Advancements in MWCNT-Enhanced Porous Thermoplastic Elastomeric Composite Foam for Electromagnetic Radiation Suppression
Topic(s) : Material science
Co-authors :
Jasomati NAYAK (INDIA), Narayan NARAYAN CHANDRA DASAbstract :
The rapid rise of information technology generates significant electromagnetic pollution, which harms electronic equipment and human health. Great effort has been put into developing unique and high-performance EMI shielding materials to reduce electromagnetic radiation. Electrically conductive polymer composites (CPCs) are promising EMI shield candidates due to their lightweight, high corrosion resistance, excellent processability, and tunable electric conductivity. The introduction of porous structure in the CPC makes it lightweight, efficient utilization of energy and materials which is more desirable in aerospace and some electronic applications1. In addition, these porous composites achieve good shielding effectiveness by absorption. Herein, A thermoplastic elastomer (Ethylene Octene copolymer(EOC)) based composite foam was prepared using MWCNT as a conductive filler, and various properties such as rheological, morphological, electrical, EMI shielding characteristics were observed.
To prepare these samples melt cum solution mixing process have been followed. A master batch of all non black materials such as polymer, blowing agent (DNPT), curing agent (DCP), and additives were mixed by melt mixing process and conductive filler was added to the required amount of master batch via solution mixing process. Later the dried mixture was molded in a compression molding machine to achieve the final foam composite.
The addition of MWCNT as a conductive filler in the composite foam acts as an external nucleating agent for the porous structure which helps to create and stabilize the pores2. As a result, the increment of filler content gives rise to the increment number of pores and reduces its size, and size distribution become narrow as shown in fig 1(b). Pristine EOC foam act as an insulative material. There is a gradual increment of conductivity was observed with the addition of filler as shown in fig 1(c) and a platuae was achieved beyond 5 wt% of filler. As there is enough quantity of MWCNT available inside the composite to have an electrically conductive path. 23 dB EMI shielding effectiveness in the X-band region, was achieved by 10 wt% MWCNT loaded of EOC composite foam as shown in fig 1(d) with 95% of shielding absorption. It is due to the multiple reflection occurred inside the pores and the conductivity of the foam. The foam composite has a maximum thermal conductivity of 0.25 W/mK and functions as a thermal management system as well. It is thus expected that these electrically conductive, lightweight, and simply processable EOC/VCB polymer composite foams would be used as EMI shielding materials in electronics, vehicles, and packaging.
To prepare these samples melt cum solution mixing process have been followed. A master batch of all non black materials such as polymer, blowing agent (DNPT), curing agent (DCP), and additives were mixed by melt mixing process and conductive filler was added to the required amount of master batch via solution mixing process. Later the dried mixture was molded in a compression molding machine to achieve the final foam composite.
The addition of MWCNT as a conductive filler in the composite foam acts as an external nucleating agent for the porous structure which helps to create and stabilize the pores2. As a result, the increment of filler content gives rise to the increment number of pores and reduces its size, and size distribution become narrow as shown in fig 1(b). Pristine EOC foam act as an insulative material. There is a gradual increment of conductivity was observed with the addition of filler as shown in fig 1(c) and a platuae was achieved beyond 5 wt% of filler. As there is enough quantity of MWCNT available inside the composite to have an electrically conductive path. 23 dB EMI shielding effectiveness in the X-band region, was achieved by 10 wt% MWCNT loaded of EOC composite foam as shown in fig 1(d) with 95% of shielding absorption. It is due to the multiple reflection occurred inside the pores and the conductivity of the foam. The foam composite has a maximum thermal conductivity of 0.25 W/mK and functions as a thermal management system as well. It is thus expected that these electrically conductive, lightweight, and simply processable EOC/VCB polymer composite foams would be used as EMI shielding materials in electronics, vehicles, and packaging.