bluuebunny/crossref_metadata_2025 huggingface dataset:
Reaction kinetics in dilute solutions of chain molecules carrying randomly spaced reactive and catalytic chain substituents. II. Dependence of the ring closure probability on the solvent medium and the nature of the chain backbone
Authors: Goodman Neil , Morawetz Herbert
Published: April 2003

Ternary copolymers of acrylamide or methacrylamide with small proportions of comonomers carrying reactive p‐nitrophenyl ester and catalytic pyridine groups in the side chains were prepared. The kinetics of the ester solvolysis was followed in highly dilute solutions, so that the rate was controlled by interaction of groups carried by the same chain backbone. Data were obtained in water and aqueous methanol and were interpreted by a computer simulation procedure in terms of the dependence of the probability of encounter between two chain substituents on their spacing along the chain backbone. This probability decreased more slowly with increasing separation of the interacting groups when the solvation of the polymer was reduced, but even in solvents approaching θ conditions the results deviated from theoretical predictions for chains without excluded volume. The formation of cyclic conformations is considerably more difficult in methacrylic than in acrylic chains, although the chain flexibility, as characterized by unperturbed chain dimensions, is very similar in the two systems.
Effect of molecular weight on the refractive increment of polyethylene and n‐alkanes
Authors: Wagner H. L. , Hoeve C. A. J.
Published: April 2003

As in the case with other polymers previously reported, the values of the refractive index increment dn/dc of polyethylene and the n‐alkanes change with molecular weight. Most of the variation may be understood by examination of the role of density in the Lorentz‐Lorenz mixing equation for specific refractivity, R12 = p1R1 + P2R2 used to calculate dn/dc. It may also be shown that as the absolute refractive index difference between solute and solvent becomes smaller, dn/dc becomes more sensitive to density change of the solute.
Fold surface of polyethylene single crystals as assessed by selective degradation. I. Ozone degradation method
Authors: Priest D. J.
Published: April 2003

Ozone has been used as a selective oxidizing agent for degrading polyethylene single crystals at room temperature in order to confirm and extend results on surface structure obtained by use of fuming nitric acid at temperatures above 60°C. The surfaces of the crystals were rendered highly accessible to the ozone gas by preparing the crystalline material in a highly expanded form; the solvent in which the crystals were suspended was removed by sublimation from the solid state. The extent and nature of the reaction were studied by measuring the increase in weight and in density, by direct chemical analyses, and by making use of infrared spectroscopy and gel‐permeation chromatography. It was found that the surfaces of the crystals are attacked at room temperature by ozone, with resulting chain scission, and the broad features of the chemical reaction were established. Some folded chains are found to be as long as the original thickness of the crystal, and once folds have been cut, continuing reaction shortens the chains. In the early stages of the degradation, during which most of the weight increase takes place, the density of the crystals increases, and the magnitude of the increase is that expected from the increase in weight alone, i.e., assuming no increase in effective volume.
Steady flow and dynamic viscosity of branched butadiene–styrene block copolymers
Authors: Kraus Gerard , Naylor F. E. , Rollmann K. W.
Published: April 2003

Steady flow and dynamic viscosities were determined for symmetrical linear and starbranched block copolymers of butadiene and styrene above their upper (polystyrene) glass transition. Block structures examined were B‐S‐B, (B‐S‐)3, S‐B‐S, (S‐B‐)3 and (S‐B‐)4. At constant molecular weight and total styrene content viscosities were greater for polymers terminating in styrene blocks, irrespective of branching. Branching decreased the viscosity of either polybutadiene‐terminated or polystyrene‐terminated block polymers, compared at equal Mw. However, comparisons at equal block lengths showed that the length of the terminal blocks, not the total molecular weight, governs the viscoelastic behavior of these polymers to a surprisingly good approximation. This unusual result is rationalized in terms of the two‐phase domain structure of these polymers, which persists to a significant degree in the melt. Below the glass transition of the polystyrene blocks the effects of branching were masked by differences in the morphology of the domain structure unrelated to branching.
Study of compositional distribution in a styrene–methyl acrylate copolymer by means of density‐gradient centrifugation
Authors: Nakazawa A. , Hermans J. J.
Published: April 2003

Several samples of a copolymer were examined by means of equilibrium centrifugation in a density gradient. The results for the samples without compositional distribution (homogeneous polymers) were used to determine the relation between the chemical composition and the distance from the center of rotation. For one of the homogeneous polymers a quantitative analysis of the schlieren curve was made in order to show the kind of accuracy that can be achieved. For the inhomogeneous polymer it was found that the schlieren curve could, in principle, be described quantitatively by the assumption that fluctuations in composition are independent of fluctuations in molecular weight, but on this basis the average square of the fluctuations in composition is more than four times smaller than the value derived from chromatographic data. A more satisfactory explanation of the experimental results is provided by assuming a linear correlation between average molecular weight and composition, but it is not claimed that this is necessarily the only model that explains the data.
Emulsion polymerization of styrene in a single continuous stirred‐tank reactor
Authors: DeGraff Andrew W. , Poehlein Gary W.
Published: April 2003

The effects of mean residence time, initiation rate, and emulsifier concentration on particle formation, particle growth, and polymerization rate are examined for the emulsion polymerization of styrene in a completely mixed continuous stirred‐tank reactor. Experimental measurements of number of particles, particle size distribution, polymerization rate, and molecular weights are compared with theoretical predictions. A theoretical model which incorporates Stockmayer's modification of the Smith‐Ewart theory into the particle growth equation allows reasonably accurate prediction of polymerization rate, particle formation rate, and particle size distribution. Agreement between experimental measurements of number‐average and weight‐average molecular weights and a theory based on Smith‐Ewart case 2 kinetics is also reasonable.
Dynamic mechanical properties of moderately concentrated polystyrene solutions
Authors: Holmes Larry A. , Kusamizu Sumio , Osaki Kunihiro , Ferry John D.
Published: April 2003

The storage (G′) and loss (G″) shear moduli have been measured in the frequency range from 0.04 to 630 Hz for solutions of narrow distribution polystyrenes with molecular weights (M) 19,800 to 860,000, and a few of poly(vinyl acetate), M = 240,000. The concentration (c) range was 0.014–0.40 g/ml and the viscosities of the solvents (diethyl phthalate and chlorinated diphenyls) ranged from 0.12 to 70 poise. Data at different temperatures (0–40°C) were combined by the method of reduced variables. Two types of behavior departing from the usual frequency dependence describable by the Rouse‐Zimm‐Tschoegl theories were observed. First, for M ≅ 20,000, the ratio (G″ − ωηs)/G′ in the neighborhood of ωτ1 = 1 was abnormally large and the steady‐state compliance J was abnormally small, especially at the lowest concentrations studied. Here ω is circular frequency, ηs solvent viscosity, and τ1 terminal relaxation time. Related anomalies have been observed by others in undiluted polymers at still lower molecular weights. Second, at the highest concentrations and molecular weights, a “crossover” region of the logarithmic frequency scale appeared in which G″ − ωηs < G′. The width of this region is a linear function of log c; the frequency dependence under these conditions can be represented by a sequence of Rouse relaxation times grafted on to a sequence of Zimm relaxation times. For each molecular weight, the terminal relaxation time τ1 was approximately a single function of c for different solvents of widely different ηs. At lower concentrations, τ1 was close to the Rouse prediction of 6ηM/π2cRT, where η is the steady‐flow viscosity; but at higher concentrations, τ1 was proportional to η/c2 and corresponded, according to a recent theory of Graessley, to an average molecular weight of 20,000 between entanglement coupling points in the undiluted polymer.
Glass transition in ionic polymers: The acrylates
Authors: Eisenberg A. , Matsura H. , Yokoyama T.
Published: April 2003

It is shown that the glass transition temperatures of the ionic acrylates are subject to the same correlation as found for the phosphates, silicates, and ionenes; the equation is Tg = 730 (q/a) − 67, where q is the cation charge and a the separation between centers of charge for the cation and anion.
Small‐angle light scattering from optically anisotropic spheres and disks. Theory and experimental verification
Authors: Samuels Robert J.
Published: April 2003

The small‐angle light scattering (SALS) theory for optically anisotropic spheres and disks is examined in depth. An error is found in the existing sphere equations. The correct form of the equations is identified and then experimentally verified for dilute starch suspensions. Increased concentrations and solid films of starch granules are used to identify the effect of concentration on the scattering envelope. Spherulitic films of isotactic polypropylene, isotactic polystyrene, nylon 610, PET, and nylon 66 are then used to examine different aspects of the SALS theory. Experimental observations are found to agree with the predictions of the correct SALS equations. Disk theory is interrogated and correlated with predictions for spheres. It is found that the predicted patterns from spheres and disks are very similar under identical optical conditions, in contradiction to earlier predictions. A method is developed for identifying the optical sign of spherulites too small to be seen in the optical microscope. This study constitutes a comprehensive examination of SALS theory and includes many other aspects of the phenomena. A catalogue of theoretical Vv SALS patterns from spheres and disks is also included.
Synthesis of polyimides by photoaddition of bismaleimides to benzene
Authors: Musa Yusuf , Stevens Malcolm P.
Published: April 2003

Polyimides have been synthesized by the sensitized photoaddition of aliphatic and aromatic bismaleimides to benzene. The reaction involves 2+2 cycloaddition to give homoannular diene intermediate followed by Diels‐Alder addition to give polymer. Proof of structure is based mainly on a comparison of infrared spectra with those of the corresponding polyimides prepared from maleic anhydride‐benzene photoadduct and diamines. The very low solubility of the polymers indicates that crosslinking probably occurred during photolysis. All the polyimides appear to decompose by decyclization at about 420–485°C. Polymer yield was dependent on bismaleimide structure.
Organometallic polymers. XVI. Copolymerization of styrenetricarbonylchromium and the reaction of polystyrene with chromium hexacarbonyl
Authors: Pittman Charles U. , Grube Paul L. , Ayers Orval E. , McManus Samuel P. , Rausch Marvin D. , Moser Glenn A.
Published: April 2003

Styrenetricarbonylchromium (IV) has been synthesized. Monomer IV did not homopolymerize with free‐radical initiation but copolymerized with styrene, methyl acrylate, and vinylcymantrene. The copolymerizations were carried out in benzene solutions at 70°C with azobisisobutyronitrile as the initiator. The relative reactivity ratios were determined for the styrene and methyl acrylate copolymerizations. They were (defining M1 as monomer IV) r1 ≅ 0, r2 ≅ 1.39 for styrene copolymerizations and r1 ≅ 0, r2 ≅ 0.75 for methyl acrylate copolymerization. Polystyrene reacted with chromium‐hexacarbonyl in refluxing DME to produce a polymer in which about 32% of the benzene rings were complexed with Cr(CO)3 units. The use of a polystyrene of narrow molecular weight distribution in this reaction demonstrated that no decomposition of the polystyrene chains occurred.
Effects of high pressure on the conductivity and dielectric constant of conductive organic polymers
Authors: Pohl Herbert A. , Wyhof John R.
Published: April 2003

Previous theory for pressure effects on conduction in amorphous macromolecular solids is extended to include pressure effects on hyperelectronic polarization. A theoretical estimate of hopping activation energies is given. Experimental studies of the frequency effects of the pressure coefficients of conduction and permittivity permits resolution of the salient factors. Carrier mobility in ekaconjugated polymers is best represented by activated hopping, for conductivity increase with frequency, and permittivity drops. Conductivity and hyperelectronic polarization increase markedly with pressure. Their activation energies, Ea0, and the pressure coefficients of their activation energies (bE + bH) are nearly identical. Ea0 is frequency‐dependent, but the (bE + bH) terms are not, showing the frequency dependence of Ea0 to lie in the hopping activation enthalpy. Similar arguments on the “total” pressure coefficients b and b for conduction and polarization show the latter coefficients to have a frequency dependence lying in the hopping activation entropy.
Solution properties of ethylene‐vinyl acetate copolymers
Authors: Salyer I. O. , Kenyon A. S. , Ohta M.
Published: April 2003

High‐pressure ethylene–vinyl acetate copolymers of four different chemical compositions(9%, 15%, 45%, and 70% VA) were characterized to determine molecular weight and distribution. The four samples were fractionated by solvent–nonsolvent precipitation methods. Light‐scattering, osmometry, and viscosity measurements were made on these fractionated copolymers to determine weight‐average molecular weight \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {M_w } $\end{document}, number‐average molecular weight \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {M_n } $\end{document}, molecular size in solution, and interaction constants. Dilute solution viscosity was measured on the fractions to determine intrinsic viscosity and Huggins' constant k′. Viscosity–molecular weight equations were established for the four copolymer compositions. The log intrinsic viscosity versus log molecular weight diagrams were analyzed and the average length of branches calculated. The composition of the polymer fractions, determined by C and H combustion analysis, was found not to vary significantly with molecular weight. The uniformly random character of the E/VA copolymers was thereby confirmed. The density of the fractions was determined by density‐gradient column method. Chain sequence distribution of monomer units for the four copolymers was calculated by using IBM 704 computations involving the actual monomer reactivity ratios. Long sequences of either ethylene or vinyl acetate are improbable, except at the extremes of copolymer composition.
Effect of fluid‐phase equilibria on ethylene‐vinyl acetate copolymer composition
Authors: Leder F. , Wisotsky M. J.
Published: April 2003

Literature reports indicate that in the copolymerization of ethylene with vinyl acetate, the reactivity ratios change with pressure. There is general agreement that reth ≅ rvac ≅ 1 at high pressure, but deviations reportedly occur at low pressure. It is shown here that this “pressure dependence” in fact arises from a failure to recognize adequately the importance of fluid‐phase equilibria in the ethylene–solvent system. In order to delineate the two‐phase region, the ethylene–benzene critical locus was measured from the ethylene critical point to 125°C. It was found that the maximum pressure was at about 1700 psia. Above the critical locus the two components are miscible in all proportions, forming a single homogeneous phase. As predicted by phase rule considerations, ethylene‐vinyl acetate copolymers prepared at constant temperature and pressure below the critical locus had fixed compositions. Copolymerizations conducted above the critical locus were not similarly constrained, and polymer compositions varied with operating procedure. This phenomenon is best understood in light of degrees of freedom afforded by the fluid phase equilibria. In either fluid regime the reactivity ratios are shown to be unity and independent of pressure. This was demonstrated at pressures as low as 50 atm.
Cis/trans copolyamides of 1,4‐bisaminomethylcyclohexane
Authors: Prince Frank R. , Turi Edith A. , Pearce Eli M.
Published: April 2003

Copolyamides prepared from cis‐ and trans‐1,4‐bisaminomethylcyclohexane with adipic, sebacic, and dodecanoic acids showed a decrease in melting point with increasing cis diamine content and increasing chain length of the diacid. Most unusual was the fact that the glass transition temperature of these copolymers were essentially independent of diamine isomer content. The existence of an intermediate conformation for some of the cyclohexane rings such as the “twistmer” is suggested to account for this discrepancy. The Tg, Tc, and Tm all decreased with increasing chain length of the diacid. The thermal stability as exemplified by the polysebacamides, was independent of diamine isomer content.
Polymers containing 12‐hydroxymethyltetrahydroabietanol
Authors: Bingham John F. , Marvel C. S.
Published: April 2003

12‐Hydroxymethyltetrahydroabietanol has been polymerized with hexamethylene diisocyanate and a low molecular weight polyurethane produced. Low molecular weight polyurethanes have also been prepared from 12‐hydroxymethyltetrahydroabietyl chloroformate, hexamethylenediamine, and sym.‐dimethylethylenediamine. 12‐Hydroxymethyltetrahydroabietanol has been “end‐capped” with tolylene‐2,4‐diisocyanate and hexamethylene diisocyanate. The resulting diisocyanates have been polymerized with polytetramethylene glycol, hexamethylenediamine and hydrazine.
Polyamides from 12‐(β‐aminoethyl) abietan‐18‐amine
Authors: Bingham John F. , Marvel C. S.
Published: April 2003

The 1:1 salt of 12‐(β‐aminoethyl)abietan‐18‐amine and adipic acid has been prepared and polymerized. This salt has been copolymerized with the 1:1 salt of hexamethylenediamine and adipic acid. 12‐(β‐Aminoethyl)abietan‐18‐amine has been polymerized with isophthaloyl and terephthaloyl chlorides with triethylamine as catalyst and terpolymerized with terephthaloyl chloride and hexamethylenediamine. All polymers have been characterized to some extent, and mechanical properties are reported for two of the polyamide films.
Polymerization of 3,3‐dimethyl selenetane
Authors: Goethals E. J. , Schacht E. , Tack D.
Published: April 2003

3,3‐Dimethyl selenetane has been polymerized under the influence of different cationic and anionic catalysts. Cationic polymerization led to limited conversions because of the occurrence of a termination reaction between the growing chains and the formed polymer. The obtained polymers had low molecular weights. Anionic polymerization gave polymers with molecular weight up to 35,000. The mechanisms of polymerization are believed to be analogous to the mechanisms proposed for the polymerization of thietanes.
Polymerization of diphenylamine with friedel‐crafts/oxidation catalysts to produce thermally stable polymers
Authors: Ellis Bryan , Stevens J. V.
Published: April 2003

The synthesis of polymers from diphenylamine by use of ferric chloride and aluminum chloride–cupric chloride catalyst–oxidant systems has been studied. Optimum conditions for yield and thermal stability were determined for the aluminum chloride–cupric chloride systems. Thermal stabilities in air were between 450 and 500°C. Infrared and ultraviolet spectra indicate that reaction has taken place by direct nuclear coupling.
γ‐radiation‐initiated emulsion polymerization of n‐butyl acrylate and of methyl methacrylate
Authors: O'Neill Thomas , Hoigné Jürg
Published: April 2003

We have investigated the γ‐radiation‐initiated polymerization of n‐butyl acrylate (BA) and of methyl methacrylate (MMA) in aqueous emulsions stabilized with sodium lauryl sulfate (SLS). The reaction rate, as measured by a nonabsolute thermocouple technique, varies as the square root of emulsifier concentration for both monomers. In the case of BA, the dose rate exponent of the reaction rate is 0.7 ± 0.3, whereas the corresponding value for MMA is approximately 0.4. The overall activation energy of the BA polymerization is close to zero, whereas for MMA a value of 4.8 ± 2.1 kcal/mole has been found. The poly(butyl acrylate) molecular weight is effectively independent of soap concentration and of dose rate but decreases as the reaction temperature is increased in the range 30–70°C. The general conclusion drawn from this work is that these radiation‐induced emulsion polymerizations differ little from conventionally initiated systems insofar as the reaction kinetics are concerned. Poly(butyl acrylate‐g‐methyl methacrylate) copolymers have been prepared by a direct irradiation method involving a poly(butyl acrylate) prepolymer seed latex. Some physical properties of this material have been examined.
Polymers of tertiary amines
Authors: Henrici‐Olivé G. , Olivé S.
Published: April 2003

Polymers of tertiary amines and their hydrochlorides of molecular weights in the range 300–2000 have been prepared, starting from trans‐1,4‐dichlorobutene‐2, and primary amines. The polymers present interesting solubility properties. Variation of the reaction conditions leads to crosslinked insoluble polymers. Reaction of the soluble tertiary amine polymers with organic acid dichlorides leads to polymers of tertiary amine–amides, a new type of polymer.
Solute absorption into molten polystyrene
Authors: Covitz F. H. , King J. W.
Published: April 2003

The equilibrium volatilities at near infinite dilution of various solutes absorbed in molten polystyrene have been determined by a gas chromatographic technique. This method is much more rapid, although, with the present apparatus, probably less accurate than conventional static techniques. The primary parameters obtained from measurements of retention volumes are the Henry's law constants, from which are derived the weight and volume fraction activity coefficients, the Flory‐Huggins interaction parameters, and the heats of dilution and solution.

Of the solutes investigated, 2‐butanone (MEK) was the least, and benzene the most compatible (highest and lowest volume fraction activity coefficients, respectively) with molten polystyrene. A small, but definite, variation of the activity coefficients with polystyrene molecular weight was observed.
The use of organotin compounds in the thermal stabilization of poly(vinyl chloride). Part III. Reactions of dialkyltin mercaptides, thioglycollates, and carboxylates with chlorohydrocarbons
Authors: Ayrey G. , Poller R. C. , Siddiqui I. H.
Published: April 2003

Reactions of dialkyltin mercaptides, thioglycollates, and carboxylates with the poly‐(vinyl chloride) model compounds tert‐butyl chloride and 3‐chlorobut‐1‐ene have been studied. At 180° the tertiary and allylic chlorine atoms in the model compounds undergo exchange reactions with the SR, SCH2COOR, and OCOR groups attached to tin. In the case of 3‐chlorobut‐1‐ene, the exchange reactions are accompanied by allylic rearrangements. The relevance of these results to the stabilization of poly(vinyl chloride) is discussed.
Heterogeneous grafting of polypropylene and physical properties of graft blends
Authors: Jabloner H. , Mumma R. H.
Published: April 2003

Polypropylene powder, as formed by typical Ziegler catalysts, can conveniently be hydroperoxidized in aqueous slurry. A cationic surfactant and potassium persulfate are used to achieve wetting and initiate oxidation. It is proposed that specific reaction between the quaternary ammonium cations and persulfate anion generates a water‐insoluble persulfate which decomposes to yield a hydrophobic radical species which initiates oxidation. Graft copolymers were prepared by using this polypropylene hydroperoxide, a redox catalyst, and either dimethylaminoethyl methacrylate or n‐butyl acrylate. These graft copolymers, dispersed in polypropylene, form two‐phase systems in the solid state. Under synthesis conditions which are believed to yield long side chains, the dispersed, more polar polymer was found in larger domains than observed with shorter side chains. Polypropylene spherulites were also distorted, although per cent crystallinity of the continuous polypropylene phase was hardly affected by the presence of graft. Mixtures of poly(propylene‐g‐butyl acrylate) and polypropylene are rather extensible and of low modulus. Low temperature tensile impact values are only slightly higher than for pure polypropylene. Addition of poly(butyl acrylate) to these blends increases both the low‐speed modulud and high‐speed tensile impact relative to the two component blends.
Optically active hydrocarbon polymers with aromatic side chains. II. Poly‐(S)‐p‐sec‐butylstyrene
Authors: Ciardelli F. , Pieroni O. , Carlini C. , Menicagli C.
Published: April 2003

The synthesis of optically active p‐sec‐butylstyrene (I) has been carried out starting with (S)‐2‐phenylbutane (II) having optical purity 88–91%. The optical purity of I thus obtained was found to be 73–75%. The polymerization of I with stereospecific coordinated anionic catalysts gave amorphous polymers, as in the case of many other p‐substituted styrene derivatives. The fractions obtained from these polymers have very similar rotatory power at 589 nm which is practically equal to that of polymer of I obtained by nonstereospecific radical initiator and of low molecular weight structural models. Accordingly the 1Lb electronic transition of the aromatic chromophore shows a very low rotatory strength in all samples examined. This result is related to the lack in solution of conformations with a predominant single chirality of the main chain of the macromolecules derived from I.
Radical terpolymerization of sulfur dioxide, styrene, and methyl methacrylate
Authors: Matsuda Minoru , Iino Masashi , Numata Shun‐Ichi
Published: April 2003

The radical terpolymerization of sulfur dioxide, styrene, and methyl methacrylate in o‐dichlorobenzene with 2,2′‐azobisisobutyronitrile was carried out in order to clarify the propagation mechanism of the radical copolymerization of sulfur dioxide and styrene, especially as a function of total concentration of sulfur dioxide and styrene. From the analysis of the trigonal composition diagrams it has been definitely shown that the radical copolymerization of sulfur dioxide and styrene proceeds by the propagation of two monomers, but the usual type of copolymerization mechanism, explicable in terms of the Lewis‐Mayo equation, is not applicable to this copolymerization. The participation in the propagation of a monomer charge‐transfer complex consisting of sulfur dioxide and styrene was also ruled out.
Radical copolymerization of sulfur dioxide and chloroprene
Authors: Matsuda Minoru , Hara Yoshinori
Published: April 2003

The radical copolymerization of sulfur dioxide and chloroprene (CP) in benzene was carried out, especially as a function of the total monomer concentration ([SO2] + [CP]). The composition of chloroprene polysulfones varies mainly with total monomer concentration and with polymerization temperature, but depends very slightly on feed composition. The microstructure of chloroprene units in chloroprene polysulfone was such that the trans‐1,4 unit was predominantly over the cis‐1,4 unit. Thus it would seem possible to rule out both radical copolymerization mechanisms, i.e., propagation of separate monomers as explained by the Lewis‐Mayo equation, and propagation processes involving a monomer charge‐transfer complex.
Use of gel‐permeation chromatography in the determination of the composition of two‐polymer mixtures
Authors: Menin Jean‐Pierre , Roux René
Published: April 2003

The possibility of evaluating with acceptable accuracy the composition of a two‐polymer mixture which is well separated by GPC, was studied by using mixtures of high molecular weight polybutadiene (M̄w = 4.5 × 105) and low molecular weight polyiso‐butylene (M̄n in the range of 103). It was concluded that a satisfactory evaluation of the composition of a polymer mixture can be achieved, provided that the variations of the refractive index with the molecular weight are taken into account for the low molecular weight polymer (the polyisobutylene).
Disposition of D‐glucopyranosyl units on the surfaces of crystalline elementary fibrils of cotton cellulose
Authors: Rowland Stanley P. , Roberts Earl J.
Published: April 2003

The results from two different chemical approaches to study the disposition of D‐glucopyranosyl segments of the cellulose chains on the surfaces of microstructural units accessible to chemical reagents in cotton cellulose are compared, correlated, and rationalized. These studies provide the basis for a suggested disposition of D‐glucopyranosyl units in the crystalline surfaces of elementary fibrils, for a proposed arrangement of hydrogen bonds on these surfaces, and for estimates of the size of the elementary fibrils.
Synthesis and characterization of some new polymeric peroxycarbamates
Authors: Baysal B. M. , Short W. T. , Tobolsky A. V.
Published: April 2003

The synthesis and characterization of several polymeric peroxycarbamates prepared by successive reaction of poly(ethylene oxides), first, with diisocyanates, and then with hydroperoxides, are described in detail for bis(2,5‐dimethyl‐2‐hydroperoxyhexane peroxycarbamate) polyethers, the chain‐extended analogs of these peroxycarbamyl polyethers and for bis(α‐cumyl peroxycarbamate) polyether. The polymerization of styrene with this last initiator was studied at 60, 80, and 100°C. Both low‐ and high‐conversion polymerizations were studied. The relationship between the rates of initiation and the inverse degree of polymerization was determined.
Polymers of C1C4 paraffin hydrocarbons from an RF discharge: Characterization and reactivity
Authors: Wendel C. T. , Wiley M. H.
Published: April 2003

The polymers deposited from mixtures of argon and the vapors of methane, ethane, propane, and n‐butane subjected to excitation in a 30‐MHz discharge have been analyzed by infrared absorption techniques and for elemental composition. The polymers show unsaturation, crosslinking, and branching. The stability of the polymers to atmospheric oxidation is discussed.
Telechelic diene prepolymers. IV: Anionic polymerization studies
Authors: Reed Samuel F.
Published: April 2003

The preparation and characterization of functionally terminated polybutadienes by an anionic polymerization technique is described. Prepolymers possessing hydroxyl end‐groups were synthesized via vacuum‐line methods. Characterization was completed through endgroup, functionality, molecular weight, molecular weight distribution, and microstructural analyses. Emphasis was placed on the reproducibility in the properties of the prepolymers, particularly in their functionality.
Sulfur‐containing polymers. II. Preparation and properties of polycarbamoylsulfenamides
Authors: Kobayashi Norio , Fujisawa Tamotsu
Published: April 2003

Polycarbamoylsulfenamides have been prepared by interfacial and solution polycondensation of chlorocarbonylsulfenyl chloride with diamines. In preparing the polycarbamoylsulfenamides, the following types of diamines were used: primary aliphatic diamines, a mixed primary‐secondary aliphatic diamine, primary aromatic diamines, and secondary aromatic diamines. The properties of the resulting polymers depended primarily on the kind of diamines used. Transparent, tough films were obtained from the polymer based on N,N′‐dimethyl‐4,4′‐diaminodiphenylmethane. The photochemical decomposition of the polymers has been studied.
Electrical properties of an epoxy resin during and after curing
Authors: Adamec Vladimir
Published: April 2003

By means of an epoxynovolac resin with BF3 complex the suitability of measurements of electrical properties for the investigation of curing process and for the evaluation of cured resins is illustrated. The origin of electrical conductivity and polarization is elucidated.
Stereochemistry of alternating isobutene–maleic anhydride, isobutene–dimethyl fumarate, and isobutene–dimethyl maleate copolymers
Authors: Bacskai R. , Lindeman L. P. , Rabenstein D. L.
Published: April 2003

The stereochemical composition of the free radical alternating isobutene–maleic anhydride (IB/MA), isobutene–dimethyl fumarate (IB/DMF), and isobutene–dimethyl maleate (IB/DMM) copolymers was investigated by proton magnetic resonance. In contrast to the singlet gem‐dimethyl resonance found in polyisobutene or in the alternating isobutene/acrylonitrile copolymer, the gem‐dimethyl resonance of IB/MA, hydrolyzed IB/MA, and esterified IB/MA is a quadruplet with peaks of approximately equal intensity. The multiplicity of the spectra is consistent with the presence of equal amounts of threo‐di‐isotactic and threo‐di‐syndiotactic triads, disproving previous claims that such copolymers are predominantly threo‐di‐isotactic. The spectrum of the analogous IB/DMF indicates that the copolymer is composed entirely of erythro‐di‐ isotactic and erythro‐di‐syndiotactic triads. This result is consistent with the exclusive trans opening of the dimethyl fumarate double bond and provides the first example for the stereospecific double bond opening of a noncyclic monomer in free radical polymerization. In contrast, the spectrum of IB/DMM shows that the dimethyl maleate double bond opens approximately 93% cis and 7% trans during copolymerization. Since the stereochemical composition of IB/DMF and IB/DMM is not the same, it is concluded that the radicals formed from dimethyl maleate and/or dimethyl fumarate do not equilibrate freely among all the possible configurations before isobutene addition.
Photodegradable polyamides
Authors: Takahashi Hiroshi , Sakuragi Masako , Hasegawa Masaki , Takahashi Hiroshi
Published: April 2003

Unique photodegradable polyamides have been prepared by solution polymerization of diphenyl α‐truxillate or δ‐truxinate with hexamethylene or nonamethylenediamine, followed by melt polymerization. Photochemical properties of resulted polyamides were studied spectroscopically and are discussed in terms of photoreversibility and monomeric derivatives for comparison. Solution viscosity of the polymer was decreased by irradiation with a high‐pressure mercury lamp. The polymers from α‐truxillic acid depolymerize by the action of monochromatic light of 224 mμ to give rise to cinnamyl groups faster than those from δ‐truxinic acid. On the photodegradation of polyalkylene‐δ‐truxinamide, two types of scission of cyclobutane were found: symmetrical scission, giving rise to two cinnamyl groups, and a symmetrical scission, giving rise to one trans‐stilbene and one fumaramide linkage. The intense absorption peak due to cinnamyl groups at 272 mμ of partially photodepolymerized films diminished by the action of 304 mμ light; this can be accounted for by the recombination of cinnamyl groups into cyclobutane ring and some unidentified crosslinking reactions. The photochemical behavior of cyclobutane in the polyamides studied proved to be consistent with that of monomeric derivatives reported previously. The study on thermal properties of the polymers by DTA and TGA revealed that this type of polyamide is quite stable as high as 350°C unless significant steric effects are involved.
Molecular weight distributions in radiation‐induced polymerization. IV. A comprehensive kinetic scheme for polymerization in the liquid state
Authors: Westlake John F. , Huang Robert Y.
Published: April 2003

A comprehensive kinetic scheme is proposed which takes into consideration γ‐ray‐initiated polymerization via free radical, cationic, or radical‐cationic species, or their combinations, and the relative contribution of each depending upon experimental conditions. From this kinetic model, equations describing the kinetics of polymerization and the resulting molecular weight distributions have been derived. The resulting expressions are complex in nature, particularly for the case where a combination of mechanisms is involved. In view of this, a general approach to the problem of generating theoretical molecular weight distributions based on the application of high speed digital computers has been presented. The proposed technique is particularly powerful since no simplifying assumptions or mathematical approximations are required in order to obtain the molecular weight distribution.
Molecular weight distributions in radiation‐induced polymerization. V. A simultaneous kinetic and molecular weight distribution analysis of the liquid‐state polymerization of styrene
Authors: Westlake John F. , Huang Robert Y.
Published: April 2003

The γ‐ray initiated polymerization of styrene in the liquid state was investigated over the temperature range 0 to −29°C at constant dose rate. The kinetics and molecular weight distributions were studied for samples prepared by standard techniques and samples subjected to exhaustive drying to remove residual water. In the former case, the rates of reaction were comparable to those for purely free radical polymerization, however, the resulting molecular weight distributions were distinctly bimodal, indicating an additional contribution from the cationic mechanism. On the other hand, the rates of polymerization for rigorously dried samples were 2 to 3 orders of magnitude greater than accepted free‐radical values, and the molecular weight distributions were unimodal in nature. The experimental results were compared with theoretical kinetic data and molecular weight distribution data generated from a kinetic scheme taking into consideration polymerization via free‐radical, cationic, and radical‐cationic species, resulting in the evaluation of a number of quantities of interest. Substitution of determined values for the rate constants and G values results in good agreement between theoretically generated and experimentally determined kinetic data and molecular weight distribution data over the range of experimental conditions studied.
Radical polymerization of vinyl acetate with primary radical termination
Authors: Ito Katsukiyo
Published: April 2003

Vinyl acetate was polymerized at high initiation rate with 2,2′‐azobis(2,4‐dimethyl valeronitrile) as initiator at 50°C. In this polymerization, the power dependence of polymerization rate on the initiation rate is smaller than at lower concentration of monomer. This dependence was kinetically analyzed at each given concentration of monomer. Average degree of polymerization of polymer formed depends on the concentration of initiator. This dependence was explained by considering chain and primary radical terminations and transfer to monomer of polymer radical, and the initiator efficiency (=0.503) was deduced. It was found that the chain termination is inversely proportional to solvent viscosity, but the primary radical termination is not inversely proportional to solvent viscosity. Further, the value of the primary radical termination rate constant (=1.4 × 109l./mole‐sec) was estimated.
Thermal degradation of polyurethanes based on xylylene diisocyanates
Authors: Rumao L. P. , Frisch K. C.
Published: April 2003

Polyurethanes derived from xylylene diisocyanates and trans‐1,4‐cyclohexanedimethanol were thermally degraded by using the techniques of thermogravimetry and pyrolysis at atmospheric pressure. Quantitative determination of the pyrolysis products such as CO2, diamine, olefin, and starting diol showed that these polyurethanes follow the typical mechanism of degradation via dissociation into starting diol and diisocyanate. Kinetic parameters for the overall degradation reaction were determined using four different methods. The results showed the influence of the experimental technique used when making a comparison of the thermal stability of polymers, as determined by the kinetic parameters of the degradation reactions.
Dye‐sensitized photopolymerization of vinyl monomers in the presence of ascorbic acid–sodium hydrogen orthophosphate complex
Authors: Nagabhushanam T. , Santappa M.
Published: April 2003

The kinetics of photopolymerization of vinyl monomers (methyl methacrylate, methylacrylate, and acrylonitrile) sensitized by the dyes acridine orange, dahlia violet, rose bengal and Pyronine G have been studied systematically. Systems containing dye, reducing agent, and monomer were irradiated with light of wavelengths 365 mμ, 546 mμ, and 405 mμ. The induction period was kept to a minimum by suitable experimental conditions. All experiments were conducted under deaerated conditions. The complex, AA–B, formed between ascorbic acid and sodium hydrogen orthophosphate (of the buffer) and reported earlier from our laboratory, played an important role in the production of the free radicals. The course of the polymerization reaction was followed by the measurements of rate of monomer disappearance −d[M]/dt (gravimetrically), rate of dye disappearance −d[D]/dt (spectrophotometrically), and the chainlengths n, of the polymer formed (viscometrically); light intensity, light wavelength, and concentrations of the dye, reducing agent, and monomer were the various variables for these measurements. A tentative scheme based on the excitation of the dye in the primary photochemical act and the interaction of the excited dye with the complex AA–B in the dark resulting in radicals (from ascorbic acid) which initiate vinyl polymerization is proposed, and the experimental results are found to conform to such a scheme. The values of various ratios of rate constants such as kp/kt½, kr/k7, ki/k6 were calculated and are discussed.
Polymerization by oxidative coupling. IV.. Synthesis and properties of poly(2‐methyl‐6‐phenylphenylene ether)
Authors: White D. M. , Klopfer H. J.
Published: April 2003

Copper‐amine catalyst systems which polymerize 2‐methyl‐6‐phenylphenol to high molecular weight polymer are described. With CuCl and N,N,N ′,N′‐tetramethyl‐1,3‐butanediamine (TMBD), an intrinsic viscosity of 1.56 dl/g was obtained. Faster rates of polymerization resulted with a CuBr‐TMBD catalyst. Catalysts from other tertiary amines and mixtures of tertiary amines also produced high polymer. Pyridine and diethylamine catalyst were less active. Samples of polymer were isolated at different stages of the polymerization. Measurements of viscosity, osmotic pressure, light scattering, gel permeation, hydroxyl groups, nitrogen content, and chemical reactivity were made on the samples. Below a molecular weight value of M̄n 60,000, M̄n/M̄w was 2.0. At higher molecular weights, there was a broadening in molecular weight distribution. No major change in the molar concentration of the “;head” endgroups with increasing molecular weight was detected by infrared analysis. However, nitrogen analyses, chemical reactivity studies, and the M̄n/M̄w ratio suggested the chemical nature of the “head” end had changed. The relationships between intrinsic viscosity in chloroform at 25°C and M̄n and M̄w for unfractionated polymer samples are log [η] = −4.26 + 0.84 log M̄n and log [η] = −3.86 + 0.70 log M̄w.
Effect of amount of medium on the radiation‐induced polymerization of ethylene in tert‐butyl alcohol
Authors: Wada Takeshi , Watanabe Terutaka , Takehisa Masaaki
Published: April 2003

The kinetics of the radiation‐induced polymerization of ethylene in the presence of various amounts of medium (tert‐butyl alcohol containing 5 vol‐% of water) was studied, and the effect of the amount of medium on the polymerization was investigated. The polymerization was carried out by use of a reactor of 100 ml capacity under the following conditions: temperature, 24 ± 3°C; pressure, 200 kg/cm2; dose rate, 2.0 × 104−1.6 × 105 rad/hr. The amount of polymerized monomer and the rate of polymerization were maximum when about 50 ml of the medium was used. Data obtained with the use of 30, 50, and 90 ml of the medium were analyzed kinetically and the rate constants of each elementary reaction were determined by the method based on a reaction mechanism which contains both first‐ and second‐order terminations for the concentration of propagating radical. These results were compared with those obtained with the use of 70 ml of the medium already reported in the previous paper. The dose rate exponents of the rate of polymerization were about 0.7–0.8. It was found that G values for the initiation of ethylene and the medium were 1.5 and 3.8, respectively, and the rate of propagation was proportional to the fugacity of ethylene. It is supposed that the medium plays an important role in the first‐order termination, because the apparent rate constant of the reaction was larger when a larger amount of medium was used.
Water‐soluble cellulose derivatives prepared by the action of solutions of nitrogen dioxide in dimethylformamide
Authors: Clermont L. P. , Bender F.
Published: April 2003

Cellulose derivatives soluble in water and in dilute alkali were prepared by dissolving a bleached sulfite pulp in solutions of nitrogen dioxide in dimethylformamide (DMF) and heating at 70–90°C for 1–3 hr. No cellulose oxidation was detected. Nitrite esters and apparently also, nitrate esters, were formed with degrees of substitution (DS) ranging from 0.18 to 0.55 and with nitrogen contents ranging from 1.47 to 4.32%. Solution viscosities in water increased with increasing nitrogen content. The degree of polymerization (DP) decreased rapidly in the initial stages of the reaction followed by a slow, gradual decrease with increasing reaction times.
Photopolymerization V. Unsensitized solution photocyclopolymerization of N,N ′‐alkylenebismaleimides
Authors: De Schryver F. C. , Boens N. , Smets G.
Published: April 2003

The term, “photopolymerization,” is defined as a polymerization process in which every chain‐propagating step involves a photo‐chemical reaction. This type of polymerization is exemplified by the unsensitized solution photocyclopolymerization of several N,N ′‐alkylenebismaleimides, substituted at the double bond. N,N ′‐Alkylenebismaleimides substituted with a bromine atom or two methyl groups at their double bond produce high polymeric products upon ultraviolet irradiation in solution. A general reaction scheme for the photopolymerization is proposed. Kinetic measurements show that the solution photopolymerization of substituted bismaleimides is a multistep reaction.
Polymerization of vinyl chloride and copolymerization with carbon monoxide by a new initiator
Authors: Kawai Wassaburo , Ichihashi Taichi
Published: April 2003

The system comprising the ethoxydized product of triethylaluminum, cuprous chloride, and carbon tetrachloride was used as an initiator for polymerization of vinyl chloride, and the polymerization kinetics was studied. From plots of the molar number of number‐average polymer chain Y/P̄ versus yield Y, the two parameters a ( = ∫ Ridt − 1/2 ∫ Rtdt) and b ( = ∫ Rtrdt/∫ Rpdt) were estimated to be 6 × 10−3 mole/l. and 6.6 × 10−4 respectively. Studies of the tacticity of the poly(vinyl chloride) showed isotactic = 49.3% and syndiotactic = 50.7%. The present initiator also permitted copolymerization of vinyl chloride with carbon monoxide; the monomer reactivity ratios were r1 = 0.40 (vinyl chloride) and r2 = 0.01 (carbon monoxide).