While you probably use products just about every day that include rubber, you might not have realized that different kinds come from different sources. Natural and synthetic rubbers each have their unique properties based on how they are processed and are both useful for different applications.
Rubber, the versatile material that bounces, stretches, and provides grip, is essential to our daily lives. Whether it’s the tires on our cars or the bands that keep things together, rubber plays a crucial role. But did you know that not all rubber is created equally? There are two main types with different characteristics: natural rubber and synthetic rubber.
Natural Rubber
Sourcing and Production
Natural rubber, as the name suggests, is derived from natural sources – rubber trees, primarily the Hevea brasiliensis species. Some of the earliest evidence of its use is from Native Americans thousands of years ago, followed by the first major production efforts beginning in the 18th century. The manufacturing process begins with tapping the trees and collecting the sap, which contains latex.
The latex is then transported to a processing facility, where it is mixed with acid to induce coagulation. Additives such as carbon black and silica may also be included based on the specific properties desired. Once the clumps are formed, they are rolled into a flat sheet and dried. The rubber is then vulcanized, which involves heating the material with chemicals and creating cross-links between the polymer chains, thus improving strength, elasticity, and resistance to heat, chemicals, and wear.
Properties and Advantages
Natural rubber tends to be quite durable and resilient, with a unique set of chemical and physical traits. Some of its main properties include:
- Excellent Elasticity: Natural rubber offers exceptional stretchability and rebound. It can stretch many times its length and return to its original shape, making it ideal for applications that require strength and flexibility.
- Low Heat Generation: Natural rubber generates less heat during rolling and friction, contributing to better performance and longevity.
- Biodegradability: Natural rubber is biodegradable, which means it can break down naturally over time, reducing environmental impact.
- Cold Resistant: Natural rubber maintains flexibility in a wide range of temperatures and is resistant to breaking between -58 and 212 degrees F.
- High Durability: Natural rubber is impressively strong, and does not easily get cut, chipped, or torn. It is resistant to repeated stress, wear, and abrasion.
Uses and Applications
Natural rubber is widely used in a variety of industries. It’s favored in situations where high resilience and durability are required. A few of its main applications are:
- Tire Manufacturing: Because of its excellent elasticity, resilience, and low heat buildup during rolling, natural rubber is a vital component in tire manufacturing. It provides grip, durability, and the ability to absorb shocks, making it ideal for off-road automotive, construction, aerospace, and other applications that require the ability to withstand harsh conditions.
- Flooring: Its water and wear resistance make natural rubber an excellent option for flooring and fatigue mats in gyms, animal shelters, and commercial kitchens where padding and anti-slip surfaces are needed.
- Clothing: The flexibility, comfort, and waterproof qualities of natural rubber make it a preferred choice for the production of various types of footwear, including sneakers, rain boots, and flip-flops, as well as other types of clothing that require stretch, such as waistbands and wetsuits.
- Latex Products: Natural rubber latex can make gloves, balloons, pencil erasers, and paint. Its natural stretchiness and flexibility make it well-suited for products that require a significant amount of elasticity.
- Industrial and Mechanical Goods: Natural rubber is used to manufacture conveyor belts, gaskets, seals, hoses, and various industrial goods. Its resilience and durability are valuable in these applications.
Synthetic Rubber
Sourcing and Production
Synthetic rubber is a man-made creation, invented during WWII when the United States was cut off from international natural rubber supply lines and needed an effective alternative to continue manufacturing essential military supplies. It is produced through chemical processes by polymerizing various petrochemical compounds derived from crude oil and natural gas. The compounds undergo a chemical process known as polymerization, where individual molecules (monomers) are chemically bonded to form long chains or networks of polymer molecules.
Various additives, such as antioxidants, accelerators, and curing agents, are mixed with the polymer to enhance specific properties like heat resistance, durability, and curing characteristics. Fillers like carbon black or silica may also be added to improve strength and wear resistance. The rubber is then cured via vulcanization.
Properties and Advantages
The versatility of synthetic rubber lies in the ability to customize its properties. Some are designed for high-temperature resistance, while others prioritize oil resistance, chemical resistance, or flexibility. Some of the main advantages of this type of rubber include:
- Versatility: Different types of synthetic rubber can be formulated for particular properties, such as oil resistance, heat resistance, or chemical resistance, making it suitable for a wide range of industrial applications.
- Damage Resistance: Synthetic rubber is highly resistant to chemicals, oxidation, and abrasion. This means it does not deteriorate easily and has excellent longevity.
- Weather Resistance: Synthetic rubber can withstand extreme temperatures, especially high heat, and is not heavily affected by outdoor conditions such as sunlight, and ozone exposure, making it less susceptible to degradation.
- Adhesion: Some synthetic rubbers can bond well with other materials, allowing them to be used as adhesives and sealants to join various components. Varieties with a tacky surface are excellent for applications where grip is essential.
- Tear Resistance: Synthetic rubber can be stretched twice its length without deformity. It can handle significant stress and immediately return to its original shape and size without tearing or permanent damage.
Uses and Applications
Synthetic rubber offers a wide range of applications due to its versatility and ability to be tailored for specific purposes. It can have a variety of uses, such as:
- Tire Manufacturing: Synthetic rubber is a key component in passenger tire manufacturing. Different synthetic polymers are blended to achieve the desired balance of properties such as tread wear resistance, traction, and impermeability.
- Automotive Components: It is also used in various other automotive components, including engine bearings, clutches, seals, and hoses. Synthetic rubber’s durability and resistance to automotive fluids make it ideal for these applications.
- Industrial Products: Synthetic rubber is used in cable installation, belts, gaskets, and rollers in machinery. Its resistance to abrasion, chemicals, and extreme temperatures makes it suitable for industrial use.
- Commercial Goods: From wearable items like hair ties, boots, and raincoats to household items such as dishwashing gloves, jar seals, and garden tools, synthetic rubber can be found in many items people use every day due to its impressive versatility.
- Medical and Laboratory Equipment: Due to its high durability and resistance to chemicals, synthetic rubber is excellent for lab flask corks, fatigue mats, and prosthetics.
Outside of their functional properties and applications, one of the biggest deciding factors when choosing between natural and synthetic rubber is typically the cost. The latter often tends to be cheaper, which makes it the best option when price point is critical. However, this is not always the case, as both types are subject to fluctuations in market rates of necessary ingredients, which can change due to a variety of factors.
In the world of rubber manufacturing, natural and synthetic rubber have unique roles and advantages. Natural rubber shines in its eco-friendliness and exceptional elasticity, making it a top choice for tires and various consumer products. On the other hand, synthetic rubber offers versatility, allowing engineers to fine-tune properties for specific needs, whether heat resistance, chemical resistance, or durability. Together, both of these types of rubber keep our world rolling, bouncing, and gripping, meeting many significant industrial and consumer demands.
To learn about rubber mixing and weighing at American Phoenix, visit our services page. And for more rubber-related content (our specialty), check out 5 Quick Facts About the Rubber Manufacturing Industry and Seven New Uses for Old Tires.
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