Solid mechanochemical milling process

A solid-state mechanochemical milling process has been developed that combines both the devulcanisation of tyre waste and its mixing into an HDPE matrix [23]. The resulting product was also dynamically vulcanised within the mill, resulting in a thermoplastic elastomer (TPE) that SEM analysis showed to have good interfacial compatibility between the rubber and thermoplastic phases. 

The mechanochemical treatment by ball milling is a very complex process, wherein a number of phenomena (such as plastic deformation, fracture and coalescence of particles, local heating, phase transformation, and chemical reaction) arise simultaneously influencing each other. The mechanochemical treatment is a non-equilibrium solid-state process whereby, the final product retains a very fine, typically nanocrystalline or amorphous structure. At the moment of ball impact, dissipation of mechanical energy is almost instant. Highly excited state of the short lifetime decays rapidly, hence a frozen disordered, metastable strucmre remains. Quantitative description of the mechanochemical processes is extremely difficult, herewith a mechanochemical reaction still lacks clear interpretations and adequate paradigm. 

Mechanochemical processing (MCP) represents a compelling method for the production of nanostructured HA, during which the reaction is activated by mechanical milling. Mechanochemical powder synthesis is a solid-state synthesis method that takes advantage of the perturbation of surface-bonded species by pressure or mechanical forces to enhance the thermodynamic and kinetic reactions between solids [77]. Pressure can be applied via conventional milling... 

Alternative methods such as coprecipitation or the sol-gel route were shown to favom the formation of ATLS already at temperatures around 800°C [37-40]. Mechanical milling of the mixture of source materials (oxides etc) in a planetary ball mill for several hours allows the production of ATLS even at room temperature [41-45]. However, such low-temperature methods have been successfully used only for the synthesis of undoped Lag 33Si6026, the data on the synthesis of the doped ATLS using mechanical milling are absent in the literature. It is well known that mechanochemical activation of the solids is a complex process, with different experimental parameters such as raw materials, type of the mill, rotation speed, ball-to-powder mass ratio, milling time etc. determining the formation of target products and a mechanism of their formation [46-47]. 

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