Akron, OH, United States
Akron, OH, United States

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Martens J.E.,Akron Rubber Development Laboratory, Inc | Terrill E.R.,Akron Rubber Development Laboratory, Inc | Lewis J.T.,Akron Rubber Development Laboratory, Inc
Rubber World | Year: 2013

Dynamic mechanical testing is a powerful predictive tool that can provide valuable insight into the tire performance of tread compounds. The improvement of tire tread performance properties through proper material selection is a subject of ongoing interest. Tire tread deformation during motion under load has been described as consisting of predominantly bending strains in which the curved tread is bent inwards and outwards as a function of the contact region. The total strain is composed primarily of the tangential strain in the plane of the tire and the shear strain between the radial and tangential directions. Strain and stress amplitudes depend on the magnitude of tire deflection. The two silica-filled S-SBR compounds were mixed using two mixing procedures in which the duration of the mixing time was varied. Both solution polymerized SBRs are of medium styrene and high vinyl content, one containing additional chain functionalization.

Terrill Ed.,Akron Rubber Development Laboratory, Inc
Rubber World | Year: 2011

In summary, the following general conclusions were found: • First, all five compounds were prepared unfilled and compounded to a very high crosslink density. At very high crosslink density, the peroxide based compounds exhibited better ultimate properties than the sulfur based compound. A clear explanation is under further investigation. • Second, modulus was directly related to crosslink density, irrespective of crosslink type. • Third, because of the high crosslink density across the samples investigated, the distribution of molecular weight between crosslinks was not significantly different in this series of compounds and was not detectably different using the Time-Domain NMR technique. • Fourth, compounds with bulky crosslink structures were more hysteretic (higher loss modulus and tangent delta) under dynamic mechanical deformation. • Last, compounds with thermally labile crosslinks were more affected by high temperature creep and compression set, as in the case of ZMDA-peroxide and SEV compounds. At very high crosslink density, as in this case, differences in crosslink type and the effect on cured physical properties are too narrow to accurately distinguish. A subsequent study should be undertaken to explore compounds at lower crosslink density more consistent with practical formulations.

Terrill E.R.,Akron Rubber Development Laboratory, Inc | Lewis J.T.,Akron Rubber Development Laboratory, Inc
Gummi, Fasern, Kunststoffe | Year: 2010

Oxygen consumption rates were measured on natural rubber compounds with varying levels of a standard antioxidant package. The oxygen consumption rate measurements were performed at temperatures between 20 °C and 80 °C. The results elucidated the mechanism of antioxidants, including their pro-oxidant effects. The pro-oxidant effect dwindled with time. Integrated oxygen uptake results were calculated from repetitive oxygen consumption rate measurements. Integrated oxygen uptake time temperature master curves with empirical shift factors were combined with elongation-to-break data to monitor the extent of ageing. The stability of the compounds at service life temperatures could be quantified by combining the integrated oxygen uptake shift factors with the tensile elongation-to-break data; thereby to produce an elongation-to-break master curve at service life temperatures.

Terrill E.R.,Akron Rubber Development Laboratory, Inc | Upton T.,Akron Rubber Development Laboratory, Inc
Rubber World | Year: 2014

A method to prepare tear test specimens from tires and molded rubber goods has been developed. A preferred geometry for quantifying tear properties which has good reproducibility is the molded groove trouser tear. It provides a steady, constant tear force as a function of displacement. The ability to make grooved trouser test specimens went through a development process. Samples were prepared with and without water as a cutting lubricant. Good grooved tear specimens were obtained from slices extracted from tires. The specimen thickness was 2 mm (80 mils) with 0.5 mm (20 mils) groove on each side. The test results were compared to the results from molded groove tear test specimens. The results were very similar to molded groove trouser tear, although the machine groove had larger variation than the molded groove. The results show that both specimens have smooth grooves located centered one above the other, which is specified in ASTM D624.

McMahan C.,U.S. Department of Agriculture | Kostyal D.,Akron Rubber Development Laboratory, Inc | Lhamo D.,U.S. Department of Agriculture | Cornish K.,Ohio State University
Journal of Applied Polymer Science | Year: 2015

Guayule (Parthenium argentatum) is under cultivation in the southwestern United States as an alternative source of natural rubber free from proteins that cause Type I latex allergies. However, since guayule lacks the protein-polymer interactions present in Hevea latex, its physical and chemical properties may differ. The solvent-soluble (Sol) and insoluble (Gel) fractions from guayule and Hevea natural rubbers were isolated through a solubilization/centrifugation deproteinization process. Protein could be reduced or removed by centrifugation, or concentrated in the gel fraction for both Hevea and guayule rubber. Separation of the sol fraction of Hevea rubber reduced the overall protein level, in some cases to below detection limits, without impacting rubber thermo-oxidative stability. Notably, no detectable cross reactions took place between guayule protein antibodies and Hevea-based materials, nor vice-versa. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42051. © 2015 Wiley Periodicals, Inc.

Flanigan C.M.,Ford Motor Company | Beyer L.,Ford Motor Company | Klekamp D.,Ford Motor Company | Rohweder D.,Ford Motor Company | And 2 more authors.
Rubber World | Year: 2012

Several key advanced fillers were evaluated to assess their performance in high silica green tire tread formulations and standard, carbon black based tread compounds. The study provide a direct comparison between emerging filler options and to evaluate key performance characteristics of the resulting tread compounds. Five unique fillers were selected for evaluation in two model tread compounds, one primarily silica filled and the other carbon black filled. A model tire tread formulation of solution styrene-butadiene rubber (S-SBR) and solution polybutadiene (S-BR) was used as the basis for this comparative filler study. The hybrid CB-silica compound exhibited longer scorch time relative to the carbon black control due to the acidic nature of the silica portion of the filler which tends to retard cure and increase scorch safety. The compounds using hybrid carbon black-silica filler showed a decrease in tensile strength to 12 MPa compared to the carbon black control at 16 MPa.

Hershberger N.,Akron Rubber Development Laboratory, Inc | Stuck B.L.,Akron Rubber Development Laboratory, Inc | Noel O.,Imerys | Meli G.,Imerys
Rubber World | Year: 2012

The effect of talc on the dispersion of various grades and blends of carbon black was studied and the influence of surface area and structure of the carbon black were examined. The talc used was Mistron Vapor R which is an ultra-fine microcrystalline talc. Akron Rubber Development Laboratory (ARDL) prepared rubber compounds with various compositions using a BR internal mixer. The comparison of mechanical properties indicates that the addition of talc results in an increase in the elongation at break and a loss in modulus above 50% elongation. It is interesting to note that the carbon blacks in Group 2 have a surface area which is halfway between that of N550 at 40 m2/gm and N234 at 120 m2/gm. The effect of talc on the dispersion of this blend of reinforcing blacks is is found to have an increased rating from 1 to 4.

Hershberger N.,Akron Rubber Development Laboratory, Inc
Rubber World | Year: 2013

Five different accelerators are evaluated at different loadings to characterize their effect on binding the free sulfur in vulcanized vegetable oil (VVO). The accelerators evaluated were TMTD (tetramethylthiuram disulfide), ZDMC (zinc dimethyldithiocarbamate), MBTS (2,2'-dibenzothiazole disulfide), TBBS (N-tertbutyl-2-benzothiazolesulfenamide) and DPG (N,N'-diphenylguanidine). Each accelerator was added in a VVO compound at 1.0 and 2.0 phr to evaluate the accelerator and loading effects on heat aging properties. Once the VVO was synthesized, it was removed from the beaker and put on an aluminum tray to cool. All VVOs rested for at least 72 hours before being mixed in a rubber compound or tested. All accelerated VVOs reacted faster than the control VVO without accelerators. The percent free sulfur was lower in the VVO compounds with 1.0 phr ZDMC, 2.0 phr TMTD, 2.0 phr ZDMC and 2.0 phr DPG than the control compound with no acceleration.

Martens J.E.,Akron Rubber Development Laboratory, Inc | Terrill E.R.,Akron Rubber Development Laboratory, Inc | Napier R.C.,ExxonMobil | Waddell W.H.,ExxonMobil
Tire Science and Technology | Year: 2015

The inflation pressure loss rate (IPLR) of a tire has been a standard test method for several decades and is used to determine the rate at which a tire will lose pressure. Following these procedures, the rate of pressure loss is obtained and expressed numerically as the percentage of loss per month. This is an investigation of two experimental variables: (1) the frequency at which the inflation pressure is measured on a daily basis, and (2) the duration of the entire test. The measurement frequency means how many data points are recorded during a 24-hour period. For example, one study may collect data as infrequently as once per day by manually reading a pressure gauge every 24 hours. Alternatively, another study may collect data electronically with pressure transducers capable of transmitting large numbers of data points over short preset periods, then numerically averaging those data into a single 24-hour daily measurement. After a 21-day period to equilibrate the newly inflated tire, the test duration can range from 90 to 180 days but is allowed to be shortened when using electronicpressure monitoring. This is a study of data-collection frequency and duration in a newly commissioned tire IPLR laboratory at Akron Rubber Development Laboratory, Inc (ARDL). It was constructed to have excellent temperature control and was equipped with 24 pressuresensitive transducers with data being directly transmitted into a dedicated computer where the ASTM F1112 equations were applied. The present study includes data measurements from 56 radial medium truck tires manufactured by different companies. Results were obtained by averaging data collected four times per hour over a test duration of 90 days but were then recalculated using 60, 45, or 30 days of data to establish the feasibility of using a shorter testing time. © 2015, Tire Society Inc. All rights reserved.

Agency: Department of Defense | Branch: Army | Program: SBIR | Phase: Phase I | Award Amount: 69.92K | Year: 2010

High operating temperatures and harsh environments have caused a significant decrease in elastomeric material durability for military vehicles. ARDL will be using recent advances in material technology, testing methodology, processing, and design-analysis concepts to develop the material model and meet the project goal. Material choices and test designs will be established based on the requirements. The goal will be to develop the ability to predict damage initiation and progression in an elastomeric material causing fatigue failure and quantifying service life. Testing techniques and systems at ARDL will be used to verify and co-relate the material model developments. ARDL is proposing to develop a damage model for estimating the fatigue life of elastomeric materials. The material model will be based on the strain energy density and the damage strain energy release rate will be derived using the principle of continuum damage mechanics. This unique material modeling system with new material model and continuum damage-formulation will allow the Army to understand the fatigue life of polymer-elastomer materials. The formulation for damage progression in an elastomeric material will be used to develop a procedure to predict the fatigue life as a function of the nominal strain amplitude under cyclic loading service conditions.

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