@article{AssagraAltafimdoCarmoetal.2020,
  author    = {Assagra, Yuri A.O. and Altafim, Ruy Alberto Pisani and do Carmo, Joao P. and Altafim, Ruy A.C. and Rychkov, Dmitry and Wirges, Werner and Gerhard, Reimund},
  title     = {A new route to piezo-polymer transducers: 3D printing of polypropylene ferroelectrets},
  series = {IEEE transactions on dielectrics and electrical insulation},
  volume    = {27},
  journal   = {IEEE transactions on dielectrics and electrical insulation},
  number    = {5},
  publisher = {Inst. of Electr. and Electronics Engineers},
  address   = {Piscataway},
  issn      = {1070-9878},
  doi       = {10.1109/TDEI.2020.008461},
  pages     = {1668 -- 1674},
  year      = {2020},
  abstract  = {Here, a promising approach for producing piezo-polymer transducers in a one-step process is presented. Using 3D-printing technology and polypropylene (PP) filaments, we are able to print a two-layered film structure with regular cavities of precisely controlled size and shape. It is found that the 3D-printed samples exhibit piezoelectric coefficients up to 200 pC/N, similar to those of other PP ferroelectrets, and their temporal and thermal behavior is in good agreement with those known of PP ferroelectrets. The piezoelectric response strongly decreases for applied pressures above 20 kPa, as the pressure in the air-filled cavities strongly influences the overall elastic modulus of ferroelectrets.},
  language  = {en}
}
@article{MazurekYuGerhardetal.2016,
  author    = {Mazurek, P. and Yu, L. and Gerhard, Reimund and Wirges, Werner and Skov, A. L.},
  title     = {Glycerol as high-permittivity liquid filler in dielectric silicone elastomers},
  series = {Journal of applied polymer science},
  volume    = {133},
  journal   = {Journal of applied polymer science},
  publisher = {Wiley-Blackwell},
  address   = {Hoboken},
  issn      = {0021-8995},
  doi       = {10.1002/app.44153},
  pages     = {8},
  year      = {2016},
  abstract  = {A recently reported novel class of elastomers was tested with respect to its dielectric properties. The new elastomer material is based on a commercially available poly(dimethylsiloxane) composition, which has been modified by embedding glycerol droplets into its matrix. The approach has two major advantages that make the material useful in a dielectric actuator. First, the glycerol droplets efficiently enhance the dielectric constant, which can reach astonishingly high values in the composite. Second, the liquid filler also acts as a softener that effectively decreases the elastic modulus of the composite. In combination with very low cost and easy preparation, the two property enhancements lead to an extremely attractive dielectric elastomer material. Experimental permittivity data are compared to various theoretical models that predict relative permittivity changes as a function of filler loading, and the applicability of the models is discussed. (c) 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44153.},
  language  = {en}
}