More Like this

1. Toward improved PVDF-BaTiO 3 composite dielectrics: mechanical activation of the filler versus filler content

   https://doi.org/10.1088/1402-4896/acff4d  

   Djoković, Vladimir ; Dudić, Duško ; Dojčilović, Radovan ; Marinković, Filip S ; Pavlović, Vera P ; Pavlović, Vladimir B ; Vlahovic, Branislav ( October 2023 , Physica Scripta)

   Barium titanate (BT) perovskite particles were surface modified by means of mechanical treatment and used as inorganic component in polyvinylidene fluoride (PVDF) based composites. The changes in electrical properties of the composite films with increasing in filler content were followed by dielectric spectroscopy, breakdown strength andD-Emeasurements. A comparison of the properties of the composites prepared with untreated and mechanically activated particles revealed that there is a significant difference in their performances at low filler concentrations (<20 wt%). Introduction of the surface modified ceramic particles into PVDF matrix led to an increase of the dielectric constant without affecting significantly the electrical breakdown strength. In contrast, when as received BT particles were used a filler, both dielectric constants and breakdown strengths of the composite films were lower than the corresponding values observed for the pure PVDF. At higher concentrations, however, the influence of pre-treatment of the filler on the effective electrical properties becomes less significant. The obtained results were discussed in terms of the pronounced crystallization of polarβandγcrystal phases of PVDF in the presence of surface modified BT fillers, which is confirmed by Raman spectroscopy.

    

   more » « less
2. Combined Dynamic Network and Filler Interface Approach for Improved Adhesion and Toughness in Pressure-Sensitive Adhesives

   https://doi.org/10.1021/acsapm.9b00992  

   Dobson, Adam L. ; Bongiardina, Nicholas J. ; Bowman, Christopher N. ( March 2020 , ACS Applied Polymer Materials)
3. Structural and thermodynamic analysis of metal filler incorporations in Si a O b (M) c C d polymer derived ceramics: Ta, Hf, Nb

   https://doi.org/10.1111/ijac.14476  

   Leonel, Gerson J. ; Scharrer, Manuel ; Singh, Gurpreet ; Navrotsky, Alexandra ( November 2023 , International Journal of Applied Ceramic Technology)

   This work systematically investigates the thermodynamic stability of Si_aO_b(M)_cC_dstructures derived from polymeric precursors incorporating metal fillers: Ta, Nb, and Hf, at 1200 and 1500°C. Structural characterization of the polymer derived ceramics (PDCs) employs X‐ray diffraction, Fourier transform infrared spectroscopy, and X‐ray photoelectron spectroscopy. Enthalpies of formation relative to crystalline components (metal oxide, silica, silicon carbide, and graphite) are obtained from thermodynamic measurements by high temperature oxide melt solution calorimetry. The enthalpies of formation (∆H°_{f, comp}) of Ta‐1200, Hf‐1200, Nb‐1200, Ta‐1500, Hf‐1500, and Nb‐1500 specimens are −137.82 ± 9.72, −256.31 ± 8.97, −82.80 ± 9.82, −182.80 ± 7.85, −292.54 ± 9.38, −224.98 ± 9.60 kJ/mol, respectively. Overall incorporation of Hf results in most thermodynamically stable structures at all synthesis temperatures. Si_aO_b(M)_cC_dspecimens employing Nb fillers undergo the most stable structural evolution in this temperature range. The results indicate strong thermodynamic drive for carbothermal reduction of metal oxide domains. Incorporation of Ta provides the greatest stabilization of SiO₃C mixed bonding environments. Ultimately, the choice of metal filler influences composition, structural evolution, and thermodynamic stability in PDCs.

    

   more » « less
4. Impact of Silanization on the Structure, Dispersion Properties, and Biodegradability of Nanocellulose as a Nanocomposite Filler

   https://doi.org/10.1021/acsanm.8b01819  

   Frank, Benjamin Phillip ; Durkin, David P. ; Caudill, Emily ; Zhu, Lingchao ; White, Donald ; Curry, Michael L ; Pedersen, Joel A. ; Fairbrother, D. Howard ( November 2018 , ACS Applied Nano Materials)
5. Ductile Braze Repairs for Ni-Based Superalloys Using Novel MPEA Filler Metal

   https://doi.org/10.29391/2022.101.007  

   SCHNEIDERMAN, BENJAMIN ; DENONNO, OLIVIA ; KLEMM-TOOLE, JONAH ; YU, ZHENZHEN ( March 2022 , Welding Journal)

   The performance of a newly developed multiprincipal-element alloy (MPEA) filler metal for brazing of nickel-based superalloys was directly compared to a conventional boron- and silicon-suppressed filler (BSSF) metal. The comparison was demonstrated on an Alloy 600 substrate with a brazing temperature of 1200°C. Single-phase solidification behavior and the absence of boron and silicon in the MPEA led to a joint microstructure devoid of eutectic constituents or brittle phases in brazes employing this filler metal. In the brazes using the conventional BSSF metal, incomplete isothermal solidification and subsequent athermal solidification of the residual liquid resulted in large particles of a chromium-rich boride phase distributed throughout the microstructure. Tensile testing of brazed butt joints at both room temperature and 600°C testing conditions demonstrated that the MPEA joints exhibited total ductility values at least one order of magnitude greater than that of BSSF joints, but they showed comparable yield strengths in both testing conditions. Fractographic assessment confirmed that boride phases nucleated cracks and resulted in brittle failure in the BSSF joints, while the MPEA joints exhibited extensive ductile microvoid coalescence. Fine-scale porosity and oxide inclusions may be the dominant factors limiting the overall ductility observed in the MPEA brazes. 

   more » « less