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

Abstract

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

The Influence of UV-Accelerated Aging Process on Industrial Waste Containing EPDM

“…As the intention of the aging was to de-vulcanize the residue, this result shows that the goal was probably achieved. The same behavior was previously observed in the literature [4,11,17]. The MH results showed a slight reduction of the molecular stiffness of some samples containing EPDM-r when compared to the Control sample.…”

“…The behavior of the mechanical properties of the EPDM-r and EPDM-r UV blends were quite distinct, due to the cited factors. of green chemistry (i.e., the use of renewable or recycled sources of raw material), while also being a source of income for many families around the world [4,40].…”

“…Millions of tons of urban solid waste are inappropriately dumped every year in landfills and dumps, including polymeric materials. In addition, concerns about the disposal of these materials are further intensified in regions where there are low tax incentives for the development of the recycling industry and in regions with precarious solid waste management systems [1][2][3][4].…”

“…Among the most-studied methods, the ultrasound method uses ultrasound waves to produce cavitation in the rubber, which generates tensions that are able to break the chemical bonds [3,5,[11][12][13][14][15][16][17][18]. Another de-vulcanization method based on the action of microwaves presents some advantages that make it one of the most promising for the recycling of rubber [2][3][4]13,15,[18][19][20][21][22], including its physical nature, the volumetric heating of the material by the microwaves, and the possibility of high productivity [23].The aging of elastomers can be defined as the degradation process produced by the interaction between a material and an environment, modifying their structure and properties (i.e., mechanical, electrical, chemical, and/or thermal). It is a complex chemical process that occurs under the influence of heat, oxygen, light, ozone, and mechanical tension, and it results in time-dependent modifications of the chemical and physical properties [24].…”

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

“…Vulcanized elastomers are materials with difficult processes of natural degradation due to their cross-linking structure and the presence of additives on their formulation, which can generate serious problems for to the environmental and public health. Additionally, recycling is considered a category of green chemistry, i.e., the use of renewable or recycled sources of raw material, and is also a source of income for many families around the world [1,2], especially those facing an economic crisis.…”