Viscoelastic characteristics of magnetic tapes with PEN substrates

Weick, Brian L.

doi:10.1002/app.28932

Cited by 9 publications

(9 citation statements)

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“…This could be due to some experimental error as described when examining the peak elastic modulus; the frequency is much higher than expected, and the moving platform holding one end of the sample may not have operated as it should have . However, past DMA experiments with PEN samples have shown these types of reversals in frequency dependence in the 50°C temperature range, and the observed peak at 50°C lines‐up well with where the β* secondary transition occurs in previous experiments . The β* transition in PEN is believed to be due to the motion of the naphthalene group in the molecular structure that leads to more viscoelastic energy dissipation in the material.…”

Section: Resultssupporting

confidence: 52%

“…Experiments for the work presented herein were performed for approximately 2 h at 30, 50, and 70 C test temperatures and room temperature (nominally 25 C) consistent with past research 4. Humidity within the small sleeve heater around the test samples could not be measured, but past research byWeick 5,8 has shown that relative humidity drops to less than 5% for 30 C experiments and less than 1% for 50 and 70 C experiments performed in larger heated test chambers used for viscoelastic testing of these types of samples. Four test frequencies were used at each temperature: 0.006, 0.010, 0.033, and 0.065 Hz.…”

mentioning

confidence: 67%

“…9 However, past DMA experiments with PEN samples have shown these types of reversals in frequency dependence in the 50 C temperature range, and the observed peak at 50 C lines-up well with where the b* secondary transition occurs in previous experiments. 5,8 The b* transition in PEN is believed to be due to the motion of the naphthalene group in the molecular structure that leads to more viscoelastic energy dissipation in the material.…”

Section: Average Peak Elastic Modulus Values and Rangesmentioning

confidence: 99%

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Dynamic mechanical analysis of barium ferrite magnetic tapes with aramid and poly(ethylene naphthalate) substrates

Berry

Weick

2014

J of Applied Polymer Sci

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Frequency‐ and temperature‐dependent viscoelastic characteristics of advanced materials used for high‐capacity digital magnetic tapes were analyzed using a custom ultra‐low frequency dynamic mechanical analyzer (ULDMA). The magnetic tapes studied both use barium ferrite (BaFe) magnetic particles. One tape uses an aromatic poly(amide) or aramid substrate, and the other tape uses a poly(ethylene naphthalate) or PEN substrate. ULDMA studies were performed for both types of tape materials using samples cut from reels and the substrates after the front and back coats were removed. Two‐hour experiments were performed at 25, 30, 50, and 70°C temperatures, and four test frequencies were used at each temperature: 0.006, 0.010, 0.033, and 0.065 Hz. Properties determined were the peak strain‐based elastic modulus, E, and the storage modulus, E′, loss modulus, E″, loss tangent, tan(δ), complex modulus, E*, and complex loss, E″/E*, expressed as a percentage. When compared with the PEN tape and substrate materials, the peak elastic modulus, storage modulus, and complex modulus were higher for the aramid materials. Substrates for each material exhibited higher elastic, storage, and complex moduli compared with their respective tapes. Through the complex loss percentage, comparisons were made between the aramid and PEN materials related to their viscoelastic characteristics. Finally, the influence of frequency was shown to have increasing relevance at higher temperatures, with the PEN tape and substrate exhibiting an increase in complex loss modulus in the 50°C range because of the β* secondary transition. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41478.

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Section: Resultssupporting

confidence: 52%

mentioning

confidence: 67%

Section: Average Peak Elastic Modulus Values and Rangesmentioning

confidence: 99%

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Dynamic mechanical analysis of barium ferrite magnetic tapes with aramid and poly(ethylene naphthalate) substrates

Berry

Weick

2014

J of Applied Polymer Sci

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“…A model with a larger number of parameters is capable of capturing the characteristic roll-off behavior observed for PEN-based tapes and substrates, which could be attributed to relaxation characteristics of the polymer and/or shrinkage. 3,4 Figure 17, showing the radial stress in the wound roll as a function of nondimensional radial position for a seven-parameter model of LTO3, illustrates the effect of the increased stress described by the sevenparameter model at long time ranges. The stress fields in the wound roll are also predicted to increase in stress at long times.…”

Section: Viscoelastic Wound Roll Results For Three- Five- and Sevenmentioning

confidence: 98%

Viscoelastic behavior of polymer tape in a wound roll

Acton¹,

Weick²

2011

J of Applied Polymer Sci

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in Wiley Online Library (wileyonlinelibrary.com).ABSTRACT: A viscoelastic computational model is developed that uses experimentally determined viscoelastic material properties as input and can be used to predict the behavior of a tape material in a wound roll as stresses relax over time. Experimental creep test results are used to find best-fit creep-compliance parameters to describe two high density data storage tape media. The two tapes used in the analysis are a developmental tape with a poly(ethylenenaphthalate) (PEN) substrate and metal particle (MP) front coat similar to linear tape open (LTO4) (referred to in this work as ''Tape C''), and LTO3, a commercially available tape with a PEN substrate and MP front coat. Sets of best-fit creep-compliance parameters are determined for both tapes. The differences between the predicted behavior using three-, five-, and sevenparameter Kelvin-Voigt models are evaluated, both for a benchmark case and in a viscoelastic wound roll model.The choice of material model is found to significantly influence the predictions of the wound roll model. The differences between different material models for the same material are on the order of the differences found between the two different materials. A material model with a higher number of creep-compliance parameters, although more computationally expensive, produces better results, particularly over long spans of time. The relative differences between the three-, five-, and seven-parameter models are shown to be qualitatively consistent for several variations in the computational model setup, allowing predictions to be made based on simple benchmarks.

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“…These parameters can be estimated by several techniques that utilize the response of the material to a properly selected external excitation. It is commonplace that estimates for the parameters are 1 found by a least squares fit to measurement data, see, for example, (Vuoristo et al, 2000;Sorvari and Malinen, 2007;Weick, 2009;Acton and Weick, 2011). A particular feature of mechanical analog models for viscoelastic materials, consisting of arrangements of springs and dashpots, is that the number of material parameters, that is, the number of springs and dashpots, is not fixed beforehands.…”

Section: Introductionmentioning

confidence: 99%

Identification of the viscoelastic parameters of a polymer model by the aid of a MCMC method

Haario

Hertzen

Karttunen

et al. 2014

Mechanics Research Communications

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A procedure to identify the viscoelastic material parameters of a solid amorphous polymer and to estimate their values is presented. Stress-strain material data is obtained for the polymer by a compression experiment. The material behavior of the polymer is modeled according to the generalized Maxwell model, which is fitted to the experimental data by the method of least squares to obtain a first approximation for the model parameters. The identification of the model parameters is completed by a Markov chain Monte Carlo (MCMC) method, which generates the probability distributions of the relevant parameters of the material. The utilized MCMC method enables us to determine a suitable complexity (i.e., the number of Maxwell elements) for the generalized Maxwell model, so that the model best fits the data and, simultaneously, leads to an identifiable set of parameters. The numerical results imply that the uniqueness of the solution is lost when the number of model parameters becomes redundant.

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Viscoelastic characteristics of magnetic tapes with PEN substrates

Cited by 9 publications

References 14 publications

Dynamic mechanical analysis of barium ferrite magnetic tapes with aramid and poly(ethylene naphthalate) substrates

Dynamic mechanical analysis of barium ferrite magnetic tapes with aramid and poly(ethylene naphthalate) substrates

Viscoelastic behavior of polymer tape in a wound roll

Identification of the viscoelastic parameters of a polymer model by the aid of a MCMC method

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