Natural rubber is a key raw material in the manufacturing sector. This elastomer is found naturally throughout the world, making up over 40% of the global supply of all rubber—natural and synthetic. What is rubber made from? Read on to learn more about the properties of natural rubber, its applications, and how it compares to synthetic rubber.
What Is Natural Rubber?
Natural rubber is a naturally occurring substance composed of poly-isoprene (94%), naturally occurring proteins and resins, and small quantities of dirt, ash, and water. Natural rubber is classified as an elastomer, which means it can stretch and revert back to its original shape.
Natural rubber is an extract of the Pará rubber tree (Hevea brasiliensis), a native Brazilian tree now grown in several countries throughout South and Southeast Asia, such as Vietnam, India, Malaysia, Indonesia, and Thailand. Other sources of natural rubber are the common dandelion, rubber fig, and Panama rubber tree. These plants produce latex, which is turned into rubber. Natural rubber is the oldest type of rubber and currently makes up over 40% of total rubber production, which comprises 10 million tons per year.
What Are the Properties of Natural Rubber?
Natural rubber gets its unique properties from three of its components: resins, proteins, and high-cis poly-isoprene. It performs well between temperatures of -58 to 212 °F. Its flexibility and moderate chemical and water resistance make it valuable in a range of applications. These are natural rubber’s other main properties.
Tensile Modulus (TM)
Tensile modulus refers to the force or stress needed to produce an elongation strain in a rubber part. TM increases with an increase in rubber hardness. Rubber with a higher tensile modulus has higher resilience. These rubbers are more difficult to extrude, which is a type of custom fabrication process.
Tensile Strength (TS)
Tensile strength is the amount of force needed to pull apart a rubber sample until it breaks. This property is critical to technical buyers and part designers since it represents the point the rubber will fail when stretched. TS is measured in megapascals or pounds per square inch (psi).
The chemical structure of elastomers, such as natural rubber, gives them inherent hardness. The hardness is adjustable and measurable on a Shore scale by durometer (duro).
Abrasion resistance refers to how well the rubber can resist wearing away due to scraping or rubbing. Rubber with high abrasion resistance is often found in O-rings, gaskets, and seals where the abrasion-resistant properties are well suited.
Also called tear strength, tear-resistance refers to the rubber’s resistance to cutting or tearing. It is measured in pound-force per inch (lbf/in) or kilonewtons per meter (kN/m). This property is a critical consideration when you need edge trim that will touch a sharp object or rough metal edge.
Natural Rubber vs. Synthetic Rubber
The structure of natural rubber consists of long and loosely connected isoprene polymer chains. Natural rubber is elastic because the chains reattach themselves when pulled apart. Unlike synthetic rubbers that consist of petrochemicals, the material in natural rubber is latex sap sourced from rubber trees. Rubber trees are still the best producers of latex for natural rubber, although there are other plants that also produce it.
Advantages of Natural Rubber
- High tensile strength
- Good adhesion
- Compression set values are very low
- Exceptional abrasion and tear resistance
- Good vibration dampening properties
Synthetic rubber is produced through the polymerization of various petroleum-based substances (monomers). Examples of synthetic rubbers include:
- Neoprene: Produced by polymerizing chloroprene
- Butyl rubber (IIR): Derived from copolymerizing isobutylene and isoprene
- Styrene-butadiene rubber (SBR): Produced by copolymerizing styrene and butadiene
- Nitrile rubber (NBR): Made by copolymerizing acrylonitrile and butadiene
Advantages of Synthetic Rubber
- Better electrical insulation
- Temperature resistance
- Improved flexibility at lower temperatures
- Chemical resistance
- Resistance to sunlight, ozone, and weather
- Not impacted by rubber crop health, weather, or rubber plantation stability
Natural Rubber Applications
Natural rubber is a key component in various industries, including aerospace, agriculture, transportation, chemical, and more. These are just some applications of natural rubber.
Contact RD Rubber for Custom Rubber Molding Services
Natural rubber is an important raw material for many industries. Its flexibility, high tensile strength, easy adherence to other materials, and resistance to water, certain chemicals, wear, tearing, and abrasion, make it a great choice for various applications.
Companies in different industries, including military, aerospace, food processing, and pharmaceutical, come to us for precision custom molding of rubber components. We have in-house testing capabilities to ensure the parts you receive from us work and meet your project needs.
To learn more about our rubber products and capabilities, contact RD Rubber.