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 |
*”プラスチック活用ノート 材料選択のための基礎資料集 四訂版” pg.272. Oi, Hidesaburo and Hirota, Yutaka.