bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetics of polymerization of N‐tert‐butylacrylamide. Part II
Authors: Cavell E. A. S. , Gilson I. T.
Published: April 2003

The effect of ferric chloride on the kinetics of the radical polymerization of N‐tert‐butylacrylamide has been investigated in methanol solution at 25°C, with the use of 4,4′‐dicyano‐4,4′‐azodipentanoic acid as initiator. A shrinkage factor of 0.193 mmole polymerized for 1 mm contraction in a capillary of 1 mm diameter has been obtained from density measurements. In the absence of ferric chloride, rates of polymerization were found to be proportional to the concentration of monomer and to the square root of the initiator concentration. With ferric chloride present, the rate of polymerization becomes directly proportional to the initiator concentration and inversely proportional to the concentration of ferric salt. From measurements of the rates of production of ferrous iron, the specific rate constant of the initiation reaction has been found to be (1.8 ± 0.4) × 10−6sec−1 at 25°C, compared with a value of 7.63 × 10−8 sec−1 calculated from the kinetic data obtained with no ferric salt present. The value of the ratio kp/k4. where kp is the propagation coefficient and k4 is the velocity coefficient for termination by ferric chloride, has been calculated to be 6.0 × 10−4 at 25°C, which is considerably smaller than the value found for the ferric chloride‐terminated polymerization of acrylamide in water. This markedly lower value of kp/k4 has been attributed principally to the steric effect of the tert‐butyl group on the magnitude of kp.
Synthesis of difunctional polystyrenes and their incorporation in block copolymers with bisphenol a polycarbonate
Authors: Berger M. N. , Boulton J. J. K. , Brooks B. W.
Published: April 2003

Block polymers of polystyrene and bisphenol A polycarbonate have been prepared and their bulk viscosities studied as functions of both shear stress and polystyrene block length. The polystyrene blocks were α,ω‐diacid chlorides prepared from the reaction of “living” polystyrenes with diacid chlorides. These reactions were studied in order to discover the most effective way of preparing the polystyrene diacid chlorides. The polystyrene diacid chlorides are best prepared by reaction of disodiopolystyrene with phosgene. The flow properties of the block copolymers depend on the composition of the polymers but do not depend on the length of the polystyrene blocks.
Fluorocyclopropanes. IV. Copolymers of perfluorocyclopropene
Authors: Sargeant P. B. , Krespan C. G.
Published: April 2003

Perfluorocyclopropene undergoes free‐radical copolymerization with ethylene, isobutylene, cis‐ and trans‐2‐butene, vinyl acetate, methyl vinyl ether, vinyl chloride, styrene, acrylonitrile, tetrafluoroethylene, vinyl fluoride, and vinylidene fluoride. The copolymerization proceeds most readily with electron‐rich olefins such as methyl vinyl ether (to yield a 1:1 copolymer), but conditions were found to give copolymers with electron‐deficient olefins such as tetrafluoroethylene and vinylidene fluoride. Copolymers with methyl vinyl ether, tetrafluoroethylene, vinyl fluoride, and vinylidene fluoride were examined in detail. Evidence is presented that the perfluorocycloproply ring is incorporated intact into the copolymer and can be subsequently isomerized to a perfluoropropenyl unit by heating at 200–300°C.
ESR spectra of poly(methacrylic acid) and poly(methyl methacrylate): Reinterpretation of the 9‐line spectrum
Authors: Iwasaki Machio , Sakai Yoshiro
Published: April 2003

The temperature dependence of the ESR spectra of poly(methacrylic acid) and poly‐(methyl methacrylate) γ‐irradiated at room temperature was studied between −196°C and +25°C. The conventional 9‐line spectrum was observed throughout this range with no significant spectral change, in contrast to the propagating radical ··· CH2°C(CH3)COOR found in methacrylic acid monomer or barium methacrylate dihydrate irradiated at −196°C. In addition, the irradiation of methacrylic acid monomer with a low dose at 0°C gave the same 13‐line spectrum as that of the propagating radical obtained by the irradiation at −196°C, while prolonged irradiation at 0°C gave the same conventional 9‐line spectrum as that of poly(methacrylic acid) or poly(methyl methacrylate). The conventional 9‐line spectrum has a much weaker 4‐line component than that of the propagating radical. The difference comes from the surrounding matrix, and the conventional 9‐line spectrum is well interpreted by introducing the concept of the distribution of the conformational angle in the irregular polymer matrix. From simulation of the ESR spectrum, it was found that the intensity of the 4‐line component is very sensitive to the distribution, and that the observed 9‐line spectrum is well reproduced assuming a Gaussian distribution (half‐height width of 5–6°) around the most probable conformation which is nearly the same as that of the propagating radical, where the conformational angles of the two CHβ bonds to the half‐filled p‐orbital are 55° and 65°.
Oxidative polymerization of diethynyl compounds
Authors: Hay Allan S.
Published: April 2003

Diethynyl compounds are readily polymerized to high molecular weight linear polymers by oxidative coupling with oxygen in the presence of an amine complex of a copper salt as catalyst. Organometallic moieties can also be introduced into these polymers. Thus polymers in which silicon, arsenic, and mercury are part of the polymer backbone have been synthesized.
Cocatalysis by epoxides in the polymerization of tetrahydrofuran with trityl hexachloroantimonate initiator
Authors: Kuntz Irving , Melchior M. T.
Published: April 2003

The polymerization of tetrahydrofuran (THF) with (C6H5)3C+SbCl6‐ initiator is markedly accelerated by small concentrations of propylene oxide or other epoxides. Molar concentrations of propylene oxide 4 to 10 times those of the carbonium‐ion salt showed increasing conversion to polymer. The equilibrium conversion level at different temperatures with epoxides is the same as in their absence; the approach to equilibrium is first‐order in THF. NMR experiments in the presence of propylene oxide indicate the formation of a trityl ether intermediate. The cocatalysis effect is interpreted on the basis of an acceleration in the initiation process in the system.
Dilute solution properties of a polyurethane. I. Linear polymers
Authors: Beachell Harold C. , Peterson Jean C.
Published: April 2003

A linear polyurethane of high molecular weight was prepared in solution by the polyaddition of equimolar amounts of ethylene glycol and methylene bis(4‐phenyl isocyanate). The polymer was fractionated by using a direct sequential extraction procedure, with a solvent–nonsolvent system consisting of N,N′‐dimethylformamide (DMF) and acetone (A). The resulting fractions were characterized by viscosity and lightscattering measurements. The relationship between the intrinsic viscosity and molecular weight was found in DMF at 25°C. to be [η] = 3.64 × 10−4M0.71. The unperturbed polymer chain dimensions were determined from intrinsic viscosity measurements carried out under experimentally determined theta conditions.
Radical polymerization behavior of hydroxystyrenes
Authors: Kato Masao
Published: April 2003

Homopolymerizations of m‐ and p‐hydroxystyrene and their copolymerizations with styrene and methyl methacrylate by use of azobisisobutyronitrile as initiator were investigated, and the results were compared with those obtained previously o‐hydroxystyrene. Intrinsic viscosities of m‐ and p‐hydroxystyrene polymers obtained by bulk and solution polymerizations were ca. 2 to 3 times larger than those of o‐hydroxystyrene polymers obtained by the similar conditions. The structures of the polymers thus produced were investigated by infrared and ultraviolet spectroscopy. These studies suggested that all of the homopolymers consisted mainly of structures of normal vinyl type polymer. Rp was proportional to [I]0.52 for m‐hydroxystyrene and to [I]0.50 for p‐hydroxystyrene, for o‐hydroxystyrene Rp was proportional to [I]0.72. A reasonable chain transfer mechanism for these monomers was postulated. The apparent activation energies of polymerization for m‐ and p‐hydroxystyrene were found to be 20.1, and 18.0 kcal/mole, respectively, compared to the value of 21.5 kcal/mole for o‐hydroxystyrene. Monomer reactivity ratios and Q − e values for m‐ and p‐hydroxystyrene were determined, and the results were also compared with the case of o‐hydroxystyrene. Copolymerization generally gave a polymer with relatively high intrinsic viscosity, even in the case of o‐hydroxystyrene.
Influence of structure of 1,1,3‐trimethyl‐5‐carboxy‐3‐(p‐carboxyphenyl)indan upon polyamide properties
Authors: Ridgway James S.
Published: April 2003

Copolyamides of nylon 66 and 1,1,3‐trimethyl‐5‐carboxy‐3‐(p‐carboxyphenyl)indan (PIDA) were prepared by melt polycondensation of nylon 66 salt with PIDA in combination with hexamethylenediamine, trans‐1,4‐cyclohexanebis(methylamine), and m‐xylylenediamine. In addition, hexamethylenediamine‐PIDA was incorporated into the copolymer system of nylon 66–poly(hexamethylene terephthalamide). The effect of PIDA upon the intrinsic viscosity, crystallinity, density, melting point, moisture regain, tenacity, initial modulus, and the boiling‐water shrinkage of such polyamides was determined. Particular emphasis was placed upon the influence of PIDA on the glass transition temperature of the polyamides. The effect of moisture on the glass transition temperature was also discussed. The physical properties of PIDA copolymers indicate that crystallinity virtually disappears above 20 mole‐% PIDA concentration; however, the glass transition temperature measured at 0 and 30% RH increases sharply with increased PIDA concentration.
Copolymerization of acrylonitrile. I. Copolymerization with styrene derivatives containing nitrile groups in the side chain
Authors: Ronel Samuel H. , Kohn David H.
Published: April 2003

Acrylonitrile was copolymerized in bulk with cinnamonitrile (I), ethyl benzylidenecyanoacetate (II), and benzylidenemalononitrile (III) by radical initiation up to low conversions. The conventional scheme of copolymerization fitted all the three copolymer pairs.
Water flow through polymeric and nonaqueous liquid membranes
Authors: Lakshminarayanaiah N. , White M. S.
Published: April 2003

Osmotic and isotopic water flows through polymeric and nonaqueous liquid membranes have been measured. The polymeric membranes were of the polyethylene–styrene graft copolymer type containing sulfonic acid groups. The nonaqueous liquid membranes were water‐saturated 1‐butanol and benzene. Osmotic water flux through both types of membranes was larger than isotopic (THO) water flux. Using these data, values for the equivalent pore radius for these membranes have been derived. The significance of such values has been briefly discussed.
Production of organometallic polymers by the interfacial technique. I. Interfacial production of polyalkyloxysilanes and a study of some reaction variables
Authors: Carraher Charles E.
Published: April 2003

The first interfacial synthesis of polyalkyloxysilanes of the form where R′ = alkylene, and R″, R = alkyl or aryl is reported. It is found, in the range studied for the stirred systems, that as organic solvent viscosity and organic phase volume are increased, rate of polymer formation is decreased. Little difference in polymer formation rate is observed when the nature of the diol is varied, but considerable difference is noted when the nature of the organosilane is varied such that the most electropositive silane has the highest rate of polymer formation. Molecular weight is approximately constant as diol is changed but varies markedly when the silane is changed, so that the silane with the most bulky substance will give polymer with the lowest molecular weight.
Production of organometallic polymers by the interfacial technique. II. Kinetic study of the production of polyoxyethyleneoxy(diphenylsilylene) by the interfacial technique
Authors: Carraher Charles E.
Published: April 2003

The stirred interfacial production of polyoxyethyleneoxy(diphenylsilylene) was found to be five‐thirds order and dependent on the concentrations of both ethylene glycol and diphenyldichlorosilane, indicating that the character of the rate‐determining step involves reaction of the ethylene glycol or ethylene glycol derivative and diphenyldichlorosilane or diphenyldichlorosilane derivative. A model consisting of ethylene glycol droplets residing in the organic phase is proposed which follows the rate expression:

This is in agreement with experimental findings. A rate constant of 1.4 × 10−4c.2/3 m2/3‐sec is found. The rates in unstirred interfacial systems are found to be slower than in the stirred systems.
Polymers from 12‐hydroxymethyltetrahydroabietic acid and its vinyl and acrylate esters
Authors: Saga Motoo , Marvel C. S.
Published: April 2003

12‐Hydroxymethyltetrahydroabietic acid has been homopolymerized by melt condensation and homopolyester has been obtained. Vinyl 12‐hydroxymethyltetrahydroabietate has been prepared from 12‐hydroxymethyltetrahydroabietic acid by vinyl interchange procedure with vinyl acetate, and has been homopolymerized, copolymerized with vinyl chloride, vinyl acetate, and terpolymerized with styrene and acrylonitrile. The acrylate ester of 12‐hydroxymethyltetrahydroabietic acid also has been prepared from 12‐hydroxymethyltetrahydroabietic acid and acrylyl chloride. The acrylate thus obtained has been homopolymerized and copolymerized with vinyl chloride and vinyl acetate. Polymers thus obtained have been characterized.
Reaction of polyepichlorohydrin with magnesium and grignard reagents
Authors: Minoura Yuji , Hironaka Hisashi , Kasabo Toshiyuki , Ueno Yukio
Published: April 2003

The reaction of polyepichlorohydrin with magnesium in tetrahydrofuran at reflux temperature was studied in the hope of obtaining a polymeric Grignard reagent. The polymeric Grignard reagent could not be obtained, but dechlorination occurred. It was confirmed that the Grignard reagent of polyepichlorohydrin was formed as an intermediate during the dechlorination. The reactions of polyepichlorohydrin with Grignard reagents were carried out in tetrahydrofuran at reflux temperature. Benzylmagnesium chloride and allylmagnesium chloride were used as Grignard reagents. It was found that the chlorine atom in polyepichlorohydrin can be replaced by benzyl and allyl groups. The extent of the substitution increased with increasing concentration of Grignard reagent. Dechlorination and scission of the ether linkage occurred simultaneously as side reactions.
Accessibility of cotton and chemically swollen cottons to methylating reagents
Authors: Head Frank S. H. , Hadfield Gladys E.
Published: April 2003

Standard Acala cotton, and modified cottons obtained from it by swelling in 5N sodium hydroxide, 62% sulfuric acid, or 81% phosphoric acid, have been methylated with moist ethereal diazomethane or with a toluene solution of dimethyl sulfate in the presence of 2N sodium hydroxide. The accessibility of cotton to either reagent is increased by swelling in the order sulfuric acid <phosphoric acid <5N sodium hydroxide. Each fiber is more accessible to the alkaline methylating agent than to diazomethane. The results confirm the view of Roberts et al. that a more rapid methylation of accessible hydroxyl groups in the surfaces of crystalline aggregates is followed by a slower penetration of the ordered material. Analysis of the methylated products and interpretation of the results on similar lines suggests that aggregates of approximately two elementary fibrils (found in cotton methylated with moist diazomethane) are split into single fibrils by 81% phosphoric acid or 2N sodium hydroxide and that mercerization transforms the elementary fibrils into smaller units, but an alternative explanation is possible. Progressive penetration of the elementary fibrils by swelling agents may increase the amount of accessible material without decreasing the size of the fibrils.
Kinetics of dispersion polymerization of soluble monomers. I. Methyl methacrylate
Authors: Barrett K. E. J. , Thomas H. R.
Published: April 2003

The kinetics of the free‐radical‐initiated polymerization of methyl methacrylate in n‐dodecane to produce dispersions of polymer stabilized with a steric barrier of soluble polymer chains have been determined by thermal analysis. The mode of the polymerization can be described in terms of a bulk polymerization within the monomerswollen polymer particles. A theoretical expression has been derived on the basis of a reaction scheme in which all the radicals produced in the diluent phase are transferred immediately to the polymer particles, monomer swells the polymer particles in partition equilibrium with monomer in the diluent, and polymerization proceeds within the polymer particle according to the kinetics of bulk polymerization, taking into account Trommsdorff acceleration and plasticization effects.
Radiation chemical studies of protein reactions: Effect of radiation on the breaking of secondary bonding in protein
Authors: Nisizawa Mizuho
Published: April 2003

The effect of radiation on the breaking of secondary bonding in protein was studied by measuring the viscosity change at different radiation doses and urea concentrations. An experimental equation for the viscosity change was obtained, and the observed behavior was explained on the basis of the molecular mechanism. The general equation for the viscosity change is given by ηred = A(X − Be−kx) + C log R, where ηred is the reduced viscosity of the solution, R is the dose of γ‐radiation, X is the concentration of urea, and A, B, C, and k are adjustable constants.
Synthesis of polyamides from rigid and sterically hindered dicarboxylic acids and diamines under mild conditions
Authors: Overberger Charles G. , S̆ebenda Jan
Published: April 2003

The rate of polycondensation of piperazine with the 2,4‐dinitrophenyl, succinimido, phthalimido, and 4‐nitrophenyl esters of bicyclo[2.2.2]octane‐trans‐2,3‐dicarboxylic acid was measured and found to decrease in this sequence. In the reaction of two moles of piperazine with one mole of diester, the reactivity of both ester groups was equal. In equimolar mixtures, the second ester group reacts with the second group about ten times slower because of steric hindrance. In the reaction of the esters with N,N′‐dimethylethylenediamine no such effects were observed. The aminolysis of the N‐hydroxyphthalimido ester stops at low conversions unless a very large excess of triethylamine is added. The catalytic effect of 1,2,4‐triazole on the aminolysis was proportional to the triazole concentration. From the rate of ester consumption in the presence of pure triethylamine, the extent of possible racemization of the optically active dicarboxylic acid was estimated. In view of the rate data, the extent of polycondensation, and side reactions, only 2,4‐dinitrophenyl and N‐hydroxysuccinimido diesters are suitable for the synthesis of polyamides derived from rigid and sterically hindered dicarboxylic acids.
Thermal degradation of polymers with phenylene units in the chain. I. Polyphenylenes and poly(phenylene oxides)
Authors: Ehlers G. F. L. , Fisch K. R. , Powell W. R.
Published: April 2003

The thermal degradation of polyphenylenes and poly(phenylene oxides) was studied under vacuum at temperatures between 350 and 620°C. The volatile and solid degradation products were analyzed by mass spectroscopy, infrared spectroscopy, and elemental analysis. Overall mechanisms for the thermal breakdown have been proposed. Polyphenylene decomposes to form polymer carbon, while hydrogen is the major volatile product. Some ring breakdown occurs with evolution of methane. Poly(phenylene oxide) forms mainly low molecular weight chain fragments, partially with hydroxyl endgroups. Some of the ether linkages decompose with ring breakdown, yielding carbon monoxide, water, and some carbon dioxide. Pendent groups on polyphenylenes and poly(phenylene oxides) are removed at the lower temperatures. The hydroxyl group yields essentially carbon monoxide and dioxide (the carbon being supplied by the rings), the methyl group methane, and the methoxy group methane and some methanol.
Effect of polymer crystallinity on the wetting properties of certain fluoroalkyl acrylates
Authors: Pittman Allen G. , Ludwig Barbara A.
Published: April 2003

The wetting properties of a series of polyacrylates containing the fluoroalkyl group \documentclass{article}\pagestyle{empty}\begin{document}$ [\rlap{--} ({\rm CF}_{\rm 2} \rlap{--} )_2 {\rm CF}_2 {\rm H}\ $\end{document} have been studied. Where n is 7 and 9, the polyacrylates are highly crystalline at room temperature. Since the polymers were prepared under atactic free‐radical conditions and the polyacrylates with shorter alkyl groups (where n is 3 or 5) were not crystalline at room temperature, the crystallinity is presumed to occur as a result of side‐chain packing and not involve the backbone. The polymers become more wet‐table (higher γc) as polymer crystallinity was reduced by quenching or heating past Tm. Correlations have been made between the work of Zisman and co‐workers on the wetting properties of various fluorinated acid monolayers and the wetting properties of these fluoroalkyl acrylates. The results obtained in this study concerning the influence of polymer crystallinity on surface wetting are discussed in relation to the findings of Schonhorn and Ryan on the wettability of polyethylene single crystal aggregates.
Cationic polymerization of α,β‐disubstituted olefins. Part 12. Theoretical consideration of the reactivities of vinyl ethers and β‐substituted vinyl ethers
Authors: Higashimura T. , Masuda T. , Okamura S. , Yonezawa T.
Published: April 2003

To elucidate the propagation mechanism in the cationic polymerization of vinyl ethers and β‐substituted vinyl ethers, the electron distribution in these monomers was computed by the extended Hückel method. Propylene and styrene derivatives were also studied in comparison with the vinyl ether derivatives. Attempts were made to explain the experimental results by various calculated reactivity indices. With the unsaturated hydrocarbons, the reactivity indices on the β‐carbon parallel with the relative reactivity in the cationic polymerization or oligomerization. This agreement suggests that the transition state for the rate‐determining step of the propagation reaction is represented by a model in which the carbonium ion interacts with the β‐carbon of a monomer. On the other hand, the effect of β‐alkyl or alkoxyl groups on the reactivity of vinyl ethers could not be explained by the model in which the carbonium ion interacts with an olefinic carbon or an ether oxygen, or both with two atoms. The following model was proposed on the basis of the electronic stabilization energy due to the de‐
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localization from the occupied orbital of a monomer to the vacant orbital of a carbonium ion. This model can explain reasonably the relative reactivity of vinyl ethers and β‐substituted vinyl ethers observed in the cationic copolymerization catalyzed by BF3·O(C2H5)2.
Polymers derived from 2,5‐diamino‐p‐benzoquinone‐diimide and related compounds
Authors: Szita J. , Marvel C. S.
Published: April 2003

A number of new polymeric materials have been prepared by the self‐condensation of 2,5‐diamino‐p‐benzoquinonediimide and by its condensation with 2,5‐diamino‐p‐benzoquinone, 2,5‐dihydroxy‐p‐benzoquinone, and 2,5‐dichloro‐p‐benzoquinone. Ladder polymers were expected, but in every case polymers with some open rings were obtained. 2,5‐Diaminohydroquinone was condensed with 2,5‐diamino‐p‐benzoquinonediimide and with 2,5‐diamino‐p‐benzoquinone to produce heat stable polymers but the expected ladder structures were not obtained. Thermogravimetric analyses of the polymers in nitrogen all showed a weight loss at 100–150°C of 3–14% which was presumably due to loss of either chemically combined or absorbed water on the polymer and then only a 5% weight loss up to about 600°C with a final weight loss of 19% at 900°C.
Structure and reactivity of α,β‐unsaturated ethers. VII. Electronic effects of the β‐methyl substitution on the cationic polymerizabilities of alkyl vinyl ethers
Authors: Fueno T. , Okuyama T. , Furukawa J.
Published: April 2003

Reactivities of propenyl alkyl ethers toward various cationic agents are summarized, and the effects of a β‐methyl group and geometrical isomerism are discussed on the basis of the extended Hückel molecular orbital theory. The reactions considered include cationic polymerization, acid‐catalyzed hydrolysis, and silver‐ion complexation. The effects of a β‐methyl substitution on the reactivity of vinyl ether are different depending on the type of the reactions. The substitution enhances the reactivity of vinyl ether in homogeneous polymerization, whereas it reduces the reactivity in hydrolysis. This contrasting effect of a β‐methyl group was found to be compatible with the results of the theoretical calculations of the electronic energy changes accompanying the formation of the relevant transition states. A π‐complex‐type transition state was concluded for the cationic polymerization. Several lines of experimental evidence in support of the conclusion are presented.
New polyimides via hydrogen‐transfer polymerization
Authors: Russo Mario , Mortillaro Luigi
Published: April 2003

The synthesis and some properties of new linear polyimides obtained via hydrogen‐transfer polymerization between divinyl sulfone and diimides of tetracarboxylic acids are described.
Primary radical termination rate constant at high conversion in radical polymerization
Authors: Ito Katsukiyo
Published: April 2003

A primary radical termination rate constant given by: kti = A1iDi, where A1i is a constant and Di is the diffusion constant of the primary radical, was examined on the basis of the variation of conversion. It was proved that this rate constant is correct at high conversion. A relationship between primary radical termination rate constant and conversion was derived. The effect of variation of conversion on the gel effect is discussed.
Influence of defects on the infrared spectra of polymers
Authors: Opaskar C. G. , Krimm S.
Published: April 2003

For an infinitely repeated regular polymer chain structure the only vibrations which are optically active are those in which the phase of the motion is the same in each unit (the factor‐group modes). Frequencies for which the phase difference is nonzero are optically inactive but can become activated by the presence of defects in the chain. Such defects would normally be chemical impurities or conformational irregularities in the chain. A simple theory is developed which shows that for a dilute system of defects the major characteristics determining possible activation of the nonfactor‐group modes are: (1) the strength of the coupling between the defect vibration and the vibrations of the neighboring chain, and (2) whether or not the natural frequency of the defect vibration lies inside a lattice band of the regular chain. An analysis of the low‐ and high‐frequency regions of the spectrum of low‐density polyethylene, based on the above considerations, indicates that several features of the spectrum can be associated with defect‐induced absorption. A similar explanation can account for certain intensity changes in the CCl stretching region of syndiotactic poly(vinyl chloroide) when this polymer is submitted to mechanical treatment.
Effect of polymer surface morphology on adhesion and adhesive joint strength. II. FEP Teflon and nylon 6
Authors: Schonhorn Harold , Ryan Frank W.
Published: April 2003

Heterogeneous nucleation and crystallization of FEP Teflon and nylon 6 melts against high energy surfaces (i.e., gold) produce an interfacial region, in these polymers, of high mechanical strength. Dissolution of the metal substrate rather than removal by mechanical means results in a polymer surface which is amenable to conventional structural adhesive bonding. Nucleation and crystallization of the polymer melts in contact with phases of low surface energy (e.g., vapor) result in the generation of weak boundary layers.
Energy dissipation by pulsating air bubbles in a viscoelastic medium
Authors: Stewart C. W.
Published: April 2003

A theoretical discussion is presented on the mechanisms by which an isolated pulsating air bubble in a viscoelastic solid dissipates its energy. The analysis is limited to the situation where the amplitude of motion is assumed to be sufficiently small that the stress strain relations may be described by linear equations with convected differentiation replaced by ∂/∂t. The theoretical thermal, radiation, and viscous damping constants are calculated for resonant air bubbles in unvulcanized natural rubber; however, the results are typical of elastomers in general.
Derivation of distributions of the degree of polymerization by probability theory
Authors: Ito Katsukiyo
Published: April 2003

A method of determining distributions of the degree of polymerization by means of probability theory is derived. This method, based on Kolmogorov's forward differential equation, is illustrated by application to two familiar kinetic schemes and is used to derive the distribution of degree of polymerization for free‐radical polymerization with diffusion‐controlled termination.
Mechanical anisotropy of regenerated cellulose films in relation to orientations of crystalline and noncrystalline phases
Authors: Nomura Shunji , Kawabata Sueo , Kawai Hiromichi , Yamaguchi Yutaka , Fukushima Akio , Takahara Hirokazu
Published: April 2003

The mechanical anisotropy of regenerated cellulose films is investigated, first, on the basis of the theory of infinitesimal elasticity. Fairly good agreement of calculated with observed results is obtained on the basis of orthogonal anisotropy with respect to the machine direction and the transverse and thickness directions of the films. The shear modulus G23 along the film plane and the Poisson ratio v32 are 1.5 times; 102 kg/mm2 and about 0.4, respectively, in the standard dry state. Second, the mechanical anisotropy in three different dry states is analyzed in terms of the degree of biaxial orientation of two kinds of structural units, cellulose II crystallites and noncrystalline chain segments, and their mechanical anisotropy. The calculation for averaging the mechanical anisotropies of these structural units on the basis of the homogeneous strain hypothesis gives results much higher than the experimental data, whereas the calculation on the basis on the homogeneous stress hypothesis gives results rather lower than experiment. As a modification of the two extreme calculations, a different averaging gives considerably better agreement between the calculated and observed results. The mechanical anisotropy in the wet state is further analyzed primarily in terms of the degree of biaxial orientation of noncrystalline chains by a modification of Krigbaum treatment, based on application of the kinetic theory of entropy elasticity for semicrystalline polymers, to anisotropic systems. The calculation gives results, however, much lower than those obtained experimentally, unless the ratio of the end‐to‐end distance of the noncrystalline chain to its fully stretched length is taken as unusually large. This may be due to underestimation of the contribution of the crystalline phase to terms of the same type as appear in the Krigbaum treatment.
Polyamides in solution. III. Viscometry of linear polycaprolactam
Authors: Mattiussi A. , Gechele G. B. , Francesconi R.
Published: April 2003

The viscometric behavior of linear polycaprolactam has been studied in the absence of the electroviscous effect in aqueous solvents containing 85% and 64.5% formic acid and in trifluoroethanol, as a function of temperature and also under unperturbed conditions. Results are discussed in terms of the existing theories; in particular, the negative temperature coefficient of the intrinsic viscosity arises only from the variation of the expansion coefficient, the molecule in the unperturbed state being a normal random coil. The absence of aggregation and draining effects in the above solvents has been varified.
Tensile yield‐stress behavior of glassy polymers
Authors: Bauwens‐Crowet C. , Bauwens J. C. , Homès G.
Published: April 2003

It is shown that, at the yield stress, glassy polymers exhibit viscous flow which is in agreement with the generalized theory of Eyring. The study of the yield stress over a wide range of temperatures and strain rates provides evidence on the secondary transitions found by other methods. From our measurements we conclude that every secondary transition corresponds to the liberation of one of the degrees of freedom of a segment of the main chain.
Statistical model of stereospecific polymerization of vinyl monomers
Authors: Luisi Pier Luigi , Mazo Robert M.
Published: April 2003

A statistical model for the stereospecific polymerization of vinly monomers on Ziegler‐Natta catalytic systems is presented. The basic assumptions of the model are: (a) the catalytic centers are asymmetric, so that at a given catalytic center the monomer CH2CHR is inserted into the chain with two different rates according to the two different configurations of the opening carbon atom having the R group; (b) the insertion of a monomeric unit in the growing chain is affected also by interactions with the previous monomeric unit. Isotactic, syndiotactic, atatic, or stereoblock polymers are obtained according to the relative values of the two energy parameters expressing these two effects.
Effect of hydrogen bonds on the axial stiffnes of crystalline native cellulose
Authors: Gillis Peter P.
Published: April 2003

Previous theoretical calculations of elastic constants for cellulose based on force constants for bond stretching and bending of valence angles have yielded axial stiffness values admittedly too low. The present analysis accounts for a hitherto unexamined geometrical effect associated with deformation of interchain hydrogen bonds. To do this, most primary bond deformations are neglected so the resulting calculation gives an upper bound for the axial stiffness. By using two different sets of hydrogen bond force constants, values of 24.6 and 31.9 × 1011 dyne/cm2 were obtained for Young's modulus in the chain direction. These values are very much larger than earlier calculations and experimental determinations from cellulosic fibers, indicating both the importance of the effect considered here and the likelihood of an exact analysis yielding an acceptable result.
Transient effects in the crystallization of polyethylene
Authors: Schultz J. M.
Published: April 2003

A specimen of linear polyethylene was subjected to isothermal secondary crystallization at a series of temperatures below the primary isothermal crystallization temperature, the melting and primary crystallization stages being held constant throughout the investigation. Dilatometric measurements exhibit an S‐character at low values of undercooling Tp – Ts, where Tp and Ts are, respectively, the primary and secondary crystallization temperatures, whereas at larger undercooling, an initial very rapid crystallization is followed by a very slow stage. When corrected for thermal contraction of the polymer, the net degree of secondary transformation is seen to peak at a temperature about 5°C below Tp. The S‐character of the isotherms and the peaked temperature variation of degree of transformation lead to the conclusion that a large portion of the secondary crystallization consists of the nucleation and growth of the new crystallites. Johnson‐Mehl‐Avrami analysis leads to a model of heterogeneous nucleation within the remaining amorphous zones, followed by one‐dimensional, diffusion‐controlled growth.
Effect of induced thermal stresses on the coefficients of thermal expansion and densities of filled polymers
Authors: Wang T. T. , Kwei T. K.
Published: April 2003

It is demonstrated that in a filled polymer the thermal stresses resulting from the difference in the thermal expansion coefficients of the filler and the polymer have significant effect on the apparent coefficient of thermal expansion of the composite. A model is constructed to aid the thermal stress analysis, and the results are found to agree well with the experimental data obtained from other sources. An expression for the apparent densities of filled polymers is also obtained but the agreement between the present prediction with an existing test result is found to be only qualitative.
Effects of ultraviolet radiation on aqueous polyelectrolyte solutions
Authors: Ishikawa Mitsuo
Published: April 2003

The effects of ultraviolet radiation on dilute aqueous solutions of poly(acrylic acid) and of other polyelectrolytes were studied by viscosity measurements in connection with the effects of ionizing radiation. It was found that ultraviolet light of wavelength below about 2300 Å brought about degradation of polymer chains mainly by indirect action via water, while light of wavelength above 2300 Å caused degradation by direct action in some polymers. It was deduced from the experiments that the protective effect of NaCl could be largely attributed to a decrease in the indirect action. It was also found that a low concentration of methanol was effective in preventing degradation by direct action, although methanol promoted degradation when present in high concentration. Since the promotive effect was not observed when light of wavelength below 3700 Å was eliminated by a filter, this effect was attributed to active products of the irradiation of methanol.
Raman spectra of extended‐chain syndiotactic poly(vinyl chloride)
Authors: Koenig J. L. , Druesedow D.
Published: April 2003

Raman spectra have been obtained for a typical poly(vinyl chloride) (PVC) of low crystallinity and for a highly crystalline sample of syndiotactic PVC obtained by irradiation of a urea‐canal complex. Raman measurements have been made on the three different ordered chain structures possible for ordinary PVC. Extended and folded conformations for the syndiotactic structure and a helical structure for the isotactic molecule obey different selection rules and have different dichroic properties in the infrared and Raman spectra. The observed Raman spectrum is consistent with the model of the extended syndiotactic conformation for crystalline PVC. With the new Raman data some additional assignments can be made in the vibrational spectra of PVC.
Solid‐state characterization of the structure and deformation behavior of water‐soluble hydroxypropylcellulose
Authors: Samuels Robert J.
Published: April 2003

A modus operandi is developed for determining the molecular structure of hydroxypropylcellulose (HPC), and characterizing, in quantitative terms, the morphological changes occurring when a water‐cast film of the polymer is deformed. This involves the application of the following eleven different physical measurements: wide‐angle x‐ray diffraction, differential scanning calorimetry, density, melt rheometry, infrared spectroscopy, refractive index, birefringence, sonic modulus, small‐angle light scattering, optical and electron microscopy. In addition, a computer was utilized as a mathematical diffractometer. Morphologically, water‐cast HPC was observed to have structure at all levels, from the molecular to the supermolecular. The HPC molecule has a backbone of anhydroglucose units twisted into an irregular 31 helix. Intramolecular hydrogen bonding of the poly(propylene oxide) side chains leads to a stiff, rodlike molecule. The molecules are packed into microfibrillar crystallites 470 Å long and 34 Å in diameter. The microfibrils in turn, associate into supermolecular rodlike structures. The structural rearrangements that occur at each morphological level during deformation of HPC film are quantitatively examined and described.
Electron microscopic study of deformation in polyethylene
Authors: Vadimsky R. G. , Keith H. D. , Padden F. J.
Published: April 2003

Thin films of polyethylene prepared from blends of fractionated polymer and a linear hydrocarbon (n‐C32H66) have been used to study the role of intercrystalline links in the deformation of semicrystalline polymer under uniaxial stress. These links have been found to be strong and virtually inextensible elements of the structure. It is shown that they are firmly attached to the chain‐folded lamellar crystals they bridge (both within the same spherulite and across boundaries between adjacent spherulites) and that, by concentrating applied stress, they commonly induce these lamellae to begin yielding in regions close to their points of attachment. Where there are many closely spaced links the stress is distributed fairly evenly, and drawing is relatively smooth and uniform. With more sparsely distributed links, however, stresses tend to be concentrated at widely separated points; deformation then tends to be severe and highly localized, often resulting in failure of the material upon drawing. There are indications that stress is also transmitted between chain‐folded lamellae in ways other than by intercrystalline links. One such way is by means of chain ends and molecular loops that emerge from the surfaces of these crystals and are embedded in interlamellar material. Experiments in which the deformed films were subsequently heated confirm earlier conclusions that extended chains in drawn polymer may undergo refolding during annealing.
Adiabatic compressibility of polyelectrolytes in aqueous solutions. II. Poly(4‐vinyl‐N‐n‐butylpyridinium bromide)
Authors: Roy‐Chowdhury Phanibhusan
Published: April 2003

The adiabatic compressibility for two samples (F‐1 with DP‐3748 and F‐2 with DP‐2114) of poly(4‐vinyl‐N‐n‐butylpyridinium bromide) in aqueous solution has been determined from ultrasonic velocity and density data. The sample (F‐1) with the higher degree of polymerization shows comparatively higher velocity and density in solution. However, the evidence for the difference in compressibility is not very decisive. The apparent molal volume ΦV2 and apparent molal compressibility ΦK2 for F‐1 are found to be slightly higher than for F‐2. In aqueous solution, the decrement of adiabatic compressibility per unit concentration, (β1 − β)/c, is found to be almost constant throughout the entire concentration range, whereas in the presence of excess added electrolyte (1.0M KBr solution), the compressibility decrement shows a decrease with dilution. The latter values are lower than those found in water, since the molecules, in the presence of excess electrolyte, are coiled up more and are less compressible. The ΦV2 and ΦK2 values in water are constant throughout the entire concentration range, as the free counterions formed on dissociation in the dilute region are not solvated and hence contribute little to the compressibility. On the other hand, in the presence of excess KBr (1.0M), the ΦV2 and ΦK2 values show a sharp decrease with increase of polyelectrolyte concentration and finally attain a constant value. This is explained by the fact that because of the formation of a charge‐transfer complex between the bromide ion and the polycation, more than the equivalent number of bromide ions is bound, leaving free an equal amount of K+ ions which are solvated and cause the lowering of apparent volumes and compressibilities. Condensation of charges begins at a certain polyelectrolyte concentration, and no further increase of K+ ions is observed. A special situation arises in 0.1M KBr solution. The ΦV2 and ΦK2 values at first increase sharply with increase of polyelectrolyte concentration, but then level off to attain a constant value, at comparatively high concentration. In 2.0% poly(4‐vinyl‐N‐n‐butylpyridinium bromide) solution, the concentration of polymer repeat unit (0.08M) is almost equal to the concentration of the added electrolyte (0.1M KBr) used to suppress dissociation. As the polyelectrolyte concentration in 0.1M KBr solution is progressively decreased, more bromide ions are made available for forming the charge‐transfer complex with the polycation, leaving the K+ ions free to contribute to the compressibility.
Raman scattering in nonplanar poly(vinylidene fluoride)
Authors: Boerio F. J. , Koenig J. L.
Published: April 2003

The Raman scattering of nonplanar (form 2) poly(vinylidene fluoride) (PVF2) is described. Unique Raman bands not observed in the infrared spectra are found at 2973, 1437, 1327, 1198, and 1059 cm−1. Band assignments are discussed by comparing infrared and Raman spectra of form 2 PVF2.
Effect of morphology on the mechanical and rheo‐optical properties of a styrene–butadiene–styrene block copolymer
Authors: Wilkes Garth L. , Stein Richard S.
Published: April 2003

The mechanical and rheo‐optical properties of a styrene–butadiene–styrene block copolymer of a given chemical composition are dependent upon the morphology of the polymer as affected by the solvent system from which a polymer film is cast. Films cast from methyl ethyl ketone and from toluene are compared. Properties found to differ are the stress–strain curve, the birefringence–strain curve, stress relaxation birefringence relaxation, and the dynamic mechanical spectra.
Transitions in trans‐1,4‐polyisoprene
Authors: Lovering Edward G. , Wooden David C.
Published: April 2003

The melting transitions of both crystalline forms of trans‐1,4‐polyisoprene, as detected by differential thermal analysis, have been identified by attendant studies with optical microscopy and x‐ray diffraction. The lower‐melting (LM) form melts initially at a temperature which depends upon the crystallization temperature but which, under our experimental conditions, is between 45 and 53°C. If recrystallization is allowed to occur, the apparent final melting point, which depends upon the recrystallization temperature, is about 58°C. The initial melting point of the higher‐melting (HM) form, also crystallization temperature‐dependent, is upwards of 57°C. Under the most easily accessible experimental conditions, it may be obscured by the final melting of the LM‐form. The apparent final melting point of the HM form is approximately 66°C. Conversion of the LM form into the HM form occurs only by fusion and crystallization. No evidence of a solid‐solid transition was found. The rate of conversion is governed principally by the rate of nucleation at the conversion temperature. If fusion of the LM form is incomplete, recrystallization of the LM form takes place instead of conversion to the HM form.
Viscoelastic properties of crosslinked solutions of poly(β‐hydroxyethyl methacrylate) in diethylene glycol. II. Dependence of creep compliance on concentration in the rubbery zone
Authors: Janáček Josef , Ferry John D.
Published: April 2003

Creep compliance data, J(t), at 35°C for poly(β‐hydroxyethyl monomethacrylate), crosslinked by ethylene glycol dimethacrylate in a range of concentration C from 0.0855 to 2.053 × 10−4 mole/cm3 and swollen to various degrees in diluents, were examined for time‐concentration superposition. From the dependence of time scale shift factors on v2, the volume fraction of polymer, free volume parameters were calculated for two samples with C = 0.0855 × 10−4 and 0.136 × 10−4 mole/cm3, swollen in the range of v2 from 0.134 to 0.591. Special attention was given to the magnitude of the shift factor on the log J(t) axis and its dependence on concentration, which was found to depend substantially on the crosslinking and the swelling degrees of the samples. This shift was approximately log v2 for lightly crosslinked samples, swollen to a small degree, measured in the neighborhood of the main transition. For higher degrees of crosslinking and/or swelling, the shift was much less and for the most highly crosslinked networks swollen to equilibrium it was even negative. The correction appears to be very sensitive to the strain of the effective chains and to the location on the time scale with respect to the transition and rubberlike zones of viscoelasic behavior. It was found that the parameters of the WLF equation calculated in our previous study from the time‐temperature superposition of the creep curves in the rubber‐glass transition are valid also for the rubberlike region.