Melt stabilization of polyethylene with dihydromyricetin, a natural antioxidant

Abstract

Experiments have been carried out to compare the stabilization effect of two flavonoid type natural antioxidants, dihydromyricetin (DHM) and quercetin (Q) in polyethylene (PE). Additive concentrations changed between 0 and 500 ppm in several steps and 1000 ppm Sandostab PEPQ phosphorus containing secondary stabilizer was also added to each compound. Both antioxidants are very efficient stabilizers for PE, sufficient melt stability was achieved already at 50 ppm DHM content. At small concentrations dihydromyricetin proved to be more efficient melt stabilizer and it protected the secondary antioxidant better than quercetin. In spite of its better efficiency in melt stabilization, polymers containing DHM had the same residual stability as those prepared with quercetin. Accordingly, the larger efficiency does not result from the larger number of active phenolic hydroxyls in the molecule, but from interactions with the phosphorous secondary stabilizer that is stronger or at least different for DHM than quercetin. In spite that DHM is a white powder, it gave the polymer a brownish color which became deeper with increasing number of extrusions and additive content. Nevertheless, both natural antioxidants can be used efficiently for the stabilization of polymers in applications in which color is of secondary importance.

Long term stabilization of PE by the controlled release of a natural antioxidant from halloysite nanotubes

“…The goal was to study the dispersion and controlled release effect and not the development of an industrial package. All our studies on natural antioxidants showed that flavonoids usually are much more efficient than traditional phenolic antioxidants currently used in industrial practice [17][18][19][20].…”

“…The number of potential natural compounds which might be used as antioxidant in polyolefins is very large and only several of them have been studied in stabilization experiments up to now. The antioxidant effect of curcumin [17], quercetin [18] and dihydromyricetin [19] was studied in a Phillips type polyethylene in the presence of a phosphorous secondary stabilizer and the stabilization efficiency of all three exceeded considerably that of the synthetic phenolic antioxidant routinely used in large quantity in industrial practice. The efficiency of another natural antioxidant, silymarin, a flavonolignan compound with the same basic structure as quercetin proved to be much less efficient [20].…”

Natural antioxidants as stabilizers for polymers

“…The solubility of the compounds in polyethylene was estimated from changes in the color of the polymer as a function of antioxidant content. In a series of recent studies, Phillips type polyethylene samples containing various amounts of the antioxidants listed in Table 3 and PEPQ secondary stabilizer were produced by multiple extrusions [114][115][116][117]. Their efficiency as processing stabilizer was determined and it was shown to depend on their chemical structure, dispersion and interaction with the secondary antioxidant.…”

Triple‐faced polypropylene: Fire retardant, thermally stable, and antioxidative

“…From an industrial standpoint, however, one may need to combine properties of different additives to gain a “multifunctional” additive that may bring about several benefits to PP polymer. The use of a multifunctional additive rather than mixture of additives with different functionalities leads to facilitation of processing and facile dispersion of additives into the molten polymer . Therefore, there has been a great deal of research to find appropriate ways for tailoring properties of different additives into a unique versatile additive as the next generation of high‐performance multifunctional derivatives—what brings about new challenges in spite of being interesting .…”