Mica is a kind of functional filler. Due to its unique properties, it is widely used in plastic modification. It is filled with polymer materials such as polyester, polyamide, polyurethane and polyolefin. The tensile strength and tear resistance of the composite materials are obtained. The strength has been improved to varying degrees. Today, this article introduces some of the application characteristics of mica in plastic modification.
About modified plastics:
Table 2 Properties of polypropylene filled with different materials
2, mechanical properties:
Mica's introduction:
Mica is divided into three categories: muscovite, biotite and lithium mica. Muscovite includes: muscovite and its subspecies sericite and less common sodium mica; biotite includes: phlogopite and biotite.
Mica Mohs hardness of 2 to 3, a specific gravity of 2.7 to 3.5, {001} cleavage completely, can be split into very thin sheet-like, flexible, bendable; volume resistivity 1013-15Ω • cm, up to the breakdown voltage of 200kv Above /mm, the coefficient of thermal expansion is about 7×10-6K-1, high temperature resistance (600°C), and the physical and chemical properties are stable.
Table 1% mica main chemical components
ingredient | content% |
SiO2 | 40-50 |
Al2O3 | 20-33 |
Fe2O3 | 2-6 |
K2O | 9-11 |
Na2O | 0.95-1.80 |
MgO | 1.3-2.0 |
S+P | 0.02-0.05 |
H2O | 0.13 |
About modified plastics:
Plastic modified plastics processing has become an integral part of a technology, it is to obtain plastic products function and weight of the best way environmental protection, economic goals. In recent years, modified inorganic mineral powder material environment-friendly material in people's lives continue to emerge, automotive, appliance, electrical, communication is increasingly becoming the focus of research in the field of plastic modification industry.
Mica contributes to the performance of modified plastics:
1, the mechanical properties:
Mica having a two-dimensional sheet-like structure acts as a plane in plastic to improve the flexural modulus and tensile strength of the article. The physical properties of mica reinforced plastics are between reinforced plastics with glass fibers and mineral fillers (such as talc). Compared with glass fiber reinforced plastics, mica reinforced materials have the advantages of higher modulus and lower warpage. ;
Table 2 Properties of polypropylene filled with different materials
nature | Unfilled PP | PP+40% talc | PP+40%CaCO3 | PP+40% untreated mica | PP+40 treatment mica |
Tensile strength Mpa | 4930 | 4270 | 2770 | 4050 | 6190 |
Bending strength Mpa | 4450 | 6420 | 4720 | 6450 | 9320 |
Bending modulus Gpa | 1.93 | 6.76 | 4.21 | 9.34 | 10.4 |
Notched impact strength | 45 | 45 | 75 | 70 | 65 |
Heat distortion temperature °C | 136 | 162 | 183 | 190 | 226 |
Hardness (D hardness tester) | 68 | 72 | 68 | 68 | 73 |
Shrinkage (longitudinal), % | 2.0 | 1.2 | 1.4 | 0.8 | 0.8 |
2, mechanical properties:
The uniform orientation of the mica in the plastic ensures the product isotropic, prevents warpage and deformation, and gives the product excellent dimensional stability. Mica is the most important mineral filler for PP and PA modified material shrinkage, which significantly reduces the molding shrinkage of the product;
3, heat resistance:
Mica powder has good thermal stability (high temperature resistance above 600 °C), inhibits the generation of volatiles in the thermal decomposition process of plastics while heat insulation, and improves the thermal stability (heat distortion temperature and high temperature creep resistance) of the material.
4, damping performance:
The addition of mica powder contributes a lot to the damping performance of the product. Under the combined effect of the volume effect and the friction effect of the flake filler, the energy loss of the material is the most, and the damping value is larger;
5, optical performance:
Mica is a natural mineral filler with UV shielding performance (above 80% shielding) and mechanical strengthening effect. In some application systems (PP), the UV shielding effect can completely replace the organic UV absorber, greatly reducing the polymer composite. Production cost;
6, electrical performance:
The insulating properties of mica have always been well known and applied. In the field of low-voltage electrical appliances (such as PA modified leakage protection, air-opening, junction boxes, electrical components, etc.), electrical communication, mica filling is an ideal choice.
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