Improved mechanical dispersion or use of coupling agents? Advantages and disadvantages for the properties of fluoropolymer/ceramic composites

• Published in: Polymer (Guilford) Vol. 154; pp. 8 - 16
• Main Authors: Dalle Vacche, Sara, Michaud, Véronique, Damjanovic, Dragan, Månson, Jan-Anders E., Leterrier, Yves
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 10.10.2018; Elsevier BV
• Subjects: Barium; Barium titanates; Ceramics; Comparative studies; Composite materials; Coupling agents; Dielectric loss; Dielectric properties; Dispersion; Fluorides; Fluoropolymers; Functional groups; Interfacial chemistry; Mechanical properties; Morphology; Organic chemistry; Particulate composites; Particulates; Polymer-matrix composite; Polymers; Porosity; Silanes; Skeletal composites; Thermal cycling; Thermomechanical properties; Vinylidene; Vinylidene fluoride; Polymer-matrix composite; Thermomechanical properties; Coupling agents; Interfacial chemistry; Dielectric properties
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2018.08.061

The aim of this work is to investigate the influence of interfacial chemistry on the properties of fluoropolymer composites, independent of effects derived from changes in morphology, in particular particle dispersion state. A comparative study of solvent cast composites of poly (vinylidene fluoride – trifluoroethylene) with barium titanate particles, at concentrations up to 60 vol%, was carried out using pristine hydrophilic particles, and particles hydrophobized with three organosilanes, bearing different functional groups (CH3, CH2NH2 and CF3). For each filler concentration, composites with good particle dispersion and comparable amount of porosity with all types of particles were prepared and characterized. While pristine particles provided higher permittivity, all silanes decreased the dielectric losses due to Maxwell-Wagner-Sillars dispersion, although to different extents. Moreover, only the aminosilane provided better thermomechanical stability to the highly filled composites. These results provide useful insights into the advantages and disadvantages of the use of different approaches to improve the dispersion of hydrophilic particles in poly (vinylidene fluoride) copolymer based composites. [Display omitted] •Good dispersion was obtained with pristine and surface modified BaTiO3 up to 60 vol%.•Silanes bearing different end-groups were used to modify the BaTiO3 particles.•Surface chemistry effects were highlighted, particle dispersion state being similar.•Pristine particles led to higher permittivity up to 60 vol%.•Aminosilane led to better thermomechanical stability and lower dielectric losses.