On the Mechanism of Autoxidation of Three Vinyl Polymers: Polypropylene, Ethylene-Propylene Rubber, and Poly(ethyl acrylate)

Tobolsky, A. V.; Norling, Parry; Frick, N. H.; Yu, Haiqing

doi:10.1021/ja01073a004

Cited by 81 publications

(27 citation statements)

References 8 publications

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“…Such condition provides an unbalanced structure with the pendent methyl groups resulting in stearic hindrance. Consequently the CαH2-CαH2 bond becomes weak which can easily break-up under favorable conditions such as in the presence of radical species [43,44].…”

Section: Reaction Mechanismmentioning

confidence: 99%

Functionalization of Liquid Natural Rubber via Oxidative Degradation of Natural Rubber

2014

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Natural rubber (NR) is a high molecular weight natural polymer and can be degraded to liquid natural rubber (LNR) leaving certain functional groups at the end of chains. In this study, LNR samples prepared via oxidative degradation using H2O2 and NaNO2 as reagents were found to have different end groups depending on the pH of the reaction medium. In an acidic medium, LNR with hydroxyl terminal groups was formed as the degradation reaction was initiated by hydroxyl radicals produced from decomposition of peroxynitrite acid. In contrast, a redox reaction took place in an alkaline medium to yield LNR with carbonyl terminal groups. The mechanisms of reaction are discussed and proposed to explain the formation of different end groups when reaction carried out in acidic and alkaline media. Chain degradation in an acidic medium seems to be more effective than in an alkaline medium, and thus yields LNR with lower Mn.

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Section: Reaction Mechanismmentioning

confidence: 99%

Functionalization of Liquid Natural Rubber via Oxidative Degradation of Natural Rubber

2014

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“…According to the mechanism of thermooxidative degradation of PP reported, the reaction of the thermooxidative degradation of PP is a complicated chain‐reaction of radical with a series of reactional steps 27, 30, 49–59. Before its rupture, some hydroxyl groups on the macromolecular chain of PP may form during the thermooxidative degradation.…”

Section: Resultsmentioning

confidence: 99%

“…Before its rupture, some hydroxyl groups on the macromolecular chain of PP may form during the thermooxidative degradation. These hydroxyl groups may be produced by the following step reactions27, 30, 49–59: …”

Section: Resultsmentioning

confidence: 99%

A real‐time study on the evolution of the degradation of polypropylene during mixing process

Wang

Nie

et al. 2011

J of Applied Polymer Sci

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A real-time study to the evolution of the mechanisms of degradation of both PP powder and PP granular during the mixing process was achieved. A quantitative analysis of combination of the rheological torque-time curves obtained by a Haake rheometer with FTIR spectra was made. The construction of a series of the characteristic functions of the torque-time curve and the FTIR characteristic functions for polypropylene (PP) made the real time and quantitative analysis relatively profound. By means of these characteristic functions, the characters of the mechanisms of thermooxidative degradation, and the mechanism of mechanochemical degradation for PP were investigated. Two criterions for the mechanism of thermooxidative degradation and the mechanism of mechanochemical degradation were obtained. In the thermooxidative treatment process and the mixing process, the necessary condition for the significant occurrence of thermooxidative degradation of PP is Dh r (i) > 0.05, whereas the sufficient condition for the significant occurrence of mechanochemical degradation is Dh r (i) 0.05 (D l (i) < 0, and i > 1). A detailed description of the evolutions of the degradations for both the PP granules in which an antideterionant was added and the PP powder without any antideterionant was made. The roles and the evolutions of both the mechanism of thermooxidative degradation and the mechanism of mechanochemical degradation were discussed.

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“…It is a common practice in the industry to introduce a small amount (<1 wt%) of antioxidants or stabilizers in the PP products, which have the ability donating hydrogen atom to the polymeric radicals (I) to halt the oxidation-degradation cycles [5], especially during melt processes and outdoor applications. The most common antioxidants used in polyolefin are hindered phenol molecules, including octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate (Irganox® 1076) and pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate) (Irganox® 1010) [6,7] as illustrated in Scheme 2.…”

Section: Introductionmentioning

confidence: 99%

Developing Polypropylene Bonded Hindered Phenol Antioxidants for Expanding Polypropylene Applications in High Temperature Conditions

Zhang¹,

C²,

Tc³

2017

J Material Sci Eng

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Polypropylene (PP) represents about a quarter of commercial plastics produced around the world. Despite its huge commercial success, PP polymer is not suitable for the applications that require long-term exposure to high temperatures (>80°C), due to its chemical and physical stability. The PP chain is prone to the oxidative chaindegradation and exhibits a relatively low material softening temperature. This paper discusses a new research approach by developing the PP-bonded hindered phenol (PP-HP) antioxidants to address this scientifically challenging issue. We have investigated two PP-HP structures, one with two methylene units adjacent to the hindered phenol group (HP-L) and one without this spacer (HP-S). In general, PP-HP polymers are advantaged with the ability to incorporate a suitable concentration of HP antioxidant groups with homogeneous distribution along the polymer chain, which provide effective protection to the PP chains from oxidative degradation. In addition, the specific PP-HP-L structure can also engage in a facile crosslinking reaction to form a 3-D network during the oxidation reaction. In one accelerated oxidation test in air at 190-210°C, the regular commercial PP polymer (containing common antioxidants and stabilizers) degrades within a few minutes; a PP-HP-L copolymer with about 1 mol% HP-L group shows almost no detectable weight loss after 24 hrs. In an ASTM endurance test at 140°C in air, the commercial PP shows 1% weight loss within about 10 days. On the other hand, the PP-HP-L polymer lasts for more than 30 years. Overall, the experiment results present the potential of expanding PP applications into a much higher temperature range (>140°C) under oxygen oxidative environments.

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On the Mechanism of Autoxidation of Three Vinyl Polymers: Polypropylene, Ethylene-Propylene Rubber, and Poly(ethyl acrylate)

Cited by 81 publications

References 8 publications

Functionalization of Liquid Natural Rubber via Oxidative Degradation of Natural Rubber

Functionalization of Liquid Natural Rubber via Oxidative Degradation of Natural Rubber

A real‐time study on the evolution of the degradation of polypropylene during mixing process

Developing Polypropylene Bonded Hindered Phenol Antioxidants for Expanding Polypropylene Applications in High Temperature Conditions

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