Hydrotalcite/unsaturated Carboxylic Acid Systems as Coagents in Ethylene-Propylene Copolymer Vulcanization

Abstract

The aim of this work was to study the activity of several hydrotalcite/unsaturated acid systems in the peroxide crosslinking of ethylene-propylene copolymer (EPM). Allylmalonic, citronellic, crotonic, itaconic, sorbic and undecylenic acids, as well as monoallyl maleate, were applied to ensure the activity of hydrotalcite in the peroxide vulcanization of EPM. In this article, we discuss the effect of the obtained coagents with respect to their particle size and tendency to agglomerate, as well as the effect of the applied type of unsaturated acid on the vulcanization kinetics of rubber compounds. The influence of hydrotalcite/unsaturated acid systems on the crosslink density, the mechanical properties of the vulcanizates and their stress relaxation tendency under external deformation were also studied. Hydrotalcite/unsaturated acid systems seem to be active as coagents in the crosslinking of EPM with peroxide. The type of unsaturated acid considerably influences the activity of hydrotalcite toward the ethylene-propylene copolymer. The application of such coagents increases the crosslink density of the vulcanizates and improves their mechanical properties.

Ionic Liquids Applied to Improve the Dispersion of Coagent Particles in an Elastomer

“…Stress is then concentrated near the hard coagent domains, which leads to the destruction of the sample upon deformation [16]. Recently, we reported the high activity of hydrotalcite grafted with monoallyl maleate as the coagent in the peroxide cross-linking of saturated elastomer [17]. The application of this coagent allowed for the realization of vulcanizates with considerably improved mechanical properties and a higher cross-link density compared with vulcanizates crosslinked only with peroxide.…”

Ionic Liquids and Calcium Oxide Grafted with Allylmalonic Acid Applied to Support the Peroxide Crosslinking of an Ethylene–Propylene Copolymer

“…The crosslink density ( ν T ) of the EPM vulcanizates was determined based on the results of equilibrium swelling in toluene. The Flory–Rehner equation [ 44 ] and the Huggins parameter of elastomer–toluen interactions given by Equation (1) [ 15 ] were used to calculate the crosslink density, where V r is the volume fraction of the elastomer in the swollen gel. χ = 0.425 + 0.340 V r …”

“…Another approach to improve the efficiency of rubber peroxide crosslinking and the mechanical properties of the vulcanizates are hybrid coagents consisting of an inorganic core and an organic shell, which were reported in our previous works [ 13 , 14 , 15 ]. These coagents are based on nanosized metal oxides (ZnO, CaO, MgO) and layered minerals (hydrotalcite, boehmite) modified with unsaturated carboxylic acids, which possess easily cleavable protons and double bonds, that are readily accessible for reactions with free radicals or polymer chains.…”

Rubber magnets cured with peroxide and coagents

“…Network enhancement through the grafting of coagents between elastomer chains, the formation of higher modulus filler-like domains of thermoset coagent, and the formation of an interpenetrating network of homopolymerized coagents and rubber chains have been suggested ( Figure 5). 14,[18][19][20] The influence of the applied coagents on cross-link density of tested composites can be derived from their chemical structure.…”