Lightweight fillers: What are cenospheres?

We’re often approached by businesses looking to transform their ordinary resin/polymer systems into extraordinary materials, and more often than not we’ll look to cenospheres if the application suits.

As one of the most widely used lightweight fillers in polymers, cenospheres are versatile and sustainable additives which can transform the properties of many formulations such as plastics, elastomers, ceramics, composites, paints and coatings.

For manufacturers looking for innovative solutions to enhance the performance of their products, cenospheres could just be the key ingredient needed to give their formulations a competitive edge.

Faber&VanderEnde specialises in helping businesses improve their product performance, efficiency and sustainability. Let’s take a look at how cenospheres can address the challenges faced by manufacturers across a range of industries.


What are cenospheres?

Cenospheres are unique free-flowing powders composed of tiny, lightweight, hollow ceramic spheres. The name ‘Cenosphere’ comes from two Greek words: ‘kenos’ (hollow) and ‘sphaira' (sphere). 

They are also referred to as hollow spheres, microspheres, hollow ceramic microspheres, glass spheres or glass bubbles.

Largely made up of alumina and silicate, cenospheres are a byproduct of fly ash generated during coal combustion in thermal power plants, and could be considered a sustainable material.

How they are obtained

It all starts when coal is burned to generate heat or electricity. Its various components are oxidised and converted into elements such as ash, gases and other solid particles.

Amongst these elements, ‘fly ash’ is formed and carried along with the combustion gases into the atmosphere. Fly ash is a fine powder consisting of silica, alumina, iron, and other minerals found in coal. 

Intense heat and rapid cooling processes are then used to create and extract cenospheres creating physical and chemical reactions in the ash particles. The process is as follows:

  1. As temperatures increase, the viscosity of molten ash decreases, forming gas bubbles within the ash particles
  2. The gas bubbles are trapped as the ash particles cool, resulting in the formation of cenospheres
  3. They are then separated from the fly ash using various techniques, before being collected and processed for use in industrial applications

obtaining cenospheres

Characteristics of cenospheres

Cenospheres are in high demand across various industries, and it's their unique characteristics that make them a highly valuable resource for manufacturers across the globe.

But what is it that makes them such a powerful and versatile additive? Some key characteristics of cenospheres include:

  • Low density: Many formulations require lightweight materials and with a density of 0.6 to 08g/cm3, cenospheres are nearly 30% lighter than conventional resins.
  • High strength: Cenospheres might have low density but they also have a very high compressive strength (around 2000-4800 psi). This makes them strong and tough enough to withstand mechanical stresses and pressures.
  • Thermal resistance: The hollow spherical structure of cenospheres gives them excellent thermal insulation properties. They are typically temperature resistant up to 1200-1600°C making them able to withstand high temperatures without significantly deforming or degrading.
  • Chemical inertness: Cenospheres have an alumino-silicate shell which is resistant to most acidic environments, making them suitable for use in particularly corrosive or harsh conditions.
  • Particle size distribution: With a uniform particle size and narrow particle size distribution, cenospheres can ensure consistent performance and distribution when added to formulations.

The unique properties of cenospheres allow researchers, engineers and manufacturers to develop innovative polymer composites that meet the evolving needs of diverse industries. 

hollow ceramic spheres

Key applications of cenospheres

Role in construction materials

Cenospheres are one of the most widely used materials in construction, often found in polymer-based composites such as concrete, coatings and insulation products. They can help to develop lightweight concrete, increase the durability of coatings and improve the insulation properties of building materials.

Uses in the automotive industry

Cenospheres contribute to lightweighting initiatives in automotive engineering, helping to improve fuel efficiency and reduce emissions. They can often be found within the composites that are used to make interior components, body panels and under-the-hood parts in vehicles to ensure the right balance between weight reduction and performance.

Transforming paints & coatings

When used as a filler in paints, coatings and sealants, cenospheres can help to improve many properties such as durability, adhesion, resistance to weathering and provide a smoother, more even finish. 

Fluid applications in the oil & gas industry

Cenospheres can be used as an additive in drilling fluids to help improve drilling efficiency and stability by controlling fluid density, reducing friction and preventing blowouts.

Fireproofing materials

The natural thermal and fire-resistant properties in cenospheres make them ideal for use in fireproofing materials such as intumescent coatings and fire-resistant panels. These have widespread applications across industries to help protect structures and equipment from fire damage and improve overall safety.

Benefits of using cenospheres in polymers

Having worked with many global companies across a multitude of industries, we recognise the versatility of cenospheres when blended with polymers and how they can benefit a wide array of polymer-based products and applications.

We’ve already discussed the characteristics of cenospheres, so when these are put into action it can create a product which is:

  • Cost-effective: Formed as a byproduct of an existing process, cenospheres are in abundance and are readily available at a relatively low cost. This makes them much more cost-effective compared to other fillers.
  • Sustainable: Incorporating cenospheres into polymers promotes sustainability by utilising recycled waste material and repurposing it. This can reduce material consumption and minimise waste generation, contributing to a more environmentally friendly production process.
  • Strong and stable: The overarching use of cenospheres in polymers is based on making them a stronger and more stable material. Manufacturers are typically looking to create an end product with high strength, stiffness, and improved dimensional stability, all of which the addition of this functional filler can offer.
  • Lightweight: By incorporating cenospheres into polymer composites, manufacturers can create lightweight materials that are ideal for applications where weight savings are crucial, such as in automotive components, aerospace structures, and building materials. 
  • Easier to process: By reducing viscosity and improving flow properties during moulding or extrusion, cenospheres can improve the processability of polymer composites ultimately making it easier to produce complex shapes.

There are many reasons why manufacturers choose to integrate cenospheres into their polymers, as the powerful advancements they can bring to polymer technology are undisputed. There’s little doubt that cenosphere-enhanced polymers make a significant impact, driving innovation and contributing to a more sustainable future.

Finding a cenosphere supplier

Faber&VanderEnde are a trusted distributor of speciality fillers,  cenospheres, hollow ceramic spheres and glass bubbles.

We specialise in providing technical advice and support to businesses across all European countries looking for new application ideas or new materials to improve their existing products. Our team of experts can help you to utilise the unique properties of cenospheres, ultimately developing innovative polymer composites that meet the needs of your application.

To make an enquiry or order a sample, please get in touch with us.

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