Comparison of the UV stabilisation effect of commercially available processing stabilizers Irganox HP 136 and Irganox 1010

Cytotoxic and Luminescent Properties of Novel Organotin Complexes with Chelating Antioxidant Ligand

A novel polydentate chelating antioxidant ligand and series of organotin complexes on its base were synthesized and characterized by NMR ¹H, ¹³C, ¹¹⁹Sn, IR spectroscopy, X-ray, and elemental analysis. Their antioxidant activity was evaluated in DPPH and NBT-tests, and as lipoxygenase inhibitory activity. It was shown that ligand alone is a radical scavenger, while introducing tin in the structure of the compound significantly decreases its activity. For the ligand alone the ability to strongly suppress the formation of advanced glycation end products (AGEs) was shown, which may be associated with the established antiradical activity. All synthesized compounds appeared to be moderate lipoxygenase inhibitors. The stability of compounds to hydrolysis under different pH was estimated. The ligand undergoes decomposition after about an hour, while organotin complexes on its base demonstrate vast stability, showing signs of decomposition only after 5 h of experimentation. Cytotoxicity of compounds was studied by standard MTT-test, which showed unorthodox results: the ligand itself demonstrated noticeable cytotoxicity while the introduction of organotin moiety either did not affect the toxicity levels or reduced them instead of increasing. Organotin complexes possess luminescence both as powders and DMSO solutions, its quantum yields reaching 67% in DMSO. The combination of luminescence with unique cytotoxic properties allows us to propose the synthesized compounds as perspective theranostic agents.

Recycling of metallocene isotactic polypropylene: importance of antioxidants

Recycling of plastics is absolutely essential in a circular economy, especially in the case of commodity polymers from fossil resources, like isotactic polypropylene (iPP). Therefore, evaluation of the factors that are decisive for an optimum performance of the recycled based materials becomes mandatory for the obtainment of new products with optimal properties. One of the most important aspects is the protection of the plastics materials not only against the external degradation agents, but also from the radicals generated during their previous service life. Accordingly, several materials have been prepared by extrusion based on virgin iPP with different amounts of the same polypropylene severely degraded, which has been used as model component to be recycled. Previous to the extrusion, a mixture of antioxidants was added to all the samples, and special attention has been paid to consumption of those additives during the extrusion. The results show an increasing reduction of antioxidants with rising content of the degraded material. But, importantly, a rather analogous mechanical response has been found for all the recycled materials in relation to the virgin iPP, pointing out a satisfactory dilution effect of the existing degradation points within the virgin polymeric chains, and indicating the very relevant action of the antioxidants used.

Stability Efficiencies of POSS and Microalgae Extracts on the Durability of Ethylene-Propylene-Diene Monomer Based Hybrids

The EPDM (ethylene-propylene-diene monomer) hybrids with improved thermal and radiation strengths containing 1 and 5 phr of polyhedral oligomeric silsesquioxane (vinyl-POSS, Ov-POSS) and/or 2 phr of microalgae (Chlorella vulgaris (CV) and Spirulinaplatensis (SP)) powders were investigated in respect to their thermal stability after γ-irradiation. The material durability under accelerated degradation was qualified by chemiluminescence and gelation, which prove the contribution of inorganic filler and microalgae extracts on the increase of hybrid thermal stability, as well as the interaction between added components (POSS and CV or SP). The activation energies and the durabilities under accelerated degradation were calculated, indicating their suitable usage as appropriate materials in various applications. The reported results indicate the improvement effect of both microalgal powders on the oxidation strength, but the contribution of Spirulinaplatensis grabs attention on its efficient effects upon the prevention of degradation under accelerated aging conditions. The thermal performances of the tested EPDM based hybrids are remarkably ameliorated, if the certain formulation includes Ov-POSS (5 phr) and Spirulinaplatensis (2 phr), certifying its suitability for the pertinent applications.

Antioxidant intercalated Zn-containing layered double hydroxides: preparation, performance and migration properties

A Zn-containing LDH/PP composition has a high thermal stability and anti-migration ability, and is a highly promising candidate for possible applications.