Towards a Circular Economy: Study of the Mechanical, Thermal, and Electrical Properties of Recycled Polypropylene and Their Composite Materials

Tongsai Jamnongkan; Nitchanan Intraramongkol; Wesarach Samoechip; Pranut Potiyaraj; Rattanaphol Mongkholrattanasit; Porntip Jamnongkan; Piyada Wongwachirakorn; Masataka Sugimoto; Hiroshi Ito; Chih-Feng Huang

doi:10.3390/polym14245482

Towards a Circular Economy: Study of the Mechanical, Thermal, and Electrical Properties of Recycled Polypropylene and Their Composite Materials

Polymers (Basel). 2022 Dec 14;14(24):5482. doi: 10.3390/polym14245482.

Affiliations

¹ Department of Fundamental Science and Physical Education, Faculty of Science at Sriracha, Kasetsart University, Chonburi 20230, Thailand.
² Department of Materials Science, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.
³ Faculty of Industrial Textiles and Fashion Design, Rajamangala University of Technology Phra Nakhon, Bangkok 10110, Thailand.
⁴ Department of Public Health and Environment, Saensuk Municipality, Chonburi 20130, Thailand.
⁵ Department of Environmental Science, Faculty of Science and Technology, Pibulsongkarm Rajabhat University, Phitsanulok 65000, Thailand.
⁶ Graduated School of Organic Materials Science, Faculty of Engineering, Yamagata University, Yonezawa 32000, Yamagata, Japan.
⁷ Department of Chemical Engineering, i-Center for Advanced Science and Technology (iCAST), National Chung Hsing University, Taichung 40227, Taiwan.

Abstract

This research focuses on the mechanical properties of polypropylene (PP) blended with recycled PP (rPP) at various concentrations. The rPP can be added at up to 40 wt% into the PP matrix without significantly affecting the mechanical properties. MFI of blended PP increased with increasing rPP content. Modulus and tensile strength of PP slightly decreased with increased rPP content, while the elongation at break increased to up to 30.68% with a 40 wt% increase in rPP content. This is probably caused by the interfacial adhesion of PP and rPP during the blending process. The electrical conductivity of materials was improved by adding carbon black into the rPP matrices. It has a significant effect on the mechanical and electrical properties of the composites. Stress-strain curves of composites changed from ductile to brittle behaviors. This could be caused by the poor interfacial interaction between rPP and carbon black. FTIR spectra indicate that carbon black did not have any chemical reactions with the PP chains. The obtained composites exhibited good performance in the electrical properties tested. Finally, DSC results showed that rPP and carbon black could act as nucleating agents and thus increase the degree of crystallinity of PP.

Keywords: carbon black; mechanical properties; plastic waste; polypropylene; sustainability.

Grants and funding

The present work was financially co-supported by National Research Council of Thailand (NRCT), Thailand, and the two-institution co-research scholarship provided by Kasetsart University and National Chung Hsing University, grant number 00072022.