Rubber compounds from pilot‐scale supercritical carbon dioxide assisted devulcanized rubber: Curing characteristics, mechanical and thermal properties

Abstract Recycling scrap tires is currently the most significant approach for promoting environmentally friendly production and consumption on an industrial scale. The cross‐linked sulfur bonds in scrap tires are broken during the devulcanization process. According to most of the literature, laborat...

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Main Authors: Sangit Paul, Manjur Rahaman, Suman Kumar Ghosh, Ankur Katheria, Narayan Ch. Das
Format: Article
Language:English
Published: Wiley 2025-04-01
Series:SPE Polymers
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Online Access:https://doi.org/10.1002/pls2.70003
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author Sangit Paul
Manjur Rahaman
Suman Kumar Ghosh
Ankur Katheria
Narayan Ch. Das
author_facet Sangit Paul
Manjur Rahaman
Suman Kumar Ghosh
Ankur Katheria
Narayan Ch. Das
author_sort Sangit Paul
collection DOAJ
description Abstract Recycling scrap tires is currently the most significant approach for promoting environmentally friendly production and consumption on an industrial scale. The cross‐linked sulfur bonds in scrap tires are broken during the devulcanization process. According to most of the literature, laboratory‐scale types of equipment were utilized for the studies on supercritical carbon dioxide (scCO2) for devulcanizing scrap tires. However, significant pilot‐scale research and a thorough examination of product reusability are essential to be broadly embraced as a feasible alternative for commercial application. Pilot‐scale supercritical fluid extraction equipment was used in this study to devulcanize crumb rubber obtained from discarded tires. The devulcanization treatment involved utilizing scCO2 and diphenyl disulfide (a decrosslinking agent). The trial adopted optimum process conditions achieved by the Taguchi‐DEAR design of experiments approach to generate devulcanized rubber. The devulcanized rubber is then re‐vulcanized with varying sulfur concentrations ranging from 1 to 2.5 phr. The re‐vulcanized rubber composites are examined by tensile test, dynamic mechanical analyzer, thermogravimetry analysis, and differential scanning calorimetry analysis. Morphology and surface roughness of composites are assessed through field emission scanning electron microscope and atomic force microscope, respectively. The optimal sulfur dose for re‐vulcanization is determined to be 1.5 phr depending on the curing, mechanical, and thermal characteristics of the composites. The lower crosslink density of the re‐vulcanized composites signifies that all crosslink sites are not accessible during the re‐vulcanization process, which can be addressed by employing other curing techniques. At the end, the study investigated the probable devulcanization and re‐vulcanization reaction mechanism. Highlights Thermochemical devulcanization of the waste tire in a pilot‐scale setup. Utilization of CO2 as a supercritical solvent and diphenyl disulfide as a decrosslinking reagent. Vulcanization of devulcanized rubber using sulfur accelerator curing system. Morphological, mechanical, and thermal properties assessed of rubber composites.
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spelling doaj-art-c04dc2380c3e4eaf8230ebd89c3b107e2025-08-20T03:53:23ZengWileySPE Polymers2690-38572025-04-0162n/an/a10.1002/pls2.70003Rubber compounds from pilot‐scale supercritical carbon dioxide assisted devulcanized rubber: Curing characteristics, mechanical and thermal propertiesSangit Paul0Manjur Rahaman1Suman Kumar Ghosh2Ankur Katheria3Narayan Ch. Das4Rubber Technology Centre Indian Institute of Technology, Kharagpur Kharagpur IndiaNano Science and Technology Indian Institute of Technology, Kharagpur Kharagpur IndiaRubber Technology Centre Indian Institute of Technology, Kharagpur Kharagpur IndiaRubber Technology Centre Indian Institute of Technology, Kharagpur Kharagpur IndiaRubber Technology Centre Indian Institute of Technology, Kharagpur Kharagpur IndiaAbstract Recycling scrap tires is currently the most significant approach for promoting environmentally friendly production and consumption on an industrial scale. The cross‐linked sulfur bonds in scrap tires are broken during the devulcanization process. According to most of the literature, laboratory‐scale types of equipment were utilized for the studies on supercritical carbon dioxide (scCO2) for devulcanizing scrap tires. However, significant pilot‐scale research and a thorough examination of product reusability are essential to be broadly embraced as a feasible alternative for commercial application. Pilot‐scale supercritical fluid extraction equipment was used in this study to devulcanize crumb rubber obtained from discarded tires. The devulcanization treatment involved utilizing scCO2 and diphenyl disulfide (a decrosslinking agent). The trial adopted optimum process conditions achieved by the Taguchi‐DEAR design of experiments approach to generate devulcanized rubber. The devulcanized rubber is then re‐vulcanized with varying sulfur concentrations ranging from 1 to 2.5 phr. The re‐vulcanized rubber composites are examined by tensile test, dynamic mechanical analyzer, thermogravimetry analysis, and differential scanning calorimetry analysis. Morphology and surface roughness of composites are assessed through field emission scanning electron microscope and atomic force microscope, respectively. The optimal sulfur dose for re‐vulcanization is determined to be 1.5 phr depending on the curing, mechanical, and thermal characteristics of the composites. The lower crosslink density of the re‐vulcanized composites signifies that all crosslink sites are not accessible during the re‐vulcanization process, which can be addressed by employing other curing techniques. At the end, the study investigated the probable devulcanization and re‐vulcanization reaction mechanism. Highlights Thermochemical devulcanization of the waste tire in a pilot‐scale setup. Utilization of CO2 as a supercritical solvent and diphenyl disulfide as a decrosslinking reagent. Vulcanization of devulcanized rubber using sulfur accelerator curing system. Morphological, mechanical, and thermal properties assessed of rubber composites.https://doi.org/10.1002/pls2.70003atomic force microscopydevulcanizationdynamic mechanical analysisre‐vulcanizationrubber recyclingsupercritical carbon dioxide
spellingShingle Sangit Paul
Manjur Rahaman
Suman Kumar Ghosh
Ankur Katheria
Narayan Ch. Das
Rubber compounds from pilot‐scale supercritical carbon dioxide assisted devulcanized rubber: Curing characteristics, mechanical and thermal properties
SPE Polymers
atomic force microscopy
devulcanization
dynamic mechanical analysis
re‐vulcanization
rubber recycling
supercritical carbon dioxide
title Rubber compounds from pilot‐scale supercritical carbon dioxide assisted devulcanized rubber: Curing characteristics, mechanical and thermal properties
title_full Rubber compounds from pilot‐scale supercritical carbon dioxide assisted devulcanized rubber: Curing characteristics, mechanical and thermal properties
title_fullStr Rubber compounds from pilot‐scale supercritical carbon dioxide assisted devulcanized rubber: Curing characteristics, mechanical and thermal properties
title_full_unstemmed Rubber compounds from pilot‐scale supercritical carbon dioxide assisted devulcanized rubber: Curing characteristics, mechanical and thermal properties
title_short Rubber compounds from pilot‐scale supercritical carbon dioxide assisted devulcanized rubber: Curing characteristics, mechanical and thermal properties
title_sort rubber compounds from pilot scale supercritical carbon dioxide assisted devulcanized rubber curing characteristics mechanical and thermal properties
topic atomic force microscopy
devulcanization
dynamic mechanical analysis
re‐vulcanization
rubber recycling
supercritical carbon dioxide
url https://doi.org/10.1002/pls2.70003
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