Addition of Unsaturated Monomers to Rubber and Similar Polymers

Abstract

The addition of different ethylene monomers to polyisoprene was studied in order to throw a light on reaction mechanisms and structures of reagents. It was attempted, during the planned transformations, to maintain as best as possible the shapes and sizes of initial macromolecules, upon which rests the property of high elasticity. For this purpose, it was decided to avoid grafting reactions, as well as any reactions affecting the nature of the polyisoprenic chain, e.g., scission, cross-linking, and cyclization. After the completion of the work carried out by one of the authors on the addition of maleic anhydride, the existence of two mechanisms was brought to light: the one is of a radical type, produced by adding an unsaturated reagent on a methylene close to a double bond of chain; the other is of a thermal nature, triggered by the action not of a catalyst, but of a rather high temperature. It is clear that the latter process does involve isomerization of a part of chain double bonds. The model to which maleic anhydride is connected has been deduced by examining the reaction aptitudes of a series of monomers. The major part of highly polymerizable materials, with the exception of acrylonitrile, were eliminated a priori, in order to avoid both homopolymerization reactions and graftings. The monomers in which double bonds are depleted in π electrons are more apt to give the desired reactions. The more favorable effect is obtained with α carbonyl (maleic anhydride and γ crotonolactone). Other factors were also taken into account. The work reviewed here enabled us to assess the way in which reactions evolve according to the considered mechanisms and produce new macromolecular materials. The resulting compounds have a high rubberlike elasticity and show a high chemical reactivity, due to anhydride or lactone side groups.

A parametric study of the terminal maleation of polypropylene through an Alder Ene reaction

“…3 From Arrhenius plots, Benn et al 14 estimated the activation energy for several alk-1-enes and for cis-and trans-dec-5-ene, to be 90, 76, and 77 KJ/mol, respectively. Rondestvedt and Wark 15 estimated the activation energy for the Alder Ene reaction between maleic anhydride and allylbenzene (84 KJ/mol) to be in the range of those determined by Benn et al 14 The presence of a free radical inhibitor had no effect on the rate of reaction; 14,16 however, in its absence and in the presence of air, maleic anhydride-alkene copolymer formation was observed.…”

Potential Application of ENR/EPDM Blends

“…Though the maleic anhydride is purported and mechanistically favoured an Diels-Alder reaction (Alder et al 1943) in the methylene/allylic double carbon bonds (> C = C <) as reported in the classical chemical reactions (Baraboim & Popov 1963), and also by Pinazzi (Pinazzi et al 1963), andFarmer (1942)in natural rubber, while Loo (1985) reported that it is possible that the dibasic acids could be used to open the epoxide ring and also used as crosslink sites, or the dibasic acids used to crosslink in the non-sulphur accelerated curing system.…”

Influência da estrutura de diferentes copolímeros de etileno e a-olefinas na funcionalização com anidrido maleico

“…O anidrido maleico (AM) tem sido utilizado para modificar diversos polímeros, como polietilenos [5,6] , polipropileno [7,8] , EPDM [9] , EPR [10] , eicosano e esqualano [11] e elastômeros [12] . A enxertia de AM pode ser realizada por diferentes métodos, como em solução [7] , em estado fundido [13] , em suspensão [12] e em estado sólido [14] .…”