Showing papers by "University of Akron published in 1975"

Anionic Polymerization of Vinyl Monomers

Abstract: Addition polymerizations involving soluble organometallic species have received intensive attention in recent years with special reference to the type of counterion and solvent. An anionic mechanism is proposed for those systems where there is good reason to assume that the metal is strongly electropositive relative to the carbon (or other) atom at the tip of the growing chain. Hence, the metal, e.g. lithium, becomes a cation either in the free state or coupled with the growing carbanion. Under the appropriate experimental conditions, spontaneous termination is avoidable in many of those systems when one of the metals of Group I is used as the counterion. The alkali metals sodium and potassium were revealed to be polymerization initiators of isoprene in the disclosures of Matthews and Strange in 1910 and Harries in 1911. The first unambiguous report of the use of lithium in reactions with diolefins appears to be that of Ziegler and coworkers in 1934. Their work consisted of an investigation of th...

Demonstration of the Effect, “Similar to Me,” in Simulated Employment Interviews

Abstract: Simulated video-taped employment interviews were constructed in which a black and a white applicant presented, in addition to job-related statements, biographical background information which was e...

Threshold fracture energies for elastomers

Abstract: Fracture energies have been measured for two types of polybutadiene elastomer, crosslinked to various extents and torn under various conditions. Threshold values, ranging from 40 to 80 jm−2, were observed for samples torn at extremely low rates of tearing, at high temperatures, and in the swollen state. These values were found to be independent of temperature and rate of tearing, and also of the degree of swelling and the nature of the swelling liquid, provided a correction is made for the reduced areal concentration of molecular chains. They decreased somewhat with increased crosslinking, in good agreement with theoretical predictions of Lake and Thomas.6 The results for the two elastomers were substantially the same. These observations are strikingly different from those made at normal temperatures and rates of tearing, when large differences in fracture energy were observed between the elastomers, and between samples crosslinked to different extents, due to energy losses from nonequilibrium deformation processes in addition to the energy required for fracture.

Transition between Cohesive and Interfacial Failure in a Laminate

Abstract: A theoretical condition has been derived for deflexion of a Griffith crack meeting a plane perpendicular interface in a thick plate of uniform elastic properties. The theory suggests that a short crack should be diverted along the interface when R ad co /4π(1 — V 2 ),

Analysis of the linear methods for determining copolymerization reactivity ratios. II. A critical reexamination of cationic monomer reactivity ratios

Abstract: A thorough examination of some cationic copolymerization systems by a new method has shown that many published r values have to be corrected significantly and that some are erroneous and meaningless, because for these systems the conventional copolymer compositions equation does not hold. Available information in regard of cationic copolymerizations has been treated in terms of three classes: (a) Systems in which the conventional copolymer composition equation adequately describes the copolymerization mechanism and previous authors justifiably used the two parameter model to calculate reactivity ratios. Our results show that the discrepancy between published r values and the more precise values obtained in this work is about ±23%. (b) Systems in which the approximations implicit in the conventional copolymer composition equation do not hold and the calculated r values are erroneous and misleading. Monomer pairs comprising monomers of significantly different reactivities belong to this class indicating that in copolymerizations in general and in cationic copolymerizations in particular a strong cast system exists, i.e., copolymerization can readily occur within the cast (between monomers of similar reactivities); however, only with difficulty if at all between casts (between monomers of differing reactivities). (c) Systems in which the use of the copolymer composition equation is completely unjustified, the calculated r values are meaningless and in some cases the existence of true copolymers is questioned.

Polymerization of carboxylic acid monomers and alkyl acrylate esters in chlorofluoroethane

Abstract: Improved copolymers of unsaturated copolymerizable carboxylic acid monomers and one or more alkyl acrylate esters containing 10 to 30 carbon atoms which serve as efficient thickeners of aqueous solutions, even in the presence of substantial amounts of inorganic salts such as sodium chloride are prepared by conducting the polymerization of the comonomers in a chlorofluoroethane.

Apparatus and method for monitoring air emboli during extracorporeal circulation

Abstract: Disclosed is a method and apparatus for detecting the presence of an embolism, such as air, during extracorporeal circulation in tubing carrying blood or other fluid such as would be present in the use of an artificial kidney machine. Electrodes are placed near the tubing to monitor the impedance thereof as well as the impedance of the fluid passing therethrough. An oscillator is attached to the electrodes and puts out a signal, the frequency of which is proportional to the basic impedance of the tubing and fluid. When an air bubble or the like passes the electrodes, the impedance will change causing a change in the frequency of the signal of the oscillator. The difference between the normal frequency and the changed frequency is indicative of the size of the embolism. Means are provided so that if a single embolism is large enough to cause damage to the patient or if a number of smaller emboli accumulate to the point of potentially causing damage to the patient, an alarm may be sounded or other remedial measures, such as system shutdown, could be taken. In addition, should the basic impedance of the fluid change, means are provided to prevent a false indication of an embolism.

Coupling from Multimode to Single-Mode Linear Waveguides Using Horn-Shaped Structures

Abstract: Coupling from a multimode to a single-mode linear waveguide using horn-shaped structures is investigated. The approximate coupling efficiency is found by numerical solution of coupled-mode equations that apply to the reciprocal problem, i.e., to the problem of propagation in an expanding horn. A coupling efficiency in excess of 90 percent is calculated when coupling is from the principal mode of a sample 50-mu m-wide multimode waveguide to a 3-mu m-wide single-mode guide (lambda = 0.63mu m). This efficiency results from a uniformly tapered horn whose length is on the order of 2 mm. The length can be decreased by using a shaped coupling region. One such region is found to result in a coupling length of approximately 1.6 mm.

Smoke retardant vinyl chloride and vinylidene chloride polymer compositions

Abstract: Smoke retardant vinyl chloride and vinylidene chloride polymer compositions are obtained by including cobaltous oxide (CoO) in the composition.

Protected amino-functional initiators and amino-terminated polymers and their production

Abstract: N,N-bis(trialkylsilyl) amino-terminated polymers are prepared by treating p-lithio-N,N-bis(trialkylsilyl) aryl amine with a diene monomer and the resulting polymers are converted to a mono- or di- primary aryl amine-ended diene polymer directly by acid hydrolysis The amine-ended polymers may be homopolymers of a conjugated diene which contain 4 to 8 carbon atoms or copolymers of such conjugated dienes or copolymers of such a conjugated diene and a vinyl monomer

Jewelry and bracelet heartbeat monitor

Abstract: A device for monitoring the heartbeat of an individual at a pulse point Fundamentally, the invention comprises two piezoelectric sensors arranged in close parallel relationship with each other and differentially connected to an amplifier circuit One of the sensors lies over the pulse point of the individual while the other lies therebeside A rate detector receives the amplified outputs of the sensors and determines the pulse rate from the heart If this rate exceeds a predetermined level, a signal is passed to enable an oscillator of audible frequency; the output of the oscillator being connected to any earphone speaker to produce a warning sound

Polyphase power control

Abstract: Power control apparatus and method for controlling polyphase excitation of a polyphase load. A first sequence of timong pulses are generated to represent each zero level voltage crossing of every phase voltage from a polyphase voltage source. After each of the predetermined numbers of the timing pulses has been generated, an energizng pulse is generated having a width of a predetermined duration. A set of power switches is provided coupling the polyphase source to the load via a set of load lines. The power switches are all rendered conductive to selectively couple phase voltages from the polyphase source to the load by each energizing pulse. This causes excitation of the load via repeating sequences of intermittent power pulses, with each power pulse being comprised of a selected grouping of the phase voltages from the polyphase voltage source. The source phase voltages comprising each group are associated in time with one another on the load lines and are: (1) of a selectable number, and (2) of a selectable permutation of phases. Variance of the rate at which the energizing pulses are generated and of the value of the predetermined duration of the pulse width determines the selected number of and the phase of the voltages in the power pulses. The selected number and phases of the voltages in each power pulse and the repetition rate of the power pulses determine the effective frequency at which the load is excited. In a preferred embodiment the load is a polyphase induction motor, and its speed is fractionally reduced without a great sacrifice in torque by adjusting the repetition rate and the pulse widths of the energizing pulses.

An Applicant's Nonverbal Behavior and Student-Evaluators' Judgments in a Structured Interview Setting:

Abstract: This study examined the effects of 5–6 min. of an applicant's nonverbal videotaped behavior on 78 student-evaluators' judgments in a simulated, structured loan interview. Three objective levels of the role-playing graduate student's suitability as an applicant (high, average, or low financial resources) and two levels of nonverbal “enthusiasm” (quantified as high or low amounts of eye contact, gesturing, smiling, and appropriate tone of voice) were manipulated in a 3 × 2 factorial design. Analysis of variance indicated significant main effects for both the applicant's suitability and “enthusiasm,” i.e., “enthusiastic” applicants were given higher evaluations by the students.

Process for preparing elastomeric copolymers of ethylene and higher alpha-olefins

Abstract: High yields of elastomeric copolymers of ethylene and higher alpha-olefins, or of ethylene, higher alpha-olefins and unsaturated monomers (polyenes) containing two or more double bonds are obtained by copolymerizing a mixture of the monomers in contact with a catalyst prepared by mixing a catalyst-forming component which is an organometallic compound of aluminum with a supported catalyst-forming component obtained by contacting a halogenated titanium compound with a carrier or support consisting of or comprising an anhydrous Mg or Mn halide partially or completely complexed with a Lewis base capable of forming a complex with it. The copolymers so obtained have valuable mechanical properties, in particular a relatively low value of permanent set and do not exhibit excessive residual deformation at break.

Polyurethane elastomers having prolonged flex life and tires made therefrom

Abstract: Polyurethane elastomers having prolonged flex life are prepared by reacting a diisocyanate with polypropylene glycol (PPG) or triol and poly(tetramethylene ether) glycol (PTEG). The diisocyanate may be reacted with each glycol separately or they may be mixed before the reaction. A smaller amount of the prepolymer obtained from the polypropylene glycol or triol is mixed with a larger amount of the prepolymer obtained from the poly(tetramethylene ether) glycol and the mixture is reacted with a hindered aromatic diamine. Elastomers cured from the resulting mixed polyurethane were found to have an exceptionally high flex life and are particularly useful in the production of products which undergo dynamic flexing, as in the preparation of pneumatic tires, particularly the sidewalls thereof, because of their exceptionally long flex life.

Model experiments illustrating fibre pull-out

Abstract: Pull-out of a rigid fibre from a solid matrix has been studied in a model of a composite material using transparent media to display the fracture Solidified gelatine solution was used to model an elastic-plastic matrix and silicone rubber used to represent a brittle elastic material The conditions dictating both brittle and plastic failure in the model have been presented theoretically and supported by experimental observations In addition, a novel type of failure, where bubble cracks propagated between fibre and matrix, was observed

Solidification and Melting of Materials Subject to Convection and Radiation

Abstract: One-dimensional heat transfer in a finite region of solid or liquid with phase change associated with radiative and convective boundary conditions at the fixed boundary surface is solved using both Blot's variational and Goodman's integral methods. The total solidification time and the rates of solidification obtained based on the present approximate analyses agree very well with the numerical solutions of an earlier work.

Mechanism of Smoke Inhibition by Hydrated Fillers

Abstract: The smoke inhibitory activity of hydrated fillers in SBR is centered primarily in condensed-phase processes and is analogous to the generally accepted mechanism of flame retardation by the hydrates. Dissipation of heat, which disfavors pyrolysis and favors competing crosslinking reactions is probably involved. These reactions should occur chiefly among polybutadiene segments of the polymers. In addition, the smoke-suppressant efficiency of hydrated fillers should depend upon the crosslinking efficiency of the rubber. Finally, although smoke generation in latex rubber goods presents a challenge, substantial practical reductions in visible smoke can be achieved through the selection of proper hydrated fillers.

Internally coated reaction vessel and process for coating the same

Abstract: A reaction vessel having on the internal surfaces thereof a coating containing, as a primary ingredient, a straight chain or branched polyaromatic amine made by the reaction of any one by itself, except the polyhydric phenols, or more than one, of the compounds selected from polyamino benzenes, polyhydric phenols, aminophenols, alkyl-substituted aminophenols, diphenylamines, and alkyl-substituted diphenylamines, which coating is applied to said surfaces from an organic solvent solution. Also included are the above compounds having a halogen substitution on the ring. Further, there is included the process for coating said internal surfaces whereby polymer build-up on said surfaces is substantially eliminated.

Modification of Concept Identification Performance in Older Adults

Abstract: A sequential training procedure combining operant and cumulative learning hierarchy principles was found effective in reducing the decrement in concept identification performance typically observed in older adults. Subjects aged 63 to 83 years were given a pretest and posttest, each involving a three-category unidimensional concept identification problem. The training and reinforced training subjects were given three training sessions between pretest and posttest. Training involved a programmed learning sequence designed to facilitate the development of an effective solution strategy. Control subjects were given only the pretest and posttest, while practice subjects were given three additional practice sessions. Substantial improvement was found in both the training and reinforced training groups, but only slight improvement obtained in the practice and control groups. These results were considered consistent with recent conceptions of cognitive and intellectual development in the older adult in which performance deficits are largely attributed to experiential factors.

Cyclopentene-dicyclopentadiene copolymers and method of making same

Abstract: Substantially gel-free copolymers of cyclopentene with dicyclopentadiene are prepared by polymerizing these monomers in the presence of (1) a catalyst comprising (a) at least one compound selected from the group consisting of dialkylaluminum iodides, alkylaluminum diiodides and mixtures of trialkylaluminum compounds with elemental iodine and (b) at least one solvent- or monomer-soluble tungsten compound, and (2) at least one nonconjugated acyclic olefin having at least one hydrogen on each double-bonded carbon atom. Catalyst component (a) is charged before catalyst component (b).

Thermoplastic polymer blends of EP or EPDM polymer with crystalline polypropylene

Abstract: EP or EPDM polymers having a high ethylene content and a high ratio of ethylene units in runs of three or more to isolated ethylene units in the polymer are physically blended with crystalline polypropylene. The blends exhibit good tensile strength and modulus, and are useful to prepare molded products, tubing, liners, and like products.

Kinetics of Contact between Smooth Solids

Abstract: The diameter of the circular contact region formed between a smooth rubber sphere and a glass plate has been studied as a function of time under a variety of loading conditions. Theoretically, the system is viewed as a circular crack which can move through the glass-rubber interface in two directions: one to form the contact and the other to break it. Discussion centres principally on the speed at which the crack propagates, and on a sudden stopping of the crack which leads to adhesive hysteresis.

Nonmetallic composite friction member

Abstract: A nonmetallic friction member is constructed of a bulk graphite component bonded to a resin impregnated carbon cloth component. The friction member is particularly useful for brake and clutch devices, especially multiple disc-type brakes for aircraft. The member may be in the form of a rotor or stator. If driving slots are provided, the member may be reinforced with resin impregnated carbon cloth at these slots.

Fracture Energy of Elastomers in Mode I (Cleavage) and Mode III (Lateral Shear)

Abstract: Attention has been drawn here to three different reasons why measurements of fracture energy by different methods may not agree: (1) When the test involves propagation of a tear by stored strain energy, as in the method shown in Figure 1, the energy available to cause rupture will be less than that supplied, because of dissipation within the elastomer. Calculation of the fracture energy on the basis of input energy would then lead to an overestimate, by about 100 per cent or more for typical filled elastomers. (2) As shown in Figures 4a and 5, the tear path is sometimes wider than the thickness of the test sheet. In consequence, fracture energy calculated from the sheet thickness would be too large, by about 40 per cent in the cases considered here. (3) Even when allowance is made for the true width of the tear path, measurements of fracture energy in shear (Mode III) are about 50 per cent larger than in cleavage (Mode I). This is attributed to frictional work expended in sliding the rough torn s...