The Effect of Natural Stabilizers on Melt Processing of Polyethylene: A Review

Polyethylene is degraded by exposure to heat, shear rate and oxygen in melting process. In order to achieve the polyethylene melt stability against thermal oxidation phenomena, the use of stabilizers is a key factor for the preservation of physical and chemical properties. In recent years, various natural stabilizers during the melting process of polyethylene have been of interest to the researchers, since during storage of food in packaging containers produced with synthetic stabilizers, these additives can migrate to food and endanger human health. Some natural stabilizers are phenolic compounds in plant sources that have higher resistance to synthetic stabilizers at high temperatures and have higher melt stability. In this paper, the effect of several natural stabilizers on the polyethylene melt stability is investigated. Stability performance is determined by measuring rheological properties, thermal oxidation stability and polymer color. The results of the flow index measurement of polyethylene containing these natural stabilizers show that the viscosity changes are insignificant during the melt process, but the synthetic stabilizers undergo changes in their molten flow index and it is degraded during the melt process. On the other hand, the evaluation of yellowness index shows that the natural stabilizer affects the color of polyethylene. However, despite this slight weakness of natural stabilizers, it can be used to prevent heat damage in cases where the color of the product is a secondary issue. As a result, natural stabilizers can be a good alternative to synthetic stabilizers during the melting process of polyethylene.