Attaining low percolation threshold in conductive polypropylene/nitrile rubber thermoplastic vulcanizates using carbon nanotube

• Published in: Journal of applied polymer science Vol. 138; no. 7
• Main Authors: Gabino, Alessandra, Soares, Bluma Guenther, Silva, Adriana Anjos
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 15.02.2021; Wiley Subscription Services, Inc
• Subjects: Attenuation; Dynamic mechanical analysis; Electromagnetic shielding; Electron microscopy; Frequency ranges; Materials science; Microscopy; Microwave absorption; Morphology; Multi wall carbon nanotubes; Nanocomposites; Nitrile rubber; Percolation; Polymer blends; Polymers; Polypropylene; Rheological properties; Sequences; Thermoplastic elastomers; Vulcanization
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.49857

Electrically conductive thermoplastic vulcanizates (TPV) based on polypropylene (PP)/nitrile rubber (NBR) blends loaded with multiwalled carbon nanotube (CNT) were prepared by dynamic vulcanization. CNT was incorporated into the system using two different mixing sequences: (i) one‐step method, by adding CNT after the PP and NBR and (ii) two‐steps method involving a previous PP/CNT master batch. Scanning electron microscopy and transmission electron microscopy were used to analyze the morphology of the nanocomposites. Dynamic‐mechanical analysis and rheological properties were also used for characterizing the TPV and TPE samples. Both mixing strategies favored the location of the CNT inside the PP phase. The one‐step approach resulted in a percolation threshold as low as 0.19 vol% with conductivity value of 0.04 S m−1 for the system loaded with only 0.50 vol% of CNT. The electromagnetic interference shielding effectiveness and microwave absorbing properties were evaluated in the X‐band frequency range. The TPV samples prepared by both methods displayed an overall electromagnetic attenuation of around 70%.