bluuebunny/crossref_metadata_2025_split huggingface dataset:
Counterion binding in partially neutralized copolymers of crotonic acid and vinyl alcohol
Authors: Sugai S. , Woodward A. E. 
Published: April 2003

AbstractA series of copolymers of partially neutralized crotonic acid and vinyl alcohol have been prepared with acid monomer contents ranging from 4 to 43 mole‐%. The extent of binding of sodium counterions was studied by a transference method employing radiotracers. Comparison of these data with those obtained previously by Nagasawa and Rice for maleic acid copolymers and Wall and co‐workers for poly(acrylic acid) gives further support to the contention that the overall charge density on a polyion governs the total counterion binding. Results of potentiometric titrations and viscosity measurements are also reported.
Anionic block polymerization. I. Block polymerization of styrene on polystyrene
Authors: Baer M. 
Published: April 2003

AbstractAnionic block polymerization of styrene onto polystyrene anions was found to be a useful diagnostic method which can readily reveal when the chosen polymerization conditions are conducive to complete catalyst consumption and quantitative block polymerization. With Na‐naphthalene as initiator, it was shown that under the proper polymerization conditions (a) the initiator is essentially completely consumed in the first polymerization step, thus avoiding initiation of new chains in the following polymerization steps, (b) in each block polymerization step, styrene adds quantitatively to the preformed live anions, and (c) essentially no termination is observed throughout the successive block polymerization steps. The ratio of monomer to initiator greatly affects the efficiency of initiator consumption. The rate of agitation is also considered to play a dominant role.
Optical rotatory properties of polyaldehydes
Authors: Abe Akihiro , Goodman Murray 
Published: April 2003

AbstractWe have studied the optical rotatory properties of several polyaldehydes possessing optically active side chains, such as poly‐(R)(+)‐citronellal, poly‐(R)(+)‐6‐methoxy‐4‐methylhexanal, and poly‐(S)(+)‐2‐methylbutanal. An enhancement is observed for the optical activity of the polymers compared to their model compounds. The magnitude of the enhancement depends on the separation between the asymmetric site and the main chain. Specific rotation values are independent of intrinsic viscosity and crystallinity of the polymers over the range measured. It was shown that the rotatory dispersion and the temperature dependence of the rotatory dispersion are essentially the same both for the polymers and their model compounds. We conclude from these data that the enhancements of the optical activity arise from a conformational rigidity around the asymmetric center in the side chain of the polymer.
Resistivity studies on polymer semiconductors
Authors: Pohl H. A. , Gogos C. G. , Cappas C. 
Published: April 2003

AbstractEighteen polyacene polymers were synthesized, and their resistivities were found to be of the order of 104–105 ohm‐cm. The resistivity of these polymer semiconductors was found to be sensitive to changes in the conditions of synthesis, changes in the structure of the polymers, and variations of pressure and temperature during experimentation. The forbidden energy gap for these polymers was about 0.5 e.v. Although the formalism of the simple intrinsic semiconductor band model was not strictly applicable to the data on these polymers, such a treatment was found instructive.
The chemical structure of polyisobutylene obtained by ziegler catalysis
Authors: Bacskai R. , Lapporte S. J. 
Published: April 2003

AbstractThe chemical structure of polyisobutylene prepared with different catalysts was studied by independent physicochemical methods. No significant difference has been found in the infrared spectra, proton magnetic resonance spectra, and viscosity behavior of polymers prepared with Ziegler catalysts compared to a sample of polyisobutylene obtained with BF3 catalyst. The methyl—methylene proton ratio in the polymers was determined from their proton magnetic resonance spectra. Based on these results, the normal polyisobutylene structure was assigned to the polymers. The rearranged structure as suggested by Topchiev and coworkers was ruled out. Alkylation studies with liquid isobutylene polymers substantiated this finding.
Adhesion. II. Relationships between viscoelasticity, interfacial equilibrium, and the temperature dependence of adhesion
Authors: Huntsberger J. R. 
Published: April 2003

AbstractThe temperature dependence of adhesion is investigated by two different techniques. Data are given for several polymers. An hypothesis is presented which appears to provide a satisfactory explanation for the observed performance, and which attributes a major role to the extent of interfacial contact (or proximity to interfacial equilibrium). Striking differences are shown in the temperature dependence of adhesion for samples of a given pair of materials which were prepared under different bonding conditions. The behavior is believed to be established by the relationships between the viscoelastic response of the adhesive, the temperature and effective strain rate of the adhesion test, and the concentration of stress at interfacial discontinuities.
Electron spin resonance of polypropylene
Authors: Loy B. R. 
Published: April 2003

AbstractRadicals produced in Co60 irradiated normal and 1,1d2‐polypropylene have been examined by electron spin resonance. It is concluded that 80% of the radicals are CH2CH(CH2.)and 20% are CH2C(CH3)CH2 in both atactic and isotactic polymer. In the isotactic, but not in the atactic material, the primary radical disappears much faster than the secondary one when heated. Interpretation of the spectra of polybutylene and polyisobutylene is also given.
The mastication of elastomers. Part III. The solution properties of masticated synthetic cis‐polyisoprene
Authors: Bristow G. M. 
Published: April 2003

AbstractData are reported on the light scattering, osmotic, and viscometric properties of solutions of masticated synthetic cis‐polyisoprene. Mastication produces a sharpening of the molecular weight distribution and this is consistent with the hypothesis that degradation proceeds by a nonrandom process.
Organic reactions under high pressure. IX. The effect of pressure on the stereochemistry of methyl methacrylate polymerization
Authors: Walling Cheves , Tanner Dennis D. 
Published: April 2003

AbstractThe radical polymerization of methyl methacrylate has been carried out at 51°C. over a pressure range of 1–8000 kg./cm.2, and the stereochemistry of the polymer analyzed by NMR spectroscopy. Over the entire pressure range, the stereochemistry of addition is independent of the stereochemistry of the growing polymer chain. The percentage of syndiotactic linkages decreases from about 75% to 62%, and the change in the resulting distribution of stereosequences is calculated. It is concluded that the transition state for syndiotactic addition is slightly larger than that for isotactic addition to the growing chain.
Synthesis of vinyl polymers containing α‐substituted γ‐butyrolactone groups in their backbones
Authors: Zutty N. L. , Welch F. J. 
Published: April 2003

AbstractWhen vinyl chloride—methyl methacrylate copolymers having a uniform chain‐to‐chain composition, are pyrolyzed at temperatures around 150°C., an intramolecular lactonization occurs forming α‐methyl‐γ‐butyrolactone groups in the polymer backbone concomitant with the quantitative elimination of methyl chloride. This reaction has been shown to be a general reaction for copolymers containing α‐substituted γ‐haloester groups in their backbone. The formation of the lactone groups in these polymers leads to increased chain rigidity and higher polymer softening points. Advantage has been taken of the gaseous alkyl halide elimination to produce rigid vinyl foams of good compressive strengths.
Polypropylene structure
Authors: Schmidt Paul G. 
Published: April 2003

AbstractThe polarized infrared spectra of one‐way and two‐way oriented polypropylene films have been investigated and compared to nonoriented films. Evidence has been compiled to show that an amorphous helical isotactic structure is nonexistent, and that it is through the crystallization process that nonhelical isotactic polypropylene is converted to helical isotactic polypropylene.
Determination of number‐average molecular weights by elastoosmometry
Authors: Yamada S. , Prins W. , Hermans J. J. 
Published: April 2003

AbstractWhen a swollen elastomer is in equilibrium with a solution, the stress at constant length is a function of the chemical potential of the solvent, and thus of the concentration and number‐average molecular weight of the solute in the solution. This is used to compare the molecular weights of some polystyrene samples among each other. The method is found to give satisfactory results. The theory of the method is given and is applied to ideal rubbery networks, for which explicit free energy expressions are available. The theoretical result obtained is used to reduce the experimental data to equal extension ratios.
Generalized approach to adhesion via the interfacial deposition of amphipathic molecules. I. Adhesion of polyethylene to aluminum
Authors: Schonhorn Harold 
Published: April 2003

AbstractOriented monolayers are employed as effective adhesives in the bonding of polyethylene to aluminum. Several monolayers are characterized and their physical properties elucidated. Measurement of the tensile shear and peel strength of polyethylene bonded to aluminum indicate that the bonds formed exceed the cohesive strength of the polymer. Contact angle and radioactive trace experiments helped to determine the conditions for maximum adhesion.
Polymerization of vinyl ether with magnesium compounds. II. Catalytic reactivity of magnesium compounds other than halides
Authors: Iwasaki K. , Fukutani H. , Tsuchida Y. , Nakano S. 
Published: April 2003

AbstractMagnesium compounds, especially Grignard reagents were studied as catalysts in the polymerization of vinyl ethers. The Grignard reagent and diethyl magnesium possessed no activity for polymerization of vinyl ether. However, if the Grignard reagent is combined with some sort of third substances, it shows good activity. For these substances, oxygen, aldehydes, some metal oxides, and halogenated hydrocarbons seemed to be effective. The molecular weight of the polyvinyl ether obtained from this combined catalyst system is markedly higher than those of polymers obtained with the Friedel‐Crafts type of catalyst, but the polymer of vinyl ether obtained from this mixed catalyst possesses little crystalline structure. The possible mechanism of the polymerization with this mixed catalyst is thought to be a cationic initiation type, because the true active species are regarded to be intermediate compounds which are analogous to magnesium halides or alkoxymagnesium halides. In this connection, alkoxymagnesium halides and magnesium oxide were examined. They had a good activity for polymerization but did not yield a high polymer.
Behavior of polymer solutions in the velocity field with parallel gradient. IV. Viscosity of dilute solutions containing flexible chain macromolecules
Authors: Takserman‐Krozer Rachela 
Published: April 2003

AbstractThe intrinsic viscosity of dilute solutions containing flexible chain macromolecules flowing in a velocity field with parallel gradient has been analyzed. It has been found that the viscosity at rest is three times the value of the shearing viscosity. The viscosity increases monotonically with velocity gradient (steady flow) and with time (at constant gradient). On the basis of the results of this and previous papers, general features of the dynamic behavior of dilute polymer solutions flowing in the velocity field with parallel gradient have been discussed.
Viscoelastic behavior of plasticized polyvinyl chloride at large deformations. I. Stress relaxation
Authors: Sabia Raffaele , Eirich F. R. 
Published: April 2003

AbstractTwo vinyl chloride polymers with intrinsic viscosities of 0.65 and 1.17 were compounded with four plasticizers. Stress relaxation data were obtained at three temperatures and analyzed by a step function of seven parameters in Maxwell representation. The relaxation times were nearly independent of plasticizer type, plasticizer content, molecular weight, and temperature. The moduli were found to decrease with increasing plasticizer content and/or temperature, the equilibrium moduli being directly dependent on the molecular weight while the delayed moduli were more dependent on plasticizer type. The molecular weight dependence of the equilibrium moduli can be attributed to a participation of the individual chains in several crystalline areas which act as crosslinking points.
Turbidimetric titration of nylon 66
Authors: Howard G. J. 
Published: April 2003

AbstractThe turbidimetric titration of nylon 66 is reported. It is shown that the precipitation of any species is independent of polymer species differing in molecular weight and that the precipitability is a function of both polymer concentration and degree of polymerization. The construction of molecular weight distributions from turbidity results is described. The distribution obtained for a reference polymer is sharper than that from a careful fractional precipitation but is superior to a simple single‐stage preparative fractionation. Distribution curves are given for other nylon 66 polymers, including photodegraded yarns.
Growth of single crystals of polytetrafluoroethylene from the melt
Authors: Symons N. K. J. 
Published: April 2003

AbstractThe melt crystallization of dispersion‐based polytetrafluoroethylene, in amounts varying from single dispersion particles to continuous films, has been studied by electron microscopy, electron diffraction, and optical microscopy. Since the maximum temperature used was only 350°C., negligible thermal degradation of the polymer is believed to have occurred during the crystallization. Using very small amounts of the polymer, single crystals with thicknesses of about 150–900 A. having their molecular chains oriented perpendicularly to the basal plane of the crystal have been observed; this shows that the melt crystallization of polytetrafluoroethylene occurs by a chainfolding mechanism as reported previously for other high polymers. This new knowledge allows a more positive interpretation of the striated band structures previously observed on fracture surfaces of bulk specimens of both dispersion‐based and granular types of this polymer. Such bands which show striations perpendicular to their length probably represent individual crystal plates which have been fractured in planes perpendicular to their bases, while bands showing longitudinal striations result from the splitting apart of stacks of such plates, or lamellae, along fracture planes approximately parallel with their surfaces. The present observation of isolated and well defined single crystals from a polymer melt, as distinct from a solution, is believed quite novel. Although seen so far with polytetrafluoroethylene only, the growth of such single crystals from the melt might be possible with other polymers also, if these were studied in very small quantities.
Infrared absorption spectra of polyacrylonitrile and deuterated polyacrylonitriles
Authors: Tadokoro Hiroyuki , Murahashi Shunsuke , Yamadera Reizô , Kamei Tei‐Ichi 
Published: April 2003

AbstractPoly‐α‐deuteroacrylonitrile and poly‐α,β,β‐trideuteroacrylonitrile were synthesized. α‐Deuteroacrylonitrile was prepared by the deuterium exchange reaction of acrylonitrile with D2O in the presence of CaO. α,β,β‐Trideuteroacrylonitrile was prepared by the addition reaction of C2D2 and DCN. The infrared spectra of polyacrylonitrile, the deuterated polyacrylonitriles, and the intermediate products of the syntheses were measured in the 4000–400 cm.‐1 region and discussed. The polarized spectra of the oriented polymer samples were also measured. The bands of PAN in the CH stretching region exhibit reasonable shifts in the spectra of the deuterated polymers, while the C≡N stretching band shows no appreciable shift. The bands in the region lower than 1400 cm.‐1 exhibit complicated behavior in deuteration. The calculation of the normal vibrations of polyacrylonitrile has been made, assuming a syndiotactic planar zigzag chain as a most simple model for calculation. The assignments of the bands are discussed.
Resonance effect of amide group on the polymerizability of lactam derivatives. III. Polymerization of many‐membered lactams ring
Authors: Ogata Naoya 
Published: April 2003

AbstractThe polymerization rate of many‐membered lactams in the presence of water and the equilibrium constant of the addition reaction between lactam and hydrogen chloride were measured to investigate the relationship between the conformation, resonance effect, and polymerizability of lactams. The polymerization velocity of lactams in the presence of the same amount of water is in the following order: 8‐membered lactam > 7‐membered lactam > 11‐membered lactam ≫ 5‐ and 6‐membered lactams. The polymerizability reaches a maximum with the 8‐membered lactam. The equilibrium constant K of the addition reaction between lactam and hydrogen chloride reaches a maximum with the 7‐membered lactam and the basicity of the lactams is highest with the 7‐ or 8‐membered lactam. The conformation of the amide group of the less than 6‐membered lactam is a cis form, while that of the 6‐ to 8‐membered lactam is a mixture of the cis and trans forms, and an equal number of cis and trans forms is found in the 8‐membered lactam in the infrared spectrum. From these results it is concluded that when the two conformations of the amide group become equal, the resonance effect of the amide group decreases, resulting in an increase in the polymerizability of lactam.
Primary radical termination in methyl methacrylate polymerization
Authors: Baldwin M. G. 
Published: April 2003

AbstractThe kinetics of polymerization of methyl methacrylate in benzene solution at 60°C., initiated by 2,2′‐azobisisobutyronitrile (AIBN), were studied for monomer concentrations of 0.03–1M. The observed deviations in polymerization rate from the rates predicted by simple theory are discussed in terms of the occurrence of primary radical termination reactions. The fraction of primary radicals terminating chains was obtained for various monomer and initiator concentrations, and the ratio of rate constants for chain initiation and chain termination by a primary radical was determined.
Phase equilibria of polymer‐solvent systems at high pressures near their critical loci: Polyethylene with n‐alkanes
Authors: Ehrlich Paul , Kurpen John J. 
Published: April 2003

AbstractAbove the crystallization temperature slightly branched polyethylene and propane are miscible in all proportions above a critical pressure, defined as upper critical solution pressure (UCSP). This pressure decreases only very slightly from 110 to 150°C. At 110°C. the UCSP varies from 450 atm. for a polymer fraction of molecular weight 17,000, to 580 atm. for one of molecular weight 250,000. The critical polymer concentrations are low as in conventional polymer‐solvent systems and shift with molecular weight in a similar manner. The pressures required to achieve solubility of the polymer in the gas at polymer concentrations less than critical (dew‐point pressures) are nearly as high as the UCSP down to very low polymer concentrations. The data determine part of the critical locus in (P, T, composition) space. Experiments with other polyethylene‐n‐alkane systems (ethane, butane, and pentane) show that the critical locus changes gradually from a liquid‐liquid to a gas‐liquid boundary and might be termed a fluid‐liquid locus. If crystallization of polymer does not intervene, this locus intersects the saturated vapor pressure curve at a lower critical end point (LCEP) which is the lower critical solution temperature (LCST) found only recently by Freeman and Rowlinson in many hydrocarbon polymers with hydrocarbon solvents. Incomplete miscibility extends over greater regions of temperature and pressure as the solvent molecule becomes smaller, but the critical locus would probably be closed along the pressure axis for a hypothetical amorphous polymethylene with ethane.
Polydiacrylylmethane
Authors: DeWinter W. , Marvel C. S. , Abdul‐Karim Aziz 
Published: April 2003

AbstractPure diacrylylmethane does not polymerize smoothly on free radical initiation. It gives a higher yield of the polymer as a sodium salt when initiated by sodium methoxide. The molecular weight is obviously low. The polymer formed from its sodium salt is insoluble. Attempts to prepare the dioxime yielded an intractable monooxime.
Stereospecific polymerization of vinyl alkyl ethers
Authors: Nakano S. , Iwasaki K. , Fukutani H. 
Published: April 2003

AbstractStereospecific polymerization of vinyl alkyl ether was studied; various kinds of compounds, such as metal oxides, metal halides, metal oxyhalides, metal sulfate complexes and organometallic compounds‐Lewis acid complexes, being used at low temperature or room temperature. The relationship between the structures of catalysts and the stereoregularities of polymers is discussed, and it is found that tetrahedral compounds which have one active edge are especially useful for making the stereoregular polymers at room temperature. Also, the shorter the length of active edge, the more suitable the catalyst is for stereospecific polymerization. On the basis of these experimental results, a mechanism of stereospecific polymerization of vinyl alkyl ether is proposed.
Application of the archibald ultracentrifugal method for the study of dilute polymer solutions. II. Examination of two solution systems near the flory temperature
Authors: Inagaki Hiroshi , Kawai Syuji , Nakazawa Atsushi 
Published: April 2003

AbstractTo test the validity of the generalized Archibald method developed previously, sedimentation experiments were made for two systems, polystyrene—cyclohexane and polymethyl methacrylate—n‐butyl chloride, near the Flory temperature relevant to each. It was found that the slope of the resultng plot between the reciprocal of the apparent molecular weight Mapp (extrapolated back to zero centrifugation time) and the concentration tends to zero at the Flory temperature, while this slope shows positive or negative values, depending on whether the temperature is higher or lower than the characteristic one. Thus the present method gives just the same information for dilute polymer solutions as does the light scattering. A further study was carried out to elucidate the time‐dependent nature of Mapp(t), calculated at each centrifugation time, in terms of the thermodynamic nonideality of solution and of the fractionating action of the ultracentrifuge on a polydisperse solute.
Calorimetric measurements of the heat of sorption of water vapor on dry swollen cellulose
Authors: Greyson J. , Levi A. A. 
Published: April 2003

AbstractCalorimetric measurements of the heat of sorption of water vapor on a dry swollen cellulose sample have been made for various swelling states of the sample. The state of swelling was characterized by the surface area of the sample as determined by nitrogen adsorption (B.E.T.) Six runs were made with the surface area varying from 140 m.2/g. to 2 m.2/g. The initial heats do not vary significantly with change in surface area and were found to be 15 to 16 kcal. per mole of water sorbed. The energetics of water sorption and the water regain, at low water concentrations, are entirely independent of the surface area range (swelling state) of the cellulose. The surface area was found to decrease logarithmically with the quantity of water sorbed on the cellulose. It is concluded that the interaction of water and cellulose is a bulk rather than a surface effect.