bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of concentration of inhibitors and retarders on the catalyzed polymerization of styrene
Authors: Sugihara James M. , Wright Richard D. , Ernsdorff Bede 
Published: April 2003

AbstractThe effect of varying concentrations of several common retarders and inhibitors on the polymerization of bulk styrene, catalyzed by benzoyl peroxide, was studied dilatometrically at a temperature of 86°C. At a benzoyl peroxide concentration of 1.77 × 10−3M, the rate of volume contraction was found to be 1.472 ± 0.103%/hr. or approximately 7.4–8.5% polymerization/hr. The rate constant for the decomposition of benzoyl peroxide in styrene was found to be 36.5 × 10−6 sec.−1 at 86°C. At any given concentration for the several retarders and inhibitors, data were obtained which provided plots of extent of polymerization versus time of three different types. Trinitrobenzene and N‐(3‐N‐hydroxyanilino‐1,3‐dimethylbutylidene)aniline N‐oxide gave plots with single lines describing retarded rates of polymerization; diphenylpicrylhydrazyl and the free radical obtained from N‐(3‐N‐hydroxyanilino‐1,3‐dimethylbutylidene)aniline N‐oxide provided plots showing decreased rates of volume contraction following inhibition periods; and diphenylpicrylhydrazine and benzoquinone gave plots with two intersecting lines, suggesting two discrete steps. Concentrations of regulators were varied between 0.0002 and 0.0027M. In every instance plots of slopes of lines, inhibition times or intersection points versus concentration or logarithm of concentration provided straight lines.
Ultrafiltration of salt solutions by ion‐excluding and ion‐selective membrances
Authors: Reid C. E. , Spencer H. G. 
Published: April 2003

AbstractSalt‐filtering properties of several polymeric membranes were investigated at 40 atm. applied pressure. The ultrafilters were classified as ion‐excluding or ion‐selective membranes according to their ohmic resistance to the ions of the sodium chloride test solution. Membranes containing hydrophilic groups which have a high resistance to both cations and anions are classified as ion‐excluding. Polyelectrolyte membranes with high resistance to cations only are considered to be ion‐selective. In addition to cellulose acetate, which has been investigated previously, cellulose isobutyrate, cellophane‐supported polyvinyl methyl ketone, and cellophane‐supported polyvinyl acetate were found to be ion‐excluding membranes. The amorphous membranes, polyvinyl methyl ketone and polyvinyl acetate, do not reject salt alone; the cellophane appears to provide a supporting matrix which restricts the interchain distances in the interfacial region. Membranes composed of mixtures of the 1:1 copolymer of methyl vinyl ether and maleic anhydride with polyvinyl alcohol were durable, ion‐selective salt filters. Baking these membranes reduced swelling and flow rate and increased salt rejection. Those membranes containing high concentrations of the copolymer were flimsy and required bonding to a cellophane supporting membrane in order to obtain high salt rejection. The effects of process variables on the ultrafiltration properties of the ion‐selective membranes were also investigated. The salt rejection by either class of membrane depends on both a high concentration of the required functional groups and restricted interchain distances. Despite differences in the mechanism, each class behaves as a filter, in that the smaller the pores, the more effective the separation and the lower the flow rate.
Influence of the initiator on the grafting of polyvinyl polymers
Authors: Smets G. , Roovers J. , Van Humbeek W. 
Published: April 2003

AbstractThe dependence of grafting on the type of initiator has been examined in the case of three polymer–monomer systems: polystyrene–methyl methacrylate, polymethyl methacrylate–vinyl acetate, and polyethyl α‐chloroacrylate–vinyl acetate. The different initiators used in these experiments were benzoyl peroxide (Bz2O2), azobisisobutyronitrile (AIBN), di‐tert‐butyl peroxide (DTBP), and tert‐butyl hydroperoxide (TBHP). In each case the graft copolymers were separated from the homopolymers by fractional precipitation or by extraction. In the case of the system polystyrene–methyl methacrylate, an appreciable degree of grafting as well as formation of graft copolymer occur in the presence of Bz2O2; in contrast, the grafting is low with DTBP and doubtful with AIBN. For the other two systems no noticeable differences occurred as function of the initiator. In the case of polyethyl α‐chloroacrylate the amount of graft copolymer is exceptionally high owing to the sensitivity of this polymer to a radical attack; this sensitivity results in the partial insolubility of the graft copolymers in the presence of TBHP and DTBP, but not in the presence of AIBN.
Determination of residual styrene (monomer) and acetophenone in polymer latices
Authors: Murphy John E. , Forrette John E. 
Published: April 2003

AbstractA rapid, quantitative, direct procedure for the determination of monomeric styrene in a styrene‐based polymer emulsion has been developed. The method includes the extraction of styrene in cyclohexane and a subsequent measurement of the ultraviolet absorbance of the solution. Determination of, and compensation for interference from, acetophenone is also described. The range of 0–5% monomeric styrene was studied by statistical methods.
The mechanism of film formation from viscose
Authors: Miller M. , Haskell V. C. 
Published: April 2003

AbstractThe coagulating and regenerating conditions that are necessary for the formation of a highly durable cellulosic film are described. It is shown that low orientation, low lateral order, low gel swelling, and cellulose with a high DP are primary requisites for best film properties. Experiments demonstrated that the application of a unidirectional stress produced an unbalance of physical properties in the film, and this, in general, had an adverse effect on the durability level of a packaging film. Studies of the rates of loss of water and sodium hydroxide from the viscose during coagulation revealed that thermal and osmotic effects were not as important in determining the rate of coagulation as was the buffering and neutralizing capacity of the bath. A bath with high acid content caused the cellulose to be regenerated prior to collapse of the sheet.
Odor control performance of carbon‐loaded rayon monofilaments
Authors: Turk Amos , Berlin Alvin 
Published: April 2003

AbstractThe odor control performance of carbon‐loaded rayon monofilaments depends on the type and proportion of activated carbon used. The filter efficiency in turn determines the rate of odor reduction in a closed space and the ultimate or equilibrium concentration when odorant generation and removal occur simultaneously. Four types of filters were evaluated: rayon loaded with air‐ or water‐purification carbon, granular air‐purification carbon, and open‐lattice commercial filters. Air laden with synthetic tobacco malodor was streamed through successive increments of adsorbent bed. Sensory odor judgments were made before and after each adsorption stage by matching the effluent odors with those from mixtures of known concentrations. It was thus possible to estimate adsorption efficiencies and, by repeating the measurements after various degrees of carbon saturation, to construct adsorption waves. It was found that airpurification carbon was superior to water‐purification carbon for loading in the rayon filaments, and that all the rayon‐carbon compositions were much superior to the commercial open‐lattice filters. The rayon‐carbon filters showed efficiencies up to 70% for one pass at 0.1 sec. detention time through a 3/4‐in. bed packed at 0.096 g./ml. with a filament comprising 20% rayon and 80% carbon.
Thermally reversible gels from carbonyl‐containing water‐soluble synthetic polymers
Authors: Jones Giffin D. 
Published: April 2003

AbstractThe reversible reaction with di‐hydrazides in acidic solution or polyamines in alkaline solution is used to cause synthetic polymers containing labile carbonyl groups to gel with sharp thermoreversibility in dilute water solution. Some of the polymers described contain active methylenes, for example, partially acetoacetylated polyvinyl alcohol and polyethylenimine, and copolymer of allyl acetoacetate with acrylamide. These polymers function also as couplers for azo and azomethine dye formation.
Chlorinated and chlorosulfonated polyolefins
Authors: Canterino P. J. , Kahle G. R. 
Published: April 2003

AbstractThe properties of chlorinated and chlorosulfonated ethylene polymers and copolymers have been examined. The effect of such variables as polymer chain structure, molecular weight, degree of chlorination, and chlorination conditions was studied. A variation in physical properties of different polyolefins chlorinated to the same degree is attributed to differences in residual crystallinity in the chlorinated product. Chlorinated linear polyethylenes are more crystalline than chlorinated branched polyethylene and are semicrystalline, flexible plastics in the 15–35 wt. % range. The chlorinated branched polyethylenes of this chlorine content are soft and rubbery. Chlorination conditions can influence the degree of residual crystallinity in the chlorinated product, and hence have a pronounced effect on the properties of the products Molecular weight of the polymer and degree of chlorination influence the properties of the chlorinated product. Chlorosulfonated linear ethylene polymers and copolymers were tested as elastomers. Stress‐strain properties were better for the chlorosulfonated linear copolymers as compared to chlorosulfonated linear polyethylene or branched polyethylene. Poor residual elongation was characteristic of the chlorosulfonated linear polymers. An increase in the number of side groups in the basic polymer chain did not affect residual elongation.
Effect of catalytic aging reactions on mechanical and solubility properties of films derived from neopentyl adipate polyesters and toluene diisocyanate
Authors: Cinadr Bernard F. , Bobalek G. 
Published: April 2003

AbstractAlthough the necessary conditions are known for formation of tough films from polyurethane intermediates, the chemistry is too complex to allow certain predictions of how variances in the polymerization process effect molecular structure and polymer properties. This research examined the hope that a correlated study of solubility and mechanical behaviors might show the effect of different catalysts and environments on crosslinking or other structural features which can modify film quality. Films (0.01 in. thick) were cast on mercury of intermediates derived from reaction in solvent of 2 moles of diisocyanate per mole of hydroxyl terminated polyesters, catalysts like N‐methylmorpholine, methyldiethanolamine, and cobalt and/or lead ions being used to promote film‐forming reactions. The films, when dry, were aged at different levels of temperature and humidity. The solubility behavior was rated by measuring swelling ratios, rates of extraction, and intrinsic viscosity of extracts. Mechanical properties were rated by measuring tensile and stress relaxation behavior. The stress‐induced microstructure and fracture process were observed microscopically in a few typical specimens. The data support the theory that hydrogen bonding provides a strong crosslinking mechanism which dominates even the effects of moderate covalent crosslinking. Polymers derived from the same intermediates show very similar mechanical properties, even though significant differences in solubility properties suggest variances in other details of molecular structure.
The extraction of admixed polymers from natural rubber vulcanizates
Authors: Cooper W. , Smith R. K. 
Published: April 2003

AbstractExtraction by solvent of admixed polymethyl methacrylate or polystyrene from natural rubber vulcanizates is dependent on the crosslink density, the solvent, the molecular weight of the polymer, and the size of sample extracted. High molecular weight polymer is extracted very slowly, and in some cases several weeks of continuous extraction have been found necessary. The rate of extraction is increased, as would be expected, by solvents which swell the rubber strongly, and by increase in temperature of extraction. In some cases the vulcanization procedure degrades the polymer, while in others there is a possibility of cocrosslinking the rubber and polymer. Graft copolymers from rubber and methylmethacrylate or styrene possess similar characteristics when vulcanized. In consequence, analysis of the content of free homopolymer is subject to considerable uncertainty. In the analysis of these rubber–polystyrene mixtures by ozonolysis, polystyrene was found to be very susceptible to attack by ozone.
The different states of polymers based on their thermomechanical properties
Authors: Chatain M. , Dubois P. 
Published: April 2003

AbstractThe different transition points which characterize eventually the three solid, plasto‐elastic and rubbery states have been determined by several methods. The authors show nevertheless that good data can be obtained using very simple traction experiments, at different temperatures. These experiments were carried out in different conditions of mechanical strain and temperature; the corresponding characteristics of breaking load and flow strain were noticed. Thus thermomechanical diagrams were obtained, either of the breaking load either flow strain, in function of the temperature for the most important classes of polymers: thermoset, thermoplastics, including crystalline linear and regular polymers, linear irregular polymers and crosslinked polymers. These diagrams give an indication on the limiting strains from which the use must be excluded taking into account flow straining at a given temperature. These diagrams make also more precise the transition points determined at given mechanical strains, of which the effect is important on the temperature where they occur. It is interesting to notice the increasing thermosensitivity of the method for the multibranched, crosslinked, irregular and regular polymers.
Dynamic mechanical spectra and limit of linear viscoelasticity of high polmers
Authors: Maxwell Bryce , Guimon Claude 
Published: April 2003

AbstractThe dynamic mechanical properties of a typical polycrystalline polymer (polyethylene) and a typical glassy state amorphous polymer (polystyrene) have been studied as a function of both frequency and temperature. The response of these materials to mechanical loading was found to be dependent upon the magnitude of strain resulting from the mechanical load above the limit of linear viscoelastic response. Therefore, the limit of linear viscoelastic response must be considered as an important material characteristic in design application of high polymers. This limit has been studied as a function of time scale of loading and polymer structure for a series of materials. A general trend of increased strain limit of linear viscoelastic response with increased heterogeneity of internal structure has been found.
Structural adhesives—characteristics and application
Authors: De Lollis Nicholas J. 
Published: April 2003

AbstractStructural adhesives are one of the more important developments in the adhesives field because they make possible bonded assemblies in lightweight structures which take full advantage of the strengths of the materials used. Structural adhesives can be divided into two classes. One class consists of hard brittle resins typified by unmodified epoxy adhesives which have high shear and tensile strengths but low peel strength. The second class consists of a combination of resins resulting in a more ductile type of adhesive which has high peel strength along with high shear and tensile strength. One application is described here in which an epoxy adhesive is used in a design which minimizes peel forces and which causes failure of the bonded assembly in the metal. The evaluation of this design showed it to be successful.
Importance of evaluation of adhesives for all environmental conditions and permanence studies
Authors: Blomquist Richard F. 
Published: April 2003

AbstractAlthough considerable research has been conducted to establish the performance of various adhesives under different conditions of service, much remains to be done. Of great importance are basic studies of the mechanisms of deterioration of adhesives in joints under known conditions so that reliable short‐term performance tests may be devised to determine the expected performance of adhesives under various service conditions. Such research needs will undoubtedly be increased in importance by the continued introduction of new adhesives of different chemical types. In all probability, the nature of the adherend influences not only initial adhesion but also subsequent joint performance. Most experience reported here on permanence of joints has been gained with wood, but research on metal adhesives is also reviewed.
Solvent‐resistant rubbers obtained by the use of metallic soaps
Authors: Korb Juan 
Published: April 2003

AbstractAt present, solvent‐resistant rubbers are obtained only by the introduction of polar groups in the polymer chain. These groups impair some physical properties of the rubber. A new way is suggested for obtaining solvent‐resistant rubbers by using nonpolar elastomers compounded with metallic soaps. These soaps can be considered polymeric materials, whose long chains are built up by weak coordinate bonds, which can be easily broken and reformed in contact with solvents. In this way a layer of solvent‐swollen soap is formed over the soap‐compounded vulcanizate, which prevents further attack. An explanation of the above behavior is given on the basis of the crystallization tendency of the metallic soap.
Basic design features of a nonimpacting, pneumatically driven, hydraulically damped high speed tester
Authors: Spangler R. D. 
Published: April 2003

AbstractThe significance of the time to acquire constant velocity in high speed testing is discussed. It is pointed out that the border line between impact and nonimpact testing depends on this time as well as the length of the test specimen and the velocity of sound in the material being tested. Equations relating force, mass, velocity, damping, and time are worked out for a pneumatically driven, hydraulically damped piston‐type machine. These equations afford a basis for the design of a high speed tester. Practical values of parameters are given for a machine which will acquire a uniform velocity of 50 ft./sec. in about 3 × 10−4 sec. Design data for a damping system are also given.
High speed measurements of dry adhesion as related to the friction and abrasion of elastomers
Authors: Vickers H. H. 
Published: April 2003

AbstractStudies of friction and abrasion of elastomers have indicated that static friction or adhesion may be one of the important parameters in the traction and wear obtained with automobile tires. In this case static friction is considered to exist where a point of contact, adhesive attachment, or an interlocking is made between the rolling tire and the road which is strong enough to hold and transfer energy from one surface to the other. To investigate the magnitude of adhesion between tire tread rubber and the road, a test was developed that would measure the dry adhesion of rubber to other materials at break‐away speeds above the recovery rate of the rubber. By using clean dry surfaces and break‐away speeds of 2000 in./min., adhesive values in the order of 100 psi were measured with butyl tread stocks against impact styrene or against a rough stone surface. Much lower values were obtained for SBR and natural rubber. The influence of surface contamination, break‐away velocity, and hysteresis was also studied. The equipment used and the procedures for these tests are described in this paper.
Investigations of the phenomena of coacervation. Part II. Coacervation of polyethylene terephthalate
Authors: Turska E. , Utracki L. 
Published: April 2003

AbstractInvestigations are reported for the influence of temperature, initial polymer concentration, and solvent composition on the course and character of the phenomenon of a division into two liquid phases of the system polyethylene terephthalate–phenol–tetrachloroethane–n‐heptane. Some curves presented show changes in volumes of the phases in polymer content in phases, and in binodials of the liquid phases (Gibbs triangles). The term “coacervate” is suggested for the phase in which concentration of polymers during titration with nonsolvent is greater than that in the balancing phase, and in which at the same time the polymer content changes from 0 to 100%. It is shown that such a division into two liquid phases can take place only when the straight line representing the changes of nonsolvent content intersects the binodial between the critical point of miscibility and the side of the triangle of Gibbs corresponding to the zero content of polymer.
Relationship of molecular structure and resin performance for a series of diglycidyl ethers
Authors: Kelly P. B. , Landua A. J. , Marshall C. D. 
Published: April 2003

AbstractAn investigation of the relationship between molecular structure and polymer performance has been made for a series of six diglycidyl ethers. The resins evaluated were those based on the bisphenols derived from methyl ethyl, methyl isobutyl, methyl n‐amyl, methyl n‐nonyl, methyl‐n‐heptadecyl and di‐n‐heptadecyl ketones. The first three members of this series gave performances close to those of the diglycidyl ether of p,p′‐bisphenol acetone. The long chain members of the series showed poorer over‐all performance but did exhibit significant hydrophobic character in the cured specimens. The cured diglycidyl ethers showed variation attributed to both length and configuration of the alkyl chain. An increase in length of straight chain resulted in lowered heat distortion temperature, hardness, shear strength, and organic solvent resistance. Branching in the alkyl chain imparts improved performance characteristics.
Effect of radiation of polyethylene on environmental stress cracking
Authors: Liebling Gerald , Barton Stephen , Ullman Robert 
Published: April 2003

AbstractThe influence of radiation on the environmental stress cracking of polyethylene is described. The polymer was irradiated by cobalt‐60 γ‐rays, and studied as a function of a variety of experimental conditions. The deleterious effects of oxygen were noted. To prevent oxidative deterioration, the free radicals created had to be terminated by a heat treatment in the absence of oxygen. Some procedures were developed in which polyethylene could be made resistant to environmental stress cracking.
Polyspiroacetal resins. Part II. Structure and properties of polyspiroacetals from pentaerythritol‐glutaraldehyde and from (pentaerythritol–dipentaerythritol)‐glutaraldehyde
Authors: Cohen S. M. , Hunt C. F. , Kass R. E. , Markhart A. H. 
Published: April 2003

AbstractPolyspiroacetal polymers and copolymers derived from pentaerythritol, and glutaraldehyde were prepared and examined for physical properties. Elemental and infrared analyses support the polyspiroacetal structure. X‐ray analysis indicates a range of 20–40% crystallinity. Dipentaerythritol was observed to influence in varying degrees the crystallinity, the solubility, and the optimum range of film curing conditions. Resins with more than 25% dipentaerythritol always crosslinked during polymerization. In addition, the variables influencing such resin properties as molecular weight and gelation were examined. Films crosslinked with pyromellitic dianhydride exhibited good flexibility and tensile strength. Moreover, their oxidative thermal stability was only slightly less than that of crosslinked poly(ethylene terephthalate).