Material processing conditions effect on the thermokinetics of end of life tyres

ABSTRACT

In this work, end of life tyres (ELTs) samples were subjected to pyrolysis in a dynamic thermogravimetry set-up under various heating rates between 5°C and 25°C min⁻¹. The experimental design involved dried and non-dried sample results in an isothermal step within the heating program, to be able to compare the data against non-dried samples, to further investigate the effect of drying on the results obtained. The drying of the samples resulted in an increase in the onset temperature by some 30°C. However, cryomilling the ELTs samples showed a great effect in reducing the onset of the degradation curve by about 10°C amongst the same set of experiments. The type of sample, in terms of size and processing/milling condition, had a significant impact on the heat flow properties and calorimetry reported. The exothermic region for the original shavings resulted in an enthalpy of −48 J g⁻¹, whilst the cutting mill samples exhibited an enthalpy increase to −184 J g⁻¹. However, the cryomilled samples showed an enthalpy increase estimated at 139 J g⁻¹.

KEYWORDS:

• Pyrolysis
• end of life tyres
• energy of activation
• kinetics
• FWO
• waste

Nomenclature

BR	=	Polybutadiene Rubber
ICTAC	=	International Confederation for Thermal Analysis and Calorimetry
m	=	Initial mass of rubber samples (g)
mf	=	Final mass of rubber sample (g)
mo	=	Mass of rubber at specific reaction time (g)
N2	=	Nitrogen Gas, NB, Natural Rubber
SBR	=	Styrene Butadiene Rubber
T50%	=	Temperature of 50% Loss (oC)
TG	=	Thermogravimetry
TGA	=	Thermogravimetric Analysis
Tif	=	Inflection Point (oC)
Tmax	=	Maximum Degradation Temperature (oC)
Tos	=	Onset Temperature (oC)
β	=	Heating rate (oC min−1)

Acknowledgment

The lead author/project leader would like to thank the Kuwait Foundation for the Advancement of Sciences (KFAS) and the Kuwait Institute for Scientific Research (KISR) for funding and supporting this research project through the Grant for Project EM085C (PN17-44SC-03). The lead author would also like to thank Kuwait Municipality (KM) for their help and support to the work conducted in this research. The Project Leader would also like to dedicate this report to Mr. Majed Al-Wadi who has retired from service as a Principal Senior Research Technician after a fruitful and prosperous 33 years career at KISR ending his work with duties assigned to this project.

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this article.

Data Availability Statement

Raw data were generated at KISR. Derived data supporting the findings of this study are available from the corresponding author (S.M.S.) on request.

Supplementary Materials File

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15567036.2022.2154870.

CRediT authorship statement

S.M. Al-Salem; Conceptualization; data analysis; fund acquisition; initial and final draft preparation, H.J. Karam; Experimental work; data analysis.

Additional information

Funding

The work was supported by the KFAS [EM085C].