Low-Temperature Mechano-Chemical Rubber Reclamation Using Terpinene as a Swelling Agent to Enhance Bond-Breaking Selectivity.

Lei Guo,Fumin Liu,Xiurui Guo,Kuanfa Hao,Miaomiao Liu,Wenchao Wang,Haichao Liu,Yuan Xu,Donghui Ren

doi:10.3390/polym13244272

Lei Guo, Fumin Liu + Show 7 more

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https://doi.org/10.3390/polym13244272

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Abstract

Common swelling agents used in the mechano-chemical rubber devulcanization process usually require high temperatures to achieve satisfactory swelling effects, which results in severe production of pollutants and reduces the selectivity of bond scissions. This work presents an environmentally friendly swelling agent, terpinene, which can swell the rubber crosslink structures at low temperatures. Both a rubber swelling experiment and a rubber reclaiming experiment with a mechano-chemical devulcanization method are conducted to explore the swelling effects of terpinene. After soaking in terpinene at 60 °C for 90 min, the length elongation of the rubber sample reaches 1.55, which is much higher than that in naphthenic oil and is comparable to that in toluene. When adding 3 phr of terpinene for every 100 phr of waste rubber during the reclaiming process, the bond scissions exhibit high selectivity. After revulcanization, the reclaimed rubbers have a tensile strength of 17 MPa and a breaking elongation of 400%. Consequently, the application of terpinene as the swelling agent in the LTMD method can greatly improve the properties of reclaimed rubbers, thereby enhancing the dual value for the economy and environment.

Highlights

With the rapid development of human society, the demand for rubber tires keeps growing
Based on the mechano-chemical method, we have developed low-temperature rubber reclaiming equipment (LTRE) in our previous work and obtained reclaimed rubbers with much higher properties than those produced by mechano-chemical methods [20,21]
12.90 MPa [33] and 11.00 MPa [17], which are relatively high tensile strength for of the obtained reclaimed rubbers we found in the literature

Summary

Introduction

With the rapid development of human society, the demand for rubber tires keeps growing. The large increase in demand for rubber tires generates large amounts of tire waste. Over three billion tires are produced and one billion tires are abandoned around the world every year [1]. Waste tires do not decompose well due to the crosslinking structure of vulcanized rubber with sulfur bonds [2,3,4], and waste tire piles act as breeding grounds for mosquitoes and other insects that spread disease, especially contributing to the spread of diseases such as malaria and dengue fever. The waste tires still have high value and can be reused/recycled through specific techniques to produce many products, such as playgrounds, sports surfaces, rubber-modified asphalt, and even low-performance tires. The disposal of waste tires is an important issue that concerns the environment and economics [5]

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