Enhanced thermo-oxidative stability through covalent attachment of hindered phenolic antioxidant on surface functionalized polypropylene

摘要

In order to prolong the thermo-oxidative stability of polypropylene and prevent antioxidant loss, this research details an effective approach to prepare polymeric antioxidant via surface functionalization of polypropylene with long-chain macromolecules containing hindered phenolic stabilizers. The polymeric antioxidant (PPNA) is prepared by amide bond formation between phenolic stabilizer containing carboxylic acid moiety and amine functionalized polypropylene (PPNH2). Test results confirmed surface changes through plasma treatment, amine and antioxidant modification. The resultant PPNH2 and PPNA exhibit reduced crystallinity while the crystallization temperature shifts toward higher values, suggesting simultaneous effects of steric hindrance and nucleation of long-chain structures. Immobilization of phenolic stabilizer results in improving thermo-oxidative stability of polypropylene. Subsequently, PPNA was used to prepare PP/PPNA blends to evaluate free radical scavenging ability and resistance to extraction. The blends demonstrate superior thermal stability and low volatility compared to stabilized polypropylene with Irganox 1010, indicating uniform distribution due to comparability. The synthesized polymer-bound antioxidant have the potential to be the material of choice as stabilizer concentrate for packaging, coating and thin film applications. (C) 2018 Elsevier Ltd. All rights reserved.