bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanical behavior of some lightly crosslinked rubbers
Authors: Nielsen Lawrence E. 
Published: April 2003

AbstractThe creep and dynamic mechanical properties of rubbers with a wide range of degree of crosslinking have been correlated with the swelling properties of the rubbers. Both butyl and styrene–butadiene rubbers were studied. Mechanical damping steadily decreases as the crosslinking increases. A damping test could replace the usual swelling tests as a measure of the tightness of the network structure. Lightly crosslinked rubbers have a minimum in the damping‐temperature curve while highly crosslinked rubbers do not. Very small degrees of crosslinking dramatically decrease the creep rate, however, even for highly crosslinked rubbers, creep does not completely stop. The Nutting equation often gives a very good correlation between damping and creep rate.
Some implications of the gel point concept to the chemistry of alkyd resins
Authors: Bobalek E. G. , Moore E. R. , Levy S. S. , Lee C. C. 
Published: April 2003

AbstractThis study explored the effects of chemical composition, extent of polyesterification and possible side‐reactions upon the rheological behavior of a variety of oil‐modified, glyceryl phthalate alkyds in both melt and in dilute solutions with several solvents. Correlative data were obtained on molecular weight and on other aspects of solubility and drying properties important to paint technology. Viscometric data proved very useful in relating variances of reaction degree with usage properties of these polymeric materials. Those data suggest a viewpoint of the gel point mechanism which enhances practical utility of polyesterification theory. This hypothesis proposes that alkyd synthesis is not a homogeneous reaction throughout, and that phase separation creates a colloidal dispersion in the reacting mass long before gelatification occurs. Classical polyesterification theory can predict the event of initial phase separation; other process variables affect the relative stability of the transition colloid which ultimately coalesces into the final gel structure. Practical properties of alkyds in paint vehicles can be adjusted to satisfy varying requirements by arresting the reaction at different levels before or in the transition region. Measurements of melt viscosity and intrinsic viscosity are especially sensitive and convenient probes for control of process and product in terms of this concept.
Molecular weight distribution in alkyd resins. Part I
Authors: Fletcher J. R. , Polgar L. , Solomon D. H. 
Published: April 2003

AbstractThe factors which could affect the molecular weight distribution of a fatty acid modified polyester (alkyd) are discussed. Specific studies on a 33% coconut oil/glycerol/phthalic anhydride polymer are described, and the effect of monoglyceride composition on alkyd distribution and film properties of an automotive baking enamel are considered.
Experimental study of the mechanism of film formation
Authors: Brodnyan John G. , Konen Thomas 
Published: April 2003

AbstractThe temperature above which a polymer latex forms a continuous film, i.e., the minimum film formation temperature (MFT), was studied as a function of particle size, surface tension, and stiffness of the polymer. The MFT was found to occur in the region where the modulus of the polymer G is decreasing very rapidly with increase in temperature. The MFT appears to be independent of particle size but very strongly dependent on polymer stiffness. The random error in MFT measurement, however, is equivalent to a change in polymer modulus of the same order of magnitude as the particle size variation investigated. Thus the ratio Gr/γ, where r is the particle radius and γ the surface tension, may be constant as predicted by Brown for a given chemical composition but the instrumentation used was not sensitive enough to prove it. The value of that ratio, however, depends markedly upon chemical composition going from an average value of 0.58 for a nonpolar copolymer (75% styrene, 25% n‐butyl acrylate) to an average value of 260 for a more polar copolymer (50% ethyl acrylate, 50% methyl methacrylate). The quantity (MFT‐Tg), where Tg is the glass temperature of the polymer, also depends upon the chemical composition going from a value of 10°C to −3°C. when changing from the nonpolar copolymere to the more polar copolymer mentioned above.
Effect of organic sulfur compounds on the autoxidation and stress relaxation of peroxide vulcanizates of natural rubber
Authors: Cunneen J. I. , Lee D. F. 
Published: April 2003

AbstractThe effect of various sulfur compounds on the oxidizability and stress relaxation of peroxide vulcanizates of natural rubber has been investigated. Many of the sulfur compounds reduce the rate of stress relaxation and oxygen absorption, but in general their inhibitory powers are considerably less than those observed when they are added to squalene.
Anomalous flow of cellulose solutions during spinning
Authors: Reeves E. V. 
Published: April 2003

AbstractAn apparatus is described for measuring the flow rate of cellulose xanthate solutions at known pressure gradients across spinning jets. It is shown that the jet hole behaves more like a capillary than an orifice in its effect on flow and that similar relationships exist for flow through spinning jet holes and a narrow pipe characterized by an equation of the form Q = Apb, where b has a value of approximately 1.5 for the high rates of shear strain found in spinning jets and 1.4 for the lower rates found in the pipe. A fundamental approach shows a similar discontinuity when comparing the relation between apparent viscosity coefficient and rate of shear strain, between low and high rates of shear. Experimental results are given for the effect of certain chemical factors in viscose solutions and the effect of spinning jet hole size, on the flow rate/pressure gradient curve.
Acrylic latex film formation in the critical temperature range
Authors: Myers Raymond R. , Schultz Ray K. 
Published: April 2003

AbstractA shear wave of 15 megacycle frequency and four microsecond duration was made to impinge on the under‐side of a series of ethyl acrylate‐methyl methacrylate copolymer films on fused quartz. Reduction in the reflection coefficient of the pulse provided a direct measure of the increased viscosity and elasticity of the film as it dried, as well as the loss in adhesion which occurred in some cases. Upon reducing the minimum film‐forming temperature (MFT) from 54 to 32°C. by increasing the ethyl acrylate content from 35 to 50%, the adhesion loss was reduced, eventually to zero, depending on the drying rate. Despite the fact that elasticity of the latex particles is the controlling parameter in film quality, a dependence on their viscosity was revealed by this work.
Hard rubber polyblends: Shear modulus–temperature relationships
Authors: Meltzer T. H. , Dermody W. J. , Tobolsky A. V. 
Published: April 2003

AbstractPolyblends which undergo two distinct modulus transitions between glassy and rubbery behavior have been made from sulfur‐vulcanized diene rubbers. In these blends butyl rubber or polyisobutylene is used to form the rubbery phase of a mixture in which an appropriate diene polymer is converted to resinous hard rubber by sulfur vulcanization. Data are given to illustrate the modification of modulus produced in polyblends bsaed on hard rubber mixtures and to show the importance of marginal compatibility in determining the properties of the product.
Temperature coefficient of vulcanization and equivalent cures for SBR hard rubber polyblends
Authors: Meltzer T. H. , Dermody W. J. 
Published: April 2003

AbstractThe temperature coefficient of vulcanization for SBR hard rubber polyblends has been determined to be approximately 2.0 for 10°C. intervals of temperature. Higher percentages of sulfur give faster rates of cure and higher glass transition temperatures. Ti at 109 provides a convenient index to the degree of vulcanization of the mixtures. The response of hard rubber polyblends to variations in time and temperature of vulcanization and to changes in the proportion of sulfur in the recipe are similar to those found for conventional rubber recipes. Vulcanization parameters for hard rubber polyblends may therefore be estimated according to procedures found valid for nonpolyblend hard rubber mixtures.
Antistatic polystyrene
Authors: Gechele Giovanni Battista , Convalle Giovanni 
Published: April 2003

AbstractMechanical blends of polystyrene with small amounts of poly(2‐methyl‐5‐vinyl‐pyridine) furnish molded objects which acquire by means of a surface treatment with chemical agents (which react with the pyridic nitrogen) satisfactory antistatic protection. Methods of measure of the static charge are discussed along with the conditions of applications of the quaternizing agents.
A study of the effect of branching on certain physical and mechanical properties of stereoregular polypropylene
Authors: Huff T. , Bushman C. J. , Cavender J. V. 
Published: April 2003

AbstractThe properties of stereoregular polypropylene have been modified by the introduction of controlled branching into the polymer chain backbone. Branching is achieved by copolymerizing propylene with certain long‐chain 1‐olefins by using a standard Ziegler Natta low pressure catalyst. Physical and mechanical properties of the copolymers are related to the degree and length of branching. It was found that ultimate strength properties of moderate molecular weight polymers could be improved at some expense in short‐range deformation properties by adjusting the degree of branching to a suitable level. The copolymers did not show a good combination of low temperature brittleness characteristics along with higher temperature strength properties. It is suggested that the branching technique described will allow the tailoring of polypropylene resins for specific end use applications.
Stress relaxation after steady shearing: Applications and empirical representation
Authors: Menefee Emory 
Published: April 2003

AbstractThe measurement of stresss relaxation following steady‐state shearing is particularly useful in the terminal relaxation zone, where the rheological properties are molecular weight dependent. This paper contains a description of the method as applied to molten polymers, and an empirical function found to be useful for fitting the data. Three examples are given to demonstrate some direct and simple applications. First, the decrease of viscosity with increasing shear rate may be estimated by simply replotting the experimental data. Second, extrapolation of calculated viscosities to very high shear rates is shown to lead to a possible explanation for melt fracture. Third, the true Newtonian viscosity can be estimated from measurements conducted at a nonzero shear rate.
Effect of molecular weight distribution on the sprayability of poly(methyl methacrylate)
Authors: Elgood E. J. , Heath N. S. , O'Brien B. J. , Solomon D. H. 
Published: April 2003

AbstractFactors which influence the sprayability of poly(methyl methacrylate) lacquers are discussed. A method of prediction this property based on considerations of the molecular weight distribution of the polymer is presented.
The relative inhibitory effect of various compounds on the rate of polymerization of vinyl acetate. II. Effect of conjugated and unconjugated acetylenes and olefins
Authors: Georgieff K. K. , Blaikie K. G. , White R. C. 
Published: April 2003

AbstractThe relative inhibitory effects of hexene‐1, hexyne‐1, trans‐hexene‐2, cis‐hexene‐2, hexyne‐2, 1,5‐hexadiene, 1,5‐hexadiyne, 1,7‐octadiyne, 1,8‐octadiyne, 1‐hexen‐5‐yne, 4‐chloro‐1,2‐butadiene, chloroprene, 2,5‐dimethyl‐2,4‐hexadiene, 2,4‐hexadiyne, 2‐methyl‐1‐buten‐3‐yne, styrene, ethynylbenzene, hydroquinone, and p‐methoxyphenol on the bulk polymerization of vinyl acetate were measured. Polymerization was carried out at 70°C. in a test tube in the presence of benzoyl peroxide. A comparison was made of the magnitude of the inhibitory effect due to isolated and conjugated, double and triple bonds as well as cumulative double bonds. A brief comparison between aliphatic and aromatic compounds was also made.
Measurement of photochemical degradation in certain plastics by color reactions with phenylenediamines
Authors: Gray Vannie E. , Wright James R. 
Published: April 2003

AbstractSamples of polyester plastics, upon exposure to solar or carbon‐arc radiant energy, were found to form oxidation products which, when reacted with N,N‐dimethyl‐p‐phenylenediamine (DMPDA), produced yellow to brown reaction products. The extent of the reaction was determined directly by the amount of diamine reacted or indirectly by differential colorimetry. Research with this color reaction was extended into the development of tests for measuring the photooxidative degradation of polyesters, rigid poly(vinyl chloride), acrylics, and cellulose acetate–butyrate plastics. The basic colorimetric method was modified as needed for each of these plastics types, by directly measuring the absorbance of the DMPDA solution instead of measuring the amount of DMPDA reacted, by the use of o‐, m‐, and p‐phenylenediamines as replacements for DMPDA in the color reaction, or by a change in the solvent. The reliability of “yellowness” as an indicator of the photochemical stability of plastics was examined.
Viscoelastic properties of plasticized poly(vinyl chloride)
Authors: Taylor R. B. , Tobolsky A. V. 
Published: April 2003

AbstractMaster curves in stress relaxation for several samples of poly(vinyl chloride) plasticized by varying proportions of dioctyl phthalate [di(2‐ethylhexyl phthalate)] are reported and discussed in terms of plasticizer concentration and polymer structure. Modulustemperature curves derived from the data are also shown. Comparisons are given of plasticized compositions of poly(vinyl chloride) and polystyrene. The useful commercial properties of poly(vinyl chloride) are discussed in the light of data on the polymer structure and plasticizer action.
Temperature–strain rate transformations with isotactic polypropylene at finite strains
Authors: Hall I. H. 
Published: April 2003

AbstractThe possibility of applying Ferry's superposition principle to the entire stress‐strain curve of oriented isotactic polypropylene is studied. Sufficient data to prove the applicability of the principle is not available, but from published information it is shown that if superposition is valid for this material, then the shift factors are independent of strain and apply to the breaking extension as well as points along the stress–strain curve.
Ozone oxidation of corn starch
Authors: Szymanski C. D. 
Published: April 2003

AbstractThe oxidation of granular corn starch with ozone under various conditions was investigated. The reaction was found to be influenced by water, with the highest degree of oxidation being obtained at 23°C. in an aqueous solution of acetic acid as the suspending medium. In each medium investigated, approximately 65–75% of the total carbonyls generated were found to be aldehydes. Approximately similar results were obtained when aqueous solutions of the sugar alcohols sorbitol and mannitol were ozonized.
Use of sol‐gel analysis to estimate chain scission during vulcanization. Part II. Peroxide vulcanization of synthetic cis‐polyisoprene
Authors: Bristow G. M. 
Published: April 2003

AbstractSol‐gel analysis indicates that in the vulcanization of synthetic cis‐polyisoprene by dicumyl peroxide there are only 2–3 sites of scission per 100 crosslinked isoprene units, a value closely comparable with that observed for natural rubber.
Preparation and properties of a neophyl type anion exchange resin
Authors: Hatch Melvin J. , Lloyd Winston D. 
Published: April 2003

AbstractThe common strongly basic Type I anion exchange resins,
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contain benzylictrimethylammonium groups. In OH− form, the resins are unstable above 60°C. due to nucleophilic attack by OH− on the benzylic and methyl carbon atoms. Reactivity of benzylic carbon sites relative to methyl sites is about 4 to 1. More stable resins would be desirable, so laboratory synthesis and stability study was made of a resin which contained neither benzylic carbon atoms nor β‐carbon atoms having hydrogen atoms which could give elimination reactions. This resin,
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containing neophyltrimethylammonium groups, nevertheless lost strong base capacity more readily than a comparative resin containing benzylic trimethylammonium groups. The breakdown was primarily at the methyl carbon atoms, however, so almost all weak base capacity was retained. The greater reactivity of methyl groups on the neophyl resin—relative to methyl groups on benzylic resin—can be due to internal compressional strain between the methyl groups of the nitrogen and the methyl groups of the β‐carbons.
Kinetic studies on the vulcanization reaction accelerated with 2‐mercaptobenzothiazole
Authors: Chatterjee Pronoy K. , Sircar Anil K. 
Published: April 2003

AbstractKinetic data for vulcanization of rubber with sulfur, accelerated with 2‐mercaptobenzothiazole (MBT) are presented. The decrease in concentration of sulfur and MBT during vulcanization under various conditions of temperatures have been determined with a precise amperometric method developed by the authors. The order of reaction for disapperance of sulfur was found to be unity. The energy of activation and frequency factor were 28.8 kcal./mole and 4.0 × 1013, respectively. The kinetics of disapperance of MBT was also first‐order, and the rate of reaction, energy of activation, as well as frequency factor were much lower than those for the disapperance of sulfur. The consumption of sulfur proceeded as long as any free sulfur was present in the sample, indicating that the consumption of MBT is closely tied up with the disapperance of sulfur. It was found that about 133 atoms of sulfur were consumed for the disappearance of one molecule of MBT. The mechanism of ring opening involving an attack by the accelerator radical as proposed by Gordon is supported by the present investigation.
Linear expansion measurements of polymers by means of a capacitance technique
Authors: Maurer John J. , Tsien H. C. 
Published: April 2003

AbstractThe design, construction, and operation of a unit for measuring linear expansion properties of polymers is described. This unit utilizes a proximity transducer capacitance gauge to measure variations in capacitance caused by expansion of a sample of polymer held in an Invar (low expansion alloy) sample holder. Measurement of displacement and of temperature is continuously recorded on an X–Y recorder. The effect of operating conditions on the measurement of the linear expansion is described, and certain experimental artifacts are shown. In addition, the application of the instrument to polypropylene, styrene–butadiene rubber, butyl rubber, and to ethylenepropylene rubber is described. Distinct, nonliner regions were found, above the normal glass transition temperatures, for butyl rubber and for ethylene–propylene rubber. In the former case, the effect is probably due to crystallinity; in the latter case, there are probably two minor transitions at about −35°C. and at about −5°C. in addition to the major transition at −67°C. These minor transitions may be due to atactic and to stereoblock propylene segments, respectively.
Plasticization of methylolacrylamide copolymers by grafting onto a styrene–butadiene backbone
Authors: Melrose G. J. H. , Solomon D. H. 
Published: April 2003

AbstractThe development of a methylolacrylamide–styrene copolymer into a product suitable for use as a general‐purpose industrial or appliance enamel has been described; the choice of a suitable means of plasticization is emphasized. The incorporation of ethyl acrylate in the copolymer is expensive and was found relatively inefficient. Plasticization by blending the copolymer with tricresyl phosphate, butyl cyclohexyl phthalate, or dioctyl phthalate gave excessive thermoplasticity. Attempted plasticization by blending the copolymer with conformationally different macromolecules failed owing to incompatibility; this was overcome by reacting the macromolecules with the acrylic copolymer instead of blending: First, a butyl alcohol modified methylolacrylamide–styrene copolymer was transetherified with cetyl alcohol and in a second synthesis, transetherified with coconut oil monoglyceride. Third, an acrylamide–styrene–acrylic acid copolymer was esterified by the same monoglyceride, methylolated, and then butylated. Finally, an acrylamide–styrene copolymer was copolymerized and grafted onto a styrene–butadiene copolymer. This latter type of plasticization, which should be a general and valuable method, was supplemented by plasticization from dioctyl phthalate and yielded, after heating, economical and durable films with good mechanical properties.
Polymerizations of nitroalkyl acrylates
Authors: Tanaka Atsushi , Sasaki Kenichi , Hozumi Yukio , Hashimoto Osamu 
Published: April 2003

AbstractWe have prepared some nitroalkyl acrylates and methacrylates by a method involving alcoholysis, and investigated their polymerizability. 2‐Nitrobutyl acrylate (NBA) was extensively studied. The especially purified NBA monomer has good polymerizability without inhibiting radical polymerization and gives a thermally stable polymer. From copolymerization experiments with styrene, methyl methacrylate, and acrylonitrile, the Q and e values of NBA were estimated to be 0.47 and 0.85, respectively. The copolymerization behavior of NBA with some polyglycol dimethacrylates and unsaturated polyesters are comparable to those of n‐butyl acrylate. This monomer has little tendency to polymerize with organometallic initiators, but some polymers obtained are found to be crystalline. The polar and steric effects of the nitro group situated on the ester side chain are discussed.
Anionic graft polymerization of vinyl monomers on cellulose and polyvinyl alcohol
Authors: Feit Ben‐Ami , Bar‐Nun Akiva , Lahav Meyer , Zilkha Albert 
Published: April 2003

AbstractGraft polymers of acrylonitrile, methacrylonitrile and methyl methacrylate on polyhydroxy polymers such as cellulose and polyvinyl alcohol were prepared by anionic graft polymerization. The alkali alkoxide derivative of the polyhydroxy polymer backbone was used as initiator of polymerization. The graft polymerizations were carried out in liquid ammonia and other inert solvents at low temperature. Grafting was accompanied by considerable homopolymerization caused by chain transfer to monomer and to ammonia. The graft polymers were separated from homopolymers and unreacted polyhydroxy polymers by extraction with suitable solvents. The per cent of the grafted vinyl polymer increased with increase in the monomer and alkoxide concentration. No crosslinking occurred during the anionic graft polymerization, and soluble graft polymers were obtained.