Development of silicone rubber-based nanocomposites: nanoparticle selection and performance analysis

ABSTRACT

Silicone rubber (SR) is high-voltage insulator, but suffers from poor mechanical properties. Nanoparticle addition is a promising way to combat this problem. Herein, SiO₂, Al₂O₃, MgO, SiC and thermally modified SiC nanoparticles were used to improve electrical resistivity, thermal stability and mechanical properties of SR. Surprisingly, electrical resistivity of SR was enhanced by one-order-of-magnitude by incorporation of small amount of nanoparticles, which induced nano-scale traps to capture charge carriers and restrict SR molecules conformation. Tensile strength and modulus of SR increased by SiO₂, Al₂O₃, MgO and SiC incorporation, while decreased elongation at break, as a consequence of agglomeration as detected by microscopic observations. Nano fillers restricted the motion of polymer chains, so storage modules and hardness were increased. Addition of 2 phr SiC resulted in less polarization current comparably. Correspondingly, dielectric breakdown strength of the assigned sample was increased. SiC thermally modified interface is more conductive than the other parts of the matrix reduced charge accumulation and provide more conductive ways for increased charge carriers mobility, dissipate more charges and then increased dielectric breakdown strength. Dynamic-mechanical-thermal analyses demonstrated that storage modulus of SR nanocomposites was comparatively higher than neat SR, owing to rigidity contributed from SiO₂ and SiC nanoparticles. Evidently, glass transition temperature shifted to a higher temperature (−109°C) compared to the neat SR (−127°C). Thermogravimetric analysis witnessed superiority of thermal stability of nanocomposites compared to SR, featured by 35°C rise in degradation temperature. The presence of nanoparticles in the polymer matrix acts as a barrier and prevents the release of gaseous products from burning and the entry of oxygen into the system lead to increase thermal stability.

GRAPHICAL ABSTRACT

KEYWORDS:

• Electrical insulators
• mechanical properties
• nanocomposites
• nanoparticle
• Silicone rubber
• thermal stability

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was not supported by any funding agency.

Notes on contributors

Mitra Zare

Mitra Zare received the B.Sc. degree in chemistry from the Shiraz University, Shiraz, Iran, in 1996, and the M.Sc. Degree in polymer engineering from the Polymer & Petrochemical Institute (IPPI), Tehran, in 2003. She is a doctoral student in polymer engineering at Islamic Azad University-south Tehran Branch. She has been also a lecturer at Islamic Azad University-Shiraz Branch since 2005. Her research interests are in the field of development of advanced polymeric materials, novel drug delivery, biomaterials and nanocomposites.

Morteza Ehsani

Morteza Ehsani received his PhD degree from the Iran Polymer and Petrochemical Institute (IPPI) in 2004. He has been working on Polymer Processing and advanced polymeric materials at IPPI where he has been Lecturer since 2004. In November 2015, he was promoted to Professorship in Polymer Processing in IPPI, Iran. Finally, his research interests are in the development of advanced polymeric materials, biomaterials, polymer blends and their nanocomposites, and their applications in sustainable polymers. He has authored over 180 publications including journal papers in textile engineering science.

Amir Abbas Shayegani Akmal

Amir Abbas Shayegani Akmal received the B.Sc. degree in power engineering from the Sharif University of Technology, Tehran, Iran, in 1996, and the M.Sc. and Ph.D. degrees in power engineering from the University of Tehran, Tehran, in 1998 and 2005, respectively, the Ph.D. degree in electrical engineering from the University of Tehran, with the cooperation of the Schering-Institute, University of Hannover, Hannover, Germany, He is currently a Faculty Member with the School of Electrical and Computer Engineering, University of Tehran. His current research interests include high-voltage insulation systems, transient, testing, and diagnostics.

Ramin Khajavi

Professor Ramin Khajavi received his master’s and doctorate degrees in chemical engineering from Islamic Azad University-South Tehran Branch. His research is focused on developing innovative solutions to enhance the functionality of polymeric materials through the creation of functional surfaces, active coatings, and composites. Professor Khajavi is also dedicated to exploring the physical and mechanical properties of materials, which is an essential area of study that contributes significantly to the advancement of engineering and technology. He is particularly passionate about smart materials, including smart and multi-functional polymers, and stimuli-responsive polymers, which have the potential to revolutionize the field of materials science.

Davood Zaarei

Davood Zaarei received his bachelor’s, master’s and doctorate degrees in polymer engineering from Amir Kabir University (Tehran Polytechnic). Since 2010, he has been working as a lecturer and researcher in the polymer engineering department of the Islamic Azad University, South Tehran branch, and now as an associate professor, in the chemical and polymer engineering department of this university, he supervises the research affairs of postgraduate students. His main field of work is coating, corrosion, dispersion and composites, and he has published several articles in this regard.