Kinetic Analysis of Pyrolysis and Thermo-Oxidative Decomposition of Tennis String Nylon Wastes.

Haibo Wan,Zhen Huang

doi:10.3390/ma14247564

Abstract

Thermal degradation of nylon-6 tennis string nylon wastes in inert nitrogen and air atmospheres was investigated by means of multiple heating-rate thermogravimetric analyses. The results obtained under the heating rates of 5–20 K/min are compared in terms of degradation feature and specific temperature for two atmospheres. Using nonisothermal data, kinetic analysis was thoroughly conducted using various isoconversional model-free methods, including Starink, Madhusudanan–Krishnan–Ninan, Tang, Coats–Redfern, and Flynn–Wall–Ozawa methods. With these kinetic analysis methods, the activation energy over the entire degradation process was successfully calculated. By means of the model-fitting master-plots method, the first-order chemical reaction model was determined to be the most appropriate mechanism function for describing pyrolysis and oxidative thermal degradation of nylon-6 waste. Using kinetic parameters, satisfactory matching against experimental data resulted using the Coats–Redfern method for both cases. Furthermore, thermodynamic parameters such as changes in entropy, enthalpy, and Gibbs free energy during thermal degradation processes were evaluated.

Highlights

Today, tennis is a very popular sport all around the world and tennis balls, rackets, and strings along with other auxiliary supplies are drastically consumed
Chaihad et al [8] studied the catalytic effect of calcined scallop shell (CSS) on pyrolysis of nylon-6 fishing net waste and found that the decomposition temperature can be decreased by 40–60 K in the presence of catalysts but the yield of ε-caprolactam has reduced to be 66 wt.%
A further examination shows that for the inert N2 pyrolysis process, the Ea values calculated from the Coats–on redmine Redfern (CR) method are 0.33, 0.35, and 1.98 kJ/mol lower on average than those, respectively, from the MKN, Tang, and FWO methods, while in the case of oxidative thermal degradation, the Ea values from the CR method are on average 0.38, 0.39, and

Summary

Introduction

Tennis is a very popular sport all around the world and tennis balls, rackets, and strings along with other auxiliary supplies are drastically consumed. Nylon-6 tennis string wastes in Tianjin, China, were collected for inert and oxidative thermal degradation considerations It is well-known that pyrolysis and combustion are two effective methods to chemically converse plastic wastes into valuable substances for sustainable energy development [1,2]. Nylon-6 has been reported to thermally degrade into ε-caprolactam monomer through a chain end backbiting process or a ring transition state formed within polymer chains [3,4,5] and a yield as high as 83–85 wt.% of ε-caprolactam could be obtained [6,7]. Bozi and Blazsó [10]

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Results

Conclusion