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

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

Tongsai Jamnongkan  1 , Nitchanan Intraramongkol  1 , Wesarach Samoechip  2 , Pranut Potiyaraj  2 , Rattanaphol Mongkholrattanasit  3 , Porntip Jamnongkan  4 , Piyada Wongwachirakorn  5 , Masataka Sugimoto  6 , Hiroshi Ito  6 , Chih-Feng Huang  7
Affiliations

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

Tongsai Jamnongkan et al. Polymers (Basel). .

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.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Feasibility images of different compounds. (A) vPP, (B) rPP20, (C) rPP30, and (D) rPP40.
Figure 2
Figure 2
Melt flow index of all prepared samples.
Figure 3
Figure 3
Tensile stress-strain curves of vPP/rPP blended with different rPP concentrations. (A) vPP, (B) rPP20, (C) rPP30, and (D) rPP40. The number of each curve indicates the testing numbers.
Figure 4
Figure 4
Optical images of all specimens after tensile test at room temperature.
Figure 5
Figure 5
Effect of varying rPP contents on the mechanical properties of PP blends.
Figure 6
Figure 6
Optical images of pellets of compound (A) rPP30 and (B) rPP30 composited with carbon black.
Figure 7
Figure 7
The stress-strain curves of (A) rPP30CBNW and (B) rPP30CBW composites. The number of each curve indicates the testing numbers.
Figure 8
Figure 8
Mechanical properties of the rPP30 and the obtained rPP30 composited with and without the plasticizer content.
Figure 9
Figure 9
FTIR spectra of (A) vPP, (B) rPP30, (C) rPP30CBW, and (D) rPP30CBNW composites.
Figure 10
Figure 10
Comparison of the surface resistivity of the neat PP and the obtained rPP composites with and without the plasticizer content.
Figure 11
Figure 11
Crystallization temperature (a) and melting temperature (b) of vPP, rPP30, and its composites.
See this image and copyright information in PMC

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