Preparation of zinc‐oxide‐free natural rubber nanocomposites using nanostructured magnesium oxide as cure activator

Roy, Kumarjyoti; Alam, Md. Najib; Mandal, Sushil Kumar; Debnath, Subhas Chandra

doi:10.1002/app.42705

Cited by 27 publications

(28 citation statements)

References 35 publications

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“…1b). Moreover, shorter t s1 times were observed for the compounds activated by MgO and green-MgO, which is consistent with the data reported by the literature for natural rubber [13][14][15].…”

Section: Vulcanization Behavior and Crosslink Densitysupporting

confidence: 92%

“…Although the authors did not observe satisfactory results regarding MgO reactivity, they presented an important proposal of reaction mechanism. Years later, Roy et al [15] published a study with interesting results at the use of MgO in nanometric particle size as activator for natural rubber vulcanization. The authors reported that only 1 phr (parts per hundred of rubber) of nanometric MgO was necessary to produce higher vulcanization rate and natural rubber vulcanizates with better thermal and mechanical properties as compared to 5 phr of conventional ZnO.…”

Section: Introductionmentioning

confidence: 99%

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Replacement of ZnO by ecofriendly synthesized MgO in the NBR vulcanization

et al. 2021

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Rubber compounds contain several additives besides the elastomer matrix, such as fillers, curing agents, activators, antioxidants, among others. However, some of these additives causes a negative impact on the environment, e.g., zinc oxide commonly used as activator in the vulcanization process. Thus, in this study, ecofriendly synthesized magnesium oxide was evaluated as substitute to ZnO in a standard nitrile rubber composition. Additionally, commercial magnesium oxide was also included in study to be used as a reference. All rubber compounds were evaluated in terms of rheometric (minimum and maximum torques, curing times), rheological (dynamic moduli), and mechanical (tear resistance, tensile resistance, hardness, and stress relaxation) properties and crosslink density. The marching-modulus was more noticeable when MgO and green-MgO was employed as activator. The vulcanization of NBR with MgO and green-MgO resulted in rubber materials with higher crosslink density, higher elastic moduli, lower phase angle δ, and lower stress relaxation than ZnO composites. Besides that, no significant difference was observed for the mechanical performance regarding tear strength, tensile strength, and hardness.

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Section: Vulcanization Behavior and Crosslink Densitysupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Replacement of ZnO by ecofriendly synthesized MgO in the NBR vulcanization

et al. 2021

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“…In fact, strongly coordinating cations (e.g., Cu 2+ , Hg 2+ ) hinder further reaction of the complex with sulfur, while the low tendency to form complexes (e.g., Mg 2+ , Ca 2+ ) makes the formation of the active sulfurating complex and the sulfur transport to the polymeric chain difficult [24]. Anyway, MgO shows a relatively fast kinetics in the first steps of the vulcanization, in particular when particles are nanosized [87] or in a mixture with ZnO [39,88], but allows for obtaining a lower cross-linking density when compared to ZnO [24]. Actually, CdO showed better activating behavior in rubber vulcanization [38], but its higher toxicity precludes its use for substituting ZnO.…”

Section: Cross-linked Productsmentioning

confidence: 99%

Zinc-Based Curing Activators: New Trends for Reducing Zinc Content in Rubber Vulcanization Process

et al. 2019

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The efficiency of sulfur vulcanization reaction in rubber industry is generally improved thanks to the combined use of accelerators (as sulphenamides), activators (inorganic oxides), and co-activators (fatty acids). The interaction among these species is responsible for the formation of intermediate metal complexes, which are able to increase the reactivity of sulfur towards the polymer and to promote the chemical cross-links between the rubber chains. The high number of species and reactions that are involved contemporarily in the process hinders the complete understanding of its mechanism despite the long history of vulcanization. In this process, ZnO is considered to be the most efficient and major employed activator and zinc-based complexes that formed during the first steps of the reaction are recognized to play a main role in determining both the kinetic and the nature of the cross-linked products. However, the low affinity of ZnO towards the rubber entails its high consumption (3–5 parts per hundred, phr) to achieve a good distribution in the matrix, leading to a possible zinc leaching in the environment during the life cycle of rubber products (i.e., tires). Thanks to the recent recognition of ZnO ecotoxicity, especially towards the aquatic environment, these aspects gain a critical importance in view of the urgent need to reduce or possibly substitute the ZnO employed in rubber vulcanization. In this review, the reactivity of ZnO as curing activator and its role in the vulcanization mechanism are highlighted and deeply discussed. A complete overview of the recent strategies that have been proposed in the literature to improve the vulcanization efficiency by reducing the amount of zinc that is used in the process is also reported.

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“…This resulted in about 10,000 tons of ZnO pollution annually at the end of the last century in the United States alone, and this number is expected to grow exponentially . These concerns have promoted ongoing research on the reduction or even complete replacement of ZnO in rubbers . Still, ZnO remains an essential ingredient in current industrial rubber production …”

Section: Introductionmentioning

confidence: 99%

Nitrogen‐doped graphene as an alternative to ecotoxic zinc oxide in rubbers

Glebova

Severin

Шершнев

et al. 2018

J of Applied Polymer Sci

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Zinc oxide (ZnO) is an essential ingredient in industrial rubber production; it regulates the onset of vulcanization, accelerates the kinetics of vulcanization, and improves the mechanical properties of rubber. However, environmental pollution with ZnO is a concern because it is recognized to be significantly ecotoxic and might also have adverse effects on human health. One of the major sources of ZnO environmental pollution is rubber items, tires in particular. Nitrogen (N)-doped graphene is a promising nextgeneration catalyst. We show here that the replacement of 3 phr ZnO by just 0.1 phr N-doped graphene in styrene-butadiene rubber reduced the vulcanization onset time by more than a factor of two while retaining the fast vulcanization kinetics and enhancing the tensile strength in comparison with rubber with just ZnO. A shorter vulcanization time implies energy savings, which, together with the nontoxicity of N-graphene, should make the resulting rubbers substantially more environmentally friendly. V C 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46116.

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Preparation of zinc‐oxide‐free natural rubber nanocomposites using nanostructured magnesium oxide as cure activator

Cited by 27 publications

References 35 publications

Replacement of ZnO by ecofriendly synthesized MgO in the NBR vulcanization

Replacement of ZnO by ecofriendly synthesized MgO in the NBR vulcanization

Zinc-Based Curing Activators: New Trends for Reducing Zinc Content in Rubber Vulcanization Process

Nitrogen‐doped graphene as an alternative to ecotoxic zinc oxide in rubbers

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