Showing papers by "University of Akron published in 1970"

Compression, bending, and shear of bonded rubber blocks

Abstract: An approximate theoretical treatment is given for small compressions of bonded rubber blocks. The component of the compressive force arising from the bonded condition at the loaded surfaces is obtained from a pressure distribution within the block, given by the solution of the corresponding torsion problem. The bending of blocks is treated in a similar way, the pressure distribution in this case being derived from the corresponding bending stress function. The apparent shear of relatively thick blocks is then treated as a combination of shear and bending displacements. The location of an internal rupture and the deformation at which it occurs are also derived from a critical (negative) value of the pressure developed within the block, at which a small cavity increases indefinitely in size. The corresponding critical deformations are calculated for extension and bending displacements. The shear stresses developed at the bonded surfaces under extension, compression or bending displacements are also evaluated.

Invertebrate predation on termites of the African Savanna

Abstract: Predation by invertebrates was observed on 11 species of termites, primarilyOdontotermes latericius exposed while building their chimneys. Ants were the most frequent predators, usuallyPheidole eegacephala andMegaponera fœtens. Staphylinids of the genusZyras sometimes were abundant on chimneys ofO. latericius and preyed on wandering workers. Other predators were beetles, hemipterans, phasmids, spiders, and turberllarians. Both soldiers and workers are anatomically equipped to defend themselves against small invertebrate predators, but both largely lack the behavioral repertoire to do so and defense is ineffective. The value of the soldier caste to the colony is not clear.

Energy absorption in polymeric foams. I. Prediction of impact behavior from instron data for foams with rate-independent modulus

Abstract: Impact behavior can be predicted for rate-dependent foams from constant rate of strain response. The response must be factorized into a rate-dependent modulus function and a strain-dependent function. In this way the rate-dependent modulus can vary throughout the impact as the velocity of the impacting object decreases.

Process for polylithiating unsaturated polymers

Abstract: A polymer is metalated with a lithiating reagent and an tetraalkylethylene, the ratio of active lithium atoms in the lithiating reagent to the molecules of the amine being from 0.01 to 1.5. Such lithiated polymer may then be further reacted to introduce reactive groups of many varieties along the polymer chain. For example, polybutadiene, polyisoprene and other unsaturated polymers may be reacted with butyl lithium and triethylene diamine; and the lithiated polymer may then be reacted with carbon dioxide, and the resulting product may be neutralized to produce a polymer containing carboxyl groups, or the lithiated polymer may be reacted with styrene or a mixture of styrene and butadiene, or styrene and isoprene, etc.

Elastomeric articles free from reinforcing elements

Abstract: Pneumatic tires and other elastomeric articles subject to tensile stress and dynamic flexure in service, said articles having no reinforcing elements, or having reinforcing elements in portions only thereof, are made from elastomers having, in the cured state, a molecular weight between covalent cross-links of 5,100 - 40,000, and a molecular weight between electrostatic cross-links of 800 - 5,000. Such articles exhibit excellent strength, elasticity, tear resistance, flat-spotting properties and overall performance in service, both at ambient and elevated temperatures.

A study of the crystallization of polyethylene terephthalate using differential scanning calorimetry and X‐ray techniques

Abstract: Differential scanning calorimetry has been used to study the kinetics of the crystallization processes of polyethylene terephthalate over a wide temperature range, 95–110°C and 230–240°C. The rates of crystallization of the two processes are in agreement with earlier dilatometric measurements. Nonintegral values of the AVRAMI exponent, n = 4.5 and n = 3.4, found for the low temperature and pre-melt processes, respectively, are not in agreement with reported values of n = 2.0 and n = 4.0 for these processes. The value of n = 4.5 for the low temperature crystallization is surprising and not easily accounted for; one possible explanation is that the time dependence of the nucleation process is greater than first order. Because of their fractionality the n values yield little information on the mechanism of crystallization. Some mechanistic information is available since the low temperature crystallization isotherms are superposable along the log-time axis, whereas the pre-melt isotherms are not. Additional X-ray data have indicated the existence of one crystalline form. The X-ray data show no significant crystallite size increase for samples crystallized at 150°C over those crystallized at 105°C. Samples crystallized at 235°C show a larger and more ordered crystalline structure than those crystallized at 105 and 150°C. The relationship between the crystalline melting points and the temperatures of crystallization is as predicted by MANDELKERN. Die Kinetik der Kristallisation von Poly(athylenterephthalat) wurde mit einem Differentialkalorimeter in einem weiten Temperaturbereich (95–110°C und 230–240°C) untersucht. Die Kristallisationsgeschwindigkeiten der beiden Prozesse sind in Ubereinstimmung mit fruheren dilatometrischen Messungen. Die nicht ganzzahligen Werte fur den AVRAMI-Exponenten, n = 4,5 und n = 3,4 fur die Kristallisation bei niederen Temperaturen bzw. vorgeschmolzenen Proben, stimmen nicht mit den veroffentlichten Werten von n = 2,0 und n = 4,0 uberein. Der Wert von n = 4,5 fur die Kristallisation bei niederen Temperaturen ist uberraschend. Eine mogliche Erklarung besteht darin, die Kristallisationskeimbildung als eine Funktion hoherer Ordnung anzunehmen. Da die n-Werte keine ganzen Zahlen sind, geben sie nur geringe Hinweise uber den Mechanismus der Kristallisation. Hinweise uber den Mechanismus geben die Isothermen der Kristallisation bei niederen Temperaturen. Diese sind entlang der log-T-Achse deckungsgleich, was fur die Isothermen der vorgeschmolzenen Proben nicht zutrifft. Zusatzliche rontgenographische Untersuchungen zeigen die Anwesenheit von nur einer Kristallform. Sie zeigen ferner keine wesentliche Zunahme der Kristallitgrose in Proben, die bei 150 bzw. 105°C kristallisiert wurden; bei 235°C kristallisierte Proben zeigen hingegen eine besser ausgebildete und hoher orientierte Struktur als die vorgenannten. Der Zusammenhang zwischen den Schmelzpunkten der kristallisierten Proben und der Kristallisationstemperatur stimmt mit den Ergebnissen von MANDELKERN uberein.

Dermal protective film

Abstract: COMPOSITION OF MATTER FOR PREVENTING SKIN IRRITATION FROM CONTACT WITH "POISON IVY." THE COMPOSITION IS BASED UPON A FILM-FORMING ACRYLIC POLYMER AND INCLUDES A LINKING AGENT SO THAT UPON APPLICATION BY A SOLVENT CARRIER TO THE SKIN A SELECTIVE MEMBRANE IS FORMED. THE COMPOSITION MAY ALSO INCLUDE AN OXIDIZING AGENT FOR BREAKDOWN OF IRRITATION CAUSING ALLERGENS SELECTIVELY RETAINED BY THE MEMBRANE.

Surface Energy Effects for Small Holes or Particles in Elastomers

Abstract: Expansion of a small spherical hole in a highly elastic solid is treated theoretically. Both elastic and surface energy terms are considered; the corresponding surface forces are assumed to be additive. The surface energy of the elastomer is assumed to be similar to that of simple liquids. Pressures or triaxial tensions required to inflate pre-existing holes to an indefinitely large size are calculated. Small holes require extremely large pressures, of the order of 1000 atm for holes of 10 A˚ radius. These results suggest a means of determining the distribution of hole sizes in elastomers and account, in principle, for experimental observations of cavitation processes. Detachment of the elastomer from a small rigid inclusion is treated in a similar way. The general absence of dilation or cavitation on stretching carbon black filled elastomers is thus accounted for solely in terms of the small size of these filler particles.

Run flat device for tires

Abstract: A one piece annular non-pneumatic run flat device for use with a pneumatic tire and a one piece rim. The run flat device has bead engaging surfaces which engage the beads of the tire which beads in turn engage respective flanges on the rim. The inner diameter of the run flat device is about equal to or greater than the outside diameter of the rim and in use, the run flat device is spaced from the rim. An outer annular surface on the run flat device is spaced from the crown of the tire in the inflated condition thereof; however, upon deflation of the tire the crown engages the outer annular surface of the run flat device and is supported by way of the bead engaging surfaces, tire beads and rim. The cross section of the run flat device is preferably designed to bend toward the rim centerline in mounting of the tire and the preferred material of construction of the run flat device is a polyurethane material.

The Influence of Aluminum-Containing Lewis Acids on Polyisobutylene, Isobutylene-lsoprene Copolymers (Butyl Rubber), and Chlorinated Isobutylene-lsoprene Copolymer (Chlorobutyl)

Abstract: The influence of aluminum-containing Lewis acids, eg, AlCl3, AlEtCl2, AlEt2Cl, AlEt3, and AliBu3, on polyisobutylene, isobutylene-isoprene copolymer (butyl rubber), and chlorinated butyl rubber has been investigated in nonpolar and polar solvents at various Lewis acid concentrations in the temperature range -10 to -78°C Polyisobutylene does not degrade even under the most aggressive conditions employed (AlEtCl2, -10°C) Butyl rubber degrades rapidly in the presence of AlEtCl2 in the range -10 to -50°C In contrast, no degradation occurs with the milder Lewis acid AlEt2Cl; however, in conjunction with small amounts of a suitable Bronsted acid (ie, HCl) immediate and extensive degradation takes place with AlEt2Cl as well Chlorobutyl rubber severely and very rapidly degrades in the presence of AlCl3 and AlEtCl2 With the less acidic AlEt2Cl and AlEt3, molecular weight breakdown can be prevented only when employing milder conditions, ie, at low Lewis acid concentrations in nonpolar solvents a

Digital computer control of polymerization process

Abstract: Changes in component concentration, heat history, and other variables which cannot be directly measured in the successive reactors in a train of polymerization reactors, are followed by periodically numerically integrating, by a digital computer, for each reactor and for each of the variables, the equation WHERE X A PROCESS VARIABLE, E.G., CONCENTRATION, CONVERSION, ETC. I, AS THE FIRST SUBSCRIPT OF X, SIGNIFIES THAT THIS IS THE ITH OF I variables N, AS THE SECOND SUBSCRIPT OF X, MEANS THAT THIS IS THE VALUE OF THIS VARIABLE IN THE NTH ONE OF THE REACTORS ON THE LINE- THUS XI,1 MEANS THE VALUE OF XI IN THE FIRST REACTOR 64-1 ETC. F total volumetric flow rate V volume of the nth reactor T TIME DIFFERENCE UNDER THE REACTION CONDITIONS delta XI,N/ delta T OVERALL RATE OF GENERATION OR DEGENERATION OF XI,N UNDER THE CONDITIONS OBTAINING THE NTH REACTOR The resultant calculated values of these variables, together with directly measured values of other variables, are manipulated by the computer and used to adjust the rate of feed of reagents and other conditions of polymerization in the train.

Fruit container pickup vehicle

Abstract: A vehicle having lifting means at its front end to raise a container filled with fruit from the ground to a position for engagement and support by a carriage movable rearwardly over the vehicle. A hopper is normally supported on the vehicle below the carriage which is adapted to dump the filled containers into the hopper, there being means to raise the hopper to an unloading position. The carriage is adapted to stack emptied containers at the rear of the vehicle and to pick up and transfer the stack to another vehicle.

Mechanical Damping in Liquid-Filled Foams

Abstract: are subjected to oscillatory compression considerable mechanical energy absorption can take place due to the flow of fluid through the matrix (1, 2, 3). The energy loss is due to the viscous nature of the flow process. As the frequency of the deformation is increased the interaction between the fluid and the matrix increases so that the matrix is forced to deform in the fluid flow direction (2, 3). A situation is eventually reached where there is no net flow of fluid through the matrix so there are no flow losses. Thus we would expect the loss tangent to pass through a maximum as the frequency is increased. Gent and Rusch (2, 3) related the dynamic mechanical properties of the foam fluid system to the mechanical properties of the fluid and the poly-

Tire-fabric-handling apparatus

Abstract: Apparatus for handling large diameter rolls of tire fabric for placement on a tire building drum. Apparatus is floor mounted and fabric is let off at controlled rate and registered laterally for selective delivery to the building drum.

Self-esteem and internal-external control: a validation study.

Abstract: A recent conceptualization of self-esteem defines it within a self-other context in an attempt to take social factors into account (Ziller, Hagey, Smith, & Long, 1969). One of the assumptions that Ziller, et al. make about their self-esteem measure is that Ss who have high self-esteem will have a higher potential for self-reinforcement. From this, one can infer that high scorers on the Ziller, ei al. self-esteem measure should score low on Roaer's (1966) Internal-External Control Scale, since low scores on the I-E scale indicate an internal orientation with respect ro the perceived locus of reinforcements. In contrast, the external person believes that reinforcements are due to luck, fate, chance, etc. A substantial negative correlation between the Ziller, et al. self-other measure of self-esteem and Rotter's I-E scale would add to the construct validity of this new self-esteem measure. Ss were 24 males at Pennsylvania Military College, 36 males at the Universiry of Akron, and 31 females at the University of Akron. They were administered the Rotter I-E scale and the Ziller, ei al. self-esteem measure during their class periods. The fullscale forms of the tesn were used with one exception: the Pennsylvania Military College Ss were given a shorr form of the I-E scale, viz., the 10 items which correlated most highly with the total score. The results clearly did not support the construct validity of the Ziller, el al. (1969) self-esteem measure as far as relationship to perceived locus of reinforcement is concerned. For Pennsylvania Military College males the r was d . 1 7 , for the Universiry of Akron males . l7, and for University of Akron females -.20. Each r is insignificantly different from zero. Although the Ziller, et al. self-esteem measure may receive construct validation via other instances of high self-esteem being associated with some kind of higher potential for self-reinforcements, rhe test did not correlate with the Rocter I-E scale. Future research may show whether the claim is unjustified or whether other measures will indicate that high self-esteem on the self-other measure is related to a higher potential for self-reinforcement.

Quick-release article holder

Abstract: A quick-release article holder adapted for mounting on a vertical surface and having a bifurcated lower support member and a spaced upper clamping member which is pivotally mounted for rotative movement into or out of engagement with the upper portion of the article to be held. The holder is particularly adapted for use in retaining cylindrical breathing apparatus which is mounted on the wall of a fire station or on a panel of a mobile fire apparatus and serves to retain and support the breathing apparatus when it is not in use or while it is being harnessed to the back of the user. A lever-operated linkage serves to pivot the upper retaining member out of clamping engagement with the apparatus so that the entire breathing apparatus can be moved horizontally away from the holder by the action of the user walking away from the holder after the breathing apparatus has been harnessed to his back. The breathing apparatus can be restored to the holder by reversing the removal procedure and moving the upper clamping member back into locking engagement with the upper part of the breathing apparatus. Adjustable features are provided for varying the spacing between the upper and lower members, changing the position of the upper member at its limits of pivotal movement and maintaining a spring-loaded clamping force on the upper member.

Vulcanizable ethylene/propylene copolymers and process for their preparation

Abstract: There are disclosed new vulcanizable copolymers of ethylene and propylene containing unsaturations resulting from the presence therein of units deriving from the mixture obtained by the catalytic isomerization of vinylnorbornene said copolymers containing ethylene, propylene, ethylidene norbornene and at least one other diene selected from the group consisting of vinyl norbornene and vinyl norbornene and dicyclopentadiene. The copolymers have vulcanization rates comparable to those of ethylene/propylene/ethylidenenorbornene copolymers and yield elastomers having characteristics comparable to those of the vulcanized ethylene/propylene/ethylidenenorbornene copolymers, but are substantially more economical. The new modified ethylene/propylene copolymers are obtained by copolymerizing a mixture of the starting monomers in contact with catalysts prepared from hydrocarbon-soluble vanadium compounds and hydrides or organometallic compounds of beryllium, aluminum, or lithium-aluminum compounds.

An assessment of tandem mechanics.

Abstract: No Available. Thesis presented for partial requirement for a Master's degree, The Ohio State University, 1968.

Tool for releasing frozen work parts

Abstract: A tool for forcibly releasing interlocked work parts, such as a frozen piston from a disc-brake caliper. The tool includes a first, separable, rigid tool part for engagement with one work part, one-piece rigid,second tool part in engagement with the other work part, and a connector means connected between the first and second tool parts and including screw means for axially adjusting the first and second tool parts toward one another to separate the interlocked work parts.

Centrifugal Effects in Inflated, Rotating Bias-Ply Tires:

Abstract: An equation is derived which governs the dynamic equilibrium contour taken by an inflated and rotating, but otherwise unloaded, bias-ply tire. This equation, which is in the form of a hyperelliptic integral, is based on the membrane theory of shells and the netting analysis of composite materials. Results are obtained for the meridional geom etry of a typical two-ply automobile tire, which are in reasonable agreement with ex perimental measurements.This integral, which describes the dynamic equilibrium contour of the tire, is then used to obtain an algebraic cord load formula. The formula shows how the cord tension at any location is dependent on mass distribution, angular velocity, inflation pressure, deformed tire geometry, and number of cords in the tire. Centrifugal effects, as they influence cord tension, are more pronounced in the bead region than in the crown region.Cord forces are experimentally measured up to 1600 rpm, using the tirecord tension transducer which is a strain-gage instrumented tens...

Method of making a pneumatic tire

Abstract: A method of making a pneumatic tire which includes the steps of separately forming first and second sidewall members and thereafter placing or locating two of the sidewall members in a centrifugal casting mold. As located in the centrifugal casting mold, the sidewall members are spaced from each other in the tread area of the finished tire. The two sidewall members are connected together by centrifugally casting a connecting material into the space between the two sidewall members and the material which forms the connection is compatible with the material of construction of the sidewall members.