bluuebunny/crossref_metadata_2025_split huggingface dataset:
The thermal expansion of cellulose, hemicellulose, and lignin
Authors: Ramiah M. V. , Goring D. A. I. 
Published: June 2010

AbstractThe thermal expansion of wood constituents has been measured dilatometrically both in the dry and the water‐swollen state. Dry measure meats were made with mercury as the confining liquid on samples pressed into dense pellets at elevated temperatures and pressures. Between −30 and 30°C, the thermal expansion coefficients for various celluloses and hemicelluloses ranged from 5.1 to 6.0 × 10−4 ml./g./°C. For lignin, the coefficient increased to about 10 × 10−5 ml./g./°C. A second order transition was noted in all samples at 19–33°C. A further transition at 8G‐110°C. was detected for the dioxane lignin, periodate lignin, and Avory cellulose. All transitions in the dry state produced an increase in the expansion above the transition temperature. In the water‐swollen state, samples were in the form of powders or broken pellets, with distilled water as the confining liquid. The thermal expansion coefficients of the water‐swollen samples were several times as great as the expansion coefficients measured in the dry state. The second order transition near 20°C. persisted, but in water the transition was negative with expansion decreasing above the transition temperature. Analogous results were obtained for glucose and cellobiose, both in the dry state and in solution. The transition in the dry state is attributed to increased thermal motion caused by the rupture of weak hydrogen bonds. The large and interesting discrepancy found in the expansion of the water‐swollen materials is interpreted as arising from the perturbation of the water structure by the hydrophilic surfaces of woody macromolecules, and a quantitative assessment of this effect is attempted.
The alkane dithioether and the polysulfide crosslinking of cellulose
Authors: Clingman A. Lionel , Schwenker Robert F. 
Published: June 2010

AbstractNew crosslinked cellulose derivatives were obtained from the reactions of potassium disulfide andn‐alkane‐α‐ω‐dithiols with partial tosyl or brosyl esters of native cellulose. Treated cotton print cloth showed significant improvement in wet and dry wrinkle recovery over untreated. Alkane dithioether crosslinks, —S(CH2)nS—, of different lengths (2–10 CH2 groups) were introduced. Treatment with aqueous or ethanolic solutions of potassium disulfide resulted in the formation of polysulfide crosslinks, such as tetrasulfide. The effect of crosslink length on the physical properties of the modified cottons was studied, and it was found that fabric wrinkle recovery tended to decrease as crosslink length increased. It was also found that the tosyl and brosyl cellulose esters were degraded by alkali. This degradation is ascribed to the loss of primary sulfonyloxy groups with subsequent hydrofuranol ring formation in the case of the anhydroglucose units involved.
The optical rotation of wood xylans
Authors: Gutmann P. J. , Timell T. E. 
Published: June 2010

AbstractPreviously derived equations relating the specific rotation and chemical composition of 4‐O‐methylghicurono‐xylans and arabino‐4‐O‐methylglucurono‐xylans have been found to be partly incorrect because of the assignment of an erroneous value to the rotatory contribution of the 4‐O‐methyl‐α‐D‐glucuronosyl xylose residue. The correct value was calculated from the known molar rotations of xylobiose and 22‐(4‐O‐methyl‐α‐D‐glucuronosyl) xylotriose. Approximately the same values were obtained from the specific rotations of five carefully purified 4‐O‐methylglucurono‐xylans, containing different proportions of acid side chains, and from the rotations of an aldopentaouronic and an aldohexaouronic acid. A revised equation was used for estimating the specific rotation of several arabino‐4‐O‐methylglucunmo‐xylans from various softwoods. Contrary to the earlier results, a satisfactory agreement was found to exist in most cases between found and calculated values.
Theory of light scattering from oriented and fiber structures
Authors: Stein R. S. , Erhardt P. , Van Aartsen J. J. , Clough S. , Rhodes M. 
Published: June 2010

AbstractRecent progress in the theory of scattering by spherulites of crystalline polymers is reviewed. The consequences of arbitrary optic axis orientation, periodicity of optic axis orientation and of spherulite deformation are described. The transmission of light by a film of a crystalline polymer having spherulitie or lower degrees of order of crystalline orientation is discussed. A theory of the scattering of light from such a film having nonrandom correlation in crystalline orientation is developed. The dependence of the scattered intensity on the polarization directions of the incident and scattered light is shown to depend upon a parameter which characterizes the nonrandomness.
Small angle light scattering from deformed spherulites. Theory and its experimental verification
Authors: Samuels Robeht J. 
Published: June 2010

AbstractThe observed small angle light scattering (SALS) from deformed spherulites is described by the theory of an anisotropic spheroid in an isotropic medium. Experimental verification of the theory, based on SALS data from both photographic and photometric measurements on isotactic polypropylene films, is presented. The theory led to a method for experimentally determining the extension ratio of the deformed spherulite and the radius of the original undeformed spherulite from the SALS pattens.
Light scattering from polymer films
Authors: Wallach M. L. 
Published: June 2010

AbstractA variety of films were examined by low angle laser light scattering to yield information on the size, shape, and orientation of superstructure. Films of poly(ethylene terephthalate) and polypropylene give distinctive scattering patterns in the form of two‐ and four‐leaf clovers which change with polarization direction, stretching, heat setting, and heat relaxation. Changes in pattern geometry vary systematically with film properties, x‐ray, and polarized infrared structural parameters. In one‐way oriented poly(ethylene terephthalate) films, the quadrant, leaves tend toward the equator and elongate with increased draw, taking on a fiberlike appearance, whereas with two‐way drawn films the leaves shift away from the equator and patterns become more circular with increased second direction draw. Melt‐pressed, quenched, unnucleated, polypropylene films show a characteristic spherulitic type pattern. The higher the quench temperature, the larger the spherulites become. Calculated spherulite diameters increase with quench temperature up to 15m for temperatures of 60°C. Upon drawing, the patterns elongate owing to Spherulite deformation and internal reorganization of crystallites, taking on a fiberlike geometry. Nucleated and slowly cooled resins show very little scattering and no spherulitic quadrant leaves. Heat setting usually led to the appearance of new pattern features characteristic of new structures. Heat relaxation tended to smear out the Scatterning patterns as a result of the disappearance of superstructure.
Small angle scattering by a three‐component system. Testing the theory for light scattering
Authors: Coalson R. L. , Marchessault R. H. , Peterlin A. 
Published: June 2010

AbstractLight‐scattering data from solvent‐exchanged, highly swollen gel cellophane were compared with the scattering theory for a three‐component system (crystalline fraction, amorphous fraction, and imbibition liquid) originally developed for the scattering of x‐rays. A rather good agreement, between theoretical and experimental data is obtained in angular dependence and dependence on the refractive index of the imbibition liquid. But the calculated “zero” angle intensities are some orders of magnitude larger than the observed values. This effect must be due to the variation of the internal electric field which is influenced not only by the local polarizability but also by the shape of the region under consideration and by the polarizability of the surrounding area. This effect does not occur with x‐rays since the refractive index is then unity. With visible light one must conclude that the absolute scattering intensity, I(O) is much more affected than the angular dependence which is sufficiently well described by the composite correlation function of the three‐component system.
Mechanical relaxation in polychlorotrifluoroethylene
Authors: Crissman John M. , Passaglia E. 
Published: June 2010

AbstractMeasurements of the viscoelastic functions Δ, G', G″, J′, and J″ as functions of temperature from −180 to +180°C. have been obtained, using a torsion pendulum apparatus, for several samples of polychlorotrifluoroethylene having widely different crystallinities as determined by density. The low crystallinity samples show two relaxations: a very broad one (γ) centered at about −35°C. which appears to be split into two processes, and one (β) at 84°C. In the higher crystallinity samples, a third process (α) appears at about 137°C., and the high temperature side of the γ relaxation peak is lower in magnitude as compared to the lower crystallinity specimens. For the β peak, which is assumed to be associated with the glass transition, the peak value for G″ is essentially independent of crystallinity, while both Δ and J″ show decreases in magnitude with increasing crystallinity. The relationship between the magnitude of the relaxation peak and crystallinity, and dependence of this relationship upon the viscoelastic function chosen to characterize the relaxation are discussed.
Effect of polar forces on the viscoelastic properties of poly(propylene oxide)
Authors: Moacanin J. , Cuddihy E. F. 
Published: June 2010

AbstractWhen lithium perchlorate is dissolved in ethers, volume contractions are observed which are caused by strong interaction forces between the field of Li+ and polarizable ether oxygens. The effect of these forces on the viscoelastic properties of both low (commercial PPG 2025) and high molecular weight/poly(propylene oxide), containing varying amounts of dissolved lithium perchlorate (LP), was investigated by means of dilatometric, modulus, and damping constant measurements over a temperature range between ‐SO and 80°C. The glass transition temperature, Tg, for PPG 2025 was raised from −70 to 40°C. for 25 wt.‐% LP. Neither modulus nor damping curves could be superposed on the reduced T‐Tg temperature scale. Below 15 wt.‐% LP the various properties could be interpreted as resulting from the superposition of the behavior of free polyether segments with that of segments nearest neighbors to LP. Above 15 wt.‐% LP no free segments are left. The behavior of the high molecular weight polyether was similar, except that below 15 wt.‐% LP the single Tg observed for PPG 2025 was split in two transitions, Tg for the polyether at −65°C, and another at −10°C. The latter is believed to be a transition for polyether helices stabilized by LP situated in the helix core.
Calculation of the elastic constants and the lattice energy of the polyethylene crystal
Authors: Odajima Akira , Maeda Takashi 
Published: June 2010

AbstractTo calculate the elastic constants, (Cij), of the polyethylene (PE), Born's dynamical theory of long wave method has been used for a model of interatomic interactions representing inter‐ and intramolecular force fields. Among various types of interaction potentials between nonbonded atoms, two sets of H‐H, C‐H, and C‐C interaction potentials have been adopted which give the best results in reasonable agreement with the data of the lattice parameters and the angle between plane of the zigzag chain and crystallographic axis in the PE lattice. It has been also verified that the lattice energy of PE can be calculated successfully by using the present, potentials. In order to calculate the elastic constant, H‐H and C‐H interactions with close distances have been taken into account for the intermolocular force fields. On the other hand the Urey‐Bradley force field has been used for intramolecular interactions. An expression is obtained which relates Horn's force constants to the macroscopic elastic constants in the orthorhombic system. The calculation has been also made on Cij in a rigid model of molecular chain, but it is found that the increments of elastic constants due to the rigid model are at most a few per cent. The elastic moduli along the a, b, and r, axes and also the normal of the (110) plane have been derived from Cij and compared with values experimentally determined by x‐ray diffractometry. Furthermore, the space averages for compressional, shear, and Young's moduli of PE polycrystals oriented in all directions, and the T3 low‐temperature dependence of heat capacity are discussed.
Dislocations in polyethylene crystals
Authors: Lindenmeyer P. H. 
Published: June 2010

AbstractA summary is given of recent work on the observation of dislocations in polyethylene crystals and the results are discussed in terms of the crystal‐defect model of polymer structure. Both inter‐ and intralamellar dislocations have been observed and their Burger's vectors determined. Most dislocations were observed to be imperfect or partials, indicating that there exist low energy stacking faults. Annealing single crystal brought about approximately a thousandfold increase in the dislocation density which indicates that dislocations are involved in the process of thickening. The observation of dislocation networks in the folds between lamella prove that these folds are sufficiently regular to pack crystallographically. Observed interactions between inter‐ and intra‐lamellar dislocations show that the interlamellar dislocations are glissile and therefore interlamellar slip can occur by a dislocation motion. These observations lend considerable support to the crystal‐defect model of polymer structure. However, it is pointed out that this model does not conflict seriously with tlie statistical equilibrium theory of polymer crystallization. Dislocations are non‐equilibrium defects and hence would not exist under true equilibrium conditions.
Fluorescence method for studying molecular orientation in polymer solids
Authors: Nishijima Yasunori , Onogi Yoshihiko , Asai Takeo 
Published: June 2010

AbstractA new method for measuring molecular orientation in polymer solids is developed involving the use of the polarization phenomena of fluorescence emitted from fluorescent groups dispersed in the media. This fluorescence method makes it possible to measure not only the extent of orientation but also the types of orientation. The theoretical background of this method is described and the theoretical patterns of the angular distribution of degree of polarization of fluorescence are given for several types of orientation, including random, perfect uniaxial, partial uniaxial, and perfect biaxial orientations. It is proved that this method is applicable to symmetrical biaxial orientations for which other optical methods fail to provide information. The procedure of this method is to measure the angular distribution of polarized components of fluorescence intensity emitted from the oriented samples. Examples are given for various orientations of poly(vinyl alcohol) films. The process of transformation in orientation pattern is observed in the course of biaxial stretching of the film. An apparatus for continuous measurements is described.
Polyisobutene Degradation in Laminar Flow: The Effect on Molecular Weight Distribution
Authors: Porter Roger S. , Cantow Manfred J. R. , Johnson Julian F. 
Published: June 2010

AbstractPolyisobntene solutions in n‐hexadecane and 1,2,4‐trichlorobenzene have been mechanically degraded in laminar flow under known and homogeneous stresses up to 105 dyne/cm.2 and at several temperatures in a thin‐film, rotational concentric cylinder viscometer. The polymer studied had an Mv of 8.0 × 105 and a broad and completely defined molecular weight distribution. The molecular weight distribution of the starting polymer and the distributions resulting from polymer exposure to shear fields of various intensities were established by both gradient elution and gel permeation fractionation techniques. The data provide an evaluation of the threshold for shear degradation and the efficiency of energy input in achieving polymer reaction. The results aid in understanding the mechanism of reaction and the effect of shear degradation on molecular weight distribution.
A Comparison of Molecular Weight Distributions for Polyisobutenes as Determined from Gel Permeation and Gradient Elution Chromatographic Fractionations
Authors: Cantow Manfred J. R. , Porter Roger S. , Johnson Julian F. 
Published: June 2010

AbstractMolecular weight distributions for polyisobutenes of broad and narrow molecular weight distribution have been determined by gel permeation and gradient elution chromatography. The molecular weight range covered was from 2,000 to over 1,000,000. Calibration of the gel permeation chromatograph was based on narrow fractions of polyisobutene. This eliminated the uncertainty as to chain extension that exists if the calibration is made with one polymer and applied to a different polymer. Comparison of results from the two methods of determining molecular weight distributions showed, in general, good agreement. Distributions from the gel permeation method were found to be somewhat broader than the known distribution. However, results from the gradient, elution method are of necessity narrower than the real distribution becaues only a finite number of fractions can be evaluated. Column efficiency, as measured in terms of theoretical plates, is found to be dependent on the sample used to make the measurement. It was concluded that the gel permeation method gives molecular weight distributions for polyisobutene with reasonable accuracy and that the method should be entirely satisfactory for comparison of distributions.
Alkaline Polymerization of Caprolactam. XXI. Dissociation of Alkali Metal Salts of 6‐Caprolactam in the Polymerization of 6‐Caprolactam
Authors: Šittler E. , Šebenda J. 
Published: June 2010

AbstractAccording to the accepted mechanism of the anionic polymerization of 6‐caprolactam the chain growth proceeds through addition of lactam anion to the imide group. For the evaluation of rate constants it is necessary to know the concentration of lactam anions in the reaction system. The dissociation constants of lithium, sodium, and potassium salts of 6‐caprolactam in the melt of caprolactam at 100–150°C. were determined by measuring the electrical conductivity of the system. At 120°C. the dissociation constants of the Li, Na, and K salts of caprolactam were found to be 1 × 10−10, 4.9 × 10−7, and 3.6 × 10−5, respectively. The heat of dissociation for sodium caprolactam was found to be 70 kcal./mole and that for the potassium salt was 50 kcal./mole. In the course of the polymerization the caprolactam cis‐amide groups are converted to trans‐amide groups of the polymer chain. The basicity of trans‐amides differs from that of cis‐amide, and therefore the basicity of the reaction mixture is changed in course of polymerization. We measured the dissociation constants of sodium caprolactam and the course of polymerization in the presence of linear N‐alkylamides and polyamides. According to the higher acidity of the trans‐amide groups the dissociation constant rises with increasing content of alkylamide. However, the minor part of anions is formed by lactam anions and therefore the polymerization proceeds more slowly in the presence of polycaprolactam or other trans‐amides. In activated anionic polymerization this influence of trans‐amides disappeared which may be explained by the formation of acidic products formed from imide groups. This lower basicity was proved by measurement of the dissociation of sodium salt in the presence of imides. Additions of amides derived from acetic acid increased the rate of the activated and non‐activated polymerizations.
Nonlinear Relaxation in Polymer Solutions
Authors: Friš P. 
Published: June 2010

AbstractThe Lagrangian function describing an isolated polymeric chain is developed in Taylor series. The solution in the first approximation, which corresponds to Rouse's model with nonconstant hydrodynamic interaction, describes the nonlinear behavior of the solution. The finding of the equation of state is converted to the eigenvalue problem for linear operator.
Einfluss der Schmelzbedingungen auf die isotherme Kristallisation von Polypropylen
Authors: Rybnikář F. 
Published: June 2010

AbstractThe effect of melting temperature and time on the crystallization mechanism of various polypropylene samples has been investigated. It was found that during polypropylene melting two opposite processes take place. The first process consists of destroying the normal heterogenous nuclei, persisted above the melting point. The second process represents a formation of new heterogenous nuclei that cannot be destroyed in an additional melting process. The polypropylene samples could be divided in two groups according to the type of heterogenous nucleation predominating under usual melting conditions. The melting temperature has a more pronounced effect on the variation of the number of nuclei than does the melting time.
Contribution au Probleme de la Corrosion et du Vieillissement des Plastiques
Authors: Bossu B. , Dubois P. , Lecordier Et M. 
Published: June 2010

AbstractWith frequent reference to the recent Russian book by M. B. Neiman, Aging and Stabilization of Polymers, the authors show that the important advances made in the field are based upon knowledge of the reaction kinetics of degradation by heat, oxidation, photooxidation, hydrolysis, and mechanochemical action. The synergy in the effects of these factors and in the search for economical mixtures of stabilizers and anti‐oxygens is illustrated by numerous examples. Bell‐shaped curves are considered, showing the rise from zero to a maximum and the subsequent return to zero, concerning the daily variation of total radiation and its seasonal variations at various latitudes. The energy distributions between ultraviolet, visible, and infrared are also given. The standardization of a radiation hydrothermal cycle, taking into account the extremes of temperature and of relative humidity encountered in moderate and tropical climates, is considered. Special cycles are suggested for arctic and desert climates. The authors give an example of a cycle and a prototype of climatizer, using a triphare or xenon source capable of establishing such cycles, with the possibility of applying a mechanical stress under various conditions. The correlation between natural and artificial aging is discussed.
Infrared Spectra and Structure of Poly‐e‐methylcaprolactam and of e‐Methylcaprolactam–Caprolactam Copolymers
Authors: Schmidt P. , Schneider B. , Čefelín P. 
Published: June 2010

AbstractIt was found that poly‐e‐methylcaprolactam can exist both in the amorphous and in the ordered state. Amorphous poly‐e‐methylcaprolactam may be transformed to the ordered state by treatment with water. In the ordered state, poly‐e‐methylcaprolactam chains assume the B conformation. The conformational structure and state of order of various‐e‐methylcaprolactam‐caprolactam copolymers was determined.