Synthesis and Property of Silicone Polymer from Chrysotile Asbestos by Acid-Leaching and Silylation

Hydrothermal conversion of chrysotile asbestos using near supercritical conditions

“…According to the literature various acids such as HCl, oxalic acid, phosphoric acid are used for the destruction of the crystal body of chrysotile asbestos [21][22][23]. To make the process more effective and attractive, additives such as acetic acid in different concentrations of less than 1% were used.…”

Polysiloxanes derived from chrysotile asbestos via acid‐leaching and silylation processes

“…That is, during the process, the selective leach of the brucite layer of magnesium hydroxide from chrysotile [Mg 3 Si 2 O 5 (OH) 4 ] by an acid affording a silica2–4 and treatment of a tetrahydrofuran (THF) solution of the silica with a silylation reagent,5–8 such as chlorodimethylvinylsilane (VDMSCl) (Scheme ), were successfully combined and performed to give a silicone polymer. The obtained polymers were totally soluble in various organic solvents 1. This should be a potential method for the disposal and utilization of hazardous chrysotile asbestos wastes as a nontoxic and valuable material.…”

“…Recently, we reported the transformation of chrysotile asbestos into a silicone polymer through several steps including acid leaching and silylation 1. That is, during the process, the selective leach of the brucite layer of magnesium hydroxide from chrysotile [Mg 3 Si 2 O 5 (OH) 4 ] by an acid affording a silica2–4 and treatment of a tetrahydrofuran (THF) solution of the silica with a silylation reagent,5–8 such as chlorodimethylvinylsilane (VDMSCl) (Scheme ), were successfully combined and performed to give a silicone polymer.…”

“…The silica obtained by the acid leaching of the brucite layer has a fibrous morphology originating from the chrysotile. In addition, the resulting polymer from the silylation reaction has an MQ‐type silicone polymer structure and may mainly consist of a ladder‐like main chain, again probably affected by the original silicate sheet structure in the starting chrysotile or the leached silica 1. Therefore, the polymer produced in this process should be characteristic and may have some novel functions.…”

“…In this study, further investigations on the conversion process from the chrysotile asbestos to the silicone polymer were carried out. Two types of chrysotile asbestos, such as serpentine slag1 and Class 4 chrysotile as the starting material and various reagents, as shown in Scheme , for the silylation step were used. The structure and thermal property of the obtained polymers were examined.…”