Antioxidant behavior of a novel sulfur-bearing hindered phenolic antioxidant with a high molecular weight in polypropylene

Synthesis and Properties of a Novel Reactive and Low-Migration-Resistant Antioxidant and Its Application in Rubber Composites

The addition of antioxidants to rubber is one of the most economical and effective methods for delaying rubber aging. However, antioxidant migration can cause environmental pollution. To address this issue, a new reactive antioxidant was synthesized via the chemical bonding of glycidyl methacrylate (GMA) and p-aminodiphenylamine (PPDA). The product was characterized by Fourier-transform infrared spectroscopy, which confirmed the successful reaction between GMA and PPDA, resulting in a compound with the expected structure. The mixture was then combined with a composite of styrene-butadiene rubber and carbon black. The tensile strength, antioxidant properties, migration, and RPA of the resulting materials were tested and compared with those of the commercial antioxidants N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N-isopropyl-N'-phenyl-1,4-phenylenediamine, and poly(1,2-dihydro-2,2,4-trimethylquinoline). After the glycidyl methacrylate antioxidant was grafted onto p-aminodiphenylamine, it became highly compatible with and dispersed in the rubber matrix. The antiaging and antimigration properties of the rubber antioxidants were enhanced without damaging the mechanical properties of the rubber matrix. The short-term and long-term antiaging and antimigration properties of this antioxidant are superior to those of commercially available antioxidants.

Enzyme-catalyzed synthesis of 4-methylcatechol oligomer and preliminary evaluations as stabilizing agent in polypropylene

In the present work, 4-methylcatechol oligomer has been prepared by using enzyme-catalyzed polymerization in water and preliminary evaluations as stabilizing agent in polypropylene (PP) was performed. In comparison with intrinsic PP, the oxidation onset temperature of the 4-methylcatechol oligomer/PP composite increased by 66°C, and the oxidation induction time increased by 40 min. In addition, the mixing of a 4-methylcatechol oligomer with PP (i.e., in the formation of a 4-methylcatechol oligomer/PP composite) did significantly enhance the long-term stability of PP in a thermal oxidative environment. Moreover, the tensile strength of this composite did not significantly decrease after aging for 800 h in an air atmosphere at 120°C. These results show that the addition of a 4-methylcatechol oligomer will markedly delay the aging and degradation of PP materials, even under extreme conditions. Thus, an enzyme-catalyzed polymerization of phenol compounds may provide a new avenue toward the preparation of novel antioxidants.

Impact of natural antioxidant systems on the oxidation resistance and mechanical properties of polypropylene

This paper describes the separation of oxidation resistant components from the seeds of pomegranate (PSA), grape (GSE) and sea buckthorn (SSE). The anti-oxidation properties of the resultant extracts, used as the natural anti-oxidants for polypropylene (PP), were compared with Irganox1010. The effects of these natural antioxidants on the antioxidant levels of PP samples were estimated by thermal oxidative aging and micromixed rheology, OIT, XRD, SEM, TEM and mechanical properties tests of samples before and after aging. The results show that adding PSA, GSE and SSE can obviously increase the mechanical properties of PP. In addition, the molding stability of polypropylene raw material is prolonged and improved. Moreover, the mechanical properties of the PP samples after 240 h of thermal oxidative aging indicates that, the best results, closest to the anti-oxidation ability of Irganox1010, can be obtained when the additive amount is 0.5% (wt%) for PSE or 0.7% (wt%) for GSE.

Synthesis and oxidative stability of hyperbranched macromolecule-bridged hindered phenols

The oxidative stability of hyperbranched macromolecule-bridged hindered phenols was investigated using the DPPH method and the oxygen uptake method.