Toward multi-functional polymer composites through selectively distributing functional fillers

The distribution of functional filler is known to have significant influence on various functionalities, yet, not been systematically investigated. Herein, we use a blends system based on PA12/PA6 containing SiC and low-temperature expandable graphite (LTEG) to study it. The effect of filler distribution in such blends on various functionalities including: thermal conductivity, electrical conductivity, and electromagnetic interference (EMI) shielding ability, has been systematically studied. Further study on altering filler distribution with polished PA6-LTEG and PA6-LTEG in different sizes reveals that, polished particle surface results in reduced electrical and thermal conductivity; and smaller particle size leads to enhanced electrical conductivity, thermal conductivity and EMI shielding ability. Finally, theoretical approach on thermal conductivity demonstrates that the system illustrates very effective contribution in thermal conductivity from large PA6-LTEG “filler” comparing to much smaller traditional fillers. Such study could provide a guideline for the processing of functional polymer composites.