Mechanisms of antioxidant action: Photoantioxidant activity of polymer‐bound hindered amines. II. Bis acrylates

Abstract

SYNOPSISl-Acryloyl-4-acryloyloxy-2,2,6,6-tetramethylpiperidine (AATP) has been covalently attached to polypropylene under conditions of reactive processing to give substantial concentrations of essentially 100% grafted antioxidant ( AATP-B) . Solution of the concentrates showed that at high concentration of grafted antioxidant some homopolymerized AATP was present and the polymer undergoes transient cross-linking during processing. Concentrates of bound AATP ( AATB-B) when used as conventional additives for polypropylene are very effective photoantioxidants due to conversion to the related polymer-bound nitroxyl radicals by photosensitized oxidation. A typical commercial hindered phenol, Irganox 1076, when used at low concentration in combination with AATP-B also acts as a photosensitizer for nitroxyl formation. Unlike low molar mass-hindered piperidinoxyl, polymer-bound nitroxyls are effective thermal antioxidants that synergize very effectively with low concentrations of Irganox 1076.

Synthesis, characterization, and evaluation of natural rubber‐graft‐N‐(4‐aminodiphenyl methane) acrylamide as an antioxidant

“…This phenomenon is known as blooming, and the subsequent loss of the antioxidant then occurs from the polymer surface by evaporation. Finally, if the polymer is in contact with appropriate solvents during service, these may lead to the loss of a soluble antioxidant via leaching 3. To avoid the loss of antioxidants through extraction or volatilization; macromolecular, polymerizable, or grafting antioxidants may be used 4.…”

Reactive processing of polymers: Melt grafting of glycidyl methacrylate on ethylene propylene copolymer in the presence of a coagent

“…16 In our laboratory, we developed a broad and versatile approach to improving the grafting efficiency of functional modifiers (agents) on polymers by in situ cografting of a small amount of a more reactive (compared to the modifier) bi-or polyfunctional comonomer, a coagent. 6,[17][18][19][20][21] The success of this method, in which the coagent acts as a reactive linker between the modifier and the polymer, relies on achieving a delicate balance between the molar ratios of the reagents (agent, coagent, initiator) and the process variables (e.g., temperature, residence time). It was shown, for example, that the use of the trifunctional coagent, trimethylol propane triacrylate (Tris), with different reactive modifiers, such as maleic anhydride 18 and antioxidants, 17,19 gave rise to a dramatic increase in the level of grafting of these modifiers on polymers.…”

Amelioration of acrylonitrile–butadiene copolymer properties using natural rubber graft p‐aminophenol

“…The second reason for migration of antioxidants, which is important to their performance in polymers and which may substantially reduce its effectiveness, is the physical loss of the antioxidants from the elastomers. 2 This is a cause of considerable concern in rubbers that are used in engineering components in which extraction of the antioxidants by solvents, mineral oils, and synthetic fluids may reduce the lifetime of the article. Besides the ability of the antioxidants to trap peroxy and hydroperoxy radicals and its catalytic action in hydroperoxide decomposition, the antioxidants should be compatible with the host polymers.…”

“…This is the reason for the increasing interest in the synthesis of grafting antioxidants. 2 Grafted antioxidants are low molecular antioxidants that partially bond to the macromolecules during the processing of polymers, and the use of grafting antioxidants is one of the best ways to protect unsaturated rubbers. 3 …”