Fracture morphology and mechanical properties of ethylene/vinyl acetate rubber vulcanizates reinforced by in situ prepared sodium methacrylate

Abstract

Ethylene/vinyl acetate rubber (EVM) was reinforced by sodium methacrylate (NaMAA) that was in situ prepared through the neutralization of sodium hydroxide and methacrylic acid in EVM during mixing. The mechanical properties of EVM vulcanizates with different NaMAA loadings and at different crosslink densities were studied and compared with those of high abrasion furnace carbon black (HAF) filled EVM vulcanizates. The fracture surfaces of gum and filled EVM vulcanizates were observed with scanning electron microscopy. The results showed that NaMAA‐reinforced EVM vulcanizates had better mechanical properties than HAF/EVM vulcanizates. When the NaMAA loading was 50 phr, the tensile strength of the NaMAA/EVM vulcanizate was 30 MPa, the tear strength was 102 kN/m, and the elongation at break was over 400%. Fourier transform infrared analysis confirmed that NaMAA formed in the compounding process and underwent polymerization during vulcanization. Scanning probe microscopy analysis revealed that nanoscale particles dispersed in the NaMAA/EVM vulcanizates. The mechanical properties were correlated with the fracture morphology of all the vulcanizates. The tensile rupture of NaMAA‐filled EVM vulcanizates occurred through tearing from a crack in the bulk of the samples. Tear deviation occurred with the addition of NaMAA and resulted in a rough surface, leading to an improvement in the tear strength of NaMAA‐filled EVM vulcanizates. The micrographs of the tear surfaces of the vulcanizates indicated that the different fracture modes depended on the NaMAA loading and the crosslink density. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1715–1724, 2004

Specific nonlinear viscoelasticity behaviors of natural rubber and zinc dimethacrylate composites due to multi‐crosslinking bond interaction by using rubber process analyzer 2000

“…Thus, not only conventional covalent crosslinks but also ionic crosslinks which exhibit special crosslinking structure and morphology coexist in the metal salts of unsaturated carboxylic acids‐reinforced rubbers [10]. Although the nano‐particles have been observed under transmission electron microscopy (TEM) [5, 6, 14], and many microstructure models [15] have been proposed, some aspects still need to be studied to improve the recognition of the essential microstructure.…”

A study on the crosslink network evolution of magnesium dimethacrylate/natural rubber composite

“…Here, the observed nonlinear behavior of the samples cured for 1 min supports the polymerization of MDMA, which provide the ionic crosslinks. This also have mentioned in the introduction 5–9. For large strain (λ −1 is 0.4–0.2), increasing of σ/2(λ − 1/λ 2 ) is due to that the end‐to‐end distance of the chains tends to its inextensible limit due to the crosslinked network.…”

“…As a new type of reinforcing agent for rubbers, and with homopolymerization and graft‐polymerization taking place in the rubber matrix, metal salts of unsaturated carboxylic acids can be polymerized to form nanodispersion phases acting as nanoparticles and to graft onto rubber chains to enhance the crosslinked network during peroxide curing. The ionic crosslinks are formed by metal salts graft‐polymerized onto the rubber chains, whereas the poly‐(metal salt) chains separate from the rubber matrix and aggregate into nano‐scaled fine particles, forming salt crosslinks 5–9. As a result, rubbers with metal salts of unsaturated carboxylic acids contain not only conventional covalent crosslinks but also ionic crosslinks and exhibit special crosslink structure and morphology 5–9.…”

“…The ionic crosslinks are formed by metal salts graft‐polymerized onto the rubber chains, whereas the poly‐(metal salt) chains separate from the rubber matrix and aggregate into nano‐scaled fine particles, forming salt crosslinks 5–9. As a result, rubbers with metal salts of unsaturated carboxylic acids contain not only conventional covalent crosslinks but also ionic crosslinks and exhibit special crosslink structure and morphology 5–9. Obviously, the microstructure of rubbers reinforced by metal salts of unsaturated carboxylic acids is complex and differs to that of conventional reinforcing filler.…”

Effect of methacrylic acid on the properties of Ethylene–Vinylene acetate rubber vulcanizates reinforced by magnesium hydroxide

“…[11][12][13] Little study has focused on MHs treated with unsaturated carboxylic acid, such as methacrylic acid (MAA). On the other hand, the reinforcement of rubbers by the addition or in situ preparation of metallic methacrylates, such as magnesium methacrylates (MDMAs), [14][15][16] sodium methacrylates, 17,18 or zinc methacrylates, 19,20 has attracted the extensive attention of researchers. Yin et al 21 reported that a small amount of MAA obviously enhanced the mechanical properties of peroxidecured styrene-butadiene rubber vulcanizates filled with aluminum hydroxide; this indicated that MAA could also be used as an effective coupling agent.…”