Effect of iron carboxylates on the photodegradability of polypropylene. II. Artificial weathering studies

Abstract

ABSTRACT:The various iron carboxylates such as ferric caprate, ferric laurate, ferric myristate, ferric palmitate, and ferric stearate were synthesized to enhance the photodegradability of polypropylene (PP). The prodegradants (0.2%) synthesized were blended with virgin PP and then blown into films. All the PP films mentioned were exposed to ultraviolet (UV) radiation of 365 nm at room temperature to study the photodegradation behavior of PP with and without the prodegradants under artificial weathering conditions. The photoirradiated films were found to degrade after certain hours of UV exposure, which could be found from the steep increase of hydroxyl, carbonyl, lactone, ester, carboxylic acid, and crystallinity index. At the same time, a sudden decrease of elongation at break percentages and tensile strength; development of surface cracks indicated the scission of the main chain of the PP. The results revealed that PP containing prodegradants degraded at a faster rate than the virgin material. However, the effectiveness of the prodegradants for the photodegradation of PP was found to be in the order: ferric caprate > ferric laurate > ferric myristate > ferric palmitate > ferric stearate. The results showed that the number of carbon atoms present in the alkyl part of the various prodegradants played a vital role in the degradation phenomenon. Furthermore, it could be concluded that the mobility of the alkyl radicals formed from the decomposition of the incorporated prodegradants during artificial weathering played a prominent role in the photooxidative degradation behavior of PP films.

Thermal characterization of the oxo-degradation of polypropylene containing a pro-oxidant/pro-degradant additive

“…Furthermore, a slight increase of the original crystalline content is also observed for pure PP during exposure to UV radiation (Table 1). It is well evidenced that the crystalline content of polypropylene increases at the beginning of oxidation [35][36][37]57,59,60,[63][64][65]. This phenomenon has been explained as due to chain scission, which initially is the major driving force of the oxidative process, and leads to increasing segment mobility and chain arrangements, favouring further crystallisation [58].…”

“…In contrast, studies on the abiotic [35][36][37][38][39] and biotic [40][41][42][43] degradability of polypropylene (PP) with pro-oxidant/pro-degradant additives are scarce as yet, although being this polyolefin one of the most widely used commodity polymers.…”

TiO2-kaolin-PE composite film: A study based on photocatalytic degradation and biodegradation

“…Figure 4 showed the ATR-FTIR spectra of the TKPE film with the different irradiation times. The bands in the region 3461 and 1712 cm 21 were the characteristic absorptions of hydroxyl (AOH) and carbonyl groups (>C@O), respectively [35,36]. It could be seen that the intensities of hydroxyl and carbonyl peaks increase with the illumination time increasing, as shown in Fig.…”

Weathering properties of coextruded polypropylene-based composites containing inorganic pigments

“…10. The carbonyl index is the most commonly used parameter for assessing the degree of degradation [15]. The initial values of the carbonyl indices for all the composites were similar and differed from zero.…”