An insight into the International Rubber Conference

Materials World magazine
27 Sep 2019

Looking at the 2019 International Rubber Conference, Shardell Joseph highlights some standout topics and technologies at the event

Hosted in the UK for the first time since 2001, the three-day International Rubber Conference (IRC) welcomed more than 600 delegates, 50 exhibitors and nearly 150 oral presentations, making it the largest rubber conference in the UK this century.

The event was organised by the IOM3 Polymer Society and the International Rubber Conference Organisation, and took place at Kia Oval, London, UK, on 3-5 September. IRC created a platform for experts in academia and industry to present pressing topics and technical advances in the global rubber market.

‘As the largest rubber event in my 30-year working life to be hosted in the UK, the event was a success,’ IRC conference co-Chair and Queen Mary University Professor, James Busfield, CEng FIMMM FHEA, told Materials World.

‘Most of the major rubber companies such as Bridgestone, Sumitomo, Pirelli, Yokohama, Apollo, Continental and Michelin participated, as well as all the major polymer and filler materials manufacturers. In particular, I was delighted to see 60 research students presenting their work, highlighting that the future for rubber materials is also looking good.’

Busfield said the key themes discussed at the event centred around making rubber products more sustainable by exploiting environmentally friendly materials, or making elastomer products such as tyres which consume less energy to manufacture.

‘Also, big breakthroughs were reported in making rubber materials that are smart or responsive, rubbers that can be additive manufactured or rubbers that can exhibit self-healing behaviour.

Of particular note was the calibre of the large number students,’ he said. Looking in greater detail at some of the topics listed, the following presentations showcased technologies with potential to disrupt the rubber industry.

Reclaimed rubber for clay products

On day two, Bridgestone Sustainable Technology Research Unit, Innovative Materials Research Department Corporation Manager, Ashoke Karmokar, discussed the influence of adding shredded reclaimed tyres into cement-treated clay products. Studies had shown that mixing rubber granules with the clay could improve the latter material’s ductility, yet still offer low permeability. This was otherwise not possible because of the tendency of the clay to become brittle once it had dried.

Karmokar said this type of clay is promising for using as sealing and filling materials because of its low permeability and reduced earth pressure on retaining structures. However, as it becomes brittle when it dries, such clay cannot follow contours of revetments when they start to deform. As such, cracks generate in the clay later itself, affecting its permeability.

However, adding the rubber granules helped improve the clay’s strength yet avoided water absorption, which enabled its use in geotechnical structures where deformation is anticipated.

Karmokar showed a Tokyo Bay area field trial of adding the shredded tyres into the mixture that formed a barrier wall in a landfill-block extension at sea. The design adopted as the best potential construction method of this project included a double-layered barrier wall and the use of cement-treated clay at the foundation of the inner wall for basement sealing. Cement-treated clay-rubber slurry was prepared onboard a ship at the construction site, which was fitted with a batch mixing facility, by using dredged clay collected from the seabed area.

Water adjusted dredged clay gathered on-site from the seabed, Portland cement and rubber grains were used in batch mixing process for preparing cemented clay rubber material.

In his paper, A potential tire recycling technology portfolio towards circular economy, Karmokar identified the use of an X-ray CT to scan the rubberised clay material. The tests showed that cracks only appear around the rubber grain as opposed to wide crack generation in the clay-matrix of the material.

Karmokar explained how this was probably due to differences in Poisson’s ratios of rubber and cement-treated clay-matrix. ‘Minute cracks those developed successively around the rubber grain have prevented the growth of wide cracks as happens typically in the material, and thus enables their use in geotechnical application anticipating structural deformation,’ the paper read.

Self-healing composites

Later on day two, the session chaired by Weir Advanced Research Centre Director, Alan Bickley, looked at self-healing and ionic elastomers. With many potential applications, such as rubber tyres that can repair themselves, the self-healing capabilities of rubber and elastomers has been prevalent in industry interest – highlighted within the IRC session.

Institute of Polymer Science and Technology (ICTP-CISC) PhD student, Javier Alejandro Araujo Morera, presented the institute’s work regarding self-healing styrene butadiene rubber (SBR) composites.

Focusing on polymer waste management, and reducing the demand of non-renewable sources, Morera presented a self-healing composite rubber, using ground tyre rubber (GTR) as a sustainability property. Morera said in the project that his team was able to use GTR as a sustainable filler, which enhanced the material’s mechanical properties without sacrificing healing effectiveness.

The paper, Development of sustainable and self-healing SBR composites, co-authored by Morera, discussed the capabilities of self-healing polymers to increasing the lifecycle of materials, while elastomers possess the ability to recover functionalities by using dynamic and reversible moieties.

According to the team, the healing protocol was optimised achieving full recovery of mechanical properties when applying 130oC heat for five hours. Then for the first time, GTR was assessed as a potential filler in self-healing SBR compounds. The maximum content of GTR without significantly compromising tensile strength was 20phr with a healing efficiency of 75%.

‘SBR compounds filled with ground tyre rubber offer a potential versatility to self-healing applications, defeating the challenge of reaching simultaneously good repairability and good mechanical performance,’ the paper read.

Cement-like ceramics

On the third day, KTH Vice-rector for Education, Professor Leif Kari, chaired the session looking at smart and responsive elastomers for the rubber industry. One of the presentations, by Indian Institute of Technology PHD Scholar, Debabrata Ganguly, gave insight into responsive rubber-ceramic composites and their potential.

Introducing the paper, Coining the attributes of cement-like ceramics in hydrogenated NBR for smart applications, Ganguly spoke about the properties, the benefits and the potential applications for stimuli responsive rubber-ceramic composites.

Ganguly’s presentation showed how a smart composite could be developed, using hydrogenated nitrile rubber (NBR) and coining the synergistic setting characteristics of fly-ash and slag.

The researchers tested different mixes in order to achieve an insulating and semiconducting material using the waste materials. According to Ganguly, the test showed the composites to be effective, especially when mixed with carbon black.

‘Some of our developed materials showed a very high degree of sensitivity to moisture and displayed synergism in terms of mechanical properties,’ the paper read. ‘Even the thermal degradation was also found to be improved significantly with such modification.

‘The synergistic composites showed dramatic improvement in conductivity when loaded with only 5phr of conducting carbon black. The tailoring of the thermally conductive and electrically insulating ceramic particles into the rubber matrix led to the formation of rubber based smart composite.’

According to Ganguly, the composites achieved the following:

  • Synergistic effect with the help of reactive byproducts and
  • industrial wastes
  • Insulating - semiconducting change in nature of the composite by stabilisation conducting path, and
  • Enhanced thermal properties and processing characteristics.

The rubber-ceramic composites also achieved flexibility in addition to strength, a green approach to technology using waste byproducts, and was stimuli responsive. The potential applications for the include stimuli-sensitive device fabrication, EMI shielding, conducting elastic materials and tyre-sealing applications in saline marine environments.

According to Busfield, the UK successfully bid for the IRC to return at the earliest opportunity in 2029.