MAXWELL-WAGNER-SILLARS RELAXATIONS IN SURFACE-MODIFIED GLASS-BEAD POLYSTYRENE-BASED COMPOSITES

Polystyrene-glass-bead and styrene/methacrylic acid copolymer-glass-be ad composites were investigated by dielectric spectrometry in order to study the Maxwell-Wagner-Sillars (MWS) interfacial relaxation. Untrea ted glass beads and glass beads with various surface coatings were bot h used in the composites. The interfacial relaxation is used to test f or the influence of the surface coating on the blocking nature of the interface. A good agreement is found between the van Beek calculated v alues of the maximum loss frequencies and the experimental ones. Throu gh this analysis, the use of a coupling agent is shown to improve the trapping of the ions at the interface between the polymer matrix and t he glass inclusions. This was especially the case in styrene-methacryl ic acid copolymer filled with glass beads coated with a methacrylic si lane. The presence of water causes the maximum loss frequency to incre ase dramatically and is also thought to improve the blocking of the el ectric charges at the matrix-inclusions interface.