Phyllosilicate kaolin

Phyllosilicates are clay-related compounds with a sheet structure such as talc, mica, kaolin, etc. for which the nucleation mechanism of PET is known to be heterogeneous, although still uncertain. 

Kaolinite is a 1 1 (T-O) phyllosilicate. The fundamental unit of its structure is an extended sheet of two constituents a silica-type layer of composition (Si4O10)4- and a gibbsite-type layer of composition (0H)6A14(0H)204 (see schematic representation in Fig. 10). Ideally, kaolinite crystals are not permanently charged. However, due to isomorphic substitution of Si by Al at the siloxane surface, kaolinite platelets carry a small, permanently negative charge (Van Olphen, 1977). Lim et al. (1980) and Talibudeen (1984) postulate that the permanent charge of kaolins is caused by contamination with small amounts of 2 1 phyllosilicates rather than a consequence of isomorphic substitution. 

SILICATE Contains sio - tetrahedron as basic structural unit Phyllosilicate SiO tetrahedra are linked together to form two-dimensional sheetlike stmcture Kaolinite (Serpentine-kaolin) Kaolinite, Dickite, Nacrite, HaUoysite, Lizardite, Amesite, Beithierine, Cronstedtite, Nepouite, KeUyite, Fraipontite, Brindleyite... 

Giese, R. F. (1988) Kaolin minerals Structures and stabilities In Hydrous Phyllosilicates (exclusive of micas), Vol 19, S. W. Bailey, ed., Miner-alogical Society of America, Washington, DC, 29-66. 

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