Environmental aging and degradation of multiwalled carbon nanotube reinforced polypropylene. (April 2018)

• Record Type: Journal Article
• Authors: Han, Changseok; Sahle-Demessie, Endalkachew; Zhao, Amy Q.; Richardson, Ter'i; Wang, Jun
• Is Part Of: Carbon. Volume 129(2018)
• Page Start: 137
• Page End: 151
• Publication Date: 2018-04
• Subjects: Polypropylene -- MWCNT -- Weathering -- Activation energy -- Melting-crystallization points; Carbon -- Periodicals; Carbone -- Périodiques; Koolstof; Toepassingen; Electronic journals; 546.681
• DOI: 10.1016/j.carbon.2017.10.038
• Languages: English
• ISSNs: 0008-6223

Abstract

Abstract: The degradation of polypropylene (PP) and PP-multiwalled carbon nanotube (PP-MWCNT) panels during environmental weathering resulted in an increased degree of crystallinity, making them brittle, and creating surface cracks. The degradation led to a breakdown of the panels and increased the potential for nanorelease. Thermal analysis revealed that the thickness of the test panels and reinforcement with MWCNTs had a significant influence on the stability of PP-MWCNT composites. Differential scanning calorimetry indicated that the MWCNTs acted as nucleation points, increasing the crystallization temperatures of PP-MWCNT, which reduced the extent of aging. Weathering decreased both the melting and crystallization temperatures of PP by as much as 20 °C. The reduction in the temperatures was inversely proportional to the thickness of the panels. The activation energy ( E a ) obtained using isoconversional kinetics of the TGA analysis showed that the effective thermo-oxidative degradations of PP changed during aging. The E a for the initial stages of thermal degradation decreased from ∼330 kJ/mol to ∼100 kJ/mol for aged PP. During the late degradation stages, the E a values increased to ∼300 kJ/mol. These results suggest that early degradation were altered because of the changes in the molecular structure of the aged PP and a shift in the degradation rate-limiting steps. Graphical abstract: Image 1