Rubber fillers
- 1. Created By : D.W.W.Sewwandi Sp. Material Science and Technology 1
- 2. Characteristics of a filler that determine the properties a filler will impart to a rubber compound are, 1. Particle size 2. Surface are 3. Structure 4. Surface Activity 2
- 3. 1. Particle Size Size of the filler particle should not exceeds the polymer interchange distance. If so it can contribute to elastomer chain rupture on flexing or stretching. According to the particle size , there are generally three types. Diluents, Semi-reinforcing , Reinforcing filler 3
- 4. 1. Particle Size 4 Particle Size (nm) Description 1000 – 10 000 Used primarily as diluents, no significant effect on rubber propertes 100 - 1000 Semi reinforcing fillers ,Improve strength and modulus properties 10 - 100 Reinforcing fillers , significantly improve rubber properties
- 5. 5 Figure 01:- Classification of fillers
- 6. 2. Surface Area Particle size is generally the inverse of surface area. For reinforcement, filler must make intimate contact with elastomer chains Fillers with high surface are have more contact are available , and thus have a higher potential to reinforce the rubber chain. 6
- 7. 3. Structure Fillers effective shape is more importance than the shape of an individual particle Reinforcing fillers such as Carbon black and Precipitated Silica have generally round primary particle but function as anisometric acicular aregates. 7
- 8. 3. Structure The more aggregate deviate from a solid spherical shape and the lager its size, the higher its structure. The higher its structure, the greater its reinforcing potential 8
- 9. 4. Surface Activity The specific activity of the filler surface per cm2 of filler- elastomer interface is determined by the physical and chemical nature of the filler surface in relation to that of the elastomer Non polar fillers are suitable to nonpolar elastomer and polar filler are suitable with polar elastomer. 9
- 10. • Carbon Black 10 Figure 02:- Carbon black particles available in different sized
- 11. Carbon Black This is a material of major significance to the rubber industry. Carbon black is essentially elemental carbon in the form of fine amorphous particles. Individual round carbon black particles form aggregated, which may be clumps or chains of various sizes and configurations. 11
- 12. Carbon Black 12 Table 01:- Classification of Carbon black according to ASTM standards
- 13. Carbon Black When Carbon Black is compounded with rubbers, tensile strength, tear strength, modulus and abrasion resistance are increased 13
- 14. Clays manufactured from naturally occurring hydrated aluminium silicates. The particles of clays are hexagonal shaped platelets. The type of clays used by the rubber industry are known to the clay industry as kaolin deposits of a hydrous aluminium silicate, known as kaolinite. 14
- 15. Clays Four types 1. Soft clays 2. Hard clays 3. Calcined clays 4. Treated Clays 15
- 16. Clays Four types 1. Soft clays - semi-reinforcing, have lower modulus, tensile strength and abrasion resistance than hard clays 2. Hard clays - gives an expected higher level of reinforcement than that found for the soft clays 16
- 17. Clays 3. Calcined clays - have been heat treated to remove the combined water, improve the electrical resistance of rubber compounds. 4. Treated Clays - Treatment of water- washed hard china clays with silanes with pendant amino or mercapto groups enables them to give improved reinforcement to rubber compounds. 17
- 18. Silica Three specific types 1. Ground mineral silica 2. Precipitated silica 3. Fumed or pyrogenic silica 18Figure 03:- Precipitated silica
- 19. Silica 1. ground mineral silica ◦ generally available below 300 mesh in size (5 m2/g) ◦ used as a cheap heat resistant filler for a variety of compounds. ◦ There is no effect on the rate or state of cure 19
- 20. 2. precipitated silica ◦ Produced by the controlled neutralization of dilute sodium silicate by either concentrate sulfuric, hydrochloric, or carbonic acid. ◦ particle sizes in the range of 10-40 nm. • The surface of silica is strongly polar in nature 20
- 21. 2. precipitated silica ◦ has a chemically bound water content of 25% with an additional level of 4-6% of adsorbed water. ◦ The use of additives to make the surface of precipitated silica less hydrophilic and more “rubberphilic” facilitates incorporation, dispersion, and more intimate filler-elastomer contact during compounding additives. 21
- 22. 2. Precipitated silica ◦ has a chemically bound water content of 25% with an additional level of 4-6% of adsorbed water. ◦ The use of additives to make the surface of precipitated silica less hydrophilic and more “rubberphilic” facilitates incorporation, dispersion, and more intimate filler-elastomer contact during compounding additives. ◦ Addives uded -silanes, titanates and zirconates 22
- 23. 3. Fumed Silica ◦ prepared by burning volatile silicon compounds such as silicon tetrachloride. ◦ contains less than 2% combined water and generally no free water. ◦ not generally used in conventional rubber compounding but find application with silicone rubber. 23
- 24. Calcium Carbonate Several types available. ◦ Prepared Ground Limestone - particle size less than 100 mesh, used as an inertdiluent and cheapening filler for rubber compounds • Ground Chalk, Whiting - white powder produced inparticle sizes down to 30 nm, used as a diluent filler giving moderate hardness and a reasonably high resilience at high loadings. • Precipitated Whiting - particle sizes is available, from 20 μm to 50 nm, semi-reinforcing resulting in compounds with better physical properties than with use of ground whiting 24
- 25. Miscellaneous Fillers ◦ Magnesium Silicate (Talc)- prepared by grinding of naturally occurring deposits, Very finely ground materials are used as reinforcing fillers, Larger particle size products are used in antistick applications. • Mica Powder- Washed and ground, natural mica of 200-300 mesh acts as a laminar filler, giving good heat resistance and low gas permeability. • Titanium Dioxide- because of its cost, titanium dioxide is usually only used as a whitening agent for rubber compounds. 25
- 26. Miscellaneous Fillers ◦ Barium Sulphate - can be supplied ground directly from the mineral, or from the precipitation of barium salts. ground natural barium sulfate, is used in acid resistant compounds because of its inertness, and as a high gravity filler where weight is desired. ◦ Calcium Sulphate - Produced by grinding from gypsum, or hydrated plaster of Paris 26
- 27. 1. Simpson, R.B., (ed.) Rubber Basics. Shropshire:Rapra Technology Limited, 2002. 2. Ciullo, P.A., Hewitt, N; The rubber formulary. New York: Noyes publications, 1999. 27
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