Mica as a filler

History

Historically, crystal of Mica has been used as a transparent plate until glass was discovered. It was also being used as an electrical insulation for a long time.

In the 1960s and the 1970s, Dr. Raymond T. Woodhams from University of Toronto played a central role for the research of Mica. He focused on the high aspect ratio of Mica and discovered its high rigidity which can be applied for plastics. This discovery drew attention on the possibility to use Mica as a sheet reinforcing material and expanded its applied field.

Features

Mica, which is used in various fields as a filler, has a number of advantages the same as other inorganic fillers as listed below.

Functions		Inorganic Filler
Mechanical	Strength	Mica, Glass Fibre, Carbon Fibre, Talc
	Dimensional Stability	Mica, Alumina, Silica, Clay, Talc
Electrical	Insulation	Mica, Clay, Talc, Silica
Thermal	Heat Resistance	Mica, Silica, Talc, Glass Fibre, Carbon Fibre
Sound/Vibration		Mica, Iron, Lead, Iron Oxide
Chemical	Flame Resisting	Mica, Aluminum Hydroxide, Antimony Trioxide, Hydrous Sillicate
	Chemical Resistance	Mica, Alumina, Silica, Clay, Talc
	Water Resistance	Mica, Silica, Clay, Talc

The difference of physical properties of Mica and other inorganic fillers compounded with PBT is illustrated in the following table.

Inorganic Filler	–	Mica	Talc	Wollas-tonite	Glass Beads	Milled Fibre	Glass Fibre
Tensile Strength(MPa)	55	76	58	60	56	60	120
Tensile Elongation (%)	>200	3	2	3	5	4	3
Bending Strength (MPa)	92	130	99	106	105	116	190
Flexural Modulus (GPa)	2.5	8.2	6.0	4.5	4.0	4.4	8.2
Impact Strength (Izod)(J/m)	45	30	28	30	33	32	82
Heat Distortion Temperature (℃)	55	162	150	100	85	120	205
Mold Shrinkage (MD)(%)	1.7	0.7	1.1	1.5	1.5	1.3	0.2
Mold Shrinkage (TD)(%)	1.8	0.8	1.5	1.7	1.6	1.2	1.3