Thermal Degradation Kinetics of Virgin Polypropylene (PP) and PP with Starch Blends Exposed to Natural Weathering

Abstract

The objective of this work is to study the thermal degradation kinetic parameters of polypropylene (PP) and compare them to those of a polypropylene/starch blend (PP/S) (70/30 (wt %)), taking into account the effect of photodegradation caused by natural weathering. Samples were taken from tree shelters exposed to four years of natural weathering and compared to the unexposed material stored under laboratory conditions. Nonisothermal (dynamic) thermogravimetery was used with five different heating rates (β): 5, 10, 15, 20, and 25 °C min −1 . Several analytical model-free methods were used to determine the kinetic parameters, including the Friedman, Coats and Redfern, Kissinger, and Flynn−Wall− Ozawa (FWO) methods. The model-fitting method of Criado was also applied to determine the optimal mechanism of degradation that the polymers followed. In addition, an analytical solution was developed to mathematically model the experimental data and estimate the kinetic parameters. The analytical approach was developed based on each degradation stage of the PP/S blend, considering starch degradation at first, followed by PP. A change in the degradation mechanism could be deduced because of the effect of weathering and starch addition, which affected the kinetic parameters of the degradation reaction. The thermal stability of the materials was also affected, because of the natural weathering and addition of starch, which, on the other hand, affected the kinetic parameters of the degradation reaction.

Thermal Response and Degressive Reaction Study of Oxo-Biodegradable Plastic Products Exposed to Various Degradation Media

“…This could be attributed to the fact that the exposure has impacted the polymeric fraction of the plastic bag irrelevant of the presence of the inorganic filler (i.e., CaCO 3 ). However, the materials were all within the same region of thermal properties and degradation profile established by other researchers for PO polymers [61][62][63]. Table S5 shows the degradation profile of the materials after 30 days of soil burial.…”

“…where m is the mass of polymeric material at a specific time of reaction (t), and m 0 and m f are the initial and final mass of the polymer at the investigated temperature desired and final reaction time, respectively. The rate for degressive kinetics is typically defined according to the change in reaction rate by incorporating the first order for the Arrhenius equation as per the following [61,62]:…”

An experimental and theoretical mechanistic analysis of thermal degradation of polypropylene/polylactic acid/clay nanocomposites

“…The Kissinger method is an integral multiple heating rate method that has been widely used in many studies based on ICTAC recommendations . It predicts a more reliable E a value for the degradation process of a system based on the following relationship: where β is the heating rate (° C / min −1 ) and T max is the temperature at maximum degradation (Table ). From plot of vs 1/ T max , the value of E a can be determined.…”

“…The Kissinger method is an integral multiple heating rate method that has been widely used in many studies based on ICTAC recommendations. 35,36,38 It predicts a more reliable E a value for the degradation process of a system based on the following relationship 42 :…”

Synthesis, characterization and thermal decomposition kinetics of a bio-based transparent nylon 10I/10T

“…Moreover, these studies are recommended by the International Confederation for Thermal Analysis and Calorimetry (ICTAC) [18,19], which are included in the present study. The kinetics parameters and activation energy were calculated by Kissinger-Akahira-Sunose (KAS), Flynn−Wall−Ozawa (FWO) and Tang methods.…”