MICA-AN UNIQUE PLASTIC FILLER
Mica have been recognised as an unique Inorganic Plastic filter because of its exceptional properties not found in any other filters. Some of the useful properties and combinations of characteristics of mica are:
1. It has an outstanding mechanical, thermal, electrical and chemical properties rarely found in any other products.
2. It is transparent, flexible and elastic and can be ground to very fine particles with a high-aspect ratio which are specially suited for reinforcing filters.
3. It is chemically inert and can easily resist actions of heat, light, water, oil, solvents, alakalies and various chemicals.
4. It is moisture proof, infusible, non-combustible having high tensile and flexural strengths and modules of elasticity.
5. It has an excellent anti-sticking and anti-friction properties and prevents massing and movements of sulphur at the same time permits its air bubbles to escape.
6. it has low density (2.8 to 3.0 g/cm ) which helps to reduce added resin weight and maximise resin savings. Its bulking value is about 0.34 cm g.
7. It has low specific gravity (2.85) and as such mica particles tend not to settle but stay uniformly dispersed and wetting out andf is completely soluble in water.
8. It uis relatively soft, with moh's hardness of 2.5 to 3.0 which further helps to minimise equipment wear and abrasion during processing. It also eliminates abrasive effects on steel plates.
9. It has high degree of whiteness (81-85%)
10. It has high surfac area and high-aspect-0ratio.
11. It is a non-asbestos facilitation filter and acts as a noise control and vibration damping agent.
12. It is strogly absorbent to Ultra Violet radiations prevents penetration of destructive sun-rays, moisture, heat and atmospheric gases, etc. and thereby helps to increase the service life and decorative value of the end products.
13. It serves to reinforce, stiffen, harden and strengthen the product and prevent the microscopic ruptures, reduce warping, increase service temperature, lower thernal expansion and conductivity, improve electrical and vibration damping properties and adherence to substrate. It doen not change color at elevated temperatures or in the presence of resins and other mineral additives.
14. Mica particle both transmit and reflect light producing decorative effects and designs. Since Mica platelets tend to orient parallel to the mould surface, it imparts a better surface appearance than those attributed by glass fibre reinforcement and superior to those obtained with fillers such as calcium carbonate talc etc.
15. In formed thermoplastics mica promotes uniform cell structure, persuming acting as a nucleating agent, lower its density, reduce cost, add low temperature impact resistance and reduce flammability.
16. Additionally mica is a relatively inexpensive additive providing significant cost saving over glass. Glass and mica are among low cost inorganic flake reinforcements. Glass flakes have a modulus of 10.5X10 psi as compared to the same mica have more than double the module (25X10) of glass at about 10 percent of the cost.
Some of the outstanding advantage of use of mica as a filler in plastics are:
MECHANICAL PROPERTIES : The addition of mica in plastics normally increases its tensile and flexural strengths. Mica has a pronounced effect on modulus of elasticity at the same time decreases its elongation. It further improves the notched impact strength of same polymers.
THERMAL PROPERTIES : The incorporation of mica reduces thermal expansion and helps to eliminate the non-uniform thermal shrinkage and causes warping it also reduces mould shrinkage and facilitates mould release. Mica has a variable and generally negative effect on impact strength.
ELECTRICAL PROPERTIES : Mica enhances the dielectric, heat-resisting and insulating properties of plastics. Mica fillers improve deflection temperature. Mica, being a natural inorganic mineral, is among the most radiation resistant dielectric material and thus is able to absorb upto 80% of incident ultra-violet radiation protecting plastics against degradation.
CHEMICAL PROPERTIES : Mica, being a stable and completely inert to the action of water, acids (with exception of concentrated sulphuric/phosphoric acid mixtures and hydrofluric acid), alkalies, conventional solvents, oils and virtually unaffected by atmospheric action. Its flake like form and virtually unaffected by atmospheric action. Its flake like form provides an excellent barrier to chemical attack and therefore is most suitable for use in polyster or spray protective coatings.
Mica provides cost effective improvements in the critical properties for a wide range of thermoplastic and thermoset composites including those based on PP, HDPE, HMWPE/PP/PE, PA, TPX, ABS, HIPS, PST, PBT/PET, PES, PVDE, PVC, SAN, etc.
POLYPROPYLENE(PP) : By far, PP is the most popular application of mica. PP is commonly filled with 20% or 40% mica, although loading upto 60% have been recorded. A 40% loading of mica increases the flexural strength by 45% from 4450 to 6450 psi. It increases the flexural modulus from 0.193 to 0.934 x 106 psi, and heat deflection temperature at 264 psi rises from 136oF to 190oF. Surface coated mica further increases tensile strength, flexural strength and modulus and heat deflection temperature. THE PRINCIPAL END-USER OF MICA FILLED PP IS THE AUTOMOBILE INDUSTRY. PP filled with 20% and 40% loadings of mica along with calcium carbonate and talc are used as ceiling fan blades, instrument panels, heater housing and tail-light retainers in automobiles. It is used in door panels, seat backs, etc. Mica is also extensively used as a filler in fire-retardant PP FOAM. A PP foam with 20% mica loading is equal in weight to fulfilled solid PP, at the same time provides a saving of 15% lower material costs, three times greater stiffness, 30% greater flexural strength and 15% greater heat deflection. A 30% mica-filled reinforced PP foam are used in side components for underground swimming pools.
Other major end users for PP are : Blow boulding medical containers and consumer packing Extrusions (Coatings, fibres/filaments, films, conduit, pipes, sheets, wires and cables). Injection moulding appliances (furnitures, housewares, luggage boxes, medical packaging, etc.).
HDPE : A 30% mica-filled HDPE treated with AZ-cup coupling agent have been used in blow-moulded rear seat back panels in automobiles. The panels which is hollow, ribbed on one side and has an average thickness of 3.4 mm, could withstand service temperatures of upto 180oF and have successfully replaced aluminium panel.
NYLON 6/6 : Mica-filled reinforced nylons are extensively used for many automobile parts, including grill opening panels, under the-bonnet parts, louvers and headlight covers. Mica provides a higher tensile strength, heat deflection temperature and notched izod impact than wollastonite, calcium carbonate, glass beads, alumina trihydrate and unfilled resins. Mica helps to reinforce nylons.
PET AND PBT : PET and PBT are filled with mica to impart particular electrical properties of these resins in addition to improve their strength and stiffness. Experiments on the inclusion of mica in unsaturated polyester bulk moulding compounds show that mica-filled compound, helps to replace 33% glass fibre and 3% calcium carbonate has similar physical properties but have a higher arc resistance and 30% higher flow.
ABS : Engineering plastics, such as ABS filled with 30% mica and 20% glass fibre by weight of resin provides a higher flexural tensile and compressive strength than ABS filled with either 20% glass fibre or 50% mica.
MICAMAFCO is India's specialist producer of a high-aspect-ratio surface treated micas most suitable for plastic polymers, established over a century. We are committed to a steady supply of consistent quality as per customer's specifications and are dedicated to satisfy customers who seek a most perfect material at cost-effective price. We specialises in large volume production and maintain large stocks to assure regular and timely deliveries as per commitment.
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