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Polymer stabilisers: Antioxidants, light stabilisers, and UV stabilisers


polymer granulates

Polymer stability is essential for ensuring the longevity and functionality of various materials in a wide range of applications. Stable polymers retain their structural integrity, mechanical strength, flexibility, optical performance and other desirable properties throughout their lifespan.

However, polymers are susceptible to degradation both in processing and in service conditions such as heat, light, oxygen, moisture, mechanical stress, and chemical exposure. To mitigate these effects, we introduce polymer stabilisers.

It’s a vast and varied field, but RBH has extensive knowledge within this sector and has been sourcing and supplying KingYorker Enterprise Ltd polymer protection solutions to industries for decades.

In this blog, we’ll explore the different types of polymer stabilisers, focusing on three key types: antioxidants, light stabilisers, and UV stabilisers, sharing insights into how they prolong the lifespan and maintain the integrity of polymers in diverse applications.

white plastic polymer

The importance of polymer stability

First, let’s expand on some of the points we made above. Investing in stabilising additives is important for manufacturers who want to unlock the full potential of polymers and meet the evolving needs of their customers. 

Some advantages include:

  1. Product durability: Elongating the lifespan of polymers is crucial. By ensuring stability, polymer products will retain their structural integrity and functional properties over time. For products such as automotive components, this means that they will resist degradation from exposure to heat, moisture, and mechanical stress, ensuring long-term reliability and safety.
  2. Cost efficiency: Stable polymers reduce the need for frequent repairs, replacement and maintenance, therefore lowering overall costs for manufacturers and end-users.
  3. Safety: By maintaining their mechanical strength, chemical resistance and thermal stability, stable polymers contribute to the overall safety of products and processes, preventing failures that could compromise safety. This is particularly important in critical applications such as aerospace components and medical equipment.
  4. Environmental impact: Improving product sustainability is of high importance and polymer stability can influence the environmental footprint of products throughout their lifecycle. By extending the lifespan of products and reducing the frequency of disposal, stable polymers contribute to waste reduction and resource conservation.
  5. Performance consistency: Stability ensures that polymer-based products maintain consistent performance, even under diverse environmental conditions. They become resistant to extreme temperatures, chemical exposure and UV radiation, ensuring they deliver predictable performance no matter the elements they are exposed to.
  6. Regulatory compliance: Many industries are subject to stringent regulations governing product safety, performance, and environmental impact. Using stable polymers that comply with regulatory standards ensures legal compliance and avoids costly penalties or recalls.
  7. Market competitiveness: Stable polymer-based products can help manufacturers gain a competitive edge in the market by offering superior reliability, durability, and performance which can help to drive market success and profitability. 
durable polymer product enhanced with stabiliser

Types of polymer stabilisers

There’s no one-size-fits-all solution when it comes to polymer stabilisation and the product required will depend on various factors including whether polymer protection is needed during production, processing or component service life.

Below, we’ll discuss some of the most widely used types of stabilisers used in polymers, resins and elastomers.

Antioxidants

One of the most common causes of degradation in polymers is oxidation. When polymers react with oxygen, they can break down, which weakens their structure and makes them less effective. 

Antioxidants are like protectors that we add to polymers to stop this from happening, as they can help prevent the reaction with oxygen so the polymer retains its strength and lasts longer.

We use two main types of antioxidants to protect polymers: primary antioxidants, which inhibit the initiation of oxidation, and secondary antioxidants, which stop oxidation reactions from spreading further.

Primary antioxidants

Primary antioxidants, like BHT (butylated hydroxytoluene) and KingNox®10, act as scavengers. They work by stopping the first step of polymer breakdown caused by oxygen. They do this by giving up hydrogen atoms to stop the chain reaction of breakdown.

The KingNox® range of additives includes ten types of highly effective primary antioxidants, compatible with a wide range of polymer systems in various industrial applications, and trusted by manufacturers worldwide.

Secondary antioxidants

Secondary antioxidants, such as KingFos®168, work differently. They step in later in the process when the breakdown has already started. These antioxidants break down the unstable parts which have formed, helping to stop the breakdown process from going further.

KingYorker produces five types of high-performance secondary antioxidants, such as KingFos® 168 and KingNox® DLTDP, formulated to work synergistically with primary antioxidants to provide comprehensive protection against oxidative degradation.

RBH also supply a range of multifunctional stabilisers where a single molecule performs more than one function. The most widely used combination stabilisers are sterically hindered phenols with sulphur substituents or sterically hindered phenols with copper chelating function (metal deactivators). KingNox® 1035 and KingNox®MD 1024 are examples of multifunctional additives.

Antioxidants find widespread use in various industries, including plastics, rubber, adhesives, and coatings, where protection against oxidative degradation is critical for product performance and longevity.

polymer antioxidant

Light stabilisers

When polymers are exposed to sunlight or artificial light, they can start to break down which can make them change colour, become brittle and lose their strength. To prevent this, we use light stabiliser additives.

Light stabilisers act as protective agents for polymers, shielding them from the harmful effects of light exposure. They are crucial for maintaining the durability and performance of polymer-based materials, especially in outdoor applications where sunlight can cause significant damage over time.

These additives include various compounds such as hindered amine light stabilisers (HALS), including KingSorb® 770 & KingSorb® 944, which function as scavengers. HALS compounds work by neutralising free radicals generated during light exposure, thereby halting the breakdown process and preserving the strength of the polymer.

Other compounds can include UV absorbers, synergists and quenchers. These compounds may be used alone or in combination with each other to provide comprehensive protection against light-induced degradation in polymer-based materials. The selection of light stabiliser additives depends on factors such as the type of polymer, the intended application, and the specific requirements for light stability and durability.

polymers exposed to artificial light

UV stabilisers

UV stabilisers are specifically designed to keep polymers safe from the harmful effects of sunlight. Unlike other light stabilisers that just soak up or scatter UV light, UV stabilisers work differently.

There are two main types of UV stabilisers: 

  • Benzophenone derivatives, such as KingSorb® BP12, act as sun protection for polymers. They absorb UV rays and react in a way that protects the polymer from getting damaged by the sun.
  • Benzotriazole UV absorbers, like KingSorb®326 and KingSorb®234, work by soaking up UV light in the range of 300-400 nanometers, where sunlight’s most damaging UV rays are. By doing this, they stop the polymer from breaking down when exposed to sunlight.

Both types of UV stabilisers are important for keeping polymer-based products, like plastics and coatings, safe from getting damaged by the sun’s rays.

KingSorb® is a complete range of anti-degradants including UV absorbers, HALS light stabilisers, optical brighteners and specialist UV absorber blends. RBH can supply KingYorker’s product portfolio including KingBlend® customised packs to meet specific requirements including pelletised mixtures with other additives.

plastic fence exposed to sunlight

Choosing the right polymer stabilisers

Polymer stability is a complex and multidisciplinary field that requires a thorough understanding of polymer chemistry, material science, engineering principles, and environmental factors. 

By carefully selecting materials, additives, and processing methods, manufacturers can develop polymer formulations that exhibit superior stability and meet the performance requirements of specific applications, ultimately ensuring the longevity and reliability of polymer-based products.

RBH works with manufacturers across a diverse range of industries and can offer tailored solutions to the most unique requirements, with unrivalled technical support and services to drive product development. To find out how we can help you, get in touch with our sales team to discuss your requirements.

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