentrations with time at a given temperature. The linear trimer of ethylene terephthalate, prepared from terephthaloyl chloride and bishydroxyethyl terephthalate, was employed as starting material. Rate constants were not corrected for catalyst concentrations. The reaction was studied over the temperature range 221–251°C. The equilibrium constant kp/k′ for the polycondensation reaction
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was found to be 0.36. Observed reaction rates were low but faster than in the uncatalyzed reaction studied by Challa. At 231°C. the values of the rate constants found in the presence of 0.025% by weight antimony trioxide were kp = 0.151.mole−1 hr.−1 and k′ = 0.33 l./mole‐hr., and the redistribution rate constant was kR = 0.11 l./mole‐hr. From data at four temperatures the estimated activation energies were Ep = 29 kcal. and ER = 24 kcal. The polycondensation rates were low compared with rates calculated from literature data. A mechanism to explain the difference requires that bishydroxyethyl terephthalate endgroups compete successfully with oligomer endgroups for antimony trioxide catalyst and that the bishydroxyethyl terephthalate catalyst product is unreactive in polymerization.
Study of Ziegler‐Natta catalysts. Part II. The liquid phase and polymerization activity of the catalyst
Authors: Kollár L. , Simon A. , Osváth J.
Published: April 2003

The polymerization activity of the Ziegler‐Natta catalysts is significantly affected by the aluminium alkyls in the liquid phase. These may be studied provided the solid phase of the catalyst remains unchanged. Part of these aluminum alkyls is adsorbed on the surface of the solid phase. It is possible to displace one type of alkyls by another one or to elute it from the adsorbed layer. This last affects the polymerization rate.
Preparation of ion‐selective membranes from crosslinked copolymers of styrene and p‐vinylbenzenesulfonic acid
Authors: Brydges T. G. , Dawson D. G. , Lorimer J. W.
Published: April 2003

Ion‐selective membranes similar to those described by Graydon and Stewart [J. Phys. Chem. 59, 86 (1955)] were prepared by improved methods involving copolymerization of styrene, n‐propyl‐p‐vinylbenzenesulfonate, and divinylbenzene (DVB) with subsequent hydrolysis of the ester. Both the highly reactive ester and DVB were purified by column chromatography and were well characterized by their infrared and proton magnetic resonance spectra. For preparation of membranes about 25% by weight of N,N‐dimethylformamide (DMF) was included with the vinyl monomers in the polymerization mixture. Thermal polymerization was initiated by benzoyl peroxide, and membranes were formed in special molds of two types. In one type a free surface of the mixture was exposed, while in the other the mixture filled the mold. The DMF in the fresh membranes was replaced with aqueous KOH by diffusion, and hydrolysis was then carried out. By this method hydrolysis times were decreased from several days to a few hours. Capacity, water content, and thickness were determined for all membranes, and density, swelling in salt solutions, and Young's modulus were measured for selected membranes. The Vermaas‐Hermans‐Flory theory of polyelectrolyte gels was found to account satisfactorily for the swelling properties and water content of these membranes, the solvent interaction parameter χ1 increasing with increasing volume fraction of polymer from 0.7 to 1.0 at zero external salt concentration and up to 1.8 for membranes deswollen in 1M KCl. No differences in average water contents for given densities of fixed charge and crosslinking were observed with (1) different molds, (2) commercial or pure DVB, and (3) a swelling agent (DMF) or no swelling agent. The results in general indicate that the state of the membrane at a given temperature and pressure can be specified by any two of the parameters: degree of ionization per unit volume of an average structural unit, concentration of crosslinking agent, and degree of swelling. Young's modulus decreased markedly with increasing water content, but data were not sufficiently extensive or precise to permit a quantitative treatment.
Studies of polymers from cyclic dienes. IV. Determination of the structure of polycyclopentadiene
Authors: Aso Chuji , Kunitake Toyoki , Ishimoto Yoshikazu
Published: April 2003

3,4‐ and 3,5‐Dimethylcyclopentenes were prepared as model compounds of the structural unit in polycyclopentadiene. These two isomers give characteristic NMR spectra. The assignment based on the 60 Mc./sec. spectrum was further confirmed by decoupling experiments on the 100 Mc./sec. spectrum of 3,5‐dimethylcyclopentene. By comparing the NMR spectra of these compounds with that of polycyclopentadiene methods were developed for estimating the polymer structure from the relative peak area of the methine–methylene and olefinic protons. Polycyclopentadiene obtained with Friedel‐Crafts catalysts at lower temperatures was shown to be composed mostly of the 1,4 and 1,2 structures. Polycyclopentadiene obtained with several Ziegler‐type catalysts possessed comparable amounts of both structures, contrary to the earlier proposals.
Studies of polymers from cyclic dienes. V. Cationic polymerization of cyclopentadiene, influence of polymerization conditions on the polymer structure
Authors: Aso Chuji , Kunitake Toyoki , Ishimoto Yoshikazu
Published: April 2003

Cationic polymerization of cyclopentadiene was studied with several Friedel‐Crafts catalysts, and the influence of polymerization conditions on the polymer structure was investigated. Polycyclopentadiene contained higher amounts of the 1,2 structure when a stronger catalyst and a more polar solvent were used. This fact is discussed in terms of the tightness of the growing ion pair. The polymer structure did not vary with polymerization temperature in toluene solvent. In methylene chloride at around 0°C. the structural variation with catalysts was much smaller, suggesting a freer nature of the growing ion pair. The viscosity data also support the change in the structure of the ion pair under similar conditions. The use of aliphatic hydrocarbon solvents gave the highest contents of the 1,2 structure. This results was ascribed to the lack of solvation, considering the dependence of the polymer structure on the monomer concentration, which was found only in this solvent. Furthermore, isomerization during propagation was observed in polar solvents at higher temperature.
Water‐absorption properties of an acetal copolymer
Authors: Braden M.
Published: April 2003

The kinetics of sorption from the liquid phase to equilibrium and desorption were studied over the temperature range 0–80°C. Equilibrium uptake was found to increase linearly with concentration in this range. Sorption‐desorption kinetics showed the diffusion coefficients to decrease with increasing concentration, although the extent of this dependence did not appear in itself to be temperature‐dependent. The apparent diffusion coefficient obeyed the law D = D0 exp {− E/RT} over the temperature range studied, giving E = 9.9 kcal./mole and D0 = 0.45 cm.2 sec.−1. These values are compared with corresponding values for other polymers.
Catalytically active form of ferric acetate hydroxide for the insertion polymerization of propylene oxide
Authors: Osgan M.
Published: April 2003

Hydrated ferric oxides prepared in the presence of acetate ions show substantially higher catalytic activity over that of ordinary hydrated ferric oxide (for the polymerization of propylene oxide). The maximum in activity is reached at a ratio of acetate to iron of 2. It is suggested that the active species are formed through the trinuclear μ‐acetato–ferric complex. This would imply that the insertion mechanism requires a particular geometry with probably a minimum of three coordination centers.
Polymers from the vinyl ester of dehydroabietic acid
Authors: Fukuda Wakichi , Marvel C. S.
Published: April 2003

The vinyl ester of dehydrogenated abietic acid has been homopolymerized, copolymerized with vinyl chloride, vinyl acetate, and butadiene and terpolymerized with styrene and acrylonitrile. Both in the homopolymerization and the copolymerization, the vinyl ester of dehydroabietic acid has given lower molecular weight polymers than were obtained with the vinyl ester of tetrahydroabietic acid. Polymers containing the vinyl ester of dehydroabietic acid can be readily crosslinked with peroxide.
Peroxide crosslinking of poly(n‐alkyl methacrylates)
Authors: Bartoň J.
Published: April 2003

The action of dicumyl peroxide on poly(n‐butyl methacrylate) and poly(n‐nonyl methacrylate) produces degradation and crosslinking reactions in both polymers. Crosslinking and degradation of poly(n‐alkyl methacrylates) are influenced also by the initial molecular weight of the polymer as well as by the type of alkyl group. The ratio of degradation to crosslinking p/q determined on the basis of the equation of Charlesby and Pinner, S + S0.5 = (p/q) + (1/qPn) is for poly(n‐butyl methacrylate) of viscosity molecular weight 0.923 × 106 and 2.16 × 106 of 0.78 and 0.60, respectively; for poly(n‐nonyl methacrylate) of weight average molecular weight 3.83 × 105, p/q is 0.16. Crosslinking efficiencies (moles of crosslinks per mole of decomposed dicumyl peroxide) of the above polymers are relatively very low: 0.014, 0.005, and 0.039, respectively. The critical concentration of dicumyl peroxide necessary for the formation of gel, provided it undergoes complete decomposition, is for the above polymers 1.82, 1.65, and 0.98 wt.‐%, respectively. Under the critical concentration of dicumyl peroxide the limiting viscosity number of poly(n‐butyl methacrylate) increases with increasing concentration of dicumyl peroxide. An initial decrease of the value of the limiting viscosity number, which is characteristic for polymers undergoing simultaneous degradation and crosslinking, was not observed.
Determination of propagation and termination rate constants for some methacrylates in their radical polymerizations
Authors: Yokota Kenji , Kani Masaru , Ishii Yoshio
Published: April 2003

Rotating sector determinations of kp and 2kt for ten methacrylates undergoing radical polymerization were carried out at 30°C. Ester groups in the monomers were: isopropyl, ethyl, β‐cyclohexylethyl, methyl, γ‐phenylpropyl, β‐phenylethyl, β‐methoxyethyl, benzyl, β‐chloroethyl, and phenyl. Values of kp obtained were 121, 126, 1190, 141, 149, 228, 249, 1250, 254, and 411 l./mole‐sec., respectively; values of 2kt × 10−6 were 4.52, 7.35, 32.8, 11.6, 0.813, 1.88, 9.30, 41.9, 6.71, and 11.9 l./mole‐sec., respectively.

Omitting the data for the β‐cyclohexylethyl and benzyl esters, a Taft correlation, log kp = (0.70 ± 0.18)σ* + 2.2, was established, where σ* denotes Taft's polar substitutent constants for the above‐mentioned ester groups. The steric substituent constants Es were found to have no influence on kp. Combination of kp with r2 data from copolymerization studies with styrene or methyl methacrylate as M1 comonomer revealed that the more reactive monomer gave rise to the more reactive polymer radical. Monomer viscosities and molar volumes of the ester groups were found to correlate with 2kt.
Synthesis and crystal structure of isotactic poly‐4‐phenyl‐1‐butene
Authors: Golemba F. J. , Guillet J. E. , Nyburg S. C.
Published: April 2003

Poly‐(4‐phenyl‐1‐butene) was prepared by using a titanium tetrachloride–triethyl‐aluminum catalyst. The crystalline polymer melts at 158°C. Double orientation could not be obtained but all the reflections on the x‐ray fiber diagram can be indexed on the basis of an hexagonal cell (a = 20.8 A., c (fiber repeat) = 6.61 A.). However the crystal structure proposed does not belong to an hexagonal space group but to the monoclinic (pseudo‐orthorhombic) space group Pa (a = 10.4 A., b = 18.0 A., c = 6.61 A.). The 31 helix, common to systems of this type, is consistent with an isotactic (not syndiotactic) configuration for the polymer chain.
Thermostability of some isomeric polyoxadiazoles
Authors: Rodè V. V. , Bondarenko E. M. , Korshak V. V. , Rusanov A. L. , Krongauz E. S. , Bochvar D. A. , Stankevich I. V.
Published: April 2003

The thermal stability of the isomeric poly‐1,2,4‐oxadiazole (PO‐2) and poly‐1,3,4‐oxadiazole (PO‐3) was investigated. The isomerism of the ring substantially influenced polymer thermostability. The weight losses in PO‐2 occur above 220–230°C. in vacuo, but PO‐3 degrades only at 280–300°C. The weight changes in isomeric polyoxadiazole at lower temperatures are connected with the completion of the cyclization process. At higher temperatures degradation of the oxadiazole ring takes place, and as a result carbon and nitrogen oxides, 4,4′‐dicarboxy (diphenyl ether) dinitrile and other products are evolved. The mechanism of polymer thermal degradation is examined; it is shown that the weakest bonds are CO and NO. These data are in a good agreement with the results of calculation of the π‐electron systems of unsubstituted oxadiazole cycles in the framework of the molecular orbital treatment in the Hückel approximation. It is shown that the oxygen in the oxadiazole ring oxidizes the products of thermal degradation of polymers and a cell effect takes place. The thermal oxidation of isomeric polyoxadiazoles does not differ essentially from the degradation in vacuo. It was found that the formation of intermediate products such as peroxides and hydroperoxides does not take place, and oxygen does not act as an initiator of polymer degradation.
The mechanism of consumption of ceric salt with cellulosic materials
Authors: Ogiwara Yoshitaka , Ogiwara Yukie , Kubota Hitoshi
Published: April 2003

Efforts were made in the present study to elucidate the mechanism of graft copolymerization of cellulose in the presence of a ceric salt as initiator. When cellulose is treated with an aqueous solution of the ceric salt, ceric ion is consumed in a roughly first‐order reaction in the oxidation of cellulose and in the adsorption on cellulose, and the ratio of the rate constants of oxidation and adsorption is about 1:3 in the case of sulfite pulp. Ceric ion is adsorbed so strongly on cellulose as not to be readily desorbed by treatment with water, dilute acid, or dilute alkali. The number of moles of adsorbed ceric ion was approximately equal to the number of moles of the total carbonyl groups in the cases of cotton and sulfite pulp, which are low in hemicellulose content, and was several times as large in the cases of kraft pulp and semichemical pulp, which contain about 22% hemicellulose. In these samples, however, it was interesting to note that the amount of the adsorbed ceric ion was roughly equal to the amount consumed in oxidation. Cellulose on which ceric ion is adsorbed reacts with methyl methacrylate to yield graft copolymers; a higher molecular weight of grafts, smaller number of grafts, and lower graft efficiency than in a standard polymerization were observed. Since the stability of the adsorbed ceric ion is high, a contribution of the adsorbed ceric ion to the graft copolymerization appears small, and the oxidation reaction, which proceeds slightly more slowly than adsorption, seems more important to the graft copolymerization.
Rate of sulfonation of bead polymers of styrene crosslinked with 1,2,4‐ and 1,3,5‐trivinylbenzene
Authors: Wiley Richard H. , Devenuto A.
Published: April 2003

Bead copolymers of styrene crosslinked with 1,2,4‐ and 1,3,5‐trivinylbenzene (TVB) are sulfonated at different rates. The copolymer beads with 4% 1,3,5‐TVB sulfonate more slowly than do those with 8% 1,2,4‐TVB. The 8% 1,2,4‐TVB crosslinked polystyrene beads sulfonate at about the same rate as do the beads prepared with 8% p‐DVB crosslinkage.
Ordered structures of styrene–butadiene block copolymers in the solid state
Authors: Bradford E. B. , Vanzo E.
Published: April 2003

Several narrow molecular weight distribution block copolymers were prepared by a two‐stage anionic polymerization technique. Films cast from these solutions were studied by electron microscopy. Replicas showed that the film surfaces were composed of layered structures with various orientations. Micrographs of ultrathin sections of stained films demonstrate that layered structure occur throughout the film. The widths of the copolymer layer spacings increase with increasing molecular weight and agree quite well with the calculated values.
Molecular weight distribution of cellulose esters by gel permeation chromatography and fractional precipitation
Authors: Brewer Richard J. , Tanghe Leo J. , Bailey Sharon , Burr John T.
Published: April 2003

Fractional precipitation and gel permeation chromatography yield comparable information on the molecular weight distribution of various cellulose esters. The GPC technique applied to samples obtained by fractional precipitation gives a much more definitive analytical tool than either method used independently. One practical application of this work showed the same molecular weight distribution of two cellulose acetates prepared by different methods.
Cationic polymerization of the geometrical isomers of β‐methylstyrene and anethole
Authors: Mizote A. , Higashimura T. , Okamura S.
Published: April 2003

Cationic polymerization of the geometrical isomers of β‐methylstyrene and anethole (p‐β‐methoxy‐β‐methylstyrene) was studied in order to clarify the relation between the geometrical structure of the α,β‐disubstituted olefins and their monomer reactivities, subsequent to previous work. Polymerization was carried out in toluene or ethylene dichloride with stannic chloride at 0°C. trans‐β‐Methylstyrene was 1.3 to 1.5 times more reactive than cis‐β‐methylstyrene to the styrene carbonium ion; copolymerization between the trans and the cis isomers of β‐methylstyrene showed little difference in monomer reactivity. By contrast, the cis anethole was 1.5–2.0 times more reactive than the trans, according to copolymerization between the two isomers together. The lower reactivity of the cis‐β‐methylstyrene could be explained by steric hindrance in the cis isomer, proposed by Overberger et al.
Retardation of radical polymerization by phenylacetylene and its p‐substituted derivatives
Authors: Higashiura K. , Oiwa M.
Published: April 2003

Radical polymerizations of styrene and methyl methacrylate in the presence of phenylacetylene and five of its p‐substituted derivatives were carried out with the use of 2,2′‐azobisisobutyronitrile as the initiator at 60°C. The initial overall rates of the polymerizations of styrene and methyl methacrylate in the presence of phenylacetylene were not proportional to the square root of the initiator concentration under the experimental conditions employed. The relationship between the overall polymerization rate and the concentration of the phenylacetylenes could be expressed by the Kice equation for the rate of a radical polymerization in the presence of a terminator. From this relationship the rate constant (ks) of the reaction of a growing polymer radical with the phenylacetylenes and the constant Cs = (ks/kp), where kp is the propagation rate constant of vinyl monomers, were determined. The Cs value thus obtained agree well with that derived from the relationship between the number‐average degree of polymerization and the molar ratio of the phenylacetylenes to the vinyl monomer. Therefore the mechanism of the reaction may be considered as being one in which the growing radical reacts with the ethynyl group of the phenylacetylenes to yield a comparatively stable radical which terminates mainly by reaction with the growing radical, and so apparently the phenylacetylenes retard the vinyl polymerization. The substituent effects on the reaction were discussed on the basis of the following modified Hammett equation proposed by Yamamoto and Otsu: log [Cs(p‐sub. PA)/Cs(PA)] = ρσ + γER where PA represents phenylacetylene, σ and ER are the Hammett polar substituent constant and resonance substituent constant, respectively, and both ρ and γ are reaction constants. The γ value for the polymerization of both styrene and methyl methacrylate was 1.7. The ρ value was 1.0 for the polymerization of styrene and approximately zero for that of methyl methacrylate. These results demonstrate that the reactivity of the phenylacetylenes with the growing chain is influenced by both polar and resonance effects of their p‐substituents in the degradative copolymerization of styrene and only by the resonance effect in that of methyl methacrylate.
Preparation of p‐[(S)(—)‐2‐phthalimidopropionyl] polystyrene
Authors: Janović Z. , Fleš D.
Published: April 2003

Samples of atactic and isotactic polystyrene were acylated with N‐phthaloyl‐L‐alanyl chloride under the conditions of Friedel‐Crafts reaction. The degree of acylation was strongly dependent on molecular weight, but not on the tacticity of polystyrene. Similarly the specific rotation of acylated polymers was not influenced by the structure of the polymer chain.
Interaction of simple acids with nylon. Part 2: Diffusion of simple acids
Authors: Marshall J.
Published: April 2003

The paper deals with the diffusion of two mineral acids, hydrobromic and sulfuric acids, and two simple dye acids, NOG (C. I. Acid Orange 7) and SY (C.I. Food Yellow 3), in water‐swollen nylon 66. Anion self‐diffusion coefficients were obtained by radiotracer techniques. The bromide ion and the SY anion self‐diffusion coefficients show very little variation with concentration in the amino‐dyeing region, whereas the H2SO4 and NOG anion diffusion coefficients are concentration‐dependent. The variation of the H2SO4 anion diffusion coefficient with concentration is consistent with the formation of small quantities of the highly mobile bisulfate ion. The low SO4 diffusion coefficient may be explained by the interaction of this ion with single, fixed sites in the polymer. The variation of the NOG anion diffusion coefficient with concentration does not follow a simple D = D0[1/(1 − θ)] relationship at intermediate concentrations but the rapid increase observed as the available sites became saturated, i.e., as θ → 1, is consistent with a site saturation model.
A study of the enzymic degradation of CMC and other cellulose ethers
Authors: Wirick M. G.
Published: April 2003

Accelerated enzymic degradation of a series of six sodium carboxymethylcelluloses (CMC) varying in degree of substitution (DS) from 0.41 to 2.45 demonstrated that stability improves with increasing substitution, the DS 2.45 sample being essentially refactory to enzyme attack. The concentration of completely unsubstituted anhydroglucose (AHG) units in these samples, determined by acid hydrolysis followed by a glucose assay, is less at all substitution levels than would be expected from the relative etherification rates of the C2, C3, and C6 hydroxyls reported in the literature. Assuming random distribution of the unsubstituted AHG units, the frequency of single (IU) and multiple adjacent (xU) sequences can be predicted. Consideration of the extent of enzymic degradation, expressed in terms of the decrease in average molecular chain length deduced from [η] measurements, indicated that in CMC chain scission occurs only at xU sites. A limited comparison of the performance of methyl‐, hydroxyethyl‐, and hydroxypropylcelluloses under identical conditions revealed that, by contrast, in these ethers enzyme‐induced chain scission is possible not only at xU but also adjacent to 1U. The hydroxyalkyl and methyl groups appear to offer approximately equivalent protection against enzyme attack.
The optical rotation of gelatin films
Authors: Coopes I. H.
Published: April 2003

Optical rotation measurements of a series of relatively thick gelatin films prepared under a variety of drying conditions were made. The technique permits rotation measurements to be made during the drying process. It is found that the temperature and humidity of the drying air do not significantly affect the rotation of the films at temperatures below about 25°C. wet bulb. Above this temperature the rotation drops sharply. Films containing formaldehyde and mucochloric acid as hardeners tend to have lower rotations than unhardened films. Various types of gelatin show differences in the gel state, but not when dried. The results of these experiments indicate that in general gelatin tends to acquire the same level of ordered structure during drying, regardless of the drying conditions and type of gelatin. This tendency is inhibited only by high temperatures or the establishment of stable intermolecular crosslinks by hardeners.
Polylactones derived from polymethacrolein and styrene–methacrolein copolymerizations
Authors: Smith W. E. , Ham G. E. , Anspon H. D. , Gebura S. E. , Alwani D. W.
Published: April 2003

Emulsion polymerization of methacrolein produces a polyacetal which can be converted through the action of sodium hydroxide to an alternating copolymer of methallyl alcohol and sodium methacrylate. Support for the alternating structure was gained primarily through a study of the polylactone formed through subsequent acidification of the sodium salt. Thus, the poly(methallyl alcohol–sodium methacrylate) copolymer was acidified under selected conditions to give a soluble polylactone containing 14.2 mole‐% of residual acid and hydroxyl groups. This number agrees quite closely with the value of 13.5 mole‐% which one would predict from the random cyclization of a true alternating copolymer. Cyclization of a random copolymer of poly(methallyl alcohol–sodium methacrylate) in a random fashion would have resulted in a value of about 36.8 mole‐%. The results also support both the 1,2 vinyl polymerization of methacrolein and a nonrandom attack of the polymethacrolein by base. In a completely separate set of experiments, the value of r1 and r2 for the copolymerization of styrene (M1) and methacrolein (M2) were determined to be 0.22 ± 0.02 and 0.88 ± 0.02, respectively.
Effect of alcohols on the gamma‐radiation‐induced polymerization of ethylene
Authors: Suganuma Fujio , Machi Sueo , Mitsui Hiroshi , Hagiwara Miyuki , Kagiya Tsutomu
Published: April 2003

Gamma‐radiation‐induced polymerization of ethylene in alcohols such as methyl, ethyl, n‐propyl, isopropyl, n‐butyl, isobutyl, sec‐butyl, tert‐butyl, and n‐pentyl alcohols was carried out under a pressure of 400 kg./cm.2at 30°C. at a dose rate of 1.4 × 105 rad/hr. in a batch reactor of 100 ml. capacity. The yield and molecular weight of polymer formed in the alcohols (except tert‐butyl alcohol) were much lower than those of the bulk polymerization under the same conditions, whereas the addition of tert‐butyl alcohol increased the yield and reduced the molecular weight. From the infrared spectra of the polymers and those of the bromination products it was concluded that only primary OH exists in the polymer formed in methyl alcohol and that both primary and secondary OH are in the polymer formed in other primary alcohols. Both secondary and tertiary OH were observed in the polymer when the secondary alcohols were used, and only tertiary OH in the case of tert‐butyl alcohol. These polymers were found to contain small amounts of vinylidene unsaturation and methyl group. On the basis of these results the roles of the alcohols in the polymerization are discussed.
Free‐radical copolymerization of 9‐vinylanthracene
Authors: Katz D. , Relis J.
Published: April 2003

Free‐radical copolymerization of methyl acrylate, ethyl acrylate, butyl acrylate, and methyl methacrylate with 9‐vinylanthracene was studied, and the reactivity ratios r1 and r2 were calculated. In the light of earlier data on copolymerization of 9‐vinylanthracene with styrene results show that the difference in polarity of the monomers participating in the copolymerization has an insignificant influence compared with that of the steric factors involved in the reaction.
Quantitative study on hydrogen bonding between urethane compound and ethers by infrared spectroscopy
Authors: Tanaka Takehide , Yokoyama Tetsuo , Yamaguchi Yukio
Published: April 2003

A quantitative infrared spectroscopic study of a model urethane‐type compound was carried out in order to obtain basic data on hydrogen bonding in polyurethanes. First, the absolute intensity of free NH groups of N‐phenylurethane, which was adopted as the model urethane, was determined by Wilson‐Wells' method to be 3.59 × 103l./mole‐cm.2. The free NH of this urethane absorbed at 3447 cm.−1, and hydrogen‐bonded NH absorbed near 3300 cm.−1. Then, the extents of hydrogen bonding of the urethane at various concentrations were determined, and the hydrogen bonding between the urethane and ethers was studied by using the above‐mentioned absolute intensity. For comparison, diphenylamine was also used as proton donor. Di‐n‐butyl ether and poly‐(oxyethylene glycol) were examined and proved to be able to act as proton acceptors. The frequency shifts of NH stretching vibration of diphenylamine and N‐phenylurethane caused by hydrogen bonding with di‐n‐butyl ether were 96 cm.−1 and 150 cm.−1, respectively. The equilibrium constants were 4.8 × 10−1l./mole for the former system 4.6 × 10−1l./mole for the latter.
Studies in some new initiator systems for vinyl polymerization. II. Ammonia–halogen system as the redox initiator
Authors: Pramanick Dinabandhu , Palit Santi R.
Published: April 2003

The ammonia–halogen redox system has proved a promising initiator for polymerizing a number of vinyl monomers in aqueous media. Chlorine and bromine are most efficient, whereas iodine fails to initiate polymerization, probably due to its inhibitive tendency. Endgroups are halogen and amine and total about 0.5 per chain. On the basis of results of endgroup analysis, a mechanism of initiation through halogen and amine radicals, mainly through hydrogen atoms, is suggested. Consistent with the proposed mechanism the endgroup profile changes significantly with changes in pH.