bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of chemical composition on selected physical properties of linear polymers
Authors: Izard E. F. 
Published: April 2003

AbstractA review of the data available in the literature and new data reported in this paper show that in any homologous series of condensation polymers there is a uniform change in the melting point as the hydrocarbon content of the polymer is increased. If all such series are treated as copolymers of the simplest modifying element and polyethylene and the composition expressed on a mole fraction basis, the data when presented graphically show that the melting points of any such series passes through a minimum at some intermediate composition. The position of the minimum as well as the depth of the minimum is dependent on the polarity of the modifying group. This survey has included aliphatic polyesters, aromatic polyesters, polysulfides, cellulose derivatives, and polyamides. Some of the series are complete enough to show a definite minimum with compositions on either side of the minimum with higher melting points. In some compositions based on the very highly polar groups, such as amides, the series is not complete enough to establish the complete shape of the curve, but the indications are strong that the minimum does exist.
Polyelectrolytes. X. Shear dependence of viscosity in aqueous solutions of poly‐4‐vinyl‐N‐n‐butylpyridinium bromide
Authors: Strauss Ulrich P. , Fuoss Raymond M. 
Published: April 2003

AbstractApparent viscosities of aqueous solutions of polyvinylbutylpyridinium bromide (DP = 2000), after correction for instrument constants, are linear in average rate of shear in the capillary viscometer. If a non‐Newtonian solute in a Newtonian solvent is assumed, the rather complicated experimental viscosity‐pressure curves at various concentrations may be summarized by the simple expression ηsp./C = z∞ (1 − αz∞β)where z∞ is ηsp./C extrapolated to zero rate of shear and β is the average velocity gradient.
Some new butadiene copolymers
Authors: Marvel C. S. , Fukuto T. R. , Berry James W. , Taft W. K. , Labbe B. G. 
Published: April 2003

AbstractCopolymers of butadiene with 2‐ethoxyethyl acrylate, 2‐ethoxyethyl methacrylate, tetrahydrofurfuryl acrylate, acrylic acid, and methacrylic acid have been prepared and evaluated as rubbers. The 2‐ethoxyethyl acrylate copolymer has good low temperature properties. The methacrylic acid copolymer has unexpectedly good oil resistance, but the low temperature properties are poor. The acrylic acid copolymers show fair oil resistance and good low temperature properties. Both acrylic acid and methacrylic acid copolymers with butadiene show unexpectedly good tensiles.
A new tool for determination of the stage of polymerization of thermosetting polymers
Authors: Sofer George A. , Hauser Ernst A. 
Published: April 2003

AbstractStudies of the change of attenuation and velocity of longitudinal ultrasonic waves with proceeding polymerization of thermosetting plastics have revealed that this new technique may permit rapid determination of the stage of polymerization under various conditions. The ultrasonic equipment used for these tests is described in detail. On the basis of results so far obtained, future possibilities for the application of this new technique in studying polymerization reactions are outlined.
The elasticity of polythene melts
Authors: Hoff E. A. W. 
Published: April 2003

AbstractThe elasticity of polythene melts was measured with a resonance method by inducing shear oscillations in the region about 30 cycles/second at small shear amplitudes. The experiments covered a temperature region of 130° to 230°C. and a range of (osmotic) molecular weights from 12,000–64,000. Shear moduli of the order 105 to 105 dyne cm.−2 were observed and a single relaxation time appeared sufficient to characterize the mechanical behavior of the polythene melts at a given temperature. The variation of mechanical parameters with temperature and molecular weight is brought into relation with known data on the amount of chain branching.
Further studies by light scattering of amylose aggregates. Particle weights under various conditions
Authors: Paschall Eugene F. , Foster Joseph F. 
Published: April 2003

AbstractDecreases in particle weight of amylose on aging in neutral and in alkaline aqueous solution are demonstrated by measurements of turbidity as a function of concentration. This further verifies that the previously reported turbidity drops are a consequence of disaggregation of an unusual type of aggregate. The same particle weights are obtained, in the case of aggregated samples, at pH 4 and in normal KOH. Anomalies arise in dilution series carried out in neutral solution and in solutions at pH 4 in the case of amyloses of low degree of aggregation, and a probable explanation is given. Samples can be partially stabilized in a given state of disaggregation by rendering the solution alkaline, and normal dilution series curves result. Disaggregation of the “native” aggregates continues along with retrogradation, and the retrograded aggregates are broken down readily by alkali. This leads to a method of disaggregation based on retrogradation followed by solution in 0.5 N KOH.
Stability of the vulcanized cross link in butyl rubber: Theory and application
Authors: Zapp R. L. , Ford F. P. 
Published: April 2003

AbstractIt has been determined analytically that, when a Butyl vulcanizate softens during exposure to high temperature, the disulfide cross links between polymer chains break down to thiol groups. Of all the accelerator types, tellurium derivatives of dithiocarbamic acids impart the greatest inherent resistance to this reversion. Such a mechanism of breakdown, however, suggested the use of oxidizing agents to reform the disulfide cross linkage, and four metallic peroxides or dioxides have been found effective. These are CaO2, PbO2, MnO2, and SrO2. Barium peroxide is too stable to be an effective oxidizing agent while magnesium peroxide expels oxygen too rapidly for an effective retarder. Other types of organic and inorganic oxidizing agents have not proved beneficial. The fact that an oxidizing action is responsible for retardation of reversion has been demonstrated by the fact that the corresponding mono‐oxides of calcium, strontium, lead, and manganese do not perform in the same manner. In rubber technology the stabilization of vulcanized materials by oxidizing agents is novel, and it appears applicable only in the case of Butyl whose low unsaturation offers greater resistance to oxidation of the chain proper. When CaO2 is added to diene type rubbers such as Buna S, Buna N, and natural rubber the common oxidative effects are accelerated. With the Buna rubbers the hardening action is more rapid, while with natural rubber a softening followed by a hardening action is promoted.A practical illustration of this principle of retarding reversion of Butyl vulcanizates by oxidizing agents has been presented. It has been demonstrated in the laboratory that the service life of automotive tire curing bags made from Butyl can be prolonged by the addition of these metallic dioxides or peroxides to the compound.
Rates of thermal degradation of polystyrene and polyethylene in a vacuum
Authors: Madorsky Samuel L. 
Published: April 2003

AbstractWhen heated in a vaccum at 325° to 375°C., polystyrene yields mainly the monomer and some dimer, trimer, tetramer, etc., indicating that the breaks in the molecular chains occur largely at the ends. Polyethylene, under similar conditions, but at a some‐what higher temperature, yields fragments of an average molecular weight of about 700, indicating that the molecular chains break, mostly at random positions. A study was made of rates of thermal degradation of these two polymers by measuring rates of loss of weight of samples by means of a very sensitive tungsten spring balance enclosed in a vaccum. The samples were limited to 5–6 mg. in order to avoid spattering during degradation. Rate curves plotted against per cent loss of weight by volatilization indicate that in the case of polystyrene the process is intermediate between a zero and first order reaction, while in the case of polyethylene, the process approximates a first order reaction. Activation energies were calculated on the basis of rates of degradation at various temperatures. The values thus obtained for polystyrene and polyethylene are 58 and 68 kilocalories, respectively.
Preparation of 1,3,5‐trivinyl‐2,4,6‐trichlorobenzene and its copolymerization with styrene
Authors: Ross Sidney D. , Markarian Moushy 
Published: April 2003

Abstract1,3,5‐Trivinyl‐2,4,6‐trichlorobenzene has been prepared and its copolymerization, at low weight percentages, with styrene has been studied by following the change in viscosity of the polymerizing systems as a function of time. The copolymerization was studied as a function of the concentration of the trivinyl compound (0.5–2 weight per cent) at two temperatures and two benzoyl peroxide concentrations. The gelation times and per cent styrene polymerized at gelation were estimated. In addition, the copolymerization of 1,3,5‐trivinyl‐2,4,6‐trichlorobenzene with styrene was compared with that of 1,4‐divinyl‐2,3,5,6‐tetrachlorobenzene and 1,3‐divinyl‐2,4,5,6‐tetrachlorobenzene, both with styrene. The infrared and ultraviolet spectra of the three cross‐linking agents were determined. The ultraviolet spectrum of 1,4‐divinyl‐2,3,5,6‐tetrachlorobenzene provides a basis for explaining its greater reactivity in copolymerization with styrene.
Ratio of tensile strength to melt viscosity for high polymeric materials
Authors: Boyer Raymond F. 
Published: April 2003

AbstractThe ratio of tensile strength of a polymer at 25°C. to its melt viscosity at some elevated temperature in the fabrication range is suggested as a quantitative figure of merit for commercial polymers. This ratio goes through a very sharp maximum as a function of molecular weight. The height of the maximum drops sharply with increasing molecular weight heterogeneity, although the location of the maximum along the molecular weight scale is unchanged. This behavior follows because tensile strength depends on number‐average, and melt viscosity on weight‐average, molecular weight. The possible role of non‐Newtonian behavior on these conclusions is discussed. Finally it is shown that the ratio of tensile strength to melt viscosity for a plasticized polymer increases exponentially with plasticizer content.
Reactivity ratios of some monomer pairs
Authors: Haas Howard C. , Simon Myron S. 
Published: April 2003

AbstractTo continue the study of the effect of structure on reactivity, an experimental investigation of the free radical copolymerization behavior of eight monomer pairs has been made. The monomer pairs include: vinyl acetate‐methyl vinyl ketone; vinyl acetate‐1,3‐acetoxybutadiene; acrylonitrile‐1,3‐acetoxybutadiene; methylacrolein‐acrylonitrile; vinylsulfonic acid‐methyl methacrylate; 2,5‐dichlorostyrene‐2,5‐dimethylstyrene; vinyl acetate‐fumaryl chloride; and styrene‐fumaryl chloride.
Redox recipes. VII. A recipe with ferric versenate, hydrazine, and hydroperoxide as activating system (veroxazine recipe)
Authors: Kolthoff I. M. , Meehan E. J. 
Published: April 2003

AbstractA new initiating system, named the “Veroxazine” system, for the copolymerization of butadiene (75)–styrene (25) is described. Ferric versenate is reduced by hydrazine to the ferrous complex which in turn reacts with hydroperoxide to produce the radicals which initiate polymerization. At 5°C., with 5 parts of K‐fatty acid soap, 0.1 part of Diox D, 0.1 part of N2H4·H2SO4, 0.0615 part of sodium hydroxide (to give free hydrazine base from the salt), 0.0005 M ferric iron (equivalent to 0.036 part ferric nitrate nonahydrate per 100 parts monomers), 0.0005 M versene, 1 part of K4P2O7 and 0.3 part sulfole, 70% conversion is reached in 12 hours. The rate of conversion can be varied within wide limits by changing the concentration of ferric iron, versene, or hydrazine. Typical conversion–time data at 5°C. with K‐fatty acid soap, 0.1 Diox D, and 1 part of K4P2O7 are summarized below.

Fe(III)
V
N2H4·H2SO4, part
Conversion, %

1
2
4
8
12 hrs.

0.005
M
0.002
M
0.1
14
25
47
90
—

0.002
M
0.001
M
0.1
11
22
44
75
—

0.001
M
0.0008
M
0.1
9
19
32
64
85

0.0005
M
0.0005
M
0.1
6
16
28
48
70

0.0003
M
0.0002
M
0.1
4
10
19
38
53

0.001
M
0.0005
M
0.4
17
31
52
92
—

0.001
M
0.0005
M
0.2
15
27
40
81
—

0.001
M
0.0005
M
0.1
11
21
33
62
83

0.001
M
0.0005
M
0.05
6
14
27
47
66

With a given concentration of ferric iron the maximum rate is found with a molar concentration of versene slightly smaller than that of ferric iron. The excess of ferric iron over versene is kept in aqueous solution as the complex with pyrophosphate. The addition of potassium pyrophosphate up to one part increases the rate of conversion and yields a normal latex free from precoagulation. In the absence of pyrophosphate a viscous latex subject to precoagulation is obtained. The effects of kind and amounts of soap, of free acid or base, of kind and concentration of hydroperoxide, kind and concentration of mercaptan, of oxygen, of methanol, and of shortstops have been investigated. Veroxazine recipes which give from 55 to 70% conversion in 12 hours at −5°C. are described.
Thermodynamics of high polymer solutions. VI. The compatibility of copolymers
Authors: Scott Robert L. 
Published: April 2003

AbstractIt is evident that a copolymeric mixture, if sufficiently heterogeneous in chemical composition and molecular weight, may separate into two or more distinct phases. The conditions for thermodynamic stability of a single‐phase system have been investigated using the modified Flory‐Huggins equations for heterogeneous polymer mixtures. The equation for a “spinodal hyper‐surface” serves as a sufficient, but not always necessary, condition for phase separation. With certain simplifying assumptions, this reduces to the requirement that two or more phases must exist if:

where M̄w is the weight average molecular weight, ρ is the density of the high polymer, xk is the mole fraction (or volume fraction) of chains with the same chain‐average chemical composition, represented by the “solubility parameter” δk, and δ is the average δ for the whole mixture. For a typical case (M̄w = 100,000, ρ = 1, T = 300°K), the standard deviation in δ cannot exceed 0.055. Since for a typical copolymer the possible range of δ (from 100% of one monomer to 100% of the other) may be 0.5–1.0 δ‐units, we conclude that most copolymers must be reasonably homogeneous in chemical composition; the over‐all composition of one chain cannot differ greatly from that of another in the same phase.
Polysoaps. IV. Dissolution phenomena of a poly‐4‐vinylpyridine derivative
Authors: Strauss Ulrich P. , Assony Steven J. , Jackson Earl G. , Layton Lionel H. 
Published: April 2003

AbstractA polysoap was prepared from poly‐4‐vinylpyridine by quaternizing 43.4% of the pyridine nitrogens with ethyl bromide and 46.7% with n‐dodecyl bromide. Temperatures considerably higher than 25°C. were necessary to bring the polysoap into solution; but, once prepared, the solutions remained stable when cooled to 25°C. Viscosities measured just after the polymer had dissolved were irreproducible. On further heating, the viscosity decreased, eventually reaching a constant value which was reproducible. The viscosity decreases of three portions of a 0.5% solution was followed at 45°C., 55°C., and 65°C., respectively, and it was found to be fastest at the highest at the highest of these temperatures and slowest at the lowest. The final values reached at all three temperatures were approximately the same. These results are consistent with the assumption that the initially irreproducible viscosities are due to clusters of polysoap molecules which have not had enough time to break up. Prolonged heating is necessary to produce complete dissolution into individual molecules. Once reproducibility was attained it was shown that the polysoap exhibited essentially the same viscosity and solubilization characteristics as had previously been observed for polysoaps derived from poly‐2‐vinylpyridine.
Ultramikroskopische beobachtungen an polystyrollösungen
Authors: Breitenbach J. W. , Duch E. 
Published: April 2003

AbstractDas Streulicht von Polystyrollösungen in Benzol, Methyläthylketon und Cyclohexan kann auch bei ausreichender Knäuelgrösse und genügender Verdünnung im Spaltultramikroskop nicht aufgelöst werden. Die in Lösungsmittel‐Fällungsmittelgemischen auftretenden Ultramikronen sind wahrscheinlich schon Molekelaggregate. Das ultramikroscopische Bild der Fällung von Polystyrol aus Benzol mit Methanol wird beschrieben.
Les possibilités de la diffusion des rayons X aux petits angles dans l'etude des grosses molécules
Authors: Guinier A. 
Published: April 2003

AbstractLes progrès récents réalisés dans la technique et dam les différentes théories de la diffraction des réactions‐X à faible angle sont analysés de façon critique en vue d'examiner les possibilités pratiques qu'ils offrent dans les recherche sur les macromolécules et les miceues.
Fitting of polymer distributions of molecular weight by the method of moments
Authors: Herdan G. 
Published: April 2003

AbstractAs an alternative method to fractionating the polymer into portions of different molecular weight, in order to obtain the distribution of molecular weights, the method of fitting by statistical moments is proposed. It is shown how from a knowledge of differen order, utilising the inequalities between such averages and their relation to the dispersion of molecular weight, estimates of the distribution function can be obtained: (A) under the assumption of a standard form for the distribution function; (B) without such an assumption, but building up the approximation from a standard form as the norm function and its derivatives; (C) without using any standard form of distribution at all. Numerical examples of the fitting procedures accompany the exposition.
Effects of the ionizable components in cast phenoplasts
Authors: Harris Thomas G. , Neville Harvey A. 
Published: April 2003

AbstractThe various stages employed in the production of a phenolformaldehyde cast resin are discussed. It is assumed that the chains formed during the condensation stage undergo a rearrangement upon acidification to yield roughly spherical, stabilized micelles. These micelles are concentrated by dehydration until coalescence begins. At this point the chains again rearrange and the resin becomes the continuous phase. Pronounced changes in the properties of the system are observed at this critical point. The effects produced by undercondensation, overcondensation, overdehydration, etc. are mentioned briefly. The ionizable components, by determining the interfacial pH during the curing stage, are shown to be directly related to the rate of cure, stability, color, light transmissibility, etc. of the cured casting. Transparent castings are expected only when an ionizable component of the proper refractive powers is oriented at the interface. An examination of the immediately available data provides a lead to the future changes that can be expected as aging progresses.
The changes induced in sodium desoxyribonucleate by dilute acid
Authors: Reichmann M. E. , Bunce Barbara H. , Doty Paul 
Published: April 2003

AbstractLight scattering and viscosity studies have been made on solutions of sodium desoxyribonucleate in 0.2 M NaCl adjusted to pH values of 6.5, 3.0, and 2.6 by dialysis in order to prevent contact with more concentrated acid. It is found that the molecular weight (7,700,000) is the same under these three conditions and remains so when the acid solutions are adjusted to pH 6.5. Upon lowering the pH the molecular size decreases due to increased coiling, but returns to its original value upon reneutralization. At pH 2.6 the mean radius of the molecule is less than half the pH 6.5 value. It is argued that these observations invalidate the existing evidence for degradation or disaggregation accompanying the appearance of new titratable groups. However, it is likely that most of the amino groups have not been titrated at pH 2.6 at the ionic strength employed here. Consequently the possibility remains that the stability at pH 2.6 is a consequence of a hydrogen‐bonded structure that is still largely intact.
Polymerization in bulk at high pressures
Authors: Klaassens K. H. , Gisolf J. H. 
Published: April 2003

AbstractIn this paper an apparatus is described for polymerizing monomers in bulk up to a pressure of 10000 atmospheres and in which the polymerizing substance can be heated and the temperature of the substance measured. Styrene shows an explosive reaction at 10000 atmospheres and at about 70°C. Indene polymerizes slowly when heating at 10000 atmospheres and shows an explosive reaction at 175°C. Both compounds give a solid polymer. Crotonaldehyde heated at 10000 atmospheres gives a brittle, high‐melting polymer. Coumarone and some chlorinated ethylenes carbonize when heated at 10000 atmospheres. Butyraldehyde polymerizes to a solid product which rapidly reverts to butyraldehyde.
Sur l'étude des mélanges de protéines au moyen de la lumière diffusèe
Authors: Guinand Sylvanie , Labeyrie Françoise , Tonnelat Jacques 
Published: April 2003

AbstractMolecular weights of lactoglobuline and trypsin, as determined at pH 6.8, agree with the data generally admitted. However the molecular weight of trypsin in 1/100 M hydrochloric acid solution in the absence of salts, is two to three times lower than the value received in buffered solution at pH 6.8. With the purpose of detecting any combination or polymerization reaction, the study of mixtures showed that no conclusion may be obtained from the values of diffused light intensity at 90° when the diffusion diagram is not rigorously symmetrical.
Determination of molecular weight of polyvinylpyrrolidone
Authors: Frank H. P. , Levy Gabor B. 
Published: April 2003

AbstractThe molecular weight of selected polyvinylpyrrolidone samples was determined by light scattering and by osmotic pressure in methanol. The corresponding limiting viscosity numbers were also determined, as well as the limiting viscosity number of the same samples in water. The data relating to the methanolic system conform with theory and the values for K and α in [η] = KMα were determined. The data relating to aqueous solutions do not show such conformity but an unexplained dependence on the degree of homogeneity of the samples. Nevertheless some empirical constants were deduced which may aid in industrial practice in which aqueous viscosity measurements are usual.