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New Ultrasonic Technique for the Study of Track-Etched Pores in Polymer Films

This presentation showcases a new ultrasonic technique, Air-Coupled Ultrasound (AC-US), for studying the properties of track-etched pores in polymer films. The objective is to demonstrate the feasibility of propagating short ultrasound pulses along pore channels in the membranes, independent of other propagation modes. Through experimental results, valuable information about the pore channels is obtained.

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New Ultrasonic Technique for the Study of Track-Etched Pores in Polymer Films

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  1. 24th International Conference on Nuclear Tracks in Solids, Bologna, 1-5 September 2008 Tomás E. Gómez Álvarez-Arenas, Pavel. Yu. Apel, Oleg Orelovitch and Manuel Muñoz. New ultrasonic technique for the study of the properties of track-etched pores in polymer films. Spanish Research Council (CSIC) Instituto de Acústica and Instituto de Física Aplicada Madrid, Spain. Flerov Laboratory of Nuclear Reactions (JINR) Dubna, Russia.

  2. Presentation schedule 24th International Conference on Nuclear Tracks in Solids, Bologna, 1-5 September 2008 • - Objective of the work • Air-Coupled Ultrasound (AC-US): a new ultrasonic technique. • -Basic description of the Ion-Track Membranes (ITM). • -Description of the experimental set-up. • - How does ultrasonic waves transmit though ITM? • -Experimental results. • -Conclusions.

  3. Objective of the work 24th International Conference on Nuclear Tracks in Solids, Bologna, 1-5 September 2008 TO DEMONSTRATE THAT: 1. It is possible to propagate short ultrasound pulses along pore channels in track-etch membranes. 2. This ultrasound propagation is independent of any other propagation mode present in the membrane. 3. It is possible to isolate and sense this propagation. 4. This provides valuable information about the pore channels. Phase and magnitude spectral analysis of air-coupled and wide-band ultrasounds.

  4. Introduction: basic ultrasonic concepts 24th International Conference on Nuclear Tracks in Solids, Bologna, 1-5 September 2008

  5. A new ultrasonic technique: Air-coupled ultrasound (AC-US). 24th International Conference on Nuclear Tracks in Solids, Bologna, 1-5 September 2008 -Novel broad- band and air-coupled ultrasonic transducers (2004) for materials characterization. Stack of two /4 matching layers A low-density matching layer IEEE-Ultrason. Ferroelec. Freq. Ctrl. (51)5, 624-633, 2004 2004-2008: stack of 3 matching layers and apiezoelectric composite: Frequency range 0.1 MHz-6 MHz

  6. Ion-track membranes (ITM) 24th International Conference on Nuclear Tracks in Solids, Bologna, 1-5 September 2008 Main properties of ITM Polymer foil 10-25 m thick. Pore diameter: 100 nm – 1.9 m. Volumetric porosity: 5-30%. Pore shape: cylindrical. Pore orientation: normal to foil. Pore aperture: open. Overlapping pores: No Alternative characterization techniques: Analysis of SEM images Analysis of AFM images. Density measurements. Air-flow measurements.

  7. Experimental set-up. 24th International Conference on Nuclear Tracks in Solids, Bologna, 1-5 September 2008 Pulser/receiver Transmitter tr. Digital oscilloscope Sample Holder Receiver tr. Transducers holder

  8. Experimental set-up. Measurement procedure 24th International Conference on Nuclear Tracks in Solids, Bologna, 1-5 September 2008 Measurement of the ITM ultrasound transmitance Calibration of the system response

  9. N o p o r e s 1 0 m c m - 2 0 - 3 0 - 4 0 i Ultrasound Transmitance (dB) - 5 0 - 6 0 0 2 4 6 F r e q u e n c y M H z Transmission of AC-US pulses through ITM. Influence of the presence of pores on the transmission of ultrasounds: Non-porous foil Foil with trach-etched pores 24th International Conference on Nuclear Tracks in Solids, Bologna, 1-5 September 2008 Different pore diameter, same porosity. 50 nm-1.9 m, porosity ~10% Different porosity, same pore diameter ~0.54 m, porosity 15%-34%

  10. -15 (b) -20 7 -25 -30 8 Ultrasound transmitance (dB) -35 -40 -45 Theory non-porous foil -50 -55 -60 -65 0,25 0,5 0,75 1 2,5 5 7,5 Frequency (MHz) Transmission of AC-US pulses through ITM. 24th International Conference on Nuclear Tracks in Solids, Bologna, 1-5 September 2008 Verification of the hypothesis of the decoupled propagation of ultrasounds in the track-etched pores (Appl. Phys. Lett. 87, 111911, 2005) Closed pores Open pores

  11. Transmission of AC-US pulses through ITM. 24th International Conference on Nuclear Tracks in Solids, Bologna, 1-5 September 2008 Foil transmission Special filtering proc. -Independent propag. -Determination of the foil contribution. -Simultaneously measurement of phase and magnitude spectra of the total membrane transmission Solid foil Total Foil transmission Pore channel transmission Pore channel Total Membrane transmission Track-etched membrane

  12. Transmission of AC-US pulses through ITM. 24th International Conference on Nuclear Tracks in Solids, Bologna, 1-5 September 2008 Factors that affect the propagation of ultrasounds in the Track-etched pores Pore diameter. Pore sinuosity. Crossing pores. Pore tortuosity. Pore aperture at the interface L’  L’=L/cos L L Open pore Closed pore

  13. Experimental measurement of ultrasound transmittance. 24th International Conference on Nuclear Tracks in Solids, Bologna, 1-5 September 2008 -Influence of porosity. -Influence of pore diameter.

  14. Experimental measurement of ultrasound transmittance. 24th International Conference on Nuclear Tracks in Solids, Bologna, 1-5 September 2008 -Influence of track density.

  15. Experimental measurement of ultrasound transmittance. 24th International Conference on Nuclear Tracks in Solids, Bologna, 1-5 September 2008 -Influence of tilting angle and crossing pores.

  16. Experimental measurement of ultrasound transmittance. 24th International Conference on Nuclear Tracks in Solids, Bologna, 1-5 September 2008 -Influence of pore shape. Cylindrical Funnel entrance Cigar like Porosity: 11% 14% Pore aperture (m): 0.65, 0.82, 0.63 0.7, 0.87, 0.67

  17. Conclusions. 24th International Conference on Nuclear Tracks in Solids, Bologna, 1-5 September 2008 Tom Porosity. Pore diameter. Pore aperture. Pore shape. Tortuosity. (tilting angle) Crossing pores To m Pore transmittance (dB) -75 dB Frequency (log) 6 MHz 0.1 MHz

  18. Conclusions. 24th International Conference on Nuclear Tracks in Solids, Bologna, 1-5 September 2008 1. Actual sensitivity of the experimental set-up presents a minimum measurable value of pore transmittance at -75 dB, in the frequency band 0.1-6 MHz: 50-75 nm, 11.6% porosity in 10 m thick membranes. 300 nm, 5% porosity in 23 m thick membranes. 2. Determine porosity variations >2% in samples having pore diameter of about 0.5 m. 3. Determine pore diameter variations: > 100 nm in membranes with 0.2 m pores and 10% porosity ~20-50 nm in membranes with 0.54 m and >10% porosity. 4. Determine variations of pore tilting angle (0º-20º). 5. Determine variations of pore shape, especially those involving variations of the pore aperture

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