Macromolecular Non‐Releasing Additives for Commercial Polyolefins

Abstract

Summary: Four comonomers bearing a highly efficient phenolic antioxidant unit and different distance between the antioxidant moiety and the double bond have been prepared and tested in co-polymerization with ethylene by means of three selected metallocene based catalysts. The possibility to obtain a masterbach suitable for melt blending with commercial polyolefins has been evaluated by modifying: i) the structure of the functionalized comonomer, ii) the kind of catalyst, iii) the polymerization conditions. The pair rac-[Me 2 Si-(2-Me-4,5-BenzInd) 2 ]ZrCl 2 catalyst and comonomer with the longest spacer (8 methylene units) allowed the highest comonomer incorporation, while with rac-(EBTHI)ZrCl 2 catalyst the highest polymerization activity was observed. TGA analysis has been carried out on some of the copolymers in order to investigate the influence of type and amount of the comonomer on their thermal stability and to test the efficiency of the antioxidant group both in nitrogen and oxygen atmosphere.

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

“…Generally, certain amount of antioxidants is essential to slow the degradation of polyolefin materials during the processing under high temperature and strong shear force, such as extrusion. [ 19 ] Good thermal stability of AO‐OPE based on its chemical structure nature has been confirmed above, which would show significance to stabilize PP matrix during the melt processing at around 210 °C. The antioxidant mechanism of phosphites, one kind of the auxiliary antioxidants, is complex and it is generally considered that they can act as both hydroperoxide decomposers and chain‐free radical terminators.…”

LDPE‐based blends and films stabilized with nonreleasing polymeric antioxidants for safer food packaging

“…In previous articles, we reported on design and syntheses that led to the exploitation of novel comonomers bearing a phenol antioxidant moiety analogous of BHA, placed at different distances from the olefinic polymerizable double bond [Scheme (a)]. Said comonomers copolymerize with ethylene in the presence of selected methylaluminoxane‐activated metallocene catalysts, such as rac ‐ethylenebis(tetrahydroindenyl)zirconium dichloride ( rac ‐(EBTHI)ZrCl 2 ), to produce ethylene‐based random copolymers with tunable antioxidant group concentration as well as molecular weight and molecular weight distribution 16, 17…”

“…Random copolymers of ethylene with 4‐allyloxy‐2,6‐di‐ t ‐butylphenol ( C1 , n = 1), 4‐hexa‐5‐enyloxy‐2,6‐di‐ t ‐butylphenol ( C4 , n = 4), and 4‐dec‐9‐enyloxy‐2,6‐di‐ t ‐butylphenol ( C8 , n = 8), in the following labeled EC1 , EC4 , and EC8 respectively, were synthesized and thoroughly characterized as described in Refs 16. and17.…”

“…In an attempt to overcome the synthetic difficulties and the technical obstacles for an industrial application of the abovementioned procedures, we have adopted an approach that takes advantage of the wide synthetic capability of metallocene catalysts of producing ethylene‐based copolymers with controlled amounts of an efficient stabilizing comonomer, to be used as “masterbatches” in the melt‐blending with commercially available polyolefinic matrices. Recently, we reported the preparation of olefinic comonomers [Scheme (a)] bearing a highly efficient antioxidant additive similar to 2,6‐di‐ t ‐butyl‐4‐methoxyphenol (BHA), and capable of easily copolymerizing in variable and tunable amount with ethylene to give random copolymers 16, 17…”

Synthesis of nanosilica‐based immobile antioxidant and its antioxidative efficiency in SBR composites

“…Fourier transform infrared spectra (FTIR) were recorded on a Perkin-Elmer-System 2000 infrared spectrum analyzer with KBr pellets in the wave number range from 4000 to 400 cm 21 . The scanning was performed 32 times with a resolution of 4 cm 21 . TG was carried out on Mettler Toledo TGA/DSC 1 instrument to determine the organic content of RT-silica and to calculate the activation energy.…”