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Environmental Performance of Bio-Based Polymer Additives: Thermal Stabilizers and Antioxidants
Published in Moayad N. Khalaf, Michael Olegovich Smirnov, Porteen Kannan, A. K. Haghi, Environmental Technology and Engineering Techniques, 2020
Hussein A. Shnawa, Moayad N. Khalaf
Practically, synthetic antioxidants such as butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) are used for stabilization of the polymers, some food products, as well as other hydrocarbons in industrial practice. But about several years ago, some warnings emerged regarding the effects of phenolic antioxidants and their reaction products on human health and on the environmental systems. Recently, polymers synthetic antioxidants and some heavy metal thermal stabilizers have been reported as nonsafe materials for human health. During the storage periods or during the service life, the antioxidants can be extracted or migrated to the food when used for stabilization the polymeric food containers. Generally, most of these warnings have not been solved yet and many attempts has been intensified on the use of some alternative natural antioxidants (from plants) to prevent the side effects of industrial antioxidants, especially for food packaging applications.11,12
Lignin in Biological Systems
Published in Severian Dumitriu, Valentin Popa, Polymeric Biomaterials, 2020
The antioxidant efficiency of different lignin samples was also studied by Boeriu et al. using two models (Boeriu et al. 2004). The first approach was to measure the ability of lignin samples to react with free radicals in aqueous solution. The ABTS+⋅ [ABTS—2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonate)] cation radicals were generated by an enzymatic system consisting of peroxidase and hydrogen peroxide. The antioxidant activities of lignins were determined by measuring the rate of disappearance of the ABTS radical in the presence of lignin. All lignin samples tested reacted with ABTS radical (Figure 21.7), but their efficiency was about 20%–30% (on mass) of that measured for the commercial antioxidant BHT (butylated hydroxytoluene). Lignin samples from abaca, sisal and jute, and the softwood lignins SW-Kr-1 and SW-Kr-3 show the highest scavenging activity against the ABTS radical.
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Published in Joseph C. Salamone, Polymeric Materials Encyclopedia, 2020
Generally, peroxides and azo compounds are used as polymerization initiators alone or in combination. A detailed discussion of initiation systems is given by Gandini and Cheradome.13 One of the most common commercially used initiators is benzoyl peroxide. This initiator also functions as a chain-transfer agent thereby also affecting the molecular weight of the product. During polymerization other additives such as impact modifiers, flame retardants, and internal lubricants can also be added.14 Antioxidants such as butylated hydroxytoluene (BHT) are added to prevent degradation of the product during extrusion, pelletizing, and storage.
A facile and practical p-toluenesulfonic acid catalyzed route to dicoumarols and their biological evaluation
Published in Green Chemistry Letters and Reviews, 2023
Sadeq M. Al-Hazmy, Donia Bensalah, Najet Aouled Dlala, Younes Bouazizi, Houcine Ghalla, Naceur Hamdi
Antioxidant activity was expressed as EC50 (the concentration that causes 50% of the effect). The free radical scavenging activity of the synthesized compounds was assessed by 2.2-diphenyl-1-picrylhydrazyl (DPPH) and 2.2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical assays. Butylated hydroxytoluene (BHT) was used as a control, and it is well known as a strong antioxidant compound.