| Phononics and Micromechanics of Bio-Colloidal Wiseana Iridovirus |
Aug-2008 |
3 pages |
| Authors:
Sangwook Sihn; Huiming Xiong; Ryan D Hartschuh; Stephen P Wargacki; Johnathan Neiswinger; Alexander Kisliuk; Vernon K Ward; Richard A Vaia; Alexei P Sokolov; AKRON UNIV OH INST OF POLYMER SCIENCE
|
 | By using Brillouin Light Scattering (BLS), we have investigated phononic properties of Wiseana iridovirus (WIV) assemblies and dispersed individual viruses at hypersonic frequency window. Propagating modes in virus assemblies and localized vibrational eigenmodes of individual virus have been identified. Based on phonon spectra, Young's modulus of the virus has been estimated to be 7 GPa, suggesting that the WIV virions are mechanically more similar to their DNA cores than to ... |
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| Processing, Properties and Morphology of Optical Limiting Silk Membranes |
28 FEB 2006 |
9 pages |
| Authors:
Ronald K. Eby; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| This Final Report is in memory of the PI: Professor Ronald Eby who passed away in Sep 2006. The goal of his program was to provide the basis for membranes and coatings that will absorb strong IR radiation to protect DOD sensors. Their approach is to use the Green Fluorescent Protein (GFP) to provide the absorption and silk protein to provide a good compatible matrix. They have previously demonstrated that ... |
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| Nanomechanical Study of Model Pressure Sensitive Adhesives by Scanning Probe Microscopy |
20 JUN 2002 |
35 pages |
| Authors:
Mark D. Foster; Seung-ho Moon; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| The overall objective is to connect the near surface behavior of a model pressure sensitive adhesive with its macroscopic adhesive performance. Work with a new tackifier suggested that for complex commercial tackifiers the mixture of species in the tackifier may benefit miscibility. When miscibility is impaired, aging phenomena become more prominent. Force-distance measurements made at different frequencies can reveal viscoelasticity effects in such adhesives, but the frequency range that can ... |
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| Tackifier Interfacial Segregation in Pressure Sensitive Adhesives |
01 MAR 2000 |
26 pages |
| Authors:
Mark D. Foster; Adriana Paiva-Ramirez; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| The aim is to precisely characterize the tackifier distribution in model pressure sensitive adhesives and correlate variations in this distribution with the adhesives properties. Work focused on investigating the mechanical properties of the model adhesives near the surface, following the aging of a phase separated model adhesive, and synthesizing and isolating a new model tackifier which is closer in structure to common commercial tackifiers derived from wood rosin. Probing of ... |
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| Blends of Linear and Branched Polymers for Useful Materials |
14 FEB 2000 |
50 pages |
| Authors:
Mark D. Foster; Carmen Greenberg; Teresa Zook; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| The aim is to study the use of molecules of novel architecture for tailoring the surface properties of blends. Key to this work is understanding the bulk miscibility of blends of linear and branched molecules and characterizing the surface segregation that occurs in such blends. The thermodynamic interaction between two polymers due only to the effect of regular branching has been measured for polystyrene blends ... |
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| Organo-Soluble, Segmented Rigid-Rod Polyimide Films: 2. Properties for Microelectronic Applications. |
1992 |
|
| Authors:
Fred E. Arnold Jr.; Stephen Z. D. Cheng; Steven L. C. Hsu; Chul J. Lee; Frank W. Harris; AKRON UNIV OH INST OF POLYMER SCIENCE
|
 | The essential properties of polyimide films of importance in microelectronic applications are thermal and thermo-oxidative stability, dimensional stability, glass transition behaviour and the relative permittivity (dielectric constant epsilon-prime). A segmented rigid-rod polyimide was synthesized from 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (PFMB) in order to develop new materials for microelectronic applications. The thermal and thermo-oxidative stability were investigated by determining the thermal degradation activation energy in air (210 KJ/mole) and in ... |
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| A New Semicrystalline Polyimide (PI-2) for Fiber-Reinforced Composites. 2. Crystal Structure, Crystallization Kinetics and Morphology. |
1992 |
|
| Authors:
Stephen Z. D. Cheng; Martin L. Mittlemann; James J. Janimak; Dexing Shen; Tammy M. Chalmers; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| The overall objective of this ongoing research is the development of impact/solvent resistant, composite resins for various aerospace applications/space applications. We recently prepared a new candidate thermoplastic polyimide (PI-2) from 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) and 1,3-bis(4-aminophenoxy)-2,2-dimethylpropane that displays outstanding toughness. In this paper, we describe its crystal structure, overall crystallization kinetics, and general crystal morphology. Copyright: American Chemical Society: Washington, D.C., 1992 Copyright: American Chemical Society: Washington, |
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| Macromolecular Smart Materials and Structures. |
1992 |
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| Authors:
D. H. Reneker; W. L. Mattice; R. P. Quirk; S. J. Kim; AKRON UNIV OH INST OF POLYMER SCIENCE
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| Fracture Mechanics and Cavitation in Rubberlike Solids |
MAR 91 |
|
| Authors:
A. N. Gent; C. Wang; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| Conditions for propagation of a pressurized crack within a rubberlike solid are derived in terms of the elastic properties of rubber, the energy G sub c and the initial radius r sub o of the crack. A previously-proposed criterion, that the critical internal pressure P sub c for crack growth is given by 5E/6, where E is the tensile (Young) modulus of elasticity, is shown to be inadequate both for ... |
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| Pull-Out and Fragmentation in Model Fibre Composites |
91 |
|
| Authors:
A. N. Gent; G. L. Liu; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| An experimental study has been carried out of debonding and fibre rupture in model composites. A single glass rod or fibre was embedded in the centre of a long transparent silicone rubber block. Strains in the rubber in close proximity to the rod or fibre were measured as the specimen was slowly stretched. Pull-out forces, strain distributions, and debonded lengths are compared with the predictions of a simple theory based ... |
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| Rheology, Morphology, and Mechanical Characteristics of Poly(Etherether Ketone)-Liquid Crystal Polymer Blends. |
1991 |
|
| Authors:
Atul Mehta; A. I. Isayev; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| This paper is in continuation of our previous paper on Poly(etherether- ketone)-liquid crystal polymer (PEEK-LCP) composites. Rheological, morphological, and mechanical properties of polyetherether ketone and a thermotropic liquid crystalline polymer based on hydroxybenzoic acid/hydroxynaphthoic acid have been reported. Addition of LCP resulted in a marked reduction of viscosity and improved processability. Tensile properties improved with increase in LCP concentration. Synergistic effects have been observed at certain LCP concentrations. The elongation ... |
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| Model Studies of the Effect of Surface Roughness and Mechanical Interlocking on Adhesion |
MAY 90 |
38 pages |
| Authors:
A. N. Gent; C. W. Lin; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| The apparent strength of adhesion has been measured for a soft elastic layer adhering to model porous substrates, consisting of rigid plates containing regular arrays of cylindrical holes. Two contributions to the apparent strength have been identified and compared with the preductions of a simple theoretical treatment. The first is adhesion to the surface itself. Because 'rough' surfaces have greater area for bonding, the strength of adhesion was increased by ... |
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| Fundamental Studies of Time-Dependent Response and Fracture of Cross- Linked Polymers |
30 JUN 89 |
148 pages |
| Authors:
Frank N. Kelley; Maurice Morton; Ernst von Meerwell; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| The objectives of these studies are: i) To determine the relationships of polymer structure, network topology and other microstructural features to time-dependent, small deformation properties such as creep and volume relaxation in thermosetting resins. ii) To determine the relationships between polymer network structure and the fracture energy of thermosetting resins. Epoxy resins based on diglycidyl ether of bisphenol A (DGEBA) and diamino diphenyl sulfone (DDS) have been prepared using an ... |
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| Pull-Out and Push-Out Tests for Rubber-to-Metal Adhesion |
MAY 89 |
28 pages |
| Authors:
A. N. Gent; S. Y. Kaang; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| A steel rod embedded in a rubber block can be debonded either by pulling it out or by pushing it out. A comparison is made between the two failure forces. It is shown that friction, aggravated by the tendency of rubber to undergo Poissonian contraction as the block is stretched, makes the pull-out force much higher for rods of large diameter, deeply embedded in the block. On the other hand, ... |
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| Plastic Yielding of Partially-Crystalline Polymers |
MAY 89 |
39 pages |
| Authors:
A. N. Gent; S. Madan; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| Measurements are described of characteristic stress strain properties in tension for several representative partially crystalline polymers, prepared by cooling from the melt. Striking differences were found in the natural draw ratio, ranging from 2X to 11X. They are interpreted in terms of a simple molecular model of the yielding process in which polymer chains, folded to different degrees in the crystallites, are pulled taut. Values of yield and draw stress ... |
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| Comparison of Peel and Lap Shear Bond Strengths for Elastic Joints with and without Residual Stresses |
MAY 89 |
32 pages |
| Authors:
A. N. Gent; C. W. Lin; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| Fracture energies have been calculated from peel and lap shear experiments on rubber strips bonded together with a pressure sensitive acrylic adhesive layer. In some cases, one strip was held stretched during bonding, to create joints with built in stresses. Good agreement was obtained in all cases, provided that elastic strain energy was taken into account, the work of detachment being about 180 J/sq. m. For thick rubber layers, about ... |
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| Adsorption of Phosphorus Acids on Alumina |
OCT 88 |
|
| Authors:
R. D. Ramsier; P. N. Henriksen; A. N. Gent; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| Penetration of moisture into adhesively bonded aluminum structures can and often does lead to deterioration and ultimate failure of the bonds. Methods of retarding moisture penetration into these systems are therefore desirable. One successful method consists of treating the oxidized aluminum (alumina) surface with an hydration inhibitor prior to application of the adhesive. In a comprehensive study of the use of hydration inhibitors to improve the durability of aluminum joints, ... |
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| Diffusion of Linear Polisoprene Molecules Into Polisoprene Networks |
OCT 88 |
52 pages |
| Authors:
A. N. Gent; S. Y. Kaang; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| Diffusion and equilibrium absorption of polyisoprene liquids into crosslinked samples of cis-polyisoprene (natural rubber) have been studied by direct observation of volume swelling. Natural rubber was crosslinked in the form of fine threads, about 40 + or - 20 micrometers in diameter, using a gaseous reaction with Sulfur dioxide and Hydrogen sulfide (the Peachey process). An optical microscope was used to observe the relatively rapid absorption of linear high-molecular-weight polyisoprene ... |
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| Heat Build-Up and Blow-Out of Rubber Blocks |
MAY 88 |
38 pages |
| Authors:
A. N. Gent; M. Hindi; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| Rubber blocks heat up under repeatedly-applied severe deformations and sometimes explode ('blow out'). This phenomenon is shown to be due entirely to the high temperatures developed internally, about 200 C, which cause decomposition of the vulcanizate, and generation of a volatile product. When the internal pressure is high enough, the surrounding rubber is torn apart and the sample bursts. The same process can be observed with a microwave oven, when ... |
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| Elastic Behavior of a Rubber Layer Bonded between Two Rigid Spheres |
MAY 88 |
|
| Authors:
A. N. Gent; Y.-c. Hwang; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| Finite element methods (FEM) have been employed to calculate the stresses set up in a thin rubber layer, bonded between two rigid spheres, when small tensile or compressive deflections are imposed. Values of stiffness have been calculated for various spacings of the spheres, i.e., for various thicknesses of the rubber layer. They are in good agreement with earlier experimental measurements of compression stiffness and with predictions of an approximate theoretical ... |
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| Adhesion between Polystyrene and Polymethylmethacrylate |
MAR 88 |
|
| Authors:
K. Cho; A. N. Gent; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| Measurements have been made of the energy required to break through unit area of polystyrene (PS), polymethylmethacrylate (PMMA), and joints prepared by molding the two polymers in contact. The interface was significantly weaker than either adherend, but surprisingly strong for two incompatible materials. Microscopy and selective dyeing revealed that fracture took place at the interface itself, with no appreciable transfer of material from one side to the other. It is ... |
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| An IETS (Inelastic Electron Tunneling Spectroscopy) Study of Surface Reactions Applicable to Adhesion |
MAR 88 |
|
| Authors:
P. N. Henriksen; A. N. Gent; R. D. Ramsier; J. D. Alexander; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| Inelastic electron tunneling spectroscopy (IETS) has been used to study two classes of adhesion promoting compounds adsorbed on alumina: trialkoxysilanes and phosphonic acids. It has been shown that both types of compounds can condense directly with hydroxyl groups on the surface. Condensation is through the alkoxy groups in the case of the silanes and through the hydroxyl groups in case of the acids. The silanes can further condense to form ... |
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| Effect of Peel Angle on Peel Force |
OCT 87 |
|
| Authors:
Richard S. Miller; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| Measurements of peel force P per unit width are reported for samples of three adhesive tapes, adhering to two different substrates. In all cases, the work of detachment per unit area of bonded interface was found to depend upon the angle theta of detachment, increasing as theta increases. This effect is attributed to dissipation of energy in bending the tape away from the substrate at the line of detachment, to ... |
|
| Cavitation in Model Elastomeric Composites |
OCT 87 |
31 pages |
| Authors:
K. Cho; A. N. Gent; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| Layers of transparent silicone rubber were bonded between two steel spheres or between two parallel steel cylinders, to make simple mechanical models of particle-filled and fiber reinforced elastomers. When the steel end- pieces were pulled apart, visible cavities appeared suddenly in the rubber layer between them, at well-defined tensile loads and displacements. The critical conditions for cavity formation are shown to be in good agreement with a theoretical criterion for ... |
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| Internal Fracture in An Elastomer Containing a Rigid Inclusion |
MAY 87 |
|
| Authors:
K. Cho; A. N. Gent; P. S. Lam; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| Rubber blocks were prepared with thin glass rods in their centers, firmly bonded to the surrounding rubber. A tensile stress applied to the ends of a block in the direction of the rod axis induced the sudden formation of voids in the rubber near the flat ends of the rod. Approximate values of the local stresses have been calculated by FEM, assuming linear elastic behavior. Voids were found to form ... |
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| New and Improved Tests for Adhesion |
MAY 87 |
|
| Authors:
A. N. Gent; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| Three methods are discussed for measuring the work G sub a required to break a bond: Outwater's double-torsion test for long plates, bonded together; a pull-off test for an elastic strip adhering to a rigid surfaces; and a blister test for an adhering elastic layer. The pull-off force F or blow-off pressure P is given by: F4(or P4) is directly proportional to KG sub a cubed where is the tensile ... |
|
| Time-Dependent Response and Fracture of Cross-Linked Polymer |
DEC 86 |
|
| Authors:
F. N. Kelley; M. Morton; D. Plazek; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| This study was concerned with the synthesis, preparation and characterization of cross-linked polymers, and their time-dependent fracture behavior. Emphasis was given to well-defined polymer network structures of two types: (1) end-linked terminally functional liquid polymers having nearly uniform or deliberately distributed initial chain lengths, and (2) model glassy networks in which the network topology was varied with respect to chain length per cross-link, and network defects such as dangling ends ... |
|
| Blow-Off Pressures for Adhering Layers |
NOV 86 |
|
| Authors:
A. N. Gent; L. H. Lewandowski; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| An analysis is given of the critical internal pressure P at which a circular debond blister will grow in size, in terms of the tensile modulus E and thickness t of an adhering layer, and the strength G sub a of its adhesion to a rigid substrate. Measurements of blow-off pressure are reported for adhering layers of pressure-sensitive tapes having widely-different effective modulus and thickness, and with blisters having a ... |
|
| Elastomer Suitable for Track Pad Use that will Change from the Amorphous to the Crystalline State on Stress Application |
08 JUN 86 |
52 pages |
| Authors:
Donald McIntyre; Eberhard A. Meinecke; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| Novel blends of model elastomers were synthesized to determine their potential use in tank track pads to be used at high temperatures, pressures, and shearing stresses. The effect of strain-induced crystallization, microgel inclusions, and reinforcing gelled filler on the physical properties of elastomers was determined. The physical and chemical properties of natural rubber at track pad temperatures and of styrene butadiene rubber pad conditions was determined. |
|
| The Influence of Chemical Structure on the Strength of Rubber |
APR 86 |
|
| Authors:
A. N. Gent; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| The detailed chemical structure of the polymer molecule has surprisingly little effect upon many of the important physical properties of crosslinked elastomers. For example, the elastic modulus, extensibility, tensile strength and tear strength are all much the same for many common elastomers. However, the strength of elastomers under some conditions is strikingly different. Two particular modes of fracture are considered here: tearing, and abrasive wear. Certain elastomers crystallize rapidly on ... |
|
| Elasticity, Tear Strength and Strength of Adhesion of Soft PVC Gels |
APR 86 |
|
| Authors:
A. N. Gent; N. Shimizu; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| An experimental study is described of the tensile modulus E of elasticity, tear strength G sub c and strength G sub a of adhesion of a Mylar substrate, for PVC gels prepared with a wide range of PVC concentrations and with four different plasticizers. The modulus E, measured under quasi- equilibrium conditions, was found to be approximately proportional to C superscript 3, where c is the volume concentration of PVC. ... |
|
| Pull-Off Forces for Adhesive Tapes |
APR 86 |
|
| Authors:
A. N. Gent; S. Kaang; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| An analysis is given of the force F required to pull an adhesive tape of unit width away from a rigid substrate in terms of the strength G sub a of adhesion, the tensile modulus E of the tape, and its thickness t. Measurements are reported for several commercial adhesive tapes and compared with the predictions of the theory. Excellent agreement is obtained, suggesting that the theory is basically correct. ... |
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| Contribution of Bending Energy Losses to the Apparent Tear Energy |
DEC 85 |
|
| Authors:
A. N. Gent; Jongkoo Jeong; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| When a strip is torn, energy is expended both in tearing it and in propagating a bend along each torn section. Estimates are given of the contribution of bending energy losses to the apparent tear energy. Experiments with highly-dissipative semi-crystalline polymers, torn with controlled amounts of bending, are then described. The bending energy losses ranged from 5 to 70 percent of the total tear energy, depending upon the degree of ... |
|
| Inelastic Electron Tunneling Spectroscopy of Silane Coupling Agents Adsorbed on Alumina |
DEC 85 |
|
| Authors:
J. D. Alexander; A. N. Gent; P. N. Henriksen; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| Inelastic electron tunneling spectroscopy (IETS) has been used to obtain vibrational spectra of alkoxysilanes adsorbed on aluminum oxide. The spectra reveal that: (1) monoalkoxysilanes are not adsorbed whereas trialkoxysilanes are readily adsorbed, (2) the reaction mechanism of triethoxysilanes and trimethoxysilanes is the same, and (3) the reaction mechanism under anhydrous conditions utilizes surface OH o OD groups present on alumina. All of these results suggest the following hypotheses: Trialkoxysilanes can ... |
|
| Compression of Rubber Layers Bonded Between Two Parallel Rigid Cylinders or Between Two Rigid Spheres |
DEC 85 |
|
| Authors:
A. N. Gent; Byoungkyeu Park; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| The stiffness of bonded rubber blocks under small compressive deformations has been studied extensively. A recent review deals with the problem in connection with the use of elastomeric laminaes as bridge bearings. However, previous studies have been mainly concerned with a flat rubber block bonded between two flat rigid plates. An approximate treatment is given here for the stiffness of a rubber layer bonded between two opposed curved rigid surfaces, ... |
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| Role of Chemical Bonding in Adhesion |
JUN 85 |
|
| Authors:
A. N. Gent; P. Dreyfuss; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| This project was concerned with the principal factors that govern the strength of elastomers when filled with rigid particles. The factors studied were: the level of adhesion between the elastomer and the rigid surface; the size and number of the rigid inclusions; and, the strength of the elastomer itself. Additional keywords: elastomeric composites; rubber. |
|
| Plastic Deformation of Crystalline Polymers |
MAR 85 |
|
| Authors:
A. N. Gent; J. Jeong; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| Draw ratios have been measured for samples of polyethylene and trans- polyisoprene, crystallized at various temperatures and at various degrees of orientation. The values obtained range from unity, i.e., no drawing is observed, up to values of about 15X for materials crystallized in the oriented state and then drawn in a perpendicular direction. The results are in rough accord with a simple molecular network model in which network strands are ... |
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| An Improved Torsional Method for Determining the Fracture Toughness of Stiff Materials and of Adhesive Joints |
MAR 85 |
|
| Authors:
K. Cho; A. N. Gent; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| A simple modification is described of the Outwater torsion test method for determining the fracture energy of stiff materials and of adhesive joints. It permits large torsions to be applied and the corresponding torque to be simultaneously monitored. The modified test method can be used with specimens of simple rectangular shape and having a wide range of stiffness. As an example, the fracture energy is determined for molded rectangular bars ... |
|
| The Role of Molecular Diffusion in the Adhesion of EDPM (Ethhylene- Propylelediene Terpolymer) and EPR (Ethylene-Propylene Copolymer) Elastomers |
MAR 85 |
|
| Authors:
M. D. Ellul; A. N. Gent; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| Adhesion of lightly crosslinked sheets of EPDM (ethylene- propylelediene terpolymer) to themselves and to a Mylar substrate has been investigated over wide ranges of peel rate and test temperature. The effect of incorporating ethylene-propylene copolymer (EPR) before crosslinking, to yield a loose macromolecular network containing dissolved linear EPR macromolecules, was also studied. The self-adhesion of these materials was found to be much greater than their adhesion to Mylar, over a ... |
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| The Role of Molecular Diffusion in the Adhesion of Elastomers |
SEP 1984 |
|
| Authors:
M. D. Ellul; A. N. Gent; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| Butyl rubber (polyisobutylene-co-isoprene) mixed with polyisobutylene was crosslinked to yield elastomeric macromolecular networks containing dissolved linear macromolecules. Adhesion of these materials to themselves (self-adhesion) and to an inert substrate was investigated over a wide range of peel rates and test temperatures. Greatly enhanced self-adhesion was found when linear polyisobutylene molecules of high molecular weight were present, but the strength of adhesion to a rigid inert substrate was hardly affected. ... |
|
| Mechanochemical Reactions of Elastomers with Metals |
SEP 1984 |
|
| Authors:
A. N. Gent; W. R. Rodgers; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| Metal powders have been incorporated into various elastomers and the mixtures subjected to intense shearing in either an air or a nitrogen atmosphere. The molecular weight after shearing was still relatively high, however, greater than 100 kg/mole. The elastomer was then dissolved and centrifuged to remove the metal particles, and the solution was then analyzed to remove the metal particles, and the solution was then analyzed for reaction products. A ... |
|
| The Role of Chemical Bonding in Adhesion |
APR 1984 |
|
| Authors:
A. N. Gent; P. Dreyfuss; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| Work during the period from March 1, 1983 to February 29, 1984 has been focussed in two main categories, namely, studies of basic failure processes in elastomeric materials and studies of factors affecting the adhesion of various materials to each other. These studies are summarized in this report which describes eight technical reports, 6 publications, and 4 technical presentations made during the year. |
|
| Durability of Adhesive Bonds between Glass or Metal Substrates and a Polybutadiene-Polyurethane |
FEB 1984 |
|
| Authors:
F. Liang; P. Dreyfuss; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| The durability of polybutadiene-polyurethane joints or glass or metals in water at room and elevated temperatures was studied. The effects of silane pretreatment of the surface and of surface morphology on adhesion were examined. The durability of the joint was related to the number of chemical bonds that could form between the polyurethane and the surface and to the type of surface treatment given to the surface. Proper treatment led ... |
|
| Effect of Interfacial Bonding on the Strength of Adhesion of Elastomers. III. Interlinking by Molecular Entanglements |
FEB 1984 |
|
| Authors:
A. N. Gent; R. H. Tobias; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| Polydimethylsiloxane (PDMS) networks have been formed by endlinking linear PDMS molecules. When second layer is cast on top of a fully-gelled lower- layer, the new molecules diffuse into the surface of the lower layer and form molecular loops ('entanglements') in the course of endlinking with themselves. The two layers are then joined only by the macromolecular loops. Measurements have been made of the work required to separate such layers under ... |
|
| Micromechanics of Fracture in Elastomers |
FEB 1984 |
33 pages |
| Authors:
A. N. Gent; C. T. R. Pulford; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| A study of torn surfaces and of the tips of propagating tears in elastomers has been carried out using scanning electron microscopy. Vertical steps separating smooth featureless torn regions are characteristics features of the torn surfaces. They are found to be more frequency and larger in stronger elastomers. They are attributed to the intersection of secondary cracks at the tear tip, displace somewhat from the general tear plane, and nucleated ... |
|
| Effect of Amine Surface Treatment on the Adhesion of a Polyurethane to the Surface |
DEC 1983 |
|
| Authors:
F. Liang; P. Dreyfuss; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| Amines in general and 3-aminopropyltriethoxysilane in particular were shown to improve the adhesion of a polyurethane to glass. At equivalent concentrations of amine in the solutions used to treat the glass the order of increase in the work of adhesion was 3-aminopropyltriethoxysilane >> 1,4- diaminobutane approximately p-phenylendiamine > piperazine >> aniline. The polyurethane was prepared from ARCO's hydroxyterminated polybutadiene, R-45HT, toluene diisocyanate, trimethylolpropane and N,N-bis(2-hydroxypropyl) aniline. The ratio ((-NCO)/(total OH)) ... |
|
| Failure Processes in Elastomers at or Near a Rigid Spherical Inclusion |
SEP 1983 |
42 pages |
| Authors:
A. N. Gent; Byoungkyeu Park; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| A systematic experimental study has been carried out of two distinct failure phenomena, cavitation and debonding, in an elastomer containing a rigid spherical inclusion. Several elastomers were employed containing glass beads of various diameters, ranging from 60 micrometer to 5000 micrometer, and with chemically-different surfaces. The critical stress for cavitation was found to depend upon Young's modulus E of the elastomer and upon the diameter of the bead. By extrapolation, ... |
|
| Fracture Toughness of Polybutadiene at Cryogenic Temperatures |
APR 1983 |
|
| Authors:
R. P. Burford; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| An estimate of fracture toughness of crosslined polybutadiene rubber at -180 degrees C has been made using the double torsin method. By using suitable specimen dimensions and strain rates, controlled crack propagatin can be achieved, together with a constant compliance to crack length ratio. Strain energy release rated for this polymer, crosslinked with either dicumyl peroxide or sulphur, were found to be an order of magnitude higher than for linear, ... |
|
| Fracture Mechanics Applied to Elastomeric Composites |
APR 1983 |
|
| Authors:
A. N. Gent; AKRON UNIV OH INST OF POLYMER SCIENCE
|
| Griffith introduced a general fracture criterion in 1920: a crack will grow only when enough energy is available in the system to cause further fracture. This simple concept has been applied to various tear processes in elastomeric materials by Rivlin and Thomas and to a variety of adhesive failures by Kendall. Their results are reviewed, with particular reference to the fracture and debonding of elastomeric composites. Two further cases are ... |
|
| Tear Strength of Elastomers under Threshold Conditions |
APR 1983 |
26 pages |
| Authors:
A. K. Bhowmick; A. N. Gent; C. T. R. Pulford; AKRON UNIV OH INST OF POLYMER SCIENCE
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| Measurements have been made of the tear strength of several elastomeric materials under threshold conditions, i.e., in the swollen state and at high temperatures when dissipative contributions to the work of fracture are minimized. The materials studied were Neoprene WRT, PB, SBR, EPDM and a castable polysulfide material, LPN-32. They were crosslinked to different degrees, using a free-radical source, or sulfur, or a metal oxide as the crosslinking reagent. Values ... |
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