Difference Between Natural Rubber and Nitrile Rubber

Origin: The Primary Distinction Between Natural Rubber and Nitrile Rubber

One of the most apparent distinctions between natural rubber and nitrile rubber lies in their sources. Although there are substantial differences in their production methods and suitability for various uses, it isn’t accurate to suggest that one is superior to the other. Both types are polymers, characterized by large, repeating molecules, exhibiting valuable properties that make them integral in numerous industrial and household applications.

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Natural rubber stems from the latex of rubber trees, primarily Heveabrasiliensis, which flourish in regions like South America and South Asia. Harvesting involves 'tapping'—a process where cuts are made to the trees, allowing the creamy sap to flow into containers. As a renewable resource, natural rubber appeals to eco-conscious consumers. However, processing this natural material can pose challenges.

Variability in Product Consistency

Unlike synthetic alternatives, natural rubber offers uniformity in consistency. The method of harvesting and processing tends to yield a standardized product. Known for its elasticity, natural rubber finds utility in diverse applications including wiper blades, machine skirting, drum practice pads, tires, gloves, and rubber mats.

Characteristics of Natural Rubber

While natural rubber possesses several desirable traits, it falls short in resistance to environmental factors like atmospheric oxygen, ozone, oils, and a range of hydrocarbon solvents. Natural rubber products also lack the chemical and thermal resilience that nitrile rubber demonstrates. This limitation makes natural rubber more appropriate for light to medium-duty applications that are non-abrasive. When envisioning natural rubber, think of its unparalleled stretchiness, akin to rubber bands.

Nitrile Rubber: The Man-Made Alternative

In contrast, nitrile rubber (NBR or Buna-N) is a synthetic polymer, developed under precise conditions during World War II to meet the escalating demand for oil-resistant materials as a durable substitute for natural rubber. Its production relies on petroleum-based components, resulting in a copolymer made from acrylonitrile (ACN) and butadiene, making it different from natural rubber in terms of environmental impact and production methods.

Nitrile Rubber Attributes

Nitrile rubber exhibits essential qualities that render it suitable for sealing applications. With higher resistance to both synthetic and natural greases, its use is highly recommended in environments where petroleum products are prevalent. NBR is ideal for crafting long-lasting components for machinery exposed to fuel or lubricants. In commercial kitchens, its resilience ensures prolonged effectiveness against spills from cooking oil or food grease. In laboratories, nitrile sheeting can safeguard against harmful chemical spills.

Nitrile Rubber: A Key Advantage Over Natural Rubber

A significant perk of nitrile rubber is its resistance to heat aging, a characteristic where natural rubber often becomes hard and loses its damping qualities. Furthermore, its synthetic nature allows for easier production, unaffected by seasonal changes or environmental conditions. NBR’s ability to encapsulate gas adds another advantage, making it an optimal option for applications requiring closed-cell sponge materials. Natural rubber, on the other hand, permits gas to escape, limiting its effectiveness in similar scenarios.

Nitrile rubber has evolved significantly from its wartime inception and is now prevalent in various machinery and daily settings.

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Numerous rubber product manufacturers are increasingly favoring various types of synthetic rubber. This trend towards synthetic rubbers over natural alternatives has surged drastically in recent years. Synthetic rubbers can be broadly classified into two groups: general-purpose synthetic rubbers and specialized rubbers. Neoprene and nitrile are two common types in the general-purpose category. The principle difference is that neoprene is produced via emulsion polymerization of chloroprene (2-chloro-1,3-butadiene), while nitrile rubber results from the copolymerization of acrylonitrile and butadiene.

Both nitrile and neoprene share comparable properties, but their unique characteristics make them suited to different applications. They are both elastic and can return to their original shape after stretching. However, nitrile offers exceptional resistance to chemicals, abrasions, and high temperatures, while neoprene excels in weather resistance and overall durability.

What distinguishes nitrile from neoprene in applications involving seals, gaskets, and insulation? Both elastomers provide good resistance to compression set and tearing, with comparable service temperature ranges. Some neoprene grades exhibit excellent abrasion resistance, but nitrile rubber stands out for its durability under elevated temperatures.

An in-depth analysis reveals that while nitrile and neoprene have many similarities, notable distinctions exist. Below, we summarize key properties and benefits, along with their respective applications.

COMPARATIVE PROPERTIES
NITRILE
NEOPRENE
ELONGATION 400% to 600% | 100% to 800%
HARDNESS 35 to 95 |
COMPRESSION SET Good | Good
ABRASION RESISTANCE Good to Excellent | Very Good to Excellent
CRACKING RESISTANCE Good | Good to Very Good
TEAR RESISTANCE Good | Good
FLAME RESISTANCE Poor | Very Good to Excellent
MINIMUM TEMP. -34 °C to -56 °C | -34 °C to -56 °C
MAXIMUM TEMP. +104 °C to +137 °C | +104 °C to +137 °C
WEATHER RESISTANCE Poor | Good
SUNLIGHT RESISTANCE Poor | Good to Very Good
OZONE RESISTANCE Poor | Good
OXIDATION RESISTANCE Good | Good
WATER RESISTANCE Good to Excellent | Excellent
STEAM RESISTANCE Fair | Poor to Good
GAS PERMEABILITY Fair to Good | Fair to Good
CHEMICAL RESISTANCE Generally resistant to gases, aliphatic hydrocarbons, oils, and fuels | Generally resistant to moderate chemicals, acids, ozone, oils, fats, greases, and solvents
NO CHEMICAL RESISTANCE Generally attacked by ketones, ozone, sunlight, aromatic oils, flames, and weather | Generally attacked by esters, ketones, and chlorinated, aromatic, and nitro hydrocarbons

Also read: A Guide To Know The Difference Between Silicone Rubber & EPDM !!

Nitrile vs. Neoprene: Their Applications

Nitrile rubber is ideal for applications requiring oil and fuel resistance, along with abrasion resistance and temperatures reaching up to 280 °F. In mobile machinery and military vehicles, nitrile seals or gaskets are prevalent in carburetor diaphragms, fuel systems, and hydraulic hoses. Nitrile also serves as a reliable choice for durable medical gloves. Its rubber-to-metal bonding capabilities render it suitable for processing industry applications, though it isn’t recommended for fire-resistant sealing and insulation.

Neoprene rubber, on the other hand, effectively resists fire and can withstand sunlight, ozone, and adverse weather conditions. Specific neoprene grades satisfy fire, smoke, and toxicity (FST) standards for mass transit applications, with uses ranging from door and window seals to vibration mounts and shock absorbers. It is also utilized in HVAC systems, electrical enclosures, and fire door weather stripping, alongside noise isolators that reduce vibrations from power transformers. Additional functions include expansion joints and bearing pads in construction.

Choosing the right rubber compound is vital; selecting an inappropriate material can lead to more than just component failure. Depending on the specific needs and requirements of your application, both nitrile and neoprene present a multitude of advantages.

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