Natural Weathering Studies of Polypropylene

Long-term aging and degradation of microplastic particles: Comparing in situ oceanic and experimental weathering patterns

“…Several reference peaks have been used previously, including 974 cm − 1 and 2720 cm − 1 for PP (Livanova and Zaikov, 1992;Rabello and White, 1997;Rajakumar et al, 2009) and 1465 cm −1 and 2020 cm −1 for PE (Albertsson et al, 1987;Roy et al, 2011). We selected 2910 cm −1 for PE and 2920 cm −1 for PP because these peaks, both also characteristic of plastic type, are thought to change little with weathering, as corroborated in our study (Socrates, 2004).…”

“…Three likely areas of weathering-related change in infrared spectra were first identified from previous research: hydroxyl groups (broad peaks from 3100 to 3700, centered at 3300-3400 cm −1 ), alkenes, or carbon double bonds (1600-1680 cm −1 ), and carbonyls (1690-1810 cm −1 , centered at 1715 cm −1 ) (Albertsson et al, 1987;Lacoste and Carlsson, 1992;Socrates, 2004;Pavia et al, 2008;Rajakumar et al, 2009). The hydroxyl peaks in our spectra had the broad peak shape and location of intermolecular hydrogen bonded O\ \H bonds (Socrates, 2004;Pavia et al, 2008).…”

“…There have been some studies of the natural weathering of plastics: Andrady et al (1993) examined natural weathering of LDPE, and Rajakumar et al (2009) examined natural weathering of PP; both experiments tested sheets of plastic film in ambient air and rain. Andrady (1990) compared the weathering of LDPE films in ambient air and ambient seawater.…”

Microstructure studies of isotactic polypropylene under natural weathering by positron annihilation lifetime spectroscopy

“…A progressive decrease of M w for weathered PP with exposure time was observed, indicating that PP macromolecules gradually degraded into small molecule chains as exposure time prolonged. This result can be attributed to the PP chain scission reaction, such as Norrish type 1 and Norrish type 2 reactions [6,25]. Table 1 shows the polydispersity index (M w /M n ) of weathered PP bars withdrawn after different exposure time.…”

“…Its further application, however, has been considerably restricted due to the poor weatherability of PP material which is vulnerable to the effect of sunlight and thermal oxidation and consequently easy to degrade. Therefore, many studies have been conducted to investigate the degradation of PP material in natural and artificial accelerated weathering conditions [1][2][3][4][5][6][7][8]. Natural weathering can give the most practical and faithful data regarding the variation of the properties of the material used in a given natural environment.…”