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MB:2 İş Merkezi No:160/1
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Aslan Kaucuk


  • Properties of Natural Rubber

    Natural rubber combines high tensile and tear strength with an outstanding resistance to fatigue

    Excellent green strength and tack – has the ability to stick to itself and other materials, making bonded natural rubber products easier to fabricate

    Exhibits excellent dynamic properties with a low hysteresis which leads to low heat generation

    Natural rubber has been successfully used as an engineering material for many years. The following range of properties shows just how versatile of a material natural rubber has proven to be to engineers:

    • —Adjustable hardness from very soft to very hard (ebonite)
    • Appearance and color ranges from translucent (soft) to black (hard)
    • Compounded to meet nearly any mechanical requirement
    • The ability to be electrically insulating or fully conductive
    • Protect, insulate and sealing properties
    • Absorb vibration and silence noise
    • Available in any surface roughness and shape


    Hardness of natural rubber products is determined by the amount and type of filler, as well as the degree of dispersion and the cross-link density. The most common rubber filler in engineering applications is carbon black. For maximum tensile properties approx. 25% volume carbon black is needed.

    To achieve low creep properties, the level of carbon black used should be kept to the minimal acceptable level. If the application in question requires a high abrasion resistance, a small particle size type carbon black should be used. The overall stiffness of a natural rubber product is a result of the modulus of the rubber, the shape of the product and its dimensions, and the mode of deformation.



    The modulus of a rubber compound is also determined by the amount of filler used. To obtain a low modulus product, low reinforcing blacks or non-reinforcing white fillers are normally used. Modulus can also be influenced by the rubber grade, or viscosity, and by the vulcanization system used.

    Low modulus properties can be achieved through the use of a soluble efficient vulcanization (EV)-system, based on soluble accelerators, activators, and also low sulfur levels.


    High Resilience

    As filler level increases in natural rubber compounds, resilience decreases. To achieve high resilience, the filler level must be kept to an acceptable level to maintain physical properties.


    High Damping

    High damping can be reached in natural rubber compounds through filler / oil extensions using highly viscous oil. This effect can also be achieved by blending natural rubber with synthetic rubbers such as SBR or EPDM.

    The damping occurs as a consequence of the synthetic polymers having a Tg not far under the normal service temperatures.


    Low Compression Set

    Vulcanization with organic peroxides can be used to achieve a low compression set for natural rubber products with outdoor applications. However, since peroxide vulcanized products have poor tear strength and are incompatible with anti-ozonants, the common practice is to use conventional vulcanization (CV) or semi-efficient vulcanization (SEV)-systems.


    Low Creep / Relaxation

    For good creep/relaxation resistance the filler content should be kept to a minimum level and make use of medium particle sized blacks. For a low creep/relaxation rate, a soluble EV-system is also advised.


    Cross Link Density

    The degree of cross-linking in natural rubber compounds affects various properties. For maximum tear strength, the cross-link density is slightly lower than for maximum tensile strength and abrasion. Compression set, resilience, creep and relaxation resistances are best at relatively higher levels of cross-linking.


    General Characteristic 

    Durometer Range (Shore A) 20-100
    Tensile Range (P.S.I) 500-3500
    Elongation (Max %) 700
    Compression Set  Excellent
    Resilience – Rebound  Excellent
    Abrasion Resistance  Excellent
    Tear Resistance  Excellent
    Solvent Resistance  Poor
    Oil Resistance  Poor
    Low Temperature Usage (F°)  -20° to -60°
    High Temperature Usage (F°)  Up to 175°
    Aging Weather – Sunlight  Poor
    Adhesion to Metals Excellent