Natural compounds from Punica granatum peel as multiple stabilizers for polyethylene

Abstract

Punica granatum peel extractive (PPE), a novel stabilizer of polyethylene, is investigated in this study. Oxidation onset temperature (OOT), carbonyl index (CI), melt flow rate (MFR), tensile strength, and elongation at break are used to characterize the effects of PPE, which are also compared with commercial antioxidant (Irganox 1010) with the presence of tetrakis (2,4-di-tert-butylphenol) [1,1-biphenyl]-4,4 0-diylbisphosphite (PEPQ). Long-term and short-term aging results show that samples modified by PPE or Irganox 1010 (PE-PPE 0.12%-P and PE-1010 0.12%-P samples) have comparable CI value and stability of OOT. However, compared with PE-PPE 0.12%-P sample, much higher CI and larger change of MFR is detected for PE-1010 0.12%-P after UV irradiation and five extrusions. It suggests that PPE is better protector for PE against UV light and mechanical shear force. All results indicate that the effect of PPE in protecting PE is comparable or much better than Irganox 1010 and it can be used as multiple stabilizers for PE. Moreover, the stabilities of PE modified with PPE alone (PE-PPE 2%) is also investigated. Results show that PE-PPE 2% sample has good thermo-oxidative, UV and processing stabilities. All results reveal that PPE is a good candidate of PE stabilizer and it could avoid the usage of PEPQ in protecting PE.

Stabilization of PE with Pomegranate Extract: Contradictions and Possible Mechanisms

“…Previous results unambiguously show that pomegranate peel extract is a potential stabilizer for polymers [ 20 , 21 ]. However, as mentioned above, the existing information is insufficient and contradictory; further research is needed to establish the full potential of the substance.…”

“…As mentioned earlier, only two reports are available on the effect of pomegranate extract on the stabilization of PE, according to our knowledge. Xia et al [ 20 ] used an ethanol extract and found it to be an excellent overall stabilizer, including processing, oxidative, and light stabilization. They used the extract at 0.12 and 0.7 wt% with and without a secondary antioxidant, PEPQ, and compared the effect to that of 0.12 wt% of Irganox 1010.…”

“…The processing stabilization effect of the two additives is approximately the same, as shown by Figure 3 . Xia et al [ 20 ] found good overall stabilization effect, including oxidative stability, but according to Tátraaljai et al [ 21 ], residual stability is small. Finally, the very small OIT contradicts also the strong antioxidant activity of the extract (DPPH assay) and the large total phenolic content.…”

“…In this latter case, active components were extracted from pomegranate peel by acetone by the researchers themselves. The findings of Xia et al [ 20 ] and Tátraaljai et al [ 21 ] obviously contradict each other on the efficiency of the extract as an antioxidant in an oxygen-rich environment.…”

“…However, we are aware of only two papers on the use of pomegranate peel extract for the stabilization of polyethylene. Xia et al [ 20 ] compared the effect of an ethanol extract of pomegranate peel to that of the hindered phenolic antioxidant used in the largest quantity in industrial practice. They found that the extract is a good overall stabilizer, which protects the polymer during processing, against oxidation, and UV radiation, and it is at least as efficient as the phenol.…”