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  • 1
    Electronic Resource
    Electronic Resource
    In-line dielectric monitoring during extrusion of filled polymers (2002)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 73 (2002), S. 2097-2102 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Real-time monitoring of the dielectric properties of polymer melts and filled polymer melts has been carried out during extrusion. The measurements are obtained using a dielectric cell that is placed directly in line with the extruder machine. The dielectric cell consists of interdigitating electrodes that are deposited on the inside of a ceramic ring that is electrically insulated and temperature controlled to the set point of extrusion. As the processed resin passes through the ring, its permittivity and conductivity are measured. The spatial sensitivity of the cell was determined experimentally and was biased to the resin flowing near the electrodes. Using the spatial sensitivity function, we examined the time profile of the transition from one composition to another during extrusion. We demonstrate the operation of the cell during the processing of polystyrene filled with aluminum oxide and calcium carbonate and of polyethylene-ethyl vinyl acetate copolymer filled with montmorillonite clay. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1470235
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  • 2
    Electronic Resource
    Electronic Resource
    Fluorescence anisotropy sensor and its application to polymer processing and characterization (2000)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 1516-1523 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An optical sensor containing polarizing optical components has been constructed to monitor fluorescence anisotropy during polymer processing and to carry out remote sensing of polymer products doped with fluorescent dyes. The sensor is a compact unit that is used to polarize incident excitation light as well as to analyze the polarization of generated fluorescent light. Optical fibers are used to carry light between the sensor head and the light source and detecting equipment. The anisotropy measurement yields information about the orientation of a fluorescent dye molecule that has been doped into polymer matrix. Fluorescent dyes that have geometrical asymmetry in their molecular structure are used. Experiments are described for which the sensor is positioned in line during extrusion, during specimen extension, and where the sensor is used to carry out area scans of films and sheets. Measurements were made on polyethylene, polyethylene terephthalate, and polybutadiene resins that contained a low concentration of fluorescent dye.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1150499
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  • 3
    Electronic Resource
    Electronic Resource
    Measurement of a piezoelectric d constant for poly(vinylidene fluoride) transducers using pressure pulses (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 113-118 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The hydrostatic piezoelectric coefficient dh has been measured for biaxially-oriented poly(vinylidene fluoride) transducers using pressure pulses having peak values of 1.8×107 Pa (2600 psi) and a pulse width of approximately 10 ms. For these measurements, the sample was placed in an oil pressure chamber at room temperature and the pressure pulse was initiated by dropping a 16-kg mass onto a plunger in the chamber. Since adiabatic compressional heating accompanies the pressure pulse, temperature compensation of the transducer was necessary. This was achieved by incorporating a thermocouple in the bilaminate configuration of the transducer and by amplifying the thermocouple signal appropriately to account for the pyroelectric response due to adiabatic heating, which was approximately 15% of the transducer signal. The calculation of dh shows that the response of the bilaminate transducer is linear up to 1.8×107 Pa (2600 psi).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.335384
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  • 4
    Electronic Resource
    Electronic Resource
    A study of thermal depolarization of polyvinylidene fluoride using x-ray pole-figure observations (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 59 (1986), S. 2345-2354 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Measurements of piezoelectric and pyroelectric activity, density, and x-ray pole figures were used to study the effect of thermal aging on the state of polarization in polyvinylidene fluoride. A rolled and poled β-phase specimen of polyvinylidene fluoride was subjected to thermal aging which consisted of temperature cycling between room temperature and successively higher maximum temperatures, TMAX, where TMAX ranged from room temperature to 164 °C. We found that the room temperature piezo and pyroelectric activity decreased linearly as a function of TMAX from 75 °C to 164 °C at which temperature the specimen had 30% of its original activity; a linear extrapolation of these data to zero activity yielded a temperature Tc=207 °C. From density measurements at room temperature, crystallinity was calculated and found to remain constant during thermal cycling. X-ray pole-figure observations of the (200) (110) composite diffraction of the β-phase crystal showed single-crystal texture of the rolled specimen and confirmed the six-site model of dipole orientation. Changes in x-ray intensity at the six sites on the pole figure, as a function of thermal aging, were associated with the depolarization process which occurs via a 60° rotation of dipoles away from the direction of primary polarization. Based on these data, we propose a model which describes the state of polarization in polyvinylidene fluoride and from which we calculate the fraction of dipoles in the crystalline state contributing to the polarization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.336332
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