Vulcanization behavior of NBR with organically modified clay

The influence of rubber devulcanization by microwaves in the reversion behavior is still modestly explored in the literature. The reversion occurs due to thermal degradation of unstable crosslinkings formed during the vulcanization process. This phenomenon results in poor final mechanical properties of the artifacts. In this work, some formulations based on natural rubber (NR) with the incorporation of NR devulcanized by microwaves at different exposure times to the microwaves were vulcanized by compression molding at the same temperature and time used for the study of their vulcanization characteristics, in order to correlate the properties obtained and understand the influence of the reversion on the mechanical properties. The results showed that levels of devulcanization/degradation of the recycled phase, as well as the additional heating time influenced on the behavior of reversion and, consequently, on the mechanical properties. the influence of density and crosslinking type in the mechanical properties of rubber has been studied by various authors, 4,6,7 since the stress-strain measurement is an indirect method for determining the crosslinking density. 5Currently, a big global problem is related to disposal of solid urban residues, and materials able to make this problem much worse are the vulcanized/cured elastomers. In the same way, the search for processes and/or sustainable materials is of great value, and it is directly related to the solution of this problem, since the use of recycled materials can reduce such problem. In addition, recycling not only protects the environment, but also saves the limited petroleum resources from which the raw material originates, 8 also being a source of income for many families around the world. The recycling method used in this work is the devulcanization by microwaves.Devulcanization is a way of providing energy to destroy, total or partially, the three-dimensional network formed during vulcanization. 9 Devulcanization by microwaves is a well-established recycling technique of vulcanized elastomers. Among its

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“…Δ M is the difference between the maximum and minimum torques, and CRA (Cure Rate Average) values were calculated by using eq. ():

C R A = \frac{100}{t_{90} - t s_{1}}

…”

Section: Vulcanization Characteristicsmentioning

confidence: 99%

Influence of reversion in compounds containing recycled natural rubber: In search of sustainable processing

Sousa

Zanchet

Scuracchio

2017

J of Applied Polymer Sci

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“…From the curves of torque versus time, the vulcanization characteristics of the samples were obtained: minimum torque (ML), maximum torque (MH), torque variation ∆M (∆M = MH − ML), security time of the process or scorch time (ts 1 ), optimum cure time (t 90 ), and Cure Rate Average (CRA). The CRA values were calculated by using the Equation (1) [22]:…”

Section: Preparation and Characterization Of The Blendsmentioning

confidence: 99%

Relationship among Vulcanization, Mechanical Properties and Morphology of Blends Containing Recycled EPDM

2017

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Abstract:The production of consumption goods made of elastomer generates large amounts of vulcanized residues. The final proper environmental disposal of this material is a serious problem, which involves high costs and a possible waste of a material with high added value. The recycling of elastomers is a very important alternative since it is related directly to the protection of the environment, energy conservation, and sustainability. An option for companies that produce elastomeric residues is their incorporation in the formulations by producing polymeric blends. Thus, this work aims to prepare polymeric blends composed of ethylene-propylene diene monomer rubber (EPDM) and raw EPDM/EPDM residue (EPDM-r) in different concentrations, when the residue is ground at room temperature. The morphology of the residue, vulcanization characteristics, mechanical properties, and morphology of the blends were analyzed, showing promising results that point to the feasibility of using EPDM-r in the production of polymeric blends and as a possible solution to the problem of the final disposal of solid residues.

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“…The parameters obtained from the curves torque versus time were as follows: the minimum torque (ML), which is related to the viscosity of the composites before vulcanization; the maximum torque (MH), which is related to the molecular stiffness after the vulcanization process, i.e., proportional to the formation of cross-links; ts 1 is known as scorch or security time, which is the time related to the onset of the vulcanization reaction; t 90 is the optimum vulcanization time, the time necessary to vulcanizate 100% of the sample; torque variation ∆M (∆M = MH-ML), proportional to the cross-link density of the samples; and cure rate index (CRI), proportional to the vulcanization rate. CRI values were calculated by using Equation (2) [27]:…”

Section: Vulcanization Characteristics Of the Compositesmentioning

confidence: 99%

Elastomeric Composites Containing SBR Industrial Scraps Devulcanized by Microwaves: Raw Material, Not a Trash

Zanchet

Sousa

2020

Recycling

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Environmental concerns about waste management systems have stimulated the search for technological and economical alternatives that introduce waste as raw material for production cycles. In this sense, this study aimed to develop and characterize styrene-butadiene rubber (SBR) composites that contain industrial rubber scraps devulcanized by microwaves (SBR-r) as a reinforcing filler. The scraps were ground under ambient conditions. From the obtained powder (SBR-r), composites were prepared, varying the exposure time of the powder to the microwaves (1, 2, and 3 min), as well as the SBR-r content. These composites were compared to a Reference sample (base formulation without SBR-r). The vulcanization parameters were determined by an oscillating disk rheometer. After vulcanization, the composites were characterized by mechanical properties (tensile and tear strength, and compression set). These properties were also evaluated after accelerated aging in an air oven and a UV chamber (ultraviolet light). The results indicated that as a result of increasing the exposure time of the waste to the microwaves, no significant influence in the composite properties was observed. Aged samples presented higher results as compared with the Reference sample (tensile strength up to 175% higher, tear strength up to 107% higher, and compression set up to 91% higher), which indicates the possibility of using these materials in technological applications, such as in the civil and automotive industries.

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Vulcanization behavior of NBR with organically modified clay

Cited by 17 publications

References 22 publications

Influence of reversion in compounds containing recycled natural rubber: In search of sustainable processing

Influence of reversion in compounds containing recycled natural rubber: In search of sustainable processing

Relationship among Vulcanization, Mechanical Properties and Morphology of Blends Containing Recycled EPDM

Elastomeric Composites Containing SBR Industrial Scraps Devulcanized by Microwaves: Raw Material, Not a Trash

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