bluuebunny/crossref_metadata_2025_split huggingface dataset:
Block copolymers based on 2,2‐bis(4‐hydroxyphenyl)‐propane polycarbonate. I. Preparation and properties of copolymers from a variety of homopolymers
Authors: Merrill Stewart H. 
Published: April 2003

AbstractLow molecular weight 2,2‐bis(4‐hydroxyphenyl)propane polycarbonate was block‐copolymerized with the bischloroformate of polymeric glycols of a variety of structural types. Poly(ethylene oxide), polytetrahydrofuran, and hydroxy‐terminated polystyrene gave the highest molecular weight copolymers with the polycarbonate. The presence of flexible blocks along the chain promoted the crystallization of the polycarbonate, which resulted in flexible polymers with high melting points. The polytetrahydrofuran copolymer was an elastomer. Preparative details and thermal and mechanical properties of cast films are given.
Studies of the ethylenediamine‐cellulose complex. IV. Decomposition of the complex by dimethylformamide
Authors: Segal Leon 
Published: April 2003

AbstractDimethylformamide applied at 100°C. and at the boil to ethylenediamine–cellulose complexes decomposed the complexes, giving products whose x‐ray diffractograms are almost identical with that of cellulose IV prepared by means of glycerol at 250°C. The product derived from cellulose II has a 002 interplanar spacing of 4.04 A., those from cellulose I and III have a spacing of 3.98. The 101 and 101 interplanar spacings are the same for all the products, 5.71 A. The infrared spectra of the products are markedly similar to those of the original cellulosic starting materials, except in the case of cellulose III. This modification has a cellulose II type of infrared spectrum; that of the product is markedly similar to the infrared spectrum of cellulose I. Application of sodium hydroxide solution and of ethylenediamine to the decomposition products of the complexes produced cellulose II and the ethylenediamine‐cellulose complexes, respectively. Anhydrous ethylamine failed to produce cellulose III.
Differential thermal analysis of silicones
Authors: Brown G. P. , Hill J. A. , Murphy C. B. 
Published: April 2003

AbstractDifferential thermal analysis has been applied to several silicone polymers and compounds with the use of oxidative conditions. The model compounds gave melting points corresponding to literature values. However, volatilization gave a broad endotherm much lower than extrapolated boiling points. The order, in oxidative resistance, was dimethyl silicone oil, silphenylene, methyl phenyl silicone oil.
Spherulitic crystallization and cracking during heat aging of polypropylene
Authors: Inoue Masakazu 
Published: April 2003

AbstractThe spherulitic crystallizations of polypropylene were investigated by a polarizing microscope. At high temperature, crystallization proceeds through the process of dendritic mechanism. Long needles grow rapidly at first from the nucleus to the supercooled melt, and then they fan out around each needle by branching. The rates of these two processes depend on the polymer and the condition of crystallization. In large well‐grown spherulites, cracks are formed both between radial fibers and at boundaries during heat aging. The cracks are void and single spherulites are separated. The boundary cracks are also caused by thermal decomposition of molecules and the radial cracks by stresses due to the rearrangement of molecules or the perfection of spherulites.
Ultraviolet irradiation of plastics. I. Degradation of physical properties
Authors: Stephenson C. V. , Moses B. C. , Wilcox W. S. 
Published: April 2003

AbstractPolyethylene, Teflon, nylon, Mylar, and Acrilan have been irradiated in vacuo and in an atmosphere of nitrogen with narrow bands of ultraviolet radiation centered at 244, 314, and 369 μ and with monochromatic ultraviolet light of wavelength 253.7 μ. The physical properties of all these polymers are ultimately degraded by ultraviolet light of any of these wavelengths, but the shorter wavelengths are much the more effective in producing changes. The degradation of polyethylene, nylon, Mylar, and Acrilan is faster when irradiation is in an inert atmosphere of nitrogen than it is when irradiation is in vacuo. Teflon, however, degrades more rapidly in vacuo than in a nitrogen atmosphere.
Ultraviolet irradiation of plastics III. Decomposition products and mechanisms
Authors: Stephenson C. V. , Lacey J. C. , Wilcox W. S. 
Published: April 2003

AbstractVolatile decomposition products of ultraviolet‐irradiated polyethylene, nylon, Mylar, and Acrilan have been analyzed. The principal decomposition products of polyethylene are hydrogen and methane. Besides hydrogen and methane, carbon monoxide occurs in considerable amounts in the decomposition products of the other polymers. There is a considerable difference in the relative abundances of methane and hydrogen in the decomposition products, depending on whether irradiation was performed in a vacuum or in nitrogen. Decomposition products of ultraviolet‐irradiated nylon include all of the primary amines from methyl through hexyl. Mechanisms consistent with the observed results of photolysis are proposed.
A study of the efficiency of oxidation inhibitors for rubber at various temperatures
Authors: Angert L. G. , Kuz'Minskiǐ A. S. 
Published: April 2003

AbstractA kinetic study of the oxidation of butadiene–styrene and butadiene polymers in the presence of secondary aromatic amine inhibitors has been made over the temperature range 70–150°C. The rate of the inhibited oxidation has been found to depend upon the inhibitor concentration. In contrast with other inhibited processes, this relation is described by a curve with a minimum. The concentration corresponding to the latter depends upon the oxidation temperature, polymer reactivity, and lability of the imino hydrogen of the inhibitor molecule. Experimental data and kinetic computation have shown that the extreme on the efficiency–concentration curve is due to the fact that the amine not only exerts a retarding but also an initiating effect on the polymer oxidation process. The latter is due to direct interaction of the amine and molecular oxygen during the inhibited oxidation of the polymer. The kinetics of oxidation of the amine have been investigated. The duration of the induction period of the polymer oxidation process does not increase in proportion with the inhibitor concentration. The relation between the length of the induction period and rate of oxidation of the polymer for various inhibitor contents has been investigated and discussed. The inhibitor concentration exerts a marked influence on the overall rate of structural changes undergone by the polymer in the oxidation process and also on the ratio of the degradation and structuration velocities of the molecular chains. The change in efficiency of the inhibitor with respect to the oxidation temperature has been examined.
Graft and block photopolymerization
Authors: Smets G. , De Winter W. , Delzenne G. 
Published: April 2003

AbstractBy polymerization of vinyl monomers in the visible light in the presence of dyes (eosin, safranine, acridine orange), ascorbic acid, and oxygen, following the method of Oster, the dye is incorporated as a leuco form into the polymer molecule. In the synthesis of N(eosin) polyvinylamine, one tenth of the amino groups carries a coloured group. This polymer was used for the synthesis of graft polymers with acrylamide, acrylic acid, acrylonitrile, and styrene. The graft polymers were isolated by fractionation; the yield is particularly high with acrylamide and acrylic acid. The per cent contents in the second monomer were 41 (acrylamide), 38 (acrylic acid), 14 (acrylonitrile), and 36 (styrene). The method also makes possible the synthesis of polymers with branches of different chemical structure by successive photopolymerizations of two different monomers, e.g., acrylamide and acrylic acid. Similarly, starting from ω‐N‐(eosin) polymethyl methacrylate, block polymers were synthesized with styrene and acrylamide; the contents in the second monomer was 40 and 79%, respectively. By hydrolysis experiments it was demonstrated that the leuco dye group constitutes the intermediate link in these block polymers between the two monomer sequences.
Radiation‐induced crosslinking and degradation of vinyl chloride‐vinylidene chloride copolymers
Authors: Harmer David E. , Raab Joseph A. 
Published: April 2003

AbstractWhile it is accepted that the high‐energy irradiation of poly (vinyl chloride) produces a predominately crosslinked material, confusion exists about the vinyl chloride–vinylidene chloride copolymer system. Degradation is generally assumed. We have shown that crosslinking (or endlinking) predominates over chain scission in several poly (vinyl chloride–vinylidene chloride) systems. The relative amounts of the two reactions are a function of vinylidene chloride content in the copolymer. While crosslinking is increased at increased temperatures during irradiation, and decresed in the presence of oxygen, a much larger effect is exerted by the physical form (or heat history) of the solid copolymer itself.
Stereospecific polymerization of isobutyl vinyl ether at elevated temperatures
Authors: Iwasaki K. 
Published: April 2003

AbstractIsotactic polyvinyl isobutyl ether was obtained using chromium trioxide as catalyst at elevated temperatures, even at 80°C. Polymerization was carried out in a heterogeneous system. A stirring device to mill the catalyst is necessary to obtain polymer which has a high crystalline fraction. The crystalline fraction, whose melting point is over 140°C., was separated by extracting the amorphous portion with methyl ethyl ketone, and was between 20 and 30% weight of the total polymer. In this connection, other transition metal oxides were examined but chromium oxides of lower valence than 6 had little activity toward polymerization. Moreover, molybdenum trioxide, vanadium pentoxide, and nickel monoxide showed activity toward polymerization, but the polymers obtained with these catalysts had no crystalline fraction.
The swelling of polymer systems in solvents. I. Method for obtaining complete swelling–time curves
Authors: Buckley Donald J. , Berger Martin , Poller Dennis 
Published: April 2003

AbstractA photometric method for measuring the swelling of polymers in solvents from zero time to equilibrium has been described. The method consists in following continually the growing “shadow” of the specimen as it imbides the solvent. Equipment details and method of operation are discussed. Typical swelling–time curves for butyl vulcanizates are reported. These serve as examples of the rapidity and reproducibility of the method and also as demonstrations of the completeness of solvent uptake. Essential agreement between the results on volume swelling at equilibrium obtained by the photometric method and by the conventional gravimetric method is observed. The new method is important in that the rate of swelling can be measured. Its use in this regard in studying the diffusion of liquids in polymers will be referred to subsequent papers in this series.
Thermal coloration and insolubilization in polyacrylonitrile
Authors: Grassie N. , Hay J. N. 
Published: April 2003

AbstractThe thermal coloration reaction in polyacrylonitrile is shown to be similar to that which occurs in polymethacrylonitrile, consisting essentially of the linking up of adjacent nitrile groups to form conjugated carbon‐nitrogen sequences. Thus infrared spectral changes in both polymers consist of a decrease in CN absorption accompanied by the development of CN and conjugated CN absorption. The reactions are accelerated similarly, by nucleophilic reagents such as acids either copolymerized into or external to the polymer chains. There are, however, two major differences between the coloration behaviors of these two materials. Firstly, while polymethacrylonitrile remains color‐stable below 200°C. in the absence of nucleophilic initiating agents, pure polyacrylonitrile colors at a finite rate which is not reduced by further attempts at monomer purification. This is due to the fact that the tertiary CH structures in polyacrylonitrile, absent in polymethacrylonitrile, are capable of initiating coloration. It seems more likely that this occurs intramolecularly than intermolecularly. Secondly, while polymethacrylonitrile remains soluble even when extensively colored, polyacrylonitrile rapidly insolubilizes. This is not due to crosslinking in an intermolecular self‐initiation process; rather, it appears that the successive linking up of nitrile groups can move. from molecule to molecule in polyacrylonitrile owing to the more intimate packing of the chains, so that “propagation crosslinks” are produced. This theory of “propagation crosslinking” is supported by the observed influence of various comonomers in inhibiting crosslinking.
Properties of polyvinylidene fluoride. Part III. Viscous behavior and thermal stability
Authors: Bagley Edward B. , Wentink Tunis 
Published: April 2003

AbstractViscosity measurements were made on the plastic polyvinylidene fluoride at 240°C. The flow properties continually change with time, the viscosity increasing steadily at constant stress and temperature. This is probably due to slight simultaneous evolution of HF gas and crosslinking of the polymer chains.
Primary and secondary hydroxyl group content of polypropylene glycols
Authors: Hanna J. Gordon , Siggia Sidney 
Published: April 2003

AbstractWhen propylene oxide is polymerized or when it is added onto an alcohol or phenol, the terminal hydroxyl groups can be of primary or secondary types, depending on how the epoxide ring opens. The nature of the terminal hydroxyl group becomes important if the polyglycol ether is reacted further, as in the case of polyurethane foams. The primary hydroxyl group reacts much more rapidly with isocyanates than the secondary hydroxyl group, and hence the performance of the polyglycol varies with the ratio of primary to secondary hydroxyl group content. An analytical method has been developed to differentiate the primary from the secondary hydroxyl groups on polypropylene glycol, and a study was made of the variation in the ratios of the two hydroxyl types versus molecular weight of the polyglycol and versus other chemical treatments to which the polyglycol was exposed.
Polyethylene unit cell variations with temperature
Authors: Swan Paul R. 
Published: April 2003

AbstractThe unit cell dimensions of a linear polyethylene are reported as determined by x‐ray diffraction measurements at five‐degree intervals from −70°C. to +130°C. and at −196°C. The relative expansion coefficient of the a dimension of the orthorhombic unit cell was found to increase from 1.1 × 10−5/°C. at −196°C. to 22 × 10−5/°C. at 30°C. to 58 × 10−5/°C. at 138°C., the melting point of the crystal. The coefficient of the b dimension was found to vary from −2.8 × 10−5/°C. at −196°C. (questionable) to +3.8 × 10−5/°C. at 30°C., and then to −7.3 × 10−5/°C. at 138°C. These values were obtained from series expansion analytical fits to the experimental points, and are less accurate at the ends of the temperature range; the 30°C. values are probably correct to a few per cent.
Heterogeneous hydrolysis of cellulose with high polymer acids. Part 3. The acid hydrolysis of cellulose with finely divided cation‐exchange resin in the hydrogen form
Authors: Hartler Nils , Hyllengren Kari 
Published: April 2003

AbstractGeneral aspects of acid hydrolysis of glycosidic bonds are presented. Homogeneous versus heterogeneous hydronium ions and glycosidic bonds, and also their various combinations, are especially noted. Cation‐exchange resin of the strongly acid type in the hydrogen form is shown to have little or no hydrolysis effect on the glycosidic bonds in cotton. The results obtained can probably be completely explained in terms of the effect of low molecular weight acids arising from degradation of the resin. The composition of small amounts of dissolved carbohydrates was the same whether a cationexchange resin or a low molecular weight acid was used.
The application of copolymerization theory on memory devices
Authors: Ham George E. 
Published: April 2003

AbstractAdvances in the mathematical treatment of copolymerization phenomena, which allow for the influence of units at any distance from the growing chain ending on reactivity with monomers, have suggested means of treating the influences of memory and nonmemory factors on the making of simple decisions and their application to memory devices. Genetics and reproduction and brain functions are believed to be influenced by considerations of the type discussed. The equations may be applied also to the preparation of proteinlike copolymers and the elucidation of sequence distributions in natural and synthetic polypeptides.
Polymer—diluent interactions. II. Polyvinyl chloride—diluent interactions
Authors: Anagnostopoulos C. E. , Coran A. Y. 
Published: April 2003

AbstractThe solvent power of a variety of diluents with polyvinyl chloride was evaluated in terms of the polymer—diluent interaction parameter χ and heat of mixing parameter B by means of a micromethod reported in the first part of this series. Among the diluents investigated are esters of phthalic, fumaric and maleic acids, alkyl‐substituted benzenes, and condensed and conjugated aromatic ring systems. Relationships between solvency and diluent structure were sought in terms of the intermolecular forces involved in polymer—diluent associations. A condition found necessary for good solvency is that both the dispersion and dipolar forces acting between solvent molecules be similar in strength to the corresponding forces acting between polymer macromolecules. Steric hindrance of the carbonyl dipoles in the ester molecules, or of the aromatic nuclei in the hydrocarbon molecules, has a pronounced effect on the values of B. The extent of resonance interactions in the hydrocarbon molecules influence their solvent power. Where such interactions are reduced due to steric effects, solvency is also reduced.
Thermodynamic properties of moderately concentrated polyisobutylene–chlorobenzene solutions
Authors: Leonard J. , Daoust H. 
Published: April 2003

AbstractThe recent Fixman's variational theory devised to compute the osmotic pressures of high polymer solutions in the moderate concentration range has been applied to the polyisobutylene—chlorobenzene system at 25°C and 40°C. The osmotic pressures have been measured with an osmometer similar to that described previously by Flory and Daoust. As predicted by the theory, a plot of the apparent osmotic second virial coefficient against concentration gives a curve which rises then flattens out as concentration increases, at both temperatures. Correlation between experimental data and theory is slightly better if the Kurata‐ Yamakawa theory is used to calculate the linear expansion factor of the polymer coil α and to define the second virial coefficient A2.
The rheology of polymer solutions in oil
Authors: Philippoff W. 
Published: April 2003

AbstractThe flow birefringence and viscosity of solutions of two samples of polyisobutylene in 14 different solvents were measured in a wide range of rates of shear and concentrations. For a match of refractive index of solvent and polymer, the conditions could be completely described by the stress‐optical coefficient C over the whole range, the value being equal to the one measured on the 100% rubberlike polymer. For nonmatching solvents, according to the occurring form effect, the C becomes dependent on both molecular weight, concentration, and shear stress. These statements are independent of the viscosity of the solvent, but depend only on the index of refraction n of the solvent. This has been proved by measurements in low viscosity solvents and in hydrocarbon oils with a change of the viscosity of the solvent of about 100‐fold. The performed measurements on higher concentrations (up to 30 wt.‐%) give essentially the same results as those extrapolated to zero concentration. For these relations, allowance has to be made for viscosity and birefringence of the solvents. One therefore can conclude that the viscosity of the solvent as such does not affect either the viscosity or flow birefringence of polymer solutions, the conditions being fully described by the intrinsic viscosity [η]v and the index of refraction of the solvent. The main factor in the flow birefringence is the shear stress set up in the flowing solution.
Shear dependence in solutions of fractionated dextran: A variable‐shear capillary viscometer for use with aqueous solutions
Authors: van Oene H. , Cragg L. H. 
Published: April 2003

AbstractThe viscosity behavior of a high molecular weight fraction (M̄w = 9.8 × 106) of dextran (B‐512) in aqueous solutions was studied at low and medium shear stresses, and its intrinsic viscosity was shown to be independent of shear stress. A convenient and precise multibulb Ubbelohde‐type viscometer, especially designed for use with aqueous solutions is described. The calibration of the viscometer and the evaluation of surfacetension corrections of relative flow times measured in it are discussed in detail.
Velocity of dissolution of polymers. Part I
Authors: Ueberreiter Kurt , Asmussen Frithjof 
Published: April 2003

AbstractA short description is given of the apparatus for the solution of a macromolecular substance in a solvent and the mathematical treatment of the curves. A relation is obtained for the velocity of penetration ⋅ (cm./sec.) of the solvent into the polymer:

where D is the integral, mutual diffusion coefficient and δ the thickness of the swollen layer on the surface of the polymer. The dependence of the process on the temperature is

The swollen layer δ is investigated in detail. It consists first on the side of the solvent of a streaming layer (liquid layer) δ1. Below this is a rubberlike layer δ2. These layers are made visible by dispersed carbon black particles. The total layer δ increases with the temperature:

The liquid, swollen polymer is removed from the surface and its polymer content measured. The mean content of polymer in the double layer δ1 + δ2 increases with the temperature. Viscosity measurements are made to draw final conclusions regarding the stability of δ. The mean viscosity in δ can be taken from these viscosity curves, as the content of polymer in δ is known. The stability (viscosity) increases with the temperature. The reason for it is the decrease of the solid, swollen layer below the rubberlike layer. The polymer content in the rubberlike layer increases to the same extent as the solid, swollen layer decreases. The total swollen layer δ is built up of four layers: a liquid layer δ1, a rubberlike layer δ2, the solid, swollen layer δ3, and an infiltration layer δ4. δ3 contains so few solvent molecules that its state at the temperature of solution is still solid and swollen. δ4 is a solid, glassy polymer, the holes and channels of which have only been filled with solvent molecules without swelling the structure. All four layers exist at temperatures of solution below the glass temperature of the polymer. δ3 and δ4 disappear at the glass temperature, and at the flow temperature the polymer and its layer are liquid. The variation of the concentration in δ is measured interferometrically. The concentration of solvent decreases sharply in δ3 + δ4 and linearly in δ1 + δ2 down to zero. The streaming of the solvent influences mostly δ1. The slope of the log ⋅ versus 1/T curves differs above and below the glass transition. The coefficient of diffusion can be calculated from the solution formula and, independently, from time lag measurements. Both values agree well.