bluuebunny/crossref_metadata_2025 huggingface dataset:
The temperature dependence of magnesium chloride interaction with polyacrylic acid
Authors: Jacobson Ada L.
Published: April 2003

The effect of temperature on a modified pH “titration” of polyacrylic acid is reported. The extent of acid ionization was varied by pretitration to various degrees with the strong base of a weak counterion binder, tetra‐n‐propyl ammonium hydroxide. The effect of subsequent additions of magnesium chloride to these pretitrated solutions at 15, 25, and 38°C. is reported. The release of hydrogen ions caused by this neutral salt addition varied with both degree of pretitration and temperature. The displacement caused by temperature on the maxima and minima behavior of hydrogen ions released as a function of degree of preionization can be explained by the effects of temperature on polymer configuration. The increased release of hydrogen ions at higher temperature can be explained by the combined effects of temperature on the polymer configuration and on the binding equilibria. The acid dissociation constants at 15, 25, and 38°C. have been obtained by titration with tetra‐n‐propyl ammonium hydroxide.
Theory of the modulus of crystalline polymers
Authors: Nielsen Lawrence E. , Stockton Fred D.
Published: April 2003

A new theory for the elastic modulus of crystalline polymers has been developed for temperatures above the glass transition. The theory is based upon the assumption that crystallites behave as crosslinks and as a rigid filler. The shear modulus G is given by G = (dRT/M̄c)F, where F is a factor giving the relative increase in modulus due to the volume of the rigid crystallites. The number‐average molecular weight M̄c of the amorphous sequences is calculated as a function of degree of crystallinity from copolymer theory. The theoretical values of the modulus as a function of degree of crystallinity agree reasonably well with experimental values over a wide range.
Changes in the stereospecificity of a ziegler catalyst used in the polymerization of butadiene
Authors: McIntosh Charles R. , Stephens William D. , Taylor Curtis O.
Published: April 2003

As a part of a program involving synthesis of various rubbers, the stereospecific polymerization of butadiene was studied. A Ziegler catalyst composed of cobaltous chloride, triethyl aluminum and aluminum chloride in benzene was used. The effect of catalyst age on stereospecificity of the polymers produced was observed over a period of nearly two years. Freshly prepared catalyst appears as a straw‐yellow liquid over black insoluble solids. Within a few weeks a black separate liquid phase begins to form at the bottom of the catalyst. The amount of the dark lower layer increases on standing until all of the solids have been dissolved. Polymers prepared from the upper layer of catalyst showed decreasing percentages of cis‐double bonds, an effect which was linear up to approximately one year. From one to two years, the upper layer produced polymers which were essentially constant at 70% cis‐olefinic bonds. In contrast, the dark lower layer of catalyst yielded polymers which were high in cis‐content (greater than 95% cis‐bonds) over the entire period of the study.
Nucleating effect on the kinetics of crystallization and the spherulites of nylon 6
Authors: Inoue Masakazu
Published: April 2003

The kinetics of isothermal crystallization and morphology of spherulites of nylon 6 nucleated by additives were discussed. Nylon 66, polyethylene terephthalate, and some inorganic phosphor compounds were used as nucleating agents. At crystallization temperatures in the range of 205 to 180°C., crystallization occurs through one‐ or two‐ dimensional growth and heterogeneous nucleation. The rate of crystallization increases by adding nucleating agents, followed by the decrease of the induction period of crystallization. Maximum crystallinity was not always obtained by the additives used for the present study. By adding nucleating agents, the size of spherulites decreases and the distribution becomes homogeneous, independent of the crystallization temperature.
A thermodynamic study of viton elastomer
Authors: Roe Ryong‐Joon , Krigbaum William R.
Published: April 2003

The temperature coefficients of the retractive force at successive fixed lengths were measured for a Viton fluoroelastomer sample. At each elongation the sample was held for at least 40 hr. before the tension measurement in order to minimize the relaxation effect. The range of elongations covered was confined to α values smaller than 1.65 because of the limited tensile strength of the sample. The results show departures from the predictions of simple gaussian theory of rubber elasticity in two respects. First, the tension f at 45°C. follows the Mooney equation with nonvanishing C2 values (2C1 = 3.324 kg./cm.2 and 2C2 = 2.865 kg./cm.2). Secondly, the internal energy makes a negative contribution to the elastic force, and moreover the ratio of the internal energy component to the total tension fe/f decreases with increasing α. The thermodynamic behavior of the Viton sample is thus qualitatively similar to that observed previously with a natural rubber network, except that the internal energy makes positive contribution in the latter. The experimental results were also compared with recent theories which purport to improve upon the simple Gaussian theory of rubber elasticity, but it is found that none of them can explain the results in satisfactory detail.
Preparation and aromatization of poly‐1,3‐cyclohexadiene. II
Authors: Frey D. A. , Hasegawa Masaki , Marvel C. S.
Published: April 2003

Further work on the polymerization of 1,3‐cyclohexadiene by the action of Zieglertype catalysis and by cationic initiation has been carried out and polymers with an inherent viscosity of 0.1–0.19 have been obtained consistently. Dehydrogenation of the poly‐1,3‐cyclohexadiene by halogenation followed by pyrolysis has given good conversion to a polyphenyl which has some units which are incompletely aromatized. This polymer has very good heat stability but is not a useful polymer for plastic purposes.
Preparation and polymerization of vinyl 12‐hydroxystearate
Authors: Shono Toshiyuki , Marvel C. S.
Published: April 2003

Vinyl 12‐hydroxystearate was prepared from 12‐hydroxystearic acid by vinyl interchange procedure with vinyl acetate. In the reaction, no products having a free hydroxyl group were obtained. The main addition product had the 1‐alkoxyethyl acetate structure. Vinyl 12‐hydroxystearate was obtained by the treatment of this addition product with acid washed activated alumina in ether solution. Vinyl 12‐hydroxystearate polymerized in an emulsion system at a pH of 7–8.5 with standard free radical initiation to give a colorless solid polymer (softening range was 71–75°C.). Vinyl 12‐hydroxystearate was copolymerized with vinyl acetate, vinyl stearate and vinyl chloride and the copolymers thus obtained have been characterized.
Counterion binding in partially neutralized copolymers of crotonic acid and vinyl alcohol
Authors: Sugai S. , Woodward A. E.
Published: April 2003

A 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

Anionic 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

We 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

Eighteen 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

The 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

The 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

Radicals 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

Data 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

The 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

When 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

The 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

When 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

Oriented 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

Magnesium 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

The 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

Two 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

The 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

The 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

Poly‐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

The 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

The 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

Above 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

Pure 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

Stereospecific 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

To 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

Calorimetric 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.
ESR study of irradiated acrylic acid and reaction of the produced radical
Authors: Shioji Yūji , Ohnishi Shun‐Ichi , Nitta Isamu
Published: April 2003

A single crystal of acrylic acid CH2CHCOOH was irradiated at −196°C. and its ESR spectrum was measured at that temperature with various crystal orientations with respect to the external magnetic field. At −196°C. the spectrum appears as a double quartet, the doublet showing anisotropy. By analyzing the spectrum, the hyperfine coupling tensor was derived. The result showed that the radical was CH3ĊHCOOH produced by hydrogen addition to the double bond. Referring to the molecular orientation of acrylic acid in the crystal, it was found that the radical was oriented in the crystalline lattice in the same way as the undamaged molecule. When the temperature was raised from −196°C. the double quartet spectrum began to decay at −100°C., and there remained a triplet spectrum showing no anisotropy. The triplet may be attributed to a propagating type radical In order to compare the ESR result with polymerization process, monomer preirradiated at −196°C. was postpolymerized at various elevated temperatures. It was found that although the radical decayed at −78°C. no discernible polymer was obtained at that temperature. These results suggest that, although the radical can move and be reactive at −78°C. which is far below the melting point, it does not seem sufficiently mobile to permit growth of the propagating chain to any observable extent.
Study of the base‐catalyzed cellulose–d,l‐butadiene diepoxide reaction
Authors: Benerito Ruth R. , Berni Ralph J. , McKelvey John B. , Burgis Beverly G.
Published: April 2003

The reaction of cotton cellulose with d,l isomers of butadiene diepoxide (BDO) in the presence of base catalysis has been investigated as a continuation of work previously reported on the reaction between cotton cellulose and the meso isomer (BDE). The BDO has been found to react similarly out of CCl4 solutions with fabrics pretreated with dilute solutions of base. However, unlike the meso isomer, which is less soluble in concentrated base, the BDO has been found to increase dry as well as wet crease resistance of cotton pretreated with aqueous solutions as concentrated at 23% NaOH. Increased wet crease resistance was imparted to cotton at low add‐ons of BDO to fabric pretreated with all concentrations of base. Increased dry crease resistance was imparted at low add‐ons of BDO to only those fabrics pretreated with dilute solutions of NaOH. For those fabrics pretreated with 10% or 15% NaOH, higher add‐ons of BDO were required to impart high dry as well as high wet crease resistance. Speed of the reaction was increased with increase of base concentration or by removal of water from fabrics pretreated with dilute base. With the latter, rate of increase of dry crease resistance also increased. Optical microscopical examinations of fibers and electron micrographs of ultrathin cross sections of these fibers after immersion in cuene gave evidence of degree of crosslinking of the cellulose. Evidence from these microscopical observations has been correlated with textile properties of fabrics. Intersting changes in fabric properties of BDO treated cotton with heat have been investigated. Optimum fabric properties have been obtained by reducing the amount of water in cotton after pretreatments with aqueous base and thus reducing the degree of polymerization of BDO. Data are also given to show influence of hydration of cation of strong base on degree of polymerization of BDO.
Properties of melt‐blends of crystalline high polymers. Fusion and crystallization behaviors
Authors: Inoue Masakazu
Published: April 2003

The fusion and crystallization behavior of melt blends of crystalline high polymers was studied by differential thermal analysis. The crystalline high polymers used for the experiments are nylon 6, nylon 66, nylon 11, high density polyethylene, and isotactic polypropylene. The thermograms of fusion of the melt blends indicate that each component produces an endothermic peak which retains its characteristic shape. In the blends of two crystalline polymers, only the melting point of high melting component is lowered, while that of low melting component hardly shifts. As for the degree of crystallization of each component in the blends, the major component crystallizes to a higher degree than the minor component. In the blends, the crystallization peak temperature of the high melting polymer decreases, while that of the low melting polymer increases. The morphological structures of each component, especially those of the low melting component, in the blends are affected by blending.
Synergistic antioxidant combinations. Mechanism of stabilization with organo‐sulfur compounds
Authors: Hawkins W. L. , Sautter H.
Published: April 2003

The ability of diaryl disulfides to inhibit polyethylene oxidation is a result of the formation of an active antioxidant from these additives. This is evident from their ineffectiveness to inhibit until substantial oxidation has occurred. Elemental sulfur also appears to form a more effective stabilizer as oxidation proceeds. Thiolsulfinates have been suggested as the active products which are formed from disulfides. However, phenyl benzenethiolsulfinate decomposes rapidly even at its melting point (70°C.), and yet the protection obtained when it is added to cumene at 120°C. far exceeds the time in which total decomposition would occur. At low concentrations, phenyl benzenethiolsulfinate also fails to inhibit until oxidation has proceeded for an appreciable time. Thermal decomposition of phenyl benzenethiolsulfinate yields sulfur dioxide in addition to other products. Elemental sulfur and the several organo‐sulfur compounds studied function as stabilizers through their ability to decompose peroxides. Sulfur dioxide is by far the most effective peroxide decomposer. It apparently functions catalytically through an ionic mechanism forming products which do not propagate oxidation. The additional role of sulfur compounds to decompose peroxides, coupled with the ability to regenerate chain terminators in antioxidant combinations may account for the high order of synergism obtained with these compounds.
Preparation and biological application of highly substituted cationic derivatives of polysaccharides
Authors: Wood John W. , Mora Peter T.
Published: April 2003

A general procedure is presented for the preparation of diethylaminohydroxylpropyl ethers of polysaccharides. This involves reaction between various ratios of 1‐diethylamino‐2,3‐epoxypropane and the polysaccharide (amylose, amylopectin, dextran, and a chemically synthesized polygalactose) and concentrated aqueous solution of sodium carbonate. These ratios control the degree of substitution, and give as high as 1.4 cationic groups per monosaccharide unit in the case of certain polysaccharides. The cationic polysaccharides possess high hemagglutinating activity which is proportional to the degree of substitution. Other biological applications are reviewed.
Thermodynamic interpretations of the elastic properties of rubbers obtained from ethylene—propylene copolymers
Authors: Natta G. , Crespi G. , Flisi U.
Published: April 2003

Stress—temperature coefficients have been measured for a high‐molecular‐weight ethylene—propylene copolymer, containing 45 mole‐% of ethylene, chlorinated and vulcanized with a cure system based on sulphur and accelerators. From the relationships:

the thermodynamic functions [∂E/∂L]T and — T [∂S/∂L]T have been determined in a range of the extension ratio up to α=6.9. A good agreement has been found between the experimental data and the stress—strain theoretical curve obtained for a non‐Gaussian type network.
Nitrosation of linear phenol‐formaldehyde polymers
Authors: Burke William J. , Higginbottom Harold P.
Published: April 2003

The nitrosation of o,o‐linked linear phenol‐formaldehyde polymers was readily affected in aqueous N,N‐dimethylformamide to give products containing p‐benzoquinone monoxime repeating units. Elemental analyses and infrared spectra indicated the presence of nitrophenol moieties also. Factors influencing the nature of the nitrosation reaction were studied.
Anionic polymerization of acrylonitrile by various catalysts
Authors: Ottolenghi Ariel , Barzakay Samuel , Zilkha Albert
Published: April 2003

The polymerization of acrylonitrile was studied using cyclopentadienyllithium, cyclopentadienyl sodium, fluorenylithium, and phenyllithium, and was compared to polymerization with butyllithium. With phenyllithium and fluorenyllithium in tetrahydrofuran, termination was found to be by chain transfer to monomer. The homogeneous polymerization in dimethylformamide carried out at both high and low catalyst concentrations showed that at high catalyst concentrations the molecular weights of polymer increased sharply with monomer concentration using cyclopentadienyllithium and cyclopentadienyl sodium, unlike the case of polymer obtained with butyllithium and fluorenyllithium. The increase in molecular weight is due to what has been previously found that the cyclopentadienyl anion acts as a polyfunctional catalyst leading to initiation of polymerization at various places on the ring. The basic strength of the catalyst investigated, as determined from the ability to polymerize monomers of decreasing acidity, was as follows: butyl ⋍ phenyl > fluorenyl > cyclopentadienyl.
Crosslinking and degradation in γ‐irradiated poly‐n‐alkyl acrylates
Authors: Burlant W. , Hinsch J. , Taylor C.
Published: April 2003

Polymers of methyl, ethyl, n‐butyl, n‐octyl, and n‐cetyl acrylate were γ‐irradiated in vacuo, and the effects of irradiation temperature (−196 to 56°C.) on energy yields for crosslinking and degradation estimated from gel fractions and swelling behavior of the gel. The extent of degradation is independent of polymer structure and reaction temperature, suggesting a molecular chain breaking process. Crosslinking, found to occur predominantly on the alkyl side chain, is independent of temperature above and below the polymer softening point, but is severalfold higher for irradiations above the softening point; these data seem to reflect the importance of segmental mobility of radiation produced polymer radicals in the crosslinking step.
Studies on structure and properties of aromatic polyamides. II. Structural elucidation of poly(m‐xylylene adipamide)
Authors: Yoda Naoya , Matsubara Ikuo
Published: April 2003

X‐ray diffraction and infrared spectra of poly(m‐xylylene adipamide) were investigated. On the basis of x‐ray diffraction studies, the twisted form of molecular model for the polymer structure of poly(m‐xylylene adipamide) was proposed which shows the calculated value of 15.2 A. to be an identity period consistent with the observed value from x‐ray diffraction. The assignment of infrared absorption bands were made with the aid of polarization measurements combined with the techniques of deuteration and iodine treatment of the polymer. It was established on the experimental evidences that the band at 725 cm.−1 is assigned to the amide V vibration. The intense bands at 1639, 1545, and 1266 cm.−1 are ascribed to the amide I, II, and III vibrations, respectively. A tentative assignment of the amide VI and VII was also made. The infrared spectra show that the observed dichroism of the amide characteristic bands of the highly oriented specimen is much lower than that of aliphatic polyamides. This is also consistent with the proposed twisted model for the polymer structure of poly(m‐xylylene adipamide).
Chain entanglements and elastic behavior of polybutadiene networks
Authors: Kraus Gerard , Moczvgemba G. A.
Published: April 2003

The role of chain entanglements in determining the stress‐strain properties of polybutadiene networks has been investigated. The number of entanglements was varied by changing the primary molecular weight and chemical crosslink concentration. Networks essentially free of entanglements were prepared by endgroup coupling of carboxy terminated polybutadiene of 5500 molecular weight. Conventional sulfur or peroxide vulcanizates obeyed the Mooney‐Rivlin stress‐strain relation, the constant C2 which represents the deviation from simple kinetic theory diminishing with the time allowed for approaching elastic equilibrium. The constant C2 was found to increase with both the total physical crosslinking and the entanglement contribution to this quantity. The endgroup vulcanizates obeyed the simple kinetic theory of rubber elasticity and approached elastic equilibrium much more rapidly than sulfur or peroxide vulcanizates. The evidence presented suggests that the apparent deviation of elastomeric vulcanizates from the kinetic theory of rubber elasticity resulting in the appearance of the Mooney‐Rivlin C2 term in the stress‐strain relation arises from a slow relaxation process involving the entanglement crosslinks.
The molecular structure of perfluorocarbon polymers. II. Pyrolysis of polytetrafluoroethylene
Authors: Siegle J. C. , Muus L. T. , Lin Tung‐Po , Larsen H. A.
Published: April 2003

Vacuum pyrolysis of thin samples of polytetrafluoroethylene follows first‐order kinetics with monomer as the only important decomposition product in the temperature range 360–510°C. The rate constant for vacuum pyrolysis is independent of both the melt viscosity and the type of polymer and is characterized by an activation enthalpy of 83.0 kcal./mole and a frequency factor of 3 × 1019 sec.−1. The molecular weight is found to decrease during pyrolysis. A plausible reaction mechanism consistent with these facts involves random chain cleavage, depropagation with short kinetic chain length, and termination by disproportionation. For thick samples the rate of vacuum pyrolysis is controlled by diffusion of monomer. The course of pyrolysis is changed by the presence of monomer or gaseous pyrolysis products. Accumulation of monomer reduces the rate of pyrolysis as measured by the weight loss and results in formation of a waxy product consisting of low molecular weight fluorocarbons.
Cyclopolymerization of diepoxides
Authors: Stille J. K. , Culbertson B. M.
Published: April 2003

The monomer 1,2,5,6‐diepoxyhexane can be polymerized by a variety of catalysts to afford a polymer which has tetrahydropyran recurring units as a result of a cyclopolymerization mechanism. A phosphorus pentafluoride‐water catalyst system gives soluble polymer with inherent viscosities as high as 0.37. The polymerization rates, conversions, and polymer molecular weights are affected both by catalyst to monomer ratio and the amount of water present. A diethylzine‐water catalyst system gives a higher molecular weight polymer with very limited solubility, the soluble portion of which has an inherent viscosity of 0.45. In contrast, 1,2,4,5‐diepoxypentane polymerizes to a completely insoluble polymer in all catalyst systems employed. Samples of poly‐1,2,5,6‐diepoxyhexane prepared with the diethylzine‐water catalyst show a higher degree of crystallinity than those samples prepared with the phosphorus pentafluoride‐water catalyst, as demonstrated by x‐ray patterns and differential thermal analyses.
X‐ray diffraction and infrared spectra studies on the fine structure of rayon improved by high temperature steaming
Authors: Okajima Saburo , Inoue Kimio
Published: April 2003

Five samples of rayon containing two high tenacity rayons and three textile rayons of viscose and Bemberg types were heat‐treated with high temperature water or steam (110–210°C.) for a few minutes or seconds, and the change in the fine structure was investigated by means of x‐ray diffraction and small‐angle scattering. An additional study by infared spectra was carried out on cellulose films similarly heat‐treated. The crystallinity increased with increasing temperature and extension of the treating time within the range of less than 10%. Crystallites thicken laterally and grow into those of a higher order. Newly formed crystallites are of cellulose IV. The change is more striking in the high tenacity rayon than in the textile rayons. The remarkable reduction in the degree of swelling is considered to be due partially to such development of crystallinity. No clear conclusion could be drawn as to the contribution of junction points in the amorphous region.
Anionic polymerization of octamethylcyclotetrasiloxane in tetrahydrofuran solution
Authors: Morton Maurice , Bostick E. E.
Published: April 2003

A study has been carried out on the base‐catalyzed polymerization of octamethylcyclotetrasiloxane (D4) in tetrahydrofuran solution by means of various anionic initiators. These included potassium hydroxide, sodium and potassium metal and sodium and potassium naphthalene. Tetrahydrofuran was found to have a very marked accelerating effect on the polymerization rate, presumably by increasing the concentration of the silanolate anions. The rates obtained with the potassium metal and potassium naphthalene were even faster than for the KOH, permitting room temperature polymerization in a few hours. The polymerization temperature was not found to affect the equilibrium conversion of monomer to polymer, indicating very similar activation energies for propagation and depropagation. For polymerizations catalyzed by potassium naphthalene, two molecules of catalyst were found to be consumed per chain formed, with one dihydronaphthalene structure included in the chain.