52
nanotube-based polymer composites reported. The data presented above suggest
that the application of functional fillers or the suitable modification of GTR allows
the sustainable development of tire waste recycling and upcycling technologies. The
functionalization and modification of GTR will be discussed in the next section.
4.3 Functionalization and Modification of GTR
Most of the current applications for GTR are based on their mixtures with different
matrices (polymers, bitumens and concretes). The main practical problem of this
approach is the weak compatibility between the GTR and most of the matrices studied. GTR is constituted by a crosslinked network with low affinity for other materials. For mixtures or composites with GTR, the resulting structure shows two phases
that are not interfacially linked, which leads to poor mechanical properties of prepared materials. This phenomenon strongly limits the potential application of
GTR. In order to provide a solution to this problem, a series of modifications have
been proposed involving changes in the surface and structure of GTR. The main
objective is to functionalize and/or modify the GTR surface allowing the physical
interfacial interactions with the other components of the composition or additional
chemical reactions in the matrix-GTR filler boundary. Data from the literature has
shown that efficient functionalization and modifications of GTR can be performed
using different strategies, which were presented in this chapter.
4.3.1 Reclaiming/Devulcanization
Many reclaiming methods of rubber wastes have been developed, which were
described comprehensively in the works of Movahed et al. (2016) and Asaroa
et al. (2018). Reclaiming process (called also devulcanization in the literature)
allows breaking of the three-dimensional crosslinked network present in
GTR. However, it should be noted that with scission of disulfide crosslinking
bonds (devulcanization), the partial degradation of the polymer main chain
(reclaiming) usually also occurs. The mechanism of crosslinked network scission
and the adequate control of conditions allow to limit of the unwanted phenomenon
of the degradation of the main chain, which affects the process selectivity (devulcanization vs. reclaiming).
Recent research trends in this field are focused on combining low temperatures
and a short-time of reclaiming in order to reduce energy consumption and production costs (Dobrotă and Dobrotă 2018). In addition, the application of mild conditions in GTR reclaiming limit the emission of hazardous volatile organic compounds
generated during the scission of disulfide bonds and the degradation of the main
chain (Gągol et al. 2015).
Ł. Zedler et al.
nanotube-based polymer composites reported. The data presented above suggest
that the application of functional fillers or the suitable modification of GTR allows
the sustainable development of tire waste recycling and upcycling technologies. The
functionalization and modification of GTR will be discussed in the next section.
4.3 Functionalization and Modification of GTR
Most of the current applications for GTR are based on their mixtures with different
matrices (polymers, bitumens and concretes). The main practical problem of this
approach is the weak compatibility between the GTR and most of the matrices studied. GTR is constituted by a crosslinked network with low affinity for other materials. For mixtures or composites with GTR, the resulting structure shows two phases
that are not interfacially linked, which leads to poor mechanical properties of prepared materials. This phenomenon strongly limits the potential application of
GTR. In order to provide a solution to this problem, a series of modifications have
been proposed involving changes in the surface and structure of GTR. The main
objective is to functionalize and/or modify the GTR surface allowing the physical
interfacial interactions with the other components of the composition or additional
chemical reactions in the matrix-GTR filler boundary. Data from the literature has
shown that efficient functionalization and modifications of GTR can be performed
using different strategies, which were presented in this chapter.
4.3.1 Reclaiming/Devulcanization
Many reclaiming methods of rubber wastes have been developed, which were
described comprehensively in the works of Movahed et al. (2016) and Asaroa
et al. (2018). Reclaiming process (called also devulcanization in the literature)
allows breaking of the three-dimensional crosslinked network present in
GTR. However, it should be noted that with scission of disulfide crosslinking
bonds (devulcanization), the partial degradation of the polymer main chain
(reclaiming) usually also occurs. The mechanism of crosslinked network scission
and the adequate control of conditions allow to limit of the unwanted phenomenon
of the degradation of the main chain, which affects the process selectivity (devulcanization vs. reclaiming).
Recent research trends in this field are focused on combining low temperatures
and a short-time of reclaiming in order to reduce energy consumption and production costs (Dobrotă and Dobrotă 2018). In addition, the application of mild conditions in GTR reclaiming limit the emission of hazardous volatile organic compounds
generated during the scission of disulfide bonds and the degradation of the main
chain (Gągol et al. 2015).
Ł. Zedler et al.