bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of metal salts on polymerization. Part II. Polymerization of vinylpyridine complexed with the group IIb metal salts
Authors: Tazuke Shigeo , Sato Noritaka , Okamura Seizo
Published: April 2003

The following stoichiometric vinylpyridine complexes have been prepared: (4‐VP)2—Zn(SCN)2, (2‐VP)2—Zn(SCN)2, (MVP)2—Zn(SCN)2, (MVP)2—ZnCl2, (MVP)2—ZnBr2, (MVP)2—ZnI2, and (MVP)2—HgCl2, where 4‐VP, 2‐VP, and MVP denote 4‐vinylpyridine, 2‐vinylpyridine, and 2‐methyl‐5‐vinylpyridine, respectively. Results of radical polymerization initiated by azobisisobutyronitrile indicate that the effect of complex formation between the monomers and the metal salts is to enhance the rate of polymerization with the exception of the 2‐VP complex. The Rp for the solution polymerization in dimethylformamide increases in the following order: (1) (MVP)2—Zn‐(SCN)2 > (MVP)2‐ZnCl2 > (MVP)2—ZnBr2 > (MVP)2—ZnI2 > free MVP; (2) (4‐VP)2—Zn(SCN)2 > (MVP)2—Zn(SCN)2 > free MVP > (2‐VP)2—Zn(SCN)2; and (3) MVP + Zn(CH3COO)2 < MVP + Cd(CH3COO)2. When ethanol, acetone, or tetrahydrofuran is used as solvent, the change in Rp is more marked, partly due to insolubility of the PMVP complexed with the metal salts. The increase in Rp would be attributed to the change in kp since the molecular weights of PMVP are nearly proportional to Rp when (MVP)2—ZnX2 where X is Cl−, Br−, I−, or SCN− is polymerized in DMF under fixed conditions. Copolymerizations of MVP—ZnX2 complexes (where X is Cl−, Br−, I−, or CH3COO−) with styrene indicate that the e values of complexed MVP are more positive than that of free vinylpyridine, and the amounts of the positive shift in e values increase with decreasing polarizability of the halide anions. These results are discussed in terms of the charge‐transfer properties of anions, the nature of coordination bonds, and the structures of vinylpyridines. The complexed monomers are hardly polymerized by a cationic or an anionic mechanism. Radiation‐induced solid‐state polymerization gives polymers in low yields.
Study of crosslink formation by partial conversion properties. IV. Copolymerization of styrene with poly(ethylene fumarate)
Authors: Burnett G. M. , Pearson J. M. , Smith J. D. B.
Published: April 2003

The mechanism of the crosslinking reaction in the copolymerization of poly(ethylene fumarate) and styrene has been studied by using partial conversion number‐average molecular weights and viscosities. In dilute solution the reaction is mainly the formation of intramolecular crosslinks, illustrated by a reduced dependence of \documentclass{article}\pagestyle{empty}\begin{document}$\overline{\overline M}_n$\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$[\overline{\overline \eta}]$\end{document} on conversion. Increasing the monomer concentrations increases the contribution from intermolecular reactions and gives a much greater dependence of \documentclass{article}\pagestyle{empty}\begin{document}$\overline{\overline M}_n$\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$[\overline{\overline \eta}]$\end{document} on conversion.
Studies of thermal cyclizations of polyamic acids and tertiary amine salts
Authors: Kreuz John A. , Endrey A. L. , Gay F. P. , Sroog C. E.
Published: April 2003

Thermal conversion rates of the polyamic acid derived from pyromellitic dianhydride and 4,4′‐diaminodiphenyl ether are presented. Formation of the imide ring proceeds by fast and slow first‐order processes. Tertiary amines give ring closures faster by a factor of 10 than the free acid. The enhancement is an activation entropy rather than an activation energy effect.
Fluorothiocarbonyl compounds. VI. Free‐radical polymerization of thiocarbonyl fluoride
Authors: Barney A. L. , Bruce J. M. , Coker J. N. , Jacobson H. W. , Sharkey W. H.
Published: April 2003

Thiocarbonyl fluoride, CF2S, and thiocarbonyl chlorofluoride, CFClS, undergo addition polymerization in free radical‐initiated systems. In addition, both compounds copolymerize with various unsaturated compounds, including typical vinyl and vinylidene monomers. The chlorofluoride, because of its rapid polymerization rate, copolymerizes best with very active monomers, of which 2,3‐dichloro‐1,3‐butadiene is an example. Thiocarbonyl fluoride polymerizes best at low temperatures. The trialkylborane—oxygen redox couple has been adapted to free‐radical polymerizations and copolymerizations from −60 to −120°C. With such initiation CF2S has been copolymerized with terminal and internal olefins, vinyl compounds, allyl compounds, and acrylic esters. Copolymerization with propylene is unusual, in that it proceeds in a manner that strongly favors a product composed of two molecules of CF2S for each propylene. In other cases, product compositions are more responsive to the ratio of monomers charged.
Copolymerization of isopropenyl and isopropylidene oxazolones with styrene
Authors: Iwakura Yoshio , Toda Fujio , Torii Yoshinori
Published: April 2003

2‐Isopropenyl‐4‐isopropyl‐2‐oxazolin‐5‐one (M2), was copolymerized with styrene (M1), and the monomer reactivity ratios were determined to be r1 = 0.31 ± 0.03, r2 = 1.12 ± 0.10. New isomerized oxazolones (M2), 2‐isopropylidene‐4‐methyl‐3‐oxazolin‐5‐one, 2‐isopropylidene‐4‐isopropyl‐3‐oxazolin‐5‐one, and 2‐isopropylidene‐4‐isobutyl‐3‐oxazolin‐5‐one were prepared and copolymerized with styrene. The monomer reactivity ratios were: r1 = 0.36 = 0.07, r2 = 0.0; r1 = 0.39 ± 0.06, r2 = 0.00 ± 0.10; r1 = 0.39 ± 0.10, r2 = 0.0, respectively. The isomerized oxazolones showed no tendency towards homopolymerization by radical initiator. From the results of infrared and NMR spectra and hydrolysis of the copolymer, it was indicated that the isomerized oxazolones participated in copolymerization in the form of 1–4 polymerization of the conjugated dienes (exo double bond at C2 and the CN in the ring). Copolymers reacted with nucleophilic reagents such as amines and alcohols.
Polymerization and crosslinking characteristics of a 3‐methoxybutyl acrylate
Authors: Costanza John R. , Vona Joseph A.
Published: April 2003

Polymers of 3‐methoxybutyl acrylate (3‐MBA) were prepared by máss, solution, and emulsion polymerization techniques. The 3‐MBA polymers could be converted from soft, rubbery, soluble, thermoplastic films to hard, glossy, flexible, crosslinked films when exposed to air and/or transition metal catalysts at elevated temperatures. The crosslinked polymers are resistant to common organic solvents and to mineral acids. Strong alkalis degraded the crosslinked polymers. The second‐order transition temperature of poly‐3‐MBA is −56°C. as determined by volume dilatometry. A comparison of the crosslinking properties of poly‐3‐MBA and other alkyl and alkoxyalkyl polymers is discussed. An autoxidative mechanism is proposed for the crosslinking of 3‐MBA polymers.
Effect of thiourea on the radical polymerization of vinyl monomers. Part III. Effect of diphenyl thiourea on the polymerization of methyl methacrylate with various organic peroxides as initiator
Authors: Sugimura Takaaki , Minoura Yuji
Published: April 2003

The effect of diphenyl thiourea (DPTU) on the radical polymerization of methyl methacrylate (MMA) has been studied in benzene solution at 50°C. with the use of cumene hydroperoxide (CHP), p‐menthane hydroperoxide (PMHP), tert‐butyl perbenzoate (tBPBz), di‐tert‐butyl peroxide (DBP), and dicumyl peroxide (DCP) as initiators. In the CHP‐initiated polymerization, the rate of polymerization increased appreciably on addition of DPTU with a linear dependence on the square root of DPTU concentration up to a maximum which was observed when the ratio of the concentration of CHP to DPTU was 2.5. Then the rate decreased gradually with increasing DPTU concentration in the range greater than the above ratio. It was found from kinetic studied that the overall polymerization rate Rp was expressed by the equation: Rp = K[peroxide]1/2 [DPTU]1/2[MMA], where K is the rate constant, α = 1.2 for CHP and α = 1.0 for tBPBz. It was thought that the acceleration effect observed was due to a redox reaction caused by the interaction of a peroxide–monomer and/or a peroxide–solvent complex with DPTU, and the decrease in the polymerization rate which was observed over a certain concentration of DPTU was due to the action of the oxidized product of DPTU as a transfer agent. The effect of substituents was studied by using para and meta‐substituted DPTU. It was found that the polymerization rate increased as electron‐donating substituents are added to the benzene ring of DPTU with considerable dependence on Hammett's equation (p = −0.36). The acceleration effect is also observed for PMPH‐and tBPBz‐initiated polymerizations, whereas the DCP‐ and DBP‐initiated systems show no effects on the polymerization rate.
Mechanism of stereospecific polymerization of propylene with titanium trichloride–aluminum alkyl catalysts
Authors: Ingberman A. K. , Levine I. J. , Turbett R. J.
Published: April 2003

The effect of various aluminum alkyls at varying concentrations on the rate and stereospecificity of propylene polymerizations with titanium trichloride was examined. It was concluded that dialkylaluminum halides were merely chemisorbed on the surface of the titanium trichloride while the trialkylaluminums reacted more extensively with the surface. In the case of diethylaluminum chloride standard chemisorption kinetics were observed. The rate of polymerization was also found to be a function of solvent, with certain aromatic solvents causing significant rate increases. With diethylaluminum chloride essentially no termination occurs; the polymers are “living polymers.”
Influence of catalyst depletion or deactivation on polymerization kinetics. II. Nonsteady‐state polymerization
Authors: Chiang R. , Hermans J. J.
Published: April 2003

The number‐average and weight‐average degrees of polymerization at the end of the polymerization process have been calculated in terms of the initial monomer concentration, initial catalyst concentration, and rate constants for various polymerization processes, all of which assume instantaneous initiation. The mechanisms differ among themselves in that there is either first‐order catalyst deactivation, or transfer to monomer, or both. The calculation is greatly simplified if only the molecular weights at the end of polymerization are considered. The method given is particularly useful for systems where the calculation of the distribution function as a function of time is complicated. The fact that the monomer concentration and catalyst concentration have a marked effect on the molecular weight provides a good test of the validity of the mechanism under consideration. A comparison of the calculated and observed molecular weights obtained for the homogeneous polymerization of acrylonitrile with an organometallic catalyst will be given in a later communication.
Polymerization of some sulfur‐containing oxetanes
Authors: Goethals E. J. , Du Prez E.
Published: April 2003

Polymerization under the influence of boron trifluoride of 2‐oxa‐6‐thia[3,3]spiroheptane gives two products: a linear polyether containing oxetane groups and a crosslinked polyether polysulfide. When the polymerization was carried out at −3°C., up to 60% of soluble polysulfide is obtained. This does not prove that the thietane group polymerizes more rapidly than the oxetane group but rather that oxetane polymerization is inhibited by the presence of thietane groups. Polymerization under the influence of boron trifluoride etherate of 3,3‐bis(mercaptomethyl)oxetane leads to a polyether containing free thiol groups. The degree of polymerization of the polymer, however, is low. In order to obtain higher degrees of polymerization several compounds with masked thiol groups were polymerized. 2‐Oxa‐6,7‐dithia‐6‐thio[3,4]spirooctane and 2‐oxa‐6,8‐dithia‐7,7‐dimethyl[3,5]‐spirononane gave crosslinked products. The diacetate of 3,3‐bis(mercaptomethyl)oxetane gave a linear polyether containing thiolacetate groups. Hydrolysis of this polymer leads to poly‐3,3‐bis(mercaptomethyl)oxetane with a softening temperature of 125–135°C.
Hydrogels of poly(hydroxyethyl methacrylate) and hydroxyethyl methacrylate—glycerol monomethacry‐late copolymers
Authors: Yasuda H. , Gochin Michael , Stone William
Published: April 2003

Hydrophilic three‐dimensional polymer networks (hydrogels) were prepared from hydroxyethyl methacrylate (HEMA) and the copolymer HEMA and glycerol monomethacrylate (GMMA). The equilibrium water content of the hydrogels in water was investigated as a function of the initial dilution of the polymerization mixture, the type of solvent, and the hydrophilicity of the polymer. The initial dilution was found to have a decisive effect on the swelling or deswelling of hydrogels after the completion of the gel formation. With relatively less hydrophilic hydrogels, there is a critical initial dilution to produce the gel which does not swell or deswell in water after the gel formation. This “isovolumic” initial dilution shifts toward a higher dilution as the hydrophilicity of the hydrogels increases; however, when hydrophilicity of the polymer rises above a certain point, gels always swell in water. Permeability of oxygen through hydrogels was also studied.
Polymerization of Cyclosiloxanes. I. Kinetic Studies on Living Polymer—Octamethylcyclotetrasiloxane Systems
Authors: Lee C. L. , Johannson O. K.
Published: April 2003

The kinetics of the anionic polymerization of octamethylcyclotetrasiloxane (D4) initiated by α‐methylstyrene living polymer in tetrahydrofuran was studied. The following kinetic scheme was postulated:
Initiation:

equation image

Propagation:

equation image

where S‐ and M represent the initiator and D4, respectively. At a living end concentration of 0.0377 mole/l. and a monomer concentration of 1.5 mole/l. in tetrahydrofuran at 25°C. the following kinetic data were obtained: k1 = 2.3 × 10−4 l./mole‐sec., k2 < 2.3 × 10−5 sec.−1, k3 = 2.75 × 10−2l./mole‐sec. k4 ≈ 1.17 × 10−2 sec.−1, K1 > 10 l./mole and K2 ≈ 2.35 l./mole. The rate constants k1 and k3 were found to be dependent on the concentration of anions. This is attributed to the dissociation of ion pairs to free ions at lower concentration. Under the experimental conditions studied the majority of the anions were present in the form of ion pairs. The reactivity of the free ions is about 100 times greater than that of ion pairs. There is no temperature effect on K2, indicating zero ΔH and positive ΔS in the propagation reaction.
Application of Molecular Weight and Particle Growth Measurements in Continuously Uniform Latices to Kinetic Studies of Styrene Emulsion Polymerization
Authors: Williams D. J. , Bobalek E. G.
Published: April 2003

It is possible to generate, in specially formulated styrene emulsion polymerizations, latices in which the monomer—polymer particles are uniform through all stages of growth. These latices are kinetically similar to their polydispersed counterparts and can therefore be used as model systems in generalized kinetic studies of emulsion polymerization. The most important feature of these systems is the fact that the particles are uniform throughout the reaction with regard to all intrinsic properties and rate processes, and the particles can be characterized by this complete, continuous uniformity. Certain remarkably simple, but precise, relationships exist between the overall, measurable kinetic parameters and the individual particle kinetic parameters, thereby resulting in a heretofore unrealized analytic accessibility. Molecular weight kinetic analyses are an order of magnitude more accurate than in non‐uniform systems. Application of these continuously uniform systems in actual kinetic studies indicates an inconsistency in the current concepts of emulsion polymerization, i.e., the generation of polymer at a constant molecular weight is predicted while an increase of several fold is observed. Before the situation can be clarified, further studies with continuously uniform systems are needed to evaluate molecular weight development, molecular weight distribution, and molecular structure and also to re‐evaluate the rate and diffusion processes which control these structural features.
Diffusion of Methanol in Polydimethylsiloxane
Authors: Barrie J. A.
Published: April 2003

The permeation and sorption of methanol in polydimethylsiloxane at 10 and 30°C. has been measured and the results analyzed to determine the concentration dependence of the steady‐state diffusion coefficient D which is found to decrease as the total concentration C is increased. An analysis of the isotherms indicates that clustering of the methanol occurs in the polymer, becoming more predominant as the concentration is increased. A polymerization model used to describe the shape of the D versus C curve for water in polydimethylsiloxane has been modified and applied with some success to describe the shape of the isotherm and the D versus C curve for methanol. The linearity of the permeation rate with relative pressure in this and a number of water—polymer systems is briefly commented on.
Copolymerization of Styrene and Methyl Methacrylate with Lithium as Initiator
Authors: Overberger C. G. , Yamamoto Naoki
Published: April 2003

Copolymers of styrene and methyl methacrylate prepared with lithium dispersion as initiator do not contain random sequences of both monomers. Fractionation of the copolymers with acetonitrile and the NMR spectra of the insoluble fractions show that these are block copolymers which consist of a polystyrene portion and a poly(methyl methacrylate) portion. When the copolymerization is stopped at low conversion the copolymer has a high styrene content, which sometimes exceeds the value expected for radical copolymerization. This fact would indicate that styrene is preferentially polymerized at the early stages of chain propagation. When the copolymerization is carried to high conversion some crosslinked polymer is formed which contains more styrene than the soluble part of the same experiment. When a piece of metallic lithium is used as initiator, it is found that the crosslinked polymer is formed on the surface of the metal. The addition of lithium phenoxide or β‐naphthoxide to the system eliminates the formation of crosslinked polymer. A possible mechanism is proposed.
Single‐crystal model for the bulk crystallization kinetics of poly(ethylene oxide) and polystyrene
Authors: Hillier I. H.
Published: April 2003

Approximations in the Avrami treatment of impingement which arise when the growing crystalline bodies are rods or disks are discussed, with particular reference to the single‐crystal model. This model, previously fitted to the isolated primary crystallization of polymethylene, is extended to discuss the growth of the composite lamellar structures, axialites, and spherulites, and is here fitted to the crystallization of poly(ethylene oxide) and polystyrene. Both polymers are found to yield anomalous values of the Avrami exponent when analyzed in terms of the conventional Avrami equation. The new analysis reveals similarities in the behavior of all three polymers. The residual deviations remaining after the fit of the model to polymethylene and poly(ethylene oxide) follow the same pattern, and the temperature dependence of the rate constants associated with the model is similar for all three polymers.
Measurements of relaxation time of a polyethylene melt
Authors: Aloisio C. J. , Matsuoka S. , Maxwell B.
Published: April 2003

A device for measuring the elasticity of polymer melts has been designed by one of us (B. Maxwell). The device was used to obtain the relaxation modulus in shear of a linear polyethylene melt. From these data a discrete relaxation spectrum was derived. The range of the obtained spectrum was confirmed to correspond to the terminal zone of the “entanglement plateau” of the spectrum. The limiting dynamic viscosity (as frequency approaches zero) was obtained by integrating the relaxation modulus with respect to time. The viscosity and its activation energy were found to agree closely with the flow viscosity and the flow activation energy, respectively, involved in capillary flow.
Rheological properties of polymer melts
Authors: Vinogradov G. V. , Ya. Malkin A.
Published: April 2003

A new method of treating experimental data on the viscous and viscoelastic properties of various polymer melts is suggested. The dependence of the apparent viscosity on the molecular weight, temperature and shear stress can be represented as the product of three independent functions, each of them having a single argument. All three functions are universal, at least in first approximation, and the dependence of the apparent viscosity on the variables indicated is determined by two parameters (glass transition temperature and critical molecular weight), characteristic of each homologous polymer series. The viscoelastic characteristics (dynamic, relaxation, creep, as well as relaxation and retardation spectra) of polymer melts are universal in shape in the linear region and contain only one individual polymer parameter, viz., maximum Newtonian viscosity. It is shown that upon normalization of certain nonlinear characteristics with respect to the maximum Newtonian viscosity, they can also be represented in the universal form.
Morphology of polypropylene crystallized from the melt
Authors: Hock Charles W.
Published: April 2003

Polypropylene was oxidized with nitric acid in a manner contrived to remove its amorphous component. Concurrent with the loss in weight there was an increase in crystallinity, a decrease in molecular weight, a drop in melting point, and a change in visible structure. The crystalline component, which survived from polymer which had orginally crystallized isothermally, consisted of separated spherulites. These spherulites could be broken apart into lamellae which gave electron diffraction patterns like those now associated with a variety of solution‐grown single crystals. As opposed to the high molecular weight of the unoxidized parents, the lamellae which survived the acid treatment consisted of short chains whose length depended on the temperature at which the parents had crystallized. If, as diffraction studies indicate, these short molecules are lined up in rank and file, then the length of the molecules and the height of the lamellae should correspond. The heights of the lamellae could not be measured precisely enough to establish an exact correlation, but the variations in average chain length calculated from viscosity data at least approximated the heights of the lamellae which were observed visually.
Infrared study of poly(vinyl fluoride)
Authors: Koenig J. L. , Mannion J. J.
Published: April 2003

Poly(vinyl fluoride) polymers prepared at different polymerization temperatures have been examined in the melt, oriented, and solid state by infrared spectroscopy. Bands arising from the head‐to‐tail and head‐to‐head‐tail‐to‐tail portions of the polymer have been isolated and assigned. The head‐to‐head‐tail‐to‐tail portion of the polymer crystallizes in the head‐to‐tail unit cell except for a portion of the 1,2‐difluorethylene units which apparently have the gauche (out‐of‐plane) structure. The head‐to‐tail portion of the polymer is nearly atactic, but is somewhat rich in syndiotactic chain structure. Bands arising from local syndiotactic order are observed.
Effects of composition on the solution properties of styrene–acrylonitrile copolymers
Authors: Shimura Yuko
Published: April 2003

Short‐range interactions between chain units of random copolymers in solution may be influenced by the composition or precisely by the distribution of sequence lengths of the same monomer units. Steric factors were derived for random copolymers of styrene and acrylonitrile with different compositions from the relation between the limiting viscosity number and the molecular weight. Mark‐Houwink relations were obtained in methyl ethyl ketone (MEK) or in N,N′‐dimethylformamide (DMF) at 30°C. for random copolymers containing 0.383 (Co‐1) and 0.626 (Co‐2) mole fraction of acrylonitrile, the expressions are: [η] = 3.6 X 10−4 Mw0.62, for Co‐1 in MEK; [η] = 5.3 X 10−4 Mw0.61, for Co‐2 in MEK; [η] = 1.2 × 10−4Mw0.77 for Co‐2 in DMF. With the Stockmayer‐Fixman expression, these correlations become, respectively: [η]/M1/2 = 1.24 × 10−3 + 8.0 × 10−7 M1/2; and [η]/M1/2 = 1.70 × 10−3 + 6.3 × 10−7 M1/2; and [η]/M1/2 = 1.68 × 10−3 + 31.3 × 10−7 M1/2. From the unperturbed mean‐square end‐to‐end distances, 〈L2〉0, determined from the first terms of the latter expressions, together with 〈L2〉0f calculated by assuming the completely free rotation, gives the steric factor σ = (〈L2〉0/〈L2〉0f)1/2 as 2.25 ± 0.05 for Co‐1, and 2.31 ± 0.10 for Co‐2. These values of σ are close to those for polystyrene (σ = 2.22 ± 0.05) and for polyacrylonitrile (σ = 2.20 ± 0.05). Therefore, it is concluded that the dimensions of random copolymers of styrene and acrylonitrile in solution are not significantly influenced by the composition. In other words, the unperturbed dimensions are not affected by a change in the alternation tendency between styrene units with phenyl side groups having a large molar volume and acrylonitrile units with nitrile groups responsible for the electrostatic interactions. On the other hand, the long‐range interactions reflect the effect of sequence length. The Huggins constant and the second virial coefficient obtained from the light‐scattering measurements have optimum values at about 0.5 mole fraction of acrylonitrile, where the greatest tendency for alternation seems to exist.
Crystallization in stretched polymer networks. II. Trans‐polyisoprene
Authors: Gent A. N.
Published: April 2003

Measurements are described of the rates of crystallization and crystal melting temperatures in stretched test pieces of trans‐polyisoprene, crosslinked to various degrees. The increase in rate with extension are attributed to the corresponding increases in melting temperature and hence degree of supercooling. The rise in the melting temperature of both the α‐ and β‐crystal forms is found to be in satisfactory agreement with Flory's treatment of oriented crystallization. The changes in tensile stress are also generally in accord with the formation of oriented crystallites. For the more lightly crosslinked materials, a pronounced rise in tensile stress occurred during the later stages of crystallization, at extensions below about 100%. Reasons are given for attributing this phenomenon primarily to the relatively large contraction in volume on crystallization, rather than to the formation of folded‐chain crystallites.
Polymerization of adsorbed monolayers. III. Preliminary structure studies in dilute solution of the insertion polymers
Authors: Blumstein Alexandre , Billmeyer Fred W.
Published: April 2003

Insertion poly(methyl acrylate) and poly(methyl methacrylate) were prepared from monomers adsorbed in monolayers on the surface of montmorillonite clay, both in the presence and in the absence of bifunctional crosslinkers (ethylene glycol dimethacrylate and tetramethylene glycol dimethacrylate). The insertion poly(methyl acrylate) and the crosslinked insertion poly(methyl methacrylate) and dilute‐solution properties quite different from conventional polymers of these monomers, the differences including high light‐scattering molecular weights combined with low viscosities, low values of the second virial coefficient, unusually large variations of the Huggins' constant k′ with the time‐temperature history of the solutions, and low sedimentation velocities. These properties suggest that the insertion polymers have compact structures and are consistent with the postulate of sheetlike macromolecules. The dilute‐solution properties of insertion poly(methyl methacrylate) made without crosslinker, unlike those of similarly prepared poly(methyl acrylate), were similar to those of conventional poly(methyl methacrylate). This difference in behavior is attributed to the different tendencies of the two monomers to undergo branching or crosslinking during radical polymerization.
Specific heats of poly(vinyl chloride) compositions
Authors: Dunlap L. H.
Published: April 2003

Specific heats of plasticized poly(vinyl chloride) can be readily obtained by means of the thin foil calorimeter when the polymer is fabricated into sheet or film. The effects of temperature and plasticizer content on the specific heat and of the plasticizer content on the glass temperature are readily observed. The data may be used to estimate the glass temperatures of plasticizers where those temperatures are not readily reached by normal techniques. The specific heat at the glass temperature is approximately 0.255 for the ranges of 0–30 phr plasticizer. A definite glass transition is not observed with 60 phr plasticizer. No other transitions were observed between 200 and 400°K. The previous history of the polymer is important, as it can change the specific heat of the polymer noticeably, especially above the glass temperature. Comparison of the values listed here with those obtained by others should be made with the understanding that these samples were fabricated by extrusion and were free of observable strain. The degree of crystallinity of these polymers is very small, probably less than 10%, since none was found by x‐ray diffraction. The plasticizing effect of some stabilizers was noted.
Axial dispersion of polymer molecules in gel permeation chromatography
Authors: Hess M. , Kratz R. F.
Published: April 2003

Gel permeation chromatography is an elution chromatographic process depending on the permeation of the solute through a bed of gel particles. This process is used in the estimation of molecular weight distributions of polymers, since elution occurs in decreasing order of molecular size. The eluting species, however, are not perfectly fractionated, and apparent broadening of the distribution occurs. This broadening results from an axial (longitudinal) mixing of the eluting species. Consideration of the accessible bed volume for each species permits a correction to be made for this axial dispersion. The concept was applied to heterodisperse distributions by solving the resulting simultaneous equations. A least‐squares regression may be employed to utilize the experimental data most effectively. The experimental chromatogram can be described in terms of accessible bed volume and dispersion coefficient of each species together with flow rate, sample concentration, and chromatograph column geometry. The chromatogram corrected for the axial dispersion describes the molecular weight distribution more accurately than does the experimentally determined curve. The correction procedure was applied to a well‐characterized polystyrene; the results of the gel permeation chromatography show excellent confirmation of the results of fractionation and of other instrumental analyses.
Effect of crosslink density on the creep behavior of natural rubber vulcanizates
Authors: Plazek Donald J.
Published: April 2003

Torsional creep measurements on four natural rubber vulcanizates, crosslinked to different degrees, were carried out in the temperature range from −50 to 90°C. This investigation complements the studies on identical samples of the stress relaxation behavior by Chasset and Thirion and of the dynamic mechanical response by Ferry, Mancke, Maekawa, Ōyanagi, and Dickie. The creep measurements reported are shown to be in agreement with the stress relaxation results. In addition to the usual temperature reduction, a superposed curve was obtained for the long time response using the apparent molecular weight between crosslinks, Mc, as a reduction variable. The variation in viscoelastic response with crosslink density is interpreted as a restrictive action of the chemical crosslinks on the transient entanglement network.
Group motions in the glassy state of some substituted polystyrenes and poly(vinyl benzoates)
Authors: Baccaredda Mario , Butta Enzo , Frosini Vittorio , Magagnini Pier Luigi
Published: April 2003

Mechanical damping measurements were carried out in the range of 103–105 cps and between 60°K. and the softening point on some substituted Polystyrenes and poly(vinyl benzoates) containing different substituents (methyl groups, methoxy groups, and halogen atoms) either in the ring or in the main chain. The ortho and meta ring‐substituted polystyrenes do not show any secondary mechanical relaxation in the glassy state, although all the other substituted polystyrenes, exhibit a low‐temperature damping peak (δ process) (which is in some way connected with ring motions) whose height and temperature location depend on nature, position, and number of substituents. Substituents in the para position of the ring or in the α position in the backbone chain shift the δ peak of the unsubstituted polystyrene towards higher temperatures; this shift is accompanied by an increase of the apparent activation energy E*. Substitution in the β position, on the contrary, does not affect the δ peak. Analogous results are obtained for substituted poly(vinyl benzoates), which exhibit, in addition, a β relaxation effect, associated with carboxyl group motions. A very good correlation is found between the values of E* and the limiting relaxation time τ for the δ relaxation of polystyrenes and poly(vinyl benzoates), similarly substituted in the ring, indicating that the δ relaxation leads to absorption curves in the mechanical relaxation spectrum which are characteristic of the structure of the aromatic side chain.
X‐ray determination of crystallinity and orientation in poly(ethylene terephthalate)
Authors: Dumbleton J. H. , Bowles B. B.
Published: April 2003

The measurement of crystallinity and orientation in poly(ethylene terephthalate) is discussed. A simple procedure is given for the estimation of orientation from the (105) plane, and it is shown that methods which use the equatorial planes are subject to certain disadvantages. In addition a method is given for the measurement of x‐ray crystallinity. The technique is applied to fibers and films of various treatments and a linear relation is found between density and x‐ray crystallinity.
Crystal structure of poly(m‐xylylene adipamide)
Authors: Ōta T. , Yamashita M. , Yoshizaki O. , Nagai E.
Published: April 2003

The crystal structure of poly(m‐xylylene adipamide) was reinvestigated by x‐ray diffraction. It is found that the helical chain model proposed by Yoda et al. needs to be corrected to a large extent. The unit cell obtained is triclinic with dimensions a = 12.01 A., b = 4.83 A., c = 29.8 A. (fiber axis), α = 75.0° = 26.0°, and γ = 65.0°, in which one molecular chain with two chemical repeating units is involved. The space group is C1i–P1. An almost planar zigzag chain conformation with a small degree of contraction from the original planar arrangement is given. The CH2 planar zigzag chain and the aromatic rings are so oriented that their planes are inclined to the c axis at an angle of a few degrees. The hydrogen‐bonded sheets nearly coincide with the (100) plane and the aromatic rings are close to the (120) plane, which is nearly perpendicular to the direction of hydrogen bonding.
Infrared characterization of polymorphism in polybutene‐1
Authors: Luongo J. P. , Salovey R.
Published: April 2003

The transformations of the polymorphic forms of polybutene‐1 (I,II,III) were studied by infrared spectroscopy. Attenuated total reflectance spectra demonstrate that the II → I transformation occurs initially and most rapidly on the film surfaces. Electron irradiation experiments showed the II → I conversion can be suppressed by irradiation. The degree of suppression was dependent on the irradiation dose. Comparison of spectra on irradiation in air and vacuum indicate that radiation‐produced radicals are scavenged by oxygen, preventing intermolecular crosslinking and allowing normal expansion of the helix during transformation. In addition, remolding an irradiated sample of II caused immediate conversion to I rather than its return to II as was noted when unirradiated samples are remolded. These observations are related to certain conformational changes in the molecular structure.
Block copolymerization of methyl methacrylate with poly(ethylene oxide) radicals formed by high‐speed stirring
Authors: Minoura Yuji , Kasuya Tanekazu , Kawamura Shinji , Nakano Akihiko
Published: April 2003

A block copolymer of methyl methacrylate with poly(ethylene oxide) was synthesized by initiation with poly(ethylene oxide) radicals formed by high‐speed stirring. The effects of the concentration of the monomer, the concentration of the polymer, the degree of polymerization, the rotation speed, and the solvent on the rate of copolymerization were studied. It was found that the rate of copolymerization was proportional to the concentration of the monomer and to the square root of the rate of scission of the polymer chain. The block copolymerization of methyl methacrylate monomer and styrene monomer (1 : 1 mole ratio) with poly(ethylene oxide) radicals was also carried out by the same method and it was found that the block copolymerization was a radical one.
α,ω‐Disubstituted polymethylpolyphosphonates and polyphenylpolyphosphonates from condensation polymerization
Authors: Grant David , Van Wazer John R. , Dungan Claude H.
Published: April 2003

Condensation polymerization of phosphonates through formation of POP linkages has been achieved by (1) volatilization of methyl chloride from mixtures of CH3P(O)Cl2 with CH3P(O)(OCH3)2; (2) volatilization or chemical removal of water from CH3P(O)(OH)2; and (3) volatilization of HCl from mixtures of CH3P(O)Cl2 with CH3P(O)(OH)2 or C6H5P(O)Cl2 with C6H5P(O)(OH)2. Depending on the proportions of the reagents, the polymerization products consist of various mixtures of chain molecules of the type \documentclass{article}\pagestyle{empty}\begin{document}${\rm X \hbox{--} P}({\rm O})({\rm R})\rlap{--}[{\rm O \hbox{--} P}({\rm O})({\rm R})\rlap{--}]_n {\rm X}$\end{document} for R = CH3 and X = OCH3, Cl, or OH, or for R = C6H5, x = Cl or OH. 31P nuclear magnetic resonance (NMR) was used to investigate both the polymethylpolyphosphonates and the polyphenylpolyphosphonates; and 1H NMR of the CH3P and CH3O moieties was also used to study the polymethylpolyphosphonates. In the methoxyl‐terminated polymethylpolyphosphonates, which was the system studied most extensively, no detectable amounts of cyclic molecules were found at equilibrium, but a crystalline methylphosphonic anhydride, CH3PO2, exhibited some ring structures. The equilibrium size distributions gave evidence that the sorting of the mono‐ and difunctional phosphorus‐based units making up the oligomeric chains is affected by neighboring units. Kinetic measurements demonstrated that the condensation polymerization is a complicated process involving considerable scrambling of terminal groups with bridging oxygen atoms.
Copolymerization parameters of acrolein and acidic vinyl monomers
Authors: D'Alelio G. F. , Huemmer T. F.
Published: April 2003

Acrolein was copolymerized by radical initiation in aqueous solutions with sodiump‐styrenesulfonate and acrylic acid, respectively, in the pH range of 3–7. The reactivities were shown to be pH‐dependent. For the acrolein (M1)–sodiump‐styrenesulfonate (M2) pair,r1= 0.33 ± 0.15 andr2= 0.32 ± 0.05 at pH 3;r1= 0.23 ± 0.12 andr2= 0.05 ± 0.03 at pH 5;r1= 0.26 ± 0.03 andr2= 0.025 ± 0.025 at pH 7. For the acrolein (M1)–acrylic acid (M2) pair,r1= 0.50 ± 0.30 andr2= 1.15 ± 0.2 at pH 3;r1= 2.40 ± 0.50 andr2= 0.05 ± 0.05 at pH 5;r1= 6.70 ± 3.00 andr2= 0.00 at pH 7. For acrolein, the new values ofQ= 1.6 ande= 1.2 have been calculated. For sodiump‐styrenesulfonate, the valuesQ= 0.76 ande= −0.26 at pH 3,Q= 0.51 ande= −0.87 at pH 5,Q= 0.39 ande= −1.00 at pH 7 were obtained; and for acrylic acid, the valuesQ= 1.27 ande= 0.50 at pH 3,Q= 0.11 ande= −0.22 at pH 5 were derived. The changes in reactivity are explained on the basis of inductive and resonance effects.
Polymerization of thietane
Authors: Price Charles C. , Blair E. Allan
Published: April 2003

Grignard reagent‐initiated polymerization of thietane gave a soluble crystalline polymer melting at 59°C. Oxidation of the polymer with one or two equivalents of hydrogen peroxide gave the sulfoxide and sulfone, respectively. The sulfoxide was noncrystalline and insoluble in all common solvents at room temperature and softened at 185–200°C. The sulfone was partially crystalline and insoluble.
Polymerization of cyclic sulfides
Authors: Stille J. K. , Empen J. A.
Published: April 2003

The ring‐opening polymerizations of cyclic sulfides containing three‐, four‐, and fivemembered rings were studied. In conjunction with these polymerizations, the relative basicities of the cyclic sulfides employed were also investigated. Polymerizations were effected by the use of phosphorus pentafluoride, boron trifluoride ethyl ether, triethylaluminum, and trimethyloxonium tetrafluoroborate. The resulting polymers were oxidized to the sulfones and differential thermal analyses were obtained on the sulfide polymers as well as the sulfone analogs.
Cationic graft copolymerization of styrene onto natural rubber
Authors: Ueno Yukio , Kasabo Toshiyuki , Hanada Takeshi , Minoura Yuji
Published: April 2003

The polymerization of styrene was carried out in a cyclohexane solution of natural rubber with stannic chloride. It was found that the grafting copolymerizations of styrene took place as well as the cyclization of rubber. The rate of polymerization of styrene was proportional to the second power of the concentration of styrene and to the concentrations of stannic chloride and natural rubber, respectively. The overall activation energy was about 6 kcal./mole. The percentage grafting increased with increasing concentration of rubber. On the other hand, the grafting efficiency showed the reverse tendency. The percentage grafting could be increased to 150% by the addition of nitrobenzene, a polar solvent.
Carborane polymers. IV. Polysiloxanes
Authors: Mayes N. , Green J. , Cohen M. S.
Published: April 2003

Carboranes attached to silicon through straight‐chain alkyl groups were prepared and characterized for thermal stability by TGA and molecular weight change on heating. The monomers for these polymers were prepared generally by platinum‐catalyzed addition of a silylhydride to an alkenyl or dialkenyl carborane. Polymerization was effected by hydrolysis‐condensation of chlorosilanes, ring opening of cyclosiloxanes, and condensation of alkoxy and chlorosilanes. Two types of polymer structures were prepared, one contained m‐carborane in the chain backbone, the other contained o‐carborane as pendant alkylcarborane groups. Both types were obtained as elastomers; however, higher proportions of carborane in the polymers reduced elasticity and finally resulted in nonelastomers. TGA of the backbone carborane siloxane polymer indicated degradation at 370°C. in nitrogen and at 235°C. in air. Chain scission, as determined by molecular weight decrease, was observed on heating in nitrogen at 350°C. TGA of the pendant carborane siloxane polymer indicated that degradation in nitrogen and in air occurred at greater than 400°C. However, chain scission, as determined by molecular weight decrease, was observed upon heating at 300°C. in nitrogen.
Computer program for calculations and automatic data plotting in binary copolymerization
Authors: Molau G. E.
Published: April 2003

The copolymer composition equation as well as the composition‐drift equation recently published by Meyer and Lowry have been transformed into a weight fraction–weight conversion form. The resulting weight‐notation equations contain the original molenotation equations as a special case. Based on the weight‐notation equations, a computer program has been written which allows calculations and automatic data plotting of composition and composition‐drift data in binary copolymer systems in either weight or mole notation.
Polymerization of 1,3‐butadiene on cobalt and nickel halides
Authors: Anderson W. S.
Published: April 2003

Butadiene polymerizes to cis‐1,4 polymer on irregularly stacked, halogen‐deficient crystals of cobalt(II) or nickel(II) halides. Halogen is removed from the halides by heating the salts under high vacuum or by photolyzing them in the presence of butadiene. Intrinsic viscosity and solubility of the polymer reach a steady state during polymerization. Cobalt chloride produces polymer of higher intrinsic viscosity than nickel chloride, but polymerization on nickel chloride is faster. Catalytic activity is attributed to the presence of ≤0.1% of nickel and cobalt monohalides in the catalyst.
New synthetic route to α‐alkylacrylonitriles and a study of their homopolymerization and copolymerization reactions
Authors: Kovács J. , Marvel C. S.
Published: April 2003

Aliphatic aldehydes have been condensed with cyanoacetic acid and the resulting olefin intermediates hydrogenated and then submitted to a Mannich‐type reaction to produce α‐alkylacrylonitriles with the alkyl groups ranging from C1 to C12. It was not necessary to isolate the intermediates when the reactions were carried out in acetonitrile solutions. The α‐alkylacrylonitriles with C7 or higher alkyl groups in the chains would polymerize by radical initiation in emulsion to give polymers which were sticky, rubbery products and showed adhesive characteristics. Anionic initiation did not yield polymers with the α‐alkylacrylonitriles containing high alkyl groups but did convert the C2 to C4 alkyl‐substituted acrylonitriles to low molecular weight colored products. Some copolymers of α‐alkylacrylonitriles with acrylonitrile were prepared in emulsion by radical initiation. The monomer ratios in these copolymers were determined by nuclear magnetic resonance spectra.
Stereospecific polymerization of methacrylonitrile. II. Influence of polymerization conditions on polymerization and on properties of polymers
Authors: Joh Yasushi , Kotake Yahide , Yoshihara Toshio , Ide Fumio , Nakatsuka Kazuo
Published: April 2003

Stereospecific polymerization of methacrylonitrile with diethylmagnesium has been studied. Polymerization temperature has an important effect on polymerization. The conversion, stereoregularity, and intrinsic viscosity of the polymer increased significantly with increasing polymerization temperature. Stereoregularity of the polymer improved with increasing the polymerization time and the monomer concentration, but it is independent of the catalyst concentration. Intrinsic viscosity of the crystalline polymer increased with increasing monomer concentration but is independent of the polymerization time and the catalyst concentration. It is suggested that two mechanisms are involved in this polymerization: coordinated anionic polymerization to from the crystalline polymer, and probably conventional anionic polymerization to form the amorphous polymer. It is found that crystalline polymer can also be obtained in homogeneous phase such as in tetrahydrofuran solvent.
Cationic and free‐radical polymerization of optically active 1‐olefins
Authors: Bacskai R.
Published: April 2003

The AlCl3‐initiated cationic polymerization of optically active 1‐olefins yields polymers of varying optical rotatory power. Polymers of (+)‐3‐methyl‐1‐pentene and (−)‐4‐methyl‐1‐hexene prepared between −78 and −55°C. in CH2Cl2 or n‐heptane are almost completely optically inactive. Under identical reaction conditions (+)‐5‐methyl‐1‐heptene gives polymers of significant optical rotatory power. Alternating SO2copolymers of the same olefins, formed in reactions which proceed through free‐radical intermediates, yield optically active products with specific rotations similar to those of low molecular weight analogs. These results are consistent with a cationic polymerization mechanism in which the growing chain undergoes intramolecular hydride shift and the asymmetric carbon atoms are converted into carbonium ions. The data also provide evidence for the lack of rearrangement in free‐radical polymerization. By comparing the specific rotations of the cationic and free‐radical polymers, the extent of rearrangement during cationic polymerization can be estimated. The calculations show that the 1,2‐polymer in cationic poly‐3‐methyl‐1‐pentene is less than 2%, the sum of 1,2‐ and 1,3‐polymer in cationic poly‐4‐methyl‐1‐hexene is less than 4%, and the sum of 1,2‐, 1,3‐, and 1,4‐polymer in cationic poly‐5‐methyl‐1‐heptene is 14–20%.