Pro-Degradant Activity of Naturally Occurring Compounds on Polyethylene in Accelerate Weathering Conditions

Abstract

In this work, naturally occurring compounds, such as Vitamin E (VE) and Ferulic Acid (FA), at high concentrations, have been considered as pro-degradant agents for Low Density Polyethylene (PE). However, all obtained results using the naturally occurring molecules as pro-oxidant agents for PE have been compared with the results achieved using a classical pro-oxidant agent, such as calcium stearate (Ca stearate) and with neat PE. The preliminary characterization, through rheological, mechanical and thermal analysis, of the PE-based systems highlights that the used naturally occurring molecules are able to exert a slight plasticizing action on PE and subsequently the PE rigidity and crystallinity slightly decrease, while the ductility increases. To assess the pro-degradant activity of the considered naturally occurring compounds, thin films of neat PE and PE-based systems containing 2 and 3 wt.% Ca stearate, VE and FA have been produced and subjected to accelerated weathering upon UVB light exposure. All obtained results point out that the VE and FA, at these high concentrations, exert a clear pro-oxidant activity in PE and this pro-oxidant activity is very similar to that exerted by Ca stearate. Moreover, the VE and FA at high concentrations can be considered as suitable eco-friendly pro-degradant additives for PE, also in order to control the polyolefin degradation times.

Photodegradation of low‐density polyethylene with prooxidant and photocatalyst

“…Therefore the manganese stearate melts before the LDPE matrix and act as a plasticizer which causes to the decrement of the polyethylene crystallinity. Tzankova et al showed that addition of prodegradant agents such as calcium stearate or ferulic acid to LDPE matrix leads to decrement of the polymer crystallinity due to a slight plasticizing effect of the additives …”

Natural Compounds as Sustainable Additives for Biopolymers

“…Some natural antioxidants have been considered as suitable stabilizing systems, also for polymers and biopolymers, in order to prevent their oxidative degradation [23]. Unexpectedly, some naturally occurring compounds, based on their chemical compositions, can cause the faster formation of oxygen-containing groups in the polymer and biopolymer-based systems, inducing premature loss of their performance and properties [23][24][25][26]. Additionally, if the natural fillers (e.g.…”

Anti-/Pro-Oxidant Behavior of Naturally Occurring Molecules in Polymers and Biopolymers: A Brief Review

“…As explained above, the oxidative degradation phenomena during processing and service life of polymers and biopolymers can be avoided through the introduction of suitable stabilizing moieties. Therefore, the natural antioxidants that meet specific requests, such as adequate protection ability, low extraction/production costs, appropriate thermal resistance, safety, ecosustainability, and biocompatibility for some industrial applications in the biomedical, agricultural, food packaging, and textile sectors, are mostly: (i) polyphenols , such as quercetin, resveratrol, rosemary, thymol, and lignins; − (ii) phenolic acid derivatives , such as vanillic acid, ferulic acid, caffeic acid, p -coumaric acid; − (iii) vitamins , such as vitamin E and C; − and (iv) carotenoids , such as β-carotene. − Surprisingly, some of these nAO molecules are able to exert a concentration-dependent anti/pro-oxidant activities and to promote the oxidation phenomena in some biopolymers and polymers, if they are added at high concentrations. − …”

“…In particular, some natural molecules are able to accelerate the oxidation, if they are added at high concentrations, i.e. >2 wt %, in biopolymers and polymers; − there is the possibility to reduce the degradation times, accelerating the abiotic oxidation, such as classic pro-oxidant agents. , …”