Accelerating the degradation of polyolefins through additives and blending

Abstract

Polyolefins are popular because of their low price, useful properties, broad supply chains, and mature processing facilities, but they do not easily degrade in the natural environment, and hence, the development of degradable polyolefins has attracted increasing interest. Oxidative degradation and blending with natural polymers can accelerate the degradation of polyolefins in natural environments. In this article, we review the research and developments in the acceleration of the degradation of polyolefin blends and composites, including both the fundamental science, such as the degradation mechanisms and characterizations, and application techniques, such as the processing conditions and formulations.

Thermo and photo-oxidation of functionalized metallocene high density polyethylene: Effect of hydrophilic groups

“…The degradation of each material causes the appearance of oxidation bands centered at 1700 cm −1 , 1714 cm −1 , 1734 cm −1 and 1780 cm −1 , which can be assigned to carboxylic acids, ketones, aldehydes and esters and lactones, respectively. This result, which agrees with those published by other authors [9,[33][34][35][36][38][39][40], can be explained by the mechanisms proposed in the literature for the degradation of PE. For instance, Gugumus [41] has suggested that the main structures in the oxidation of PE are keto-hydroperoxides that lead to chain scission with simultaneous formation of carboxylic acids, aldehydes and methyl-ketone groups.…”

“…As it could be expected, the pro-oxidant substance accelerates the thermal degradation after the period of protection of the antioxidant additive (around 70 days in these experiments). These findings are in good agreement with those reported by different researchers [9,34,35,[38][39][40]. It has been found in all cases that the additive promotes the polyethylene degradation through freeradical chain scission reactions involving the atmospheric oxygen.…”

Effect of the Prodegradant-Additive Plastics Incorporated on the Polyethylene Recycling

“…Oxo-degradable additives are commonly incorporated in polyolefins such as the highly used polyethylene (PE) and polypropylene (PP) [16]. The reaction mechanism of the oxodegradable additives is based on the oxidative degradation of the material through the reaction of the molecular oxygen present in the atmosphere with free radicals generated in the polymer molecule by light and heat [17,18] The oxo-degradation is an abiotic process and, thanks to the incorporation of oxygen in the polyethylene molecule, functional groups that contribute to the generation of peroxides and hydroperoxides are formed.…”

Ionizing radiation as adjuvant for the abiotic degradation of plastic bags containing pro‐oxidant additives

“…The so‐called oxo‐biodegradable PE bags are designed to last up to 3 or 4 years before they start to decompose 24 . These bags are very popular and their production has been expanded in the last decades 17,25,26 . However, it is not clear what the necessary conditions to obtain complete degradation are.…”