Poly(butylene therephthalate) based composites containing alumina whiskers: influence of the filler functionalization on dielectric properties

Poly(butylene terephthalate) (PBT) is one of the most widely used semicrystalline thermoplastics polyester because of its superior thermal and mechanical properties, high dimensional stability and excellent processability. In this research PBTbased nanocomposites, including various amounts (up to 10 wt%) of commercial alumina whiskers, have been prepared by using a Brabender internal chamber mixer and analysed in terms of morphological features and dielectric properties. Specific attention has been focused on the effect of the filler functionalization considering 3-glycidoxy propylmethoxysilane (GPS) or 3- methacryloxypropyltrimethoxysilane (MPS) as coupling agents. Tests, performed on compounds filled with neat and functionalized alumina whiskers, show a clear dependence of relative dielectric permittivity (?r), invariance of dissipation factor (tg?), and a sensible increase of volume electrical resistivity (?V) with the filler's content and are encouraging for a future introduction of such composites in many electrical applications.