Synthesis of Polyethylene‐Grafted Phosphite Antioxidant and Its Antioxidant Behavior in Polypropylene

Abstract

A novel macromolecular auxiliary antioxidant with polyethylene (PE) as polymer skeleton and phosphites as side groups is prepared based on commercial ethylene‐vinyl acetate (EVA) copolymers and its potential as polyolefin stabilizers is studied in depth. The synthesis approach of this PE‐grafted antioxidant consists of a typical EVA hydrolysis reaction and a two‐step nucleophilic substitution reaction of PCl3, 2,4‐di‐tert‐butylphenol, and the hydrolysis product. Results of the thermogravimetric analysis show that the macromolecular structures endow the as‐synthesized antioxidant with much better thermal stability than that of the commercial antioxidant 168. In addition, antioxidant behaviors of the PE‐grafted antioxidants in polypropylene (PP) matrix are investigated in detail through characterization of the melt flow index of multiple‐extruded stabilized PP as well as the short‐term oxidation induction time test and the long‐term thermo‐oxidative aging test. Results show that even with extremely low content of the effective antioxidant groups, the as‐synthesized macromolecular antioxidant still has excellent antioxygenic properties.

Application of ferrocene‐grafted polyethylene as UV‐absorbers

“…EVOH was synthesized by adapting literature procedures 35,36 . First, EVA (6 g) and xylene (100 mL) were magnetically stirred in a 250 mL three‐necked round‐bottom flask under reflux.…”

“…EVOH was synthesized by adapting literature procedures. 35,36 First, EVA (6 g) and xylene (100 mL) were magnetically stirred in a 250 mL three-necked roundbottom flask under reflux. Then NaOH-ethanol solution (25 mL, 2 mol L À1 ) was added dropwise into the reaction.…”

Antimigration Polypropylene Antioxidants: A Review

“…Furthermore, the novel PP-HP polymer can retain or even improve its mechanical strength under increased application temperatures (>100 °C), as opposed to being vulnerable to PP chain breakdown and material softening. Zhang et al synthesized a novel class of macromolecular auxiliary antioxidants (phosphites as side groups) by utilizing commercial ethylene–vinyl acetate copolymer (EVA) as raw materials in order to fill in the blank of the synthesis of macromolecular phosphorus-containing antioxidants . The chemical decomposition and physical evaporation or migration are the two most common degradation ways.…”

“…Zhang et al synthesized a novel class of macromolecular auxiliary antioxidants (phosphites as side groups) by utilizing commercial ethylene−vinyl acetate copolymer (EVA) as raw materials in order to fill in the blank of the synthesis of macromolecular phosphoruscontaining antioxidants. 35 The chemical decomposition and physical evaporation or migration are the two most common degradation ways. In an accelerated thermal aging test, macromolecular antioxidants invariably exhibited strong evaporation-resistance capabilities.…”

Repurposing Mitsunobu Reactions as a Generic Approach toward Polyethylene Derivatives

“…After hydrolysis under alkaline conditions (saponification), EVA turns into poly­(ethylene- co -vinyl alcohol) (EVOH), which can be further derivatized. However, traditional EVOH functionalization reactions mostly relied on the formation of O -carbonyl and O -phosphorus bonds, which are unstable under strong acidic and basic conditions. ,− Other methods, such as direct alkylation, epoxide ring opening, or acetal formation, are not suitable for EVOH functionalization due to low yielding. Therefore, we turned our attention to the Mitsunobu reaction, which is one of the most practical reactions converting alcohols into new C–N, C–O, C–S, C–C, and C–halide bonds using protic nucleophiles .…”