Study of the effect of natural antioxidants in polyethylene: Performance of β-carotene

Abstract

The effect of β-carotene on the behaviour of polyethylene stabilized with α-tocopherol and a phosphonite antioxidant was studied under processing and storage conditions. The amount of β-carotene ranged between 0 and 2000 ppm. The polymer was characterised by different methods after processing then during and after storage at ambient temperature in light and dark. β-Carotene hinders the oxidation of polyethylene and does not increase the chain extension reactions during processing, though more vinyl groups and phosphonite molecules react. β-Carotene colours polyethylene strongly already at low concentrations. The reactions of the polymer and β-carotene are affected strongly by the storage conditions. The presence of β-carotene does not influence the stabilizing efficiency of the primary and secondary antioxidants. In dark the molecular structure of the polymer does not change appreciably, while the reactions of β-carotene lead to an increase in the yellowness index. In light the molecular characteristics of polyethylene undergo significant changes indicating long chain branching. The polymer fades rapidly after an induction period. The length of the induction period is not influenced by light. The rate of the degradation reactions of β-carotene during storage is controlled by its concentration and film thickness. Visible autoaccelerated decomposition in light renders β-carotene candidate as an indicator in active packaging materials.

Natural antioxidants as stabilizers for polymers

“…The processing stabilization efficiency of β-carotene was investigated also in a Phillips type polyethylene [58]. The stabilizer was used in combination with a phosphorous secondary antioxidant, PEPQ (Sandostab PEPQ, a mixture of diphosphonite, monophosphonite and phosphite compounds) and α-tocopherol, which protects β-carotene against oxidation [59,60].…”

Natural compounds from Punica granatum peel as multiple stabilizers for polyethylene

“…[6][7][8][9][10][11] Dihydromyricetin and β-carotene were used as thermo-oxidative stabilizers of PE and PP. [12][13][14] Phytic acid, cross-linked tannin and flavonoids (quercetin, chrysin, silibinin, naringin, and hesperidin) as additives of PP and PE could reduce the impact of photooxidative degradation. [15][16][17] These natural compounds were beneficial to the stability of polyolefin, but the purification of them requires a great deal of effort.…”

Puerarin, an efficient natural stabilizer for both polyethylene and polypropylene

“…Quite a few of natural compounds derived from plants have been used as stabilizer for foods [3][4]5,6] and polymer. [7][8][9][10][11][12][13][14][15][16][17][18][19] Lignin that comes from cell walls of woods and grasses is a natural macromolecule polyphenol. PE mixed with a mass of lignin exhibited preferable thermooxidative stability and processing stability.…”

“…β-Carotene as the most important representatives of carotenoids [1] could improve the thermo-oxidative stability and processing stability of PE. [11] The application of quercetin, [12][13][14] rutin, [15] silymarin, [16] and curcumin [17,18] as thermo-oxidative and processing stabilizer for PE even at low concentrations has been proved by many investigators. Phytic acid mixed with PE and PP to improve their thermo-oxidative stability.…”