Open Photoacoustic Cell study of thermal diffusivity of Nafion® as a function of water content

Dias, Daniele Toniolo; Mura, J.; Baesso, Mauro Luciano; Medina, A. N.; Bento, A. C.; Shen, Jun

doi:10.1051/jp4:2005125089

Cited by 4 publications

(8 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The value for ␣ Al agrees very well with the literature value for Al. On the other hand, ␣ CL has not been measured before, but if compared to the Nafion itself that was measured alone as ␣ Nafion = 0.7ϫ 10 −3 cm 2 / s, 23 it is one fifth of the CL value, perhaps due to particles of Pt/carbon as doping in the sample. Note that the dotted line represents the expected value for the thermal diffusivity, using Eq.…”

Section: Resonant Opc Resultsmentioning

confidence: 99%

An open-photoacoustic-cell method for thermal characterization of a two-layer system

Astrath¹,

Astrath²,

Shen³

et al. 2010

Journal of Applied Physics

View full text Add to dashboard Cite

In the present work, we use an open-photoacoustic-cell ͑OPC͒ operating at high frequency to measure thermal properties of two-layer system samples. Photothermal deflection technique is also employed to measure the samples. The effective thermal diffusivity measured using the OPC method is interpreted using the concept of effective thermal resistance for a series two-layer system. The results show the reliability of the photoacoustic method for a complete thermal characterization of the samples. In addition, by varying the sample effective thickness, the thermal diffusivity and conductivity of each layer are precisely determined. The effective thermal diffusivity, thermal conductivity, and specific heat of a porous catalyst layer ͑thickness varying from 13 to 53 m͒ deposited on an aluminum foil ͑53 m in thickness͒ were thus measured and found to be ͑3.7Ϯ 0.3͒ ϫ 10 −3 cm 2 / s, ͑7.5Ϯ 0.7͒ ϫ 10 −3 W / cm K, and ͑1.6Ϯ 0.2͒ J / gK, respectively.

show abstract

Section: Resonant Opc Resultsmentioning

confidence: 99%

An open-photoacoustic-cell method for thermal characterization of a two-layer system

Astrath¹,

Astrath²,

Shen³

et al. 2010

Journal of Applied Physics

View full text Add to dashboard Cite

show abstract

“…13,18 For the OPC measurements it was used a microphone (Sennheiser) with sensitivity $ 10 mV/Pa and the sample was illuminated by a tungsten white lamp (250 W at 24 V). 16 For the TLS measurements, samples were illuminated with an argon ion laser ($80 mW at 514 nm). 16 The thermogravimetry (TG) experiments and the DSC curves were obtained using a high-performance modular simultaneous TG-DSC (Setaram Labsys EVO STA).…”

Section: Methodsmentioning

confidence: 99%

“…16 For the TLS measurements, samples were illuminated with an argon ion laser ($80 mW at 514 nm). 16 The thermogravimetry (TG) experiments and the DSC curves were obtained using a high-performance modular simultaneous TG-DSC (Setaram Labsys EVO STA). The thermal analysis experiments were performed using the assays described in Table I after PA results were obtained elsewhere.…”

Section: Methodsmentioning

confidence: 99%

“…13,14 The experiments were carried out in the range of 1300-2300 nm, since overtones and combinations of hydroxyl bonds were easily defined in this spectral region. 15 Thermal diffusivity measurements 15,16 using the open photoacoustic cell technique (OPC) [16][17][18] were compared to another photothermal technique, 16 thermal lens spectroscopy (TLS), to evaluate the structural changes in the swelling and hydration-dehydration processes of the pristine membrane. Thermal analysis using TG and DSC has been used to check the stability, crystallization transition, and water retention of membranes.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Thermo-Optical Properties of Perfluorinated Sulfonic Acid Membranes: An Investigation of Hydration Based on Absorption Spectra

et al. 2017

View full text Add to dashboard Cite

The Nafion membranes are widely used in electrochemical applications such as fuel cells, chlor-alkali cells, and actuators-sensors. In this work, the thermal-optical characterization of Nafion in acid form was performed by photoacoustic spectroscopy, thermogravimetry, and differential scanning calorimetry. In the experimental procedure three distinct hydration levels were considered: (1) pristine membrane (λ ≅ HO/-SOH ≅ 5.6); (2) swelling process (λ ≅ 17.4); and (3) drying at controlled room temperature after swelling process (λ ≅ 6.5). The discovered behaviors showed significant irreversible structural changes induced by water retention in the membrane. These structural changes depend on the water population present in the clusters and also affect the directional thermal diffusivity of the membrane irreversibly.

show abstract

“…viscosity of the instant corn dry masa flour ͑cornmeal dough, actually a corn flour soaked with water and used for cooking Mexican tortillas͒ was established in the photoacoustic study conducted by Yanez-Limon et al 9 Other interesting PA investigations include some additional properties of biological materials, fungi in tomatoes, 10 emission of ethylene by papaya, 11 and the dependence of thermal diffusivity on the water content in fuel cell membrane such as nafion resin ͓perfluorosulfonic acid/polytetrafluoroethylene ͑Teflon ® ͒ copolymer͔. 12 Another powerful PT method, called PT radiometry ͑PTR͒, was used to directly assess thermal effusivity of several raw agricultural commodities. 13 Furthermore, optothermal emission radiometry ͑OTTER͒, a variant of PTR, was applied to determine, in a nondestructive and rapid fashion, the hydration level as well as the depth dependent hydration profiles in intact tomato fruits of various cultivars.…”

Section: Introductionmentioning

confidence: 99%

Thermal diffusivity of periderm from tomatoes of different maturity stages as determined by the concept of the frequency-domain open photoacoustic cell

Velasco

Baesso

Medina

et al. 2011

Journal of Applied Physics

View full text Add to dashboard Cite

The frequency-domain open photoacoustic cell ͑OPC͒ approach was used to determine room temperature thermal diffusivity of skins ͑pericarps͒ from the raw tomatoes ͑Lycopersicon esculetum Mill.͒ characterized by the three different stages of ripeness ͑from immature-green to a mature-red͒. Periodically interrupted 532 nm laser radiation was used to heat the dry tomato skins, typically 10 mm in diameter and up to 68 m thick; the modulating frequency f varied from 8 to 150 Hz. Initially, a combined OPC-model that takes into account both, the thermoelastic bending and the effect of thermal diffusion ͑TD͒, has been applied. Preliminary results showed that until at least 40 Hz, the effect of TD dominates; above this value the combined model fits the experimental data only poorly. For this reason a less complex OPC-TD approach was applied to all investigated skins instead, which predicts an exponential decrease for the amplitude of measured photoacoustic signal S with increasing f. For a specimen that is simultaneously opaque and thermally thick, S depends on f as Sϳ exp͑−b f 1/2 ͒ where b is a fitting parameter. The S versus f plot enables one to deduce the numerical value for b which, on its turn allows for the assessment of skin's thermal diffusivity ␣. Thermal diffusivities obtained for the immature green, orange, and red skins ͑periderms͒ are 9.9 ϫ 10 −8 m 2 s −1 , 7.2ϫ 10 −8 m 2 s −1 , and 4.6ϫ 10 −8 m 2 s −1 , respectively; the uncertainty was typically 5% of the measured value.

show abstract

Open Photoacoustic Cell study of thermal diffusivity of Nafion® as a function of water content

Cited by 4 publications

References 1 publication

An open-photoacoustic-cell method for thermal characterization of a two-layer system

An open-photoacoustic-cell method for thermal characterization of a two-layer system

Thermo-Optical Properties of Perfluorinated Sulfonic Acid Membranes: An Investigation of Hydration Based on Absorption Spectra

Thermal diffusivity of periderm from tomatoes of different maturity stages as determined by the concept of the frequency-domain open photoacoustic cell

Contact Info

Product

Resources

About