Microballoon and high energy radiation engineered Polycaprolactone-carbon nanotube based segregated conducting network for suppressing of electromagnetic radiation interference

Thin, lightweight polymer composite based electromagnetic interference shielding (EMI) materials are highly desirable for various application. Carbon nanotube (CNT) based conducting composites are particularly helpful in achieving the high conductivity required for strong EMI shielding. However, the high conductivity contributes to the reflection dominant mechanism, which is undesirable. To mitigate this, a low-density micro sphere filler was incorporated. This not only improve the absorption of EM radiation by increasing the conductivity and creating a heterogenous interface but also reduce the material’s overall density. The prepared hybrid composite also shows a very low density of 0.76 g/cc and 0.69 g/cc for PC10M10 and PC10M20, respectively. It was found that a 0.7 mm thick PCL/CNT/MB based hybrid polymer composites exhibits EMI SE of 34 dB which could be able to cut the EMI by more than 99.9 %. This high EMI SE performance was said to originate from high electrical conductivity and multiple internal reflection from CNT-MB and CNT-polymer interface. In addition to EMI shielding capabilities the gamma radiation crosslinked composites also showed high modulus and mechanical stability at elevated temperature. For instance, the stress at 20 % strain for hybrid composites reached 0.95 MPa which was sufficient to achieve high mechanical stability. Furthermore, the crosslinked composites also show reversible shape recovery properties due to shape memory effect of crosslinked polymers while maintaining high EMI SE.