Synthesis and antioxidant activities in polyolefin of dendritic antioxidants with hindered phenolic groups and tertiary amine

Abstract

Two novel primary antioxidants with dendritic structure and hindered phenolic groups were synthesized using 3- (3,5-diter-butyl-4-hydroxyphenyl) propionic acid as raw material and dendritic poly(amidoamine) (PAMAM) as linker in chloroform. The antioxidant activities of the dendritic antioxidants were evaluated in polyolefin by melt flow index (MFI), yellowness index (Y.I.), and oxidation induction time (OIT). The dendritic antioxidants had excellent processing property and oxidation resistance behavior in polyolefin. At the same weighed amount of antioxidant, the MFI and Y.I. values of mulitiple-extruded polyethylene (PE) stabilized with the dendritic antioxidants were smaller than those of the commercial antioxidants, as well as the OIT values of polyethylene (PE) stabilized with the dendritic antioxidants were larger. Applying to polypropylene, the antioxidant ability of the second-generation dendritic antioxidant (G2.0 dendritic antioxidant) with larger molecular weight was superior to the commercial antioxidants and that of the first-generation dendritic antioxidant (G1.0 dendritic antioxidant) was equal to the commercial antioxidants. The dendritic antioxidants can prevent polyolefin from breaking of macromolecular chain in processing and had stabilizing effect in polyolefin in service life by donating H-atoms and electron to free radicals. The dendritic antioxidants combined with Irgafos 168 had improvement of antioxidant activities of the dendritic antioxidants in polyolefin.

Synthesis and Properties of Polyethylene‐Bound Antioxidants

“…[ 3,4 ] Moreover, safety concern arises when polyolefi ns used for food packaging materials. [ 5,6 ] Many approaches have been developed to retard the physical loss of antioxidants, such as producing antioxidants with high MW, [ 7,8 ] immobilizing antioxidants onto nanoparticles, [ 9 ] and chemically attaching antioxidants to polymers. Polymer-bound antioxidants can be prepared by (co)polymerizations of monomers bearing stabilizing functionalities [ 5,[10][11][12] and polymer functionalization of: i) pre-functionalized polymer bearing reactive groups with low-MW compounds bearing stabilizing moieties and ii) conventional polymers with monomers…”

Relationship between bridged groups and antioxidant activity for aliphatic diamine bridged hindered phenol in polyolefins

“…According to the generally accepted mechanism underlying the oxidation of polyolefin as first described by Bolland and Gee, there are some weak sites in the polymer chain where oxidation starts during processing, resulting in free radical chain reactions and the formation of hydroperoxide. The hydroperoxide would initiate new oxidation cycles and accelerate polyolefin oxidation degradation . LLDPE without any antioxidant was oxidized quickly when the atmosphere was changed to oxygen from nitrogen.…”

“…The hydroperoxide would initiate new oxidation cycles and accelerate polyolefin oxidation degradation. 11 LLDPE without any antioxidant was oxidized quickly when the atmosphere was changed to oxygen from nitrogen. After aliphatic diamine bridged hindered phenols were added into LLDPE, the OIT values increased.…”

Stabilized polypropylene synthesis using supported titanium catalyst system in presence of phenolic compounds

“…The b color values for virgin resin increase significantly after thermal aging, mainly due to the formation of various chromophores having carbonyl groups. [37][38][39] The minor changes in b color values of PH1 from 0.8 to 0.9 by increasing antioxidant concentration from 0.6 to 1.2 mmol indicate slow consumption after 0.6 mmol for oxidative stabilization. [37] Molecular weight characteristics of polymers before and after thermal aging process are given in Table 3.…”