Acoustic Properties of Polymers

Sinha, Moitreyee; Buckley, Daniel H.

doi:10.1007/978-0-387-69002-5_60

Cited by 33 publications

(40 citation statements)

References 41 publications

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“…However, the second run longitudinal measurement for PC is 2213 ± 15 m s −1 , which is in good agreement with the value of 2220 m s −1 in Ref. 19, but the first run does not match as well. These comparisons suggest that the sound speed in polymers is sufficiently chemistry-and processing-sensitive, such that for critical applications, measurements on the actual billet, or parts, of interest are required if accurate engineering or design data are to be obtained.…”

Section: Resultssupporting

confidence: 83%

Some Observations on Measuring Sound Speeds in Polymers Using Time-of-Flight

Rae

Brown

2015

Exp Techniques

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The time-of-flight method has been used to measure the longitudinal and shear wave speeds in six polymers (polyether ether ketone [PEEK], PEEK with 10% carbon fibers, polytetrafluoroethylene [PTFE], high-density polyethylene [HDPE], ultra-high-molecular-weight polyethylene [UHMWPE], and polycarbonate) and two metals (6061-T6 aluminum and copper). Using transducers producing a nominally sinusoidal input resulted in no indication of a longitudinal dispersion effect that might lead to different longitudinal sound speed being measured as a function of sample thickness. The analysis of the experimental errors showed that, as might be expected, testing thicker samples in using this time-of-flight method lowers the measurement uncertainty, provided that the signal is not too attenuated by the generally highly attenuating polymer samples. It is recommended that when available, samples of polymer greater than 9 mm thick are used for generating accurate sound-speed data.

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Section: Resultssupporting

confidence: 83%

Some Observations on Measuring Sound Speeds in Polymers Using Time-of-Flight

Rae

Brown

2015

Exp Techniques

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“…A part of the ultrasonic energy is transmitted and the rest is reflected at the interface of sonotrode and polymer. The reflected energy is calculated by the reflection coefficient R ij indicating the amplitude of the sound reflected from the interface of material i and j (Sinha and Buckley 2007):…”

Section: Temperature Generation By Ultrasoundmentioning

confidence: 99%

“…However, when the surfaces of the layers are rough, the enclosed air will reflect ultrasound. Besides this, impedance and absorption of ultrasound by a polymer are a strong function of temperature (Sinha and Buckley 2007), and therefore, increase quickly when the temperature starts rising somewhere.…”

Section: Temperature Generation By Ultrasoundmentioning

confidence: 99%

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Heat generation and distribution in the ultrasonic hot embossing process

et al. 2016

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“…Many polymers used for MEMS applications exhibit viscoelastic behavior [7]–[9]. The Young's modulus and the Poisson's ratio change as functions of loading frequency.…”

Section: Introductionmentioning

confidence: 99%

Encapsulation of Capacitive Micromachined Ultrasonic Transducers Using Viscoelastic Polymer

Lin

Zhuang

Wong

et al. 2010

J. Microelectromech. Syst.

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The packaging of a medical imaging or therapeutic ultrasound transducer should provide protective insulation while maintaining high performance. For a capacitive micromachined ultrasonic transducer (CMUT), an ideal encapsulation coating would therefore require a limited and predictable change on the static operation point and the dynamic performance, while insulating the high dc and dc actuation voltages from the environment. To fulfill these requirements, viscoelastic materials, such as polydimethylsiloxane (PDMS), were investigated for an encapsulation material. In addition, PDMS, with a glass-transition temperature below room temperature, provides a low Young's modulus that preserves the static behavior; at higher frequencies for ultrasonic operation, this material becomes stiffer and acoustically matches to water. In this paper, we demonstrate the modeling and implementation of the viscoelastic polymer as the encapsulation material. We introduce a finite element model (FEM) that addresses viscoelasticity. This enables us to correctly calculate both the static operation point and the dynamic behavior of the CMUT. CMUTs designed for medical imaging and therapeutic ultrasound were fabricated and encapsulated. Static and dynamic measurements were used to verify the FEM and show excellent agreement. This paper will help in the design process for optimizing the static and the dynamic behavior of viscoelastic-polymer-coated CMUTs.

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Acoustic Properties of Polymers

Cited by 33 publications

References 41 publications

Some Observations on Measuring Sound Speeds in Polymers Using Time-of-Flight

Some Observations on Measuring Sound Speeds in Polymers Using Time-of-Flight

Heat generation and distribution in the ultrasonic hot embossing process

Encapsulation of Capacitive Micromachined Ultrasonic Transducers Using Viscoelastic Polymer

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