Researchers in China have discovered a way of improving how graphene is used in polymer segregated composites for electromagnetic shielding, using a novel in situ thermal reduction technique that maximizes electromagnetic interference shielding effectiveness (EMI SE) while reducing agglomeration.
The use of graphene to build up polymer segregated conductive networks in polymer matrices has had important applications in EMI shielding. However, the eventual agglomeration of graphene from the chemical reduction of graphene oxide during this process dramatically reduces the graphene polymer’s shielding capabilities. While procedures for overcoming this agglomeration exist, these methods are often complicated and require toxic reagents.
Now, scientists at China’s Sichuan University have formulated—using an in situ reduction technique during hot compaction that utilizes ultrahigh molecular weight polyethylene (UHMWPE) as a model polymer upon which to apply graphene networks—a graphene/polymer composite that displays high EMI SE at an ultra-low graphene loading. This new graphene/polymer composite resists the agglomeration of graphene, without needing to use the kind of toxic reagents previously employed to accomplish a similar task.
“The as-prepared composite exhibits a typical segregated network structure with graphene squeezed along specific paths instead of a uniform distribution throughout the whole polymer matrix,” reported lead scientist Ding-Xiang Yan. “The well-defined graphene networks lead to an ultralow percolation threshold of 0.063 vol% and saturated electrical conductivity of 3.4 S/m–1. Excellent EMI SE as high as 28.3–32.4 dB is achieved at an ultralow graphene loading of 0.660 vol%, which means there is only 0.15–0.06% electromagnetic radiation transmitting through the shielding material.”
In this way, this new composite displays powerful interference shielding capabilities in an environmentally-friendly manner. As Yan noted, “The absorption dominant shielding mechanism in this work is very important for the potential application of such segregated composites as absorption materials in automotive, consumer and medical electronics.”
The accompanying study is published in the journal Nanotechnology.
-Melanie Abeygunawardana
