Microstructure of Maleic Anhydride Grafted Polyethylene by High-Resolution Solution-State NMR and FTIR Spectroscopy

Abstract

The microstructure of maleic anhydride (MA) grafted polyethylene (PE), MA-g-PE, has been successfully characterized by high-resolution NMR and FT-IR spectroscopy. The carbonyl asymmetric and symmetric stretchings of MA-g-PE exhibit lower shifts with an increase in the grafting degree of MA, suggesting stronger inductive interactions between different grafts in a solid state. The 1H and 13C NMR spectroscopy of [2,3-13C2]MA grafted PE with a low molecular weight (lmPE), [2,3-13C2]MA-g-lmPE, demonstrates that [2,3-13C2]MA-g-lmPE contains fewer succinic anhydride (SA) oligomeric grafts with a terminal unsaturated MA ring (oligo-MA) in addition to more SA oligomeric grafts terminated with a saturated SA ring (oligo-SA), the only structure that had been observed prior to this study. The formation of oligo-MA and oligo-SA can be explained by a mechanism based on two different termination processes: disproportionation between a grafting radical and a macroradical on a secondary carbon in lmPE or another grafting radical as well as hydrogen abstraction of a grafting radical from a secondary carbon on lmPE.

Enhancement of Polyolefins Compatibility with Natural Fibers through Chemical Modification

“…It is obvious from these figures the presence of new peaks at 1720 cm -1 and at 1787 cm -1 when MAH is grafted successfully onto PE. The band at 1787 cm -1 is due to the asymmetric stretching modes of carbonyl (C=O) group of saturated maleic anhydride, units while the band at 1720 cm -1 belongs to the symmetric stretching of carbonyl (C=O) of maleic acid grafted onto PE [20][21][22]. …”

Grafting of maleic anhydride on polypropylene by reactive extrusion: effect of maleic anhydride and peroxide concentrations on reaction yield and products characteristics

“…Despite the number of publications on the topic, there are still some discussions on particular reactional mechanisms [11,[24][25][26][27]. However, in a general way and according to Nachtigall et al [28], we can propose the following simplified mechanism: the free radicals generated by the peroxide decomposition lead by hydrogen abstraction to tertiary alkyl polymer radicals.…”

Preparation and Characterization of Maleic Anhydride Grafted Poly(Hydroxybutirate-CO-Hydroxyvalerate) – PHBV-g-MA

“…The MA grafted to thermoplastic polymer can increase the polarity, which leads to better adhesion with biofillers 8 that have polar groups on their surfaces. Some works in the literature have proposed the use of MA grafted to thermoplastics as polyethylene and polypropylene [8][9][10][11][12][13] to improve the interfacial adhesion between the matrix and some reinforcement agents, as oak wood flour 5 , bamboo pulp fiber 14 , kenaf fiber 4 , clay 6,13,15 , bio-flour-filled 8 and others. It was observed that the presence of the compatibilizer agent induces a stronger interfacial adhesion and improvement of the mechanical properties, compared to uncompatibilized composites 4,15 , besides improving the particle dispersion into polymer matrix 13 , and the thermal stability of composite 8 .…”