Characterization of the role of mica in enhancing the flow and thermal performance of advanced polyamide 11 composites

Complex flow behavior of mica/polyamide 11 (PA11) composites were explored by oscillatory rheometry to present the effects of the particle size and concentration, and the consequences of the surface modification on the rheological properties are discussed thoroughly. It was revealed that surface treated mica suppresses complex viscosity as well as the energy storage and dissipation capability in a greater extent than the untreated version. On the other hand, after silanization of mica liquid-solid transition point disappeared, and tanδ results proved that viscous behavior dominates the elastic one. Homogenous compositions were confirmed, however, all Cole-Cole, Han and van Gurp-Palmen analysis sensitively captured the influence of the surface treatment on the filler-matrix interaction, while the larger treated particles did not follow the linear effective volume relationship described by the Lewis-Nielsen model at high concentration. Amplitude sweep examination showed the irreversible destruction of the 3D filler structure at high strain. Based on all these observations, the hypothesis of a non-directly connecting physical network of the surface treated fillers was supported. Simultaneously, improved thermal stability was demonstrated in the presence of the lamellar impermeable fillers. Molecular background and beneficial effects of the mica on the processing of PA11 are summarized, too.