Microwave treatment in waste rubber recycling – recent advances and limitations

Formela, Krzysztof; Hejna, Aleksander; Zedler, Łukasz; Colom, X.; Cañavate, Javier

doi:10.3144/expresspolymlett.2019.48

Cited by 88 publications

(54 citation statements)

References 87 publications

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“…23,24 Currently, microwave devulcanization is one of the most promising technologies because of the good properties of the treated material and the promise of high productivity as well as relative low costs. 25 Microwave heating takes advantage of volumetric heating: a fast and uniform rise of temperature can be achieved. The process does not require additional chemicals and is considered an eco-friendly technology.…”

Section: Introductionmentioning

confidence: 99%

Microwave devulcanization of ground tire rubber and applicability in SBR compounds

Simon

Pirityi

Tamás‐Bényei

et al. 2019

J of Applied Polymer Sci

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Rubber recycling is a major environmental challenge, as their covalently crosslinked structure makes it impossible to reprocess via conventional polymer processing technologies. Devulcanization of rubber waste, whereby crosslinks are selectively broken, may provide a solution, as it allows it to be remolded into new shapes. We used two types of ground tire rubbers (GTRs) for this study; mechanically ground and waterjet‐milled GTRs with different particle sizes. First, we revealed the effects of GTR particle size on the devulcanization process. We examined the sol content of the samples before and after devulcanization with two different microwave ovens, a power‐controlled conventional one, and a temperature‐controlled laboratory oven. In the latter one, heating rate and maximum temperature were controlled. We studied the effects of temperature, atmosphere in which the rubber was treated, heating rate, and holding time at maximum temperature. We prepared styrene‐butadiene rubber‐based rubber compounds containing GTR and optimally devulcanized GTR (dGTR_WJ). The physical and mechanical properties of the samples were assessed. The results indicate that both GTR_WJ and dGTR_WJ have an accelerating and a mildly softening effect on curing and dGTR_WJ has a less significant negative effect on mechanical properties: 15 phr GTR_WJ has the same effect as 45 phr dGTR_WJ. © 2019 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48351.

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Section: Introductionmentioning

confidence: 99%

Microwave devulcanization of ground tire rubber and applicability in SBR compounds

Simon

Pirityi

Tamás‐Bényei

et al. 2019

J of Applied Polymer Sci

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“…The last advantage is particularly important since each type of rubber has its own characteristics and needs a specific degree of devulcanization to produce useful materials. The most recent literature has proven the benefits of this recycling technique [9,10].…”

Section: Introductionmentioning

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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“…This type of waste increases annually by around 17 million tons. Recent studies project that, by 2030, about 1200 million tons of tires will be discarded every year [1]. Discarded tires generate problems as accumulation of mosquitos, and cause of unwanted res generating toxic vapors [2].…”

Section: Introductionmentioning

confidence: 99%

“…After ultrasound treatments ne rubber particles of 100-150 µm were obtained with a with a potential devulcanized surface [22]. The energy consumption was around 2.5 times lower than a conventional mill [1]. The use of microwaves at low temperatures is also described as a devulcanization treatment.…”

Section: Introductionmentioning

confidence: 99%

Desulfurization of Vulcanized Rubber Particles Using Biological and Chemical Methods

Valdés¹,

Hernández²,

Morales-Vera³

et al. 2020

Preprint

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Currently, recycling or degradation treatments for tires are an enormous challenge. Despite efforts to dispose of or recycle it, rubber waste is increasing year by year worldwide. To create a rubber-recycling system, several researchers have proposed tire desulfurization. In this study, we compare two methods: one biological, using Acidobacillus ferroxidans in shake 250 mL flask experiments, and one chemical using, for the first time, microwaves and an aqueous solution. The results of these methods were analyzed through sulfate quantification, cross-linking differences, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy with energy disperse spectroscopy (SEM-EDS). We observed that the amount of sulfates generated by the chemical system was 56 mg / L, which was 10-times higher than the biological system, which generated 5.3 mg / L. Similarly, after cross-linking studies, a 36% higher decrease after the chemical treatment was observed. When using FTIR analysis, the disappearance of characteristic bands corresponding to functional groups containing sulfur bonds was observed by treating the sample with both desulfurization mechanisms. Morphological changes on the rubber surface structure was also demonstrated by SEM-EDS analysis with the appearance of holes, cracks and changes in the porosity of the material. This work analyzed two different non-aggressive desulfurization mechanisms that might be used as sustainable methods for rubber recycling processes.

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Microwave treatment in waste rubber recycling – recent advances and limitations

Cited by 88 publications

References 87 publications

Microwave devulcanization of ground tire rubber and applicability in SBR compounds

Microwave devulcanization of ground tire rubber and applicability in SBR compounds

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

Desulfurization of Vulcanized Rubber Particles Using Biological and Chemical Methods

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