Glass transition characterization of homogeneous and heterogeneous polymers by an ultrasonic method

Nguyen, Nhi Tru; Lethiecq, Marc; Gérard, Jean‐François

doi:10.1016/0041-624x(95)98709-l

Cited by 16 publications

(8 citation statements)

References 15 publications

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“…As epoxies of decreasing T g are considered, the range of plotted temperatures becomes closer to the material’s T g , and eventually spans the T g . The decreasing quadratic coefficient term with decreasing T g indicates that the curves transition from concave-up to concave-down, implying a sigmoid shape, as found in previous work [16]. Fig.…”

Section: Resultssupporting

confidence: 77%

Filled and unfilled temperature-dependent epoxy resin blends for lossy transducer substrates

Eames

Hossack

2009

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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In the context of our ongoing investigation of low-cost 2-dimensional (2-D) arrays, we studied the temperature-dependent acoustic properties of epoxy blends that could serve as an acoustically lossy backing material in compact 2-D array-based devices. This material should be capable of being machined during array manufacture, while also providing adequate signal attenuation to mitigate backing block reverberation artifacts. The acoustic impedance and attenuation of 5 unfilled epoxy blends and 2 filled epoxy blends—tungsten and fiberglass fillers—were analyzed across a 35°C temperature range in 5°C increments. Unfilled epoxy materials possessed an approximately linear variation of impedance and sigmoidal variation of attenuation properties over the range of temperatures of interest. An intermediate epoxy blend was fitted to a quadratic trend line with R2 values of 0.94 and 0.99 for attenuation and impedance, respectively. It was observed that a fiberglass filler induces a strong quadratic trend in the impedance data with temperature, which results in increased error in the characterization of attenuation and impedance. The tungsten-filled epoxy was not susceptible to such problems because a different method of fabrication was required. At body temperature, the tungsten-filled epoxy could provide a 44 dB attenuation of the round-trip backing block echo in our application, in which the center frequency is 5 MHz and the backing material is 1.1 mm thick. This is an 11 dB increase in attenuation compared with the fiberglass-filled epoxy in the context of our application. This work provides motivation for exploring the use of custom-made tungsten-filled epoxy materials as a substitute PCB-based substrate to provide electrical signal interconnect.

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Section: Resultssupporting

confidence: 77%

Filled and unfilled temperature-dependent epoxy resin blends for lossy transducer substrates

Eames

Hossack

2009

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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“…With the use of ultrasound, Perepechko has made a detailed study of relaxation and crystallization phenomena in some thermoplastic polymers. 11 More recently, several authors have studied the temperature dependence of the acoustic properties of both thermoplastic 17,23−34 and thermosetting 35,36 polymers. Compared with conventional dynamic mechanical analysis (DMA), the ultrasonic technique (UDMA) requires a simpler sample geometry.…”

Section: Applications Of Ultrasonic Wave Propagation Transitions In Lmentioning

confidence: 99%

Polymer characterization by ultrasonic wave propagation

Lionetto

Maffezzoli

2008

Adv Polym Technol

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The propagation of low-intensity ultrasound in polymers, acting as a high-frequency dynamic mechanical deformation, can be successfully used to monitor changes in the modulus of polymers associated with glass transition, crystallization, cross-linking, and other chemical and physical phenomena related to changes in the viscoelastic behavior, such as gelation phenomena. The velocity of sound is related to the polymer storage modulus and density, whereas the absorption of ultrasonic waves is related to the energy dissipation in the material and, therefore, to the loss modulus. Accordingly, ultrasonic measurements have been used by several authors to monitor the evolution of the viscoelastic moduli of polymers as a function of time or temperature and, recently, become a characterization technique of its own right, generally known as ultrasonic dynamic mechanical analysis (UDMA). Often the technique is used in conjunction with rheological methods as a means of providing a better insight into the viscoelastic behavior of polymer systems. As yet UDMA is underutilized primarily because of the low operating temperatures (usually below 100 • C) of commercially available ultrasonic transducers, and also due to the requirement of a coupling medium to ensure an efficient energy transfer mechanism between the transducer and the test material. Despite these limitations, this paper shows that the use of ultrasonics is potentially a powerful method for the characterization of polymers, particularly as a tool for online monitoring of events occurring during polymer processing and in the manufacture of polymer matrix composites. The aim of this paper is to review the progress made in recent years, highlighting the potential and reliability of UDMA for monitoring physical transitions in polymers such as glass transition, melting, crystallization, as well as physical

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“…As the a-transition obeys the William-Landel-Ferry model, we have followed the approach used by Nguyen et al (1997). Hence we have adjusted experimental values of C(f) (obtained with the linear regression of our data) with the WLF model: …”

Section: Resultsmentioning

confidence: 99%

“…On the other hand, several authors have used ultrasonic waves for a-or b-transitions investigation in polymer materials or viscoelastic liquids (Nguyen et al, 1997;Nozdrev, 1965;Matheson, 1971). As these transitions are related to the molecular structure, these ultrasonic evaluations have been qualified as Molecular Acoustics.…”

Section: Introductionmentioning

confidence: 98%

α-Relaxation in honey study versus moisture content: High frequency ultrasonic investigation around room temperature

Laux

Camara

Rosenkrantz

2011

Journal of Food Engineering

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Glass transition characterization of homogeneous and heterogeneous polymers by an ultrasonic method

Cited by 16 publications

References 15 publications

Filled and unfilled temperature-dependent epoxy resin blends for lossy transducer substrates

Filled and unfilled temperature-dependent epoxy resin blends for lossy transducer substrates

Polymer characterization by ultrasonic wave propagation

α-Relaxation in honey study versus moisture content: High frequency ultrasonic investigation around room temperature

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