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COMPOUNDING

Understanding Custom Rubber
Compounding and Its Uses

Compounding is about two major things: process optimization and the creation of unique compound mixtures.

Our materials engineers push the boundaries of rubber compounding science. As a result, we continuously strive to improve traditional rubber properties, such as temperature resistance and dampening capabilities, by working with emerging technologies and industry innovators.

Innovation of this nature is what our clients and the future of rubber compounding demand. Our compounds are used around the globe to enhance manufacturing processes and improve manufactured products across a wide spectrum of applications.

But what is rubber compounding, and why is it so important?

rubber beads
CHAPTER 1

What is Rubber Compounding?

Understanding rubber compounding and its myriad uses begins with a simple breakdown of rubber and how it’s made.

rubber collection

What Is Natural Rubber?

Natural rubber is a polymer derived directly from the sap of specific trees and plants (polymer is a long chain of repeating molecules).

While a variety of plants can produce sap for rubber compounding, 99% of the world’s rubber production is derived from the Hevea brasiliensis rubber tree.

Within rubber trees resides a milky liquid called latex, a natural compound that is around 30% rubber. Harvesters tap rubber trees when they cut into the bark and collect the liquid in containers. These containers are then shipped to and later processed at manufacturing facilities.

Although the properties of natural rubber are difficult to change, when processed, natural rubber features good tensile strength, high resilience, and strong tear resistance. Plus, natural rubber is both replenishable and biodegradable, so rubber tree plantations support sustainability in the long-term.

Common natural rubber products include car tires, shoe soles, mattresses, rubber boots, and seal rings.

What Is Synthetic Rubber?

Synthetic rubber is a polymer synthesized under controlled conditions. Typical synthetic rubber products are derived from crude oil byproducts and processed with various solutions, emulsions, and polymerization techniques.

While the quality of natural rubber varies greatly across plant type and growing region, synthetic rubber products are consistent, high-quality, and feature low amounts of impurities. This makes them suitable for a variety of commercial and industrial applications, particularly when used in modern rubber compounding techniques.

Common synthetic rubber products include engine bearings, rubber gaskets, tubing, cords, and many types of molded rubber products.

What Is Rubber Compounding?

Rubber compounding is the process in which elastomers and various other ingredients are selected and integrated to produce rubber products.

A rubber compound is any product made by combining a rubber base (either natural or synthetic) with chemicals to create a product with desirable performance, environmental, or cost-effective characteristics.

Note the distinction between a rubber compound and synthetic rubber.

Synthetic rubbers were designed as a replacement for natural rubber, created by combining different polymers, monomers, and laminates.

Rubber compounds, on the other hand, are specially treated to give a product certain characteristics—such as chemical crosslinking—to make the rubber stronger or more elastic. Such compounding can be applied to either natural or synthetic rubber, depending on its end application.

The Rubber Compounding Process

When rubber is made for industrial uses, the process follows several steps:

1

Compounding:

Chemical processing aids (such as oils, liquids, esters, or waxes) are added to a rubber base to strengthen or stabilize the rubber to suit the desired application or other desired characteristics.
2

Micing

Additional fillers, antioxidants, and antiozonants are incorporated to support vulcanization (see definition below) and protect the rubber from outside elements.
3

Shaping

Rubber is molded to a desired shape through various techniques that include coating, extrusion, and casting.
4

Vulcanization

Also known as “curing,” the rubber is heated with sulfur, accelerator, and activator to form cross-links between rubber molecules and improve the product’s elasticity, viscosity, and hardness.

Pros and Cons of Natural and Synthetic Rubbers

How do natural and synthetic rubbers compare? You can learn more about the different types of rubber and rubber compounds but this quick breakdown compares a few key characteristics:

Natural Rubber

rubber collection

PROs

  • Flexible and resilient by nature
  • Strong physical durability against tears, cuts, and chips
  • Good with adhesion and bonding to metal components

CONs

  • Poor resistance to light and UV rays
  • Poor durability against oxidation and ozone
  • Production costs and viability depend on economic and plant-growing conditions

Synthetic Rubber

synthetic rubber block

PROs

  • Better durability and longevity, especially in extreme conditions
  • Easier and (generally) more economical to produce
  • Much easier to customize to different industrial and commercial applications

CONs

  • Reliant on crude oil, crude petroleum, and natural gas
  • Poor comparative tensile strength
  • Cost of production fluctuates with price of oil and gas

Believe it or not, rubber compounds are almost everywhere, from the tires on your car to the tools in your kitchen. It’s why rubber compounding is such an important industry.

CHAPTER 2

Why is Rubber Compounding so Important Today?

Rubber compounding is one of many production innovations that has improved rubber capabilities over the years. Custom rubber compounds are used throughout a wide spectrum of industries, and it’s the unique properties of specialized compounds that make these rubber products so desirable.

Rubber compounds have been fine tuned to improve everything from increased tolerances to heat, vibration, and noise dampening and have helped define never-before-seen rubber refinement processes.

As a result, rubber compounds are more important today than ever before.

A Brief Overview of the History of Rubber

The earliest instances of the use of natural rubber (the latex sap-based polymer collected from rubber trees) is often attributed to Mesoamerican tribes as far back as 1600 B.C.E. These peoples processed the substance using various saps and vine juices and then rolled the resulting rubber into bouncing balls, used it to hold metal tools to wooden handles, and applied it to clothing to make it water resistant.

Since its discovery, natural rubber hasn’t changed much in how it’s gathered. Efforts around the globe have been made to continue sustainable natural rubber processing, but a number of technological advancements have optimized the material’s functionality.

Important Advancements in Rubber Processing and Compounding

Natural rubber was used sparingly before modern commercial powers started tinkering with it. Its elasticity, water resistance, and ability to rub out pencil marks (which is how rubber got its name) were early-use cases for rubber prior to the 20th century.

But early natural rubber was sticky, smelled bad, and could rot in its uncured state. It wasn’t until pneumatic rubber bicycle tires became popular in the late 1800s that material scientists tried to improve rubber’s natural tolerances.

Important advancements in rubber processing and compounding include:

Vulcanization (1839)

Charles Goodyear discovered that by heating rubber with added sulfur, the material retains its elasticity, has a higher tensile strength, and is resistant to swelling and abrasion. Vulcanization opened the door for more commercial rubber products and a wider range of uses.

01

First synthetic rubber (1909)

A German team led by Fritz Hofmann created the world’s first synthetic rubber by polymerizing isoprene.

02

Neoprene (1931)

Developed by the DuPont company, neoprene (a synthetic rubber) was highly resistant to heat and chemicals like oils and gasoline.

03

World War II and increased synthetic rubber production (1940s and ‘50s)

Synthetic rubbers like Buna-N and Butyl Rubber were created just before World War II.

04

Increased demand for synthetic rubber during the war spurred production and development around the world during the 1940s and 1950s. This led to the invention of more synthetic rubbers (like polyurethane) and more specialized rubber compounds.

Natural rubber, synthetic rubber, and rubber compounds all fill specific niches, as synthetic rubbers and rubber compounds have served to complement natural rubber production.

The Benefits of Rubber Compounds

Remember, rubber compounds are created when additives are combined with natural or synthetic rubber. In general, rubber compounds are customized to optimize properties inherent to natural rubber. Need a rubber that’s more elastic; denser; can withstand more heat? Then you want a custom rubber compound.

Benefits of rubber compounds abound because material scientists continue to test the limits of where rubber compound processing can take them.

Custom rubber compounds perform better than natural rubber counterparts for a number of reasons.

Unique material properties: Chemical crosslinking allows rubber compounds to be harder or softer as required, less susceptible to vibration, more tolerant of high heats, and more resilient when it comes to chemical interactions and longevity.

Increased processibility: Simply put, being able to optimize flexibility and imbue unique properties wouldn’t be possible without the improved processibility of modern rubber compounds.

Noise, vibration, and hardness (NVH) improvements: NVH measurements are standards by which automakers determine how impactful external sounds, vibrations, and the general transfer of energy are to a vehicle’s performance. Rubber compounds and their resulting rubber products have helped refine NVH tolerances throughout the automotive industry.

Products and components made using custom rubber compounds are more specialized than ever before. Modern compounds are responsible for improvements like reduced vibration in rubber bushings. Material scientists like the experts at AirBoss continue to improve existing products while they create never-before-seen rubber compounds.

The more challenging and complex the product, the more specialized and refined the rubber compound will be.

CHAPTER 3

Modern Use Cases for Rubber Compounds

These days, rubber compounds are used in a wide variety of products with unique compound “recipes” designed to suit different applications. More use cases for unique rubber compounds are created every year, and estimates suggest that the global rubber compound market will reach over $9.5 billion by 2026.

Where Is the Majority of Rubber Used? Where Rubber Meets Road

The majority of rubber is used in three broad categories of products: vehicle tires, tubes, and general rubber goods. In fact, a full 75% of global rubber production is used for car tires alone.

Car tires are roughly 56% rubber by weight (28% natural rubber and 28% synthetic rubber), and the remaining percentage is carbon black filler and a variety of chemical agents.

While car tire manufacturing has long been a hot topic in environmental sustainability, tire-makers are turning to new methods of production that rely more on renewable products and less on petroleum-based ingredients. Advancements in rubber compounding have made it easier to create tires that maintain rigorous standards for durability and flexibility while they remain cost effective.

There are limitless applications for rubber compounds. Dedicated industries continue to sprout up around the creation of custom rubber molded products and precision rubber products based on unique compound formulations.

Far from the tires themselves, rubber is a key component in the automotive industry overall. Rubber compounds and components exist in many aspects of automotive production:

  • Gaskets, seals, tubes, and O-rings
  • Fluid transfer systems
  • Body sealing systems
  • Adhesives and coatings
  • Components like air bags and pedals
  • Tires, dashboard coverings, wiper blades
  • Interior latex foam and cushioning

The majority of these rubber components are made from synthetic rubber compounds, though some materials (such as the tires) still use significant amounts of natural rubber.

Common Applications for Rubber Products

Rubber is a cornerstone material for most industries. It’s commonly seen in building construction materials, such as waterworks, conduit seals, and elastomeric bridge bearing parts.

Hospitals use substantial amounts of rubber for examination gloves, surgical tubing, catheters, and specialized prosthetics.

Even outside the industrial world, we find rubber just about anywhere in our day-to-day lives. Just think about some of the household goods you own, and chances are rubber is involved in some way.

For example, your bedroom may feature rubber in your clothing, shoes, bed mattress, cushions, and floor rugs.

Heading over to the kitchen, you’ll see plenty of rubber used in utensils, cookware, potholders, and jar seals, but you’ll also find rubber door/tub gaskets in your dishwasher and coffee maker.

Take a stroll to the backyard, and you’ll notice rubber in things like garden hoses, but it’s also a common component in yard mulches, synthetic turf, and decorative edging. Let’s not forget the pets – rubber is a primary ingredient for your pup’s chew toys, flea collars, brushes, and tennis balls.

Rubber is just about everywhere in modern society. In most cases, rubber products are compounded by specialists to give the product certain characteristics.

Car tires are compounded with carbon black and silica fillers to increase tear resistance, tire life, and traction. Industrial conveyor belts are made of vulcanized rubber to ensure heat resistance and durability. Even the latex in birthday party balloons is treated with coagulants, curing agents, accelerators, and oils before production.

Even for something as simple as a balloon or rubber gasket, rubber compounding relies on precise compound recipes. There’s no other way to ensure that the product will perform as it should.

We can thank the advent of modern rubber compounding techniques for letting us enjoy the wide variety of rubber products in use today. What’s more, rubber compounds and responsible rubber processing has led companies to be more ethical in their material sourcing, AirBoss included.

Rubber is Essential for Healthcare and Defense

It’s easy to think of modern amenities when identifying rubber products around your home, vehicle, or workplace. These are products you interact with daily, and they’re useful to you.

Rubber products that aren’t so common around the house–but are still as useful to those who need them–are products used by healthcare workers, first responders, and military and defense groups around the globe.

AirBoss and its subsidiary, ADG, provide specialized high-quality rubber compounds to industries that need them most, both during times of stress and everyday operation.

High-conflict areas around the world require a wide range of specialized equipment to operate efficiently and effectively. AirBoss Defense Group works with agencies and operators to create, deliver, and maintain equipment and components that excel in some of the most challenging terrain on the planet.

Contact Our Global Experts

To learn more about how we can make a material difference in your business, contact our skilled staff for more detailed information.

CHAPTER 4

Rubber Sustainability and Compounding Safety

Almost since the creation of synthetic rubbers, experts have also recognized the environmental impacts of manufacturing man-made rubber and have worked to reduce these. What’s evolved over the last century—not just for AirBoss but companies around the globe—is a response to manufacturing/business practices that supports environmental, social, and corporate governance (ESG).

This modern approach to company responsibility helps guide businesses into more eco-friendly processes.

Environmental, Social, and Corporate Governance (ESG) Explained

The ideas behind environmental, social, and corporate governance (ESG) aren’t new ones.

Boiled down, ESG is a business strategy that helps define how a company can be more environmentally, socially, and corporately conscious. Again, iterations of ESG practices have been around for ages, but a relatively new push to incorporate ESG standards across all aspects of a business has companies reassessing day-to-day operations.

  • Environmental: Environmental considerations in ESG strategies might focus on the impact a company has on the environment, challenges and opportunities associated with environmental change, or how local ecosystems are influenced by company practices.
  • Social: Social considerations of ESG strategies might focus on how the company is perceived by and interacts with local and global communities.
  • Corporate: Corporate considerations of ESG strategies might focus on company policies and how employees are treated, from the C-suite to the manufacturing floor.

Sustainability at AirBoss

Sustainability efforts at AirBoss are only one piece of the ESG puzzle and have long been considered part of the overall approach the company takes toward manufacturing.

AirBoss operates under the ever-present umbrella of a number of sustainability tenets, regardless of the compound, product, or manufacturing process.

These considerations include but are not limited to:

  • Pollution prevention
  • Waste reduction
  • Recycling and repurposing
  • Sustainable sourcing of materials
  • Adherence to government compliance standards
  • Environmental education and awareness

Furthermore, AirBoss rubber compound recipes comply with AWWA, UL, NSF, ASTM, CSA, and ASSHTO, and NSF Standard 61 specifications, as required. Our teams, from the material scientists to the manufacturing floor managers, ensure that AirBoss processes adhere to strict safety and sustainability guidelines.

This extends beyond company efforts to source natural rubber. AirBoss and its subsidiaries are committed to ethical and sustainable sourcing of rubber compound materials as well as the application of ESG standards throughout the company.

Is It Possible to Produce Sustainable Rubber Compounds?

Complex custom rubber compounds might not be 100% sustainable, but AirBoss continues to find ways to improve sustainability practices.

As mentioned above, ESG-focused manufacturing and sourcing standards help define the company’s comprehensive rubber compounding processes. What’s more, the science and technologies that fuel the company’s day-to-day operations continue to advance in ways that positively influence sustainability efforts.

As a result, AirBoss’s manufacturing practices are cleaner and more environmentally friendly than ever. We’ve also learned that our ESG standards—when applied throughout the company—present unique partnership opportunities.

AirBoss and Electric Vehicles

As technologies advance, so, too, do demands for complex behind-the-scenes components. AirBoss, having worked within the automotive and advanced systems spheres for decades, finds itself uniquely positioned to provide high-quality, environmentally-conscious rubber compounds to emerging markets within these industries.

Making components for electric vehicles (EVs) often means AirBoss must meet a stricter, more specialized standard of not only product quality but safety and material sourcing. Companies that focus on changing the status quo—like electric vehicle makers—expect partners to share their ESG goals.

For AirBoss, partnering with EV makers is a win-win. Our ESG goals already keep us to a higher operating standard. As a result, our products are perfectly suited to serve industries that aim to be kinder to the environment. We’re helping pave the way for a more sustainable manufacturing future.

CHAPTER 5

The Future of Rubber Compounding

Rubber compounding has come a long way since the early days of synthetic rubbers. Over the last 150 years of material advancements, rubber compounds have evolved to solve a wide array of application challenges.

It can be argued that consumer products—and all kinds of manufacturing processes—wouldn’t be the same without rubber compounds.

AirBoss Chemists

We’ve discussed how new technologies demand higher-quality, finer-tuned components. Industries like automotive manufacturing now invest significant resources into emerging markets like electric vehicles, and these new markets present new compounding challenges.

What’s more, the global synthetic rubber market is booming. In 2021, demand for synthetic rubber around the world reached $30.64 billion, and market analysts speculate that this number will continue to rise. Synthetic rubbers and rubber compounds are in higher demand than ever before.

Companies like AirBoss provide forward-thinking partners with both more complex versions of existing components and brand new compounds that solve unique challenges.

What does this mean for the future of rubber compounding?

As long as clients continue to demand new, specialized rubber compounds, AirBoss’s compound scientists will continue to create them.

AirBoss and its subsidiaries are more than just rubber producers. We’re innovators that push the boundaries of what custom rubber compound science can do. We’re making rubber that’s more reliable, compounds that are more capable, and products that redefine how rubber is used by modern manufacturers.

More Demand Means More Specialization and Sustainability

If anything, custom rubber compounding will become more specialized in the face of future manufacturing challenges. Already, research and development at AirBoss is focused on creating compounds that improve in-demand properties of already cutting-edge rubbers.

Improving rubber compounds is as much about optimizing process control these days as it is about the creation of never-before-seen mixtures. We’ve reached the point in material processing where little changes to compound mixtures can provide big results. We work with industry innovators—across a number of enterprise-level markets—to redefine what rubber compounds are capable of doing.

The future of rubber compounding also demands a higher degree of environmental, social, and corporate governance (ESG). Higher than those we’re seeing today. Companies like AirBoss continue to optimize ESG-focused initiatives to make our compounding processes more sustainable. This will always be an organizational goal.

We continue to partner with raw material providers that share our sustainability standards, now and in the future. We believe that both investors and consumers are more focused than ever on supporting companies that build their business around strong ESG-focused practices.

More specialization and an increased focus on sustainable processing will be front and center as the global market demand for rubber compounds continues to rise. The demand from eco-friendly partners for like-minded material providers like AirBoss will only add to the specialization and sustainability push.

Technology Helps Optimize Rubber Compounding Processes

Rubber compounding processes both answer emerging technology challenges (like creating components for electric vehicles) and are influenced by emerging technology advancements. Simply put, we’re using state-of-the-art technology to help define the future of rubber compounding at AirBoss.

We focus on waste reduction, improved proficiency, and maximized efficiency. That’s why AirBoss engineers have incorporated things like 3D printing into our prototyping phases and advanced automated machinery on the manufacturing floor.

In our search for process optimization solutions—and because of our goals to operate more sustainably—AirBoss adopts new technologies to improve our rubber compounding processes.

Rubber Compounds Continue to Solve Unique Material Challenges

Custom rubber compounds—alongside synthetic rubbers—were first created in response to unique material challenges. Rubber compounds continue to provide property enhancements that natural rubber and things like metal and plastic can’t. Today, specialized custom rubber compounds are used across countless industries to improve processes, enhance products, and advance technologies.

AirBoss has succeeded as a company because it diversifies our compound offerings in ways that not only solve customer challenges but continue to push the boundaries of what compounds can do.

Whether that’s increasing temperature tolerances or providing never-before realized dampening capabilities, our rubber compounds are designed to solve material challenges effectively and efficiently.

In an ever-crowded marketplace—where manufacturer margins are slim and competition is fierce—mastering our compound processes has made all the difference.

Lab equipment rubber production