Polymer producers have responded to the changing tyre industry expectations, their innovations take into account a more reactive functionality within polymer architecture, and this is closely matched by increasingly greater degrees of filler surface chemistry. As a result, tyre compound properties may now be tailored to meet quite specific tyre performance targets.

Tyre processing methods also underwent progressive stages of modernisation in recent years, for example, more sophisticated reactive mixing technology together with high-speed extrusion systems allowing for direct extrusion onto the building drum become established as cost effective production routes for many of the major producers.

These advancements however bring about their own conflicts, processing pathways involving multiple stages, often with the ability to rework compound or adjust rheological properties by additional time or energy input during the process are no longer viable options for most tyre producers. It has thus become necessary to achieve processability through an increasingly narrow operating window.

Formulations optimised to achieve peak tyre performance in most cases also tend towards more challenging processing characteristics. This is to be expected; the use of high and narrow molecular weight reactive polymers alongside fillers having high surface area and chemistry, often in loadings above that of the polymer are the norm. The trend towards usage of high loading of plasticiser and resinous materials to adjust tyre tread grip and traction response all contribute to a less forgiving processing nature. Often those compounds that are highly reinforced appear the most fragile during processing and poor green strength with an easily tearing or crumbly compound appearance are often-discussed processability issues. By contrast, the use of high loadings of resins and plasticisers, for example in winter or high-performance tyre formulations, results in compounds that during processing can more resemble chewing gum than tyre treads!

The use of process additive chemicals in an attempt to overcome the processing limitations observed gives rise to further conflicts; Lubricant additives might improve compound surface appearance; however, green strength will probably further reduce due to the unwanted softening effect. The same is true for release additives where lower tack unfortunately remains at a higher value than the also lowered tensile strength of the compound. Filler dispersion is often targeted by additives, however higher loading of fillers mandate equally higher additive loadings, we should more accurately discuss loading as “parts per hundred of filler” not rubber, and under the appropriately higher additive loading, the risk of interference with vulcanisation properties or even additive migration leading to surface bloom become realistic concerns.

Conflicting performance characteristics

The development team at Schill + Seilacher has recognised the need to decouple conflicting performance characteristics found within conventional process additive chemistries. As a result, innovation within our Struktol® range offers tyre compounders opportunities to achieve processability without compromise.

Reduced viscosity leading to better extruder flow properties and improved surface appearance, whilst at the same time achieving an increased compound green strength can be realised by use of Struktol HT 300, a new generation of reactive process additive.

An extract of key processing and property influence in a typical highly silica filled sSBR tread compound are highlighted in the following data.

Significantly lowered Mooney viscosity as well as better mixer batch off with reduced sticking to the mixer rotor and gate with Struktol HT 300 are observed.

An increase in compound green strength was obtained by the addition of Struktol HT 300; this is the opposite of expectation for conventional process additive chemistry, where reduced viscosity is obtained. In addition, the filler dispersion as evidenced by a reduction in the so-called “Payne Effect” as tested in uncured compound by means of RPA strain sweep, is also improved.

Lab extrusion trials, using cold feed extruder demonstrate improved surface appearance and lower compound pressure achieved by use of Struktol HT 300, both desirable processing conditions.      

Physical properties are also acceptable, with a progressive increase in tensile strength an elongation and maintenance of stiffness with loading of 6 phr of process additive, only at higher loading of 12 phr would a balancing slight reduction in process oil be required.

Compound hardness remained unchanged alongside improved wear resistance, as measured by DIN abrasion loss testing, even when using higher loading of process additive, are important aspects.

The ability to decouple the relationship between lubrication, important for improved rheological behaviour, and the maintenance of strength and stiffness in both the uncured and vulcanised condition is only possible with such new and innovative class of process additive. This departure from conventional thinking offers the tyre compounder significant degree of freedom to retain the benefits in terms of easier processability without sacrifice of key tyre performance properties.

In this example, the use of Struktol HT 300 prioritised green strength alongside reduced viscosity. By contrast, our new Struktol HT 250 decouples release from other properties, especially effective for winter tyre tread; compound stickiness is resolved without compromise of viscoelasticity.

Ensuring that migration and ultimately bloom within rubber compounds is kept to the lowest level is important for final article aesthetics, for tyres additional considerations arise; they are composite structures, therefore it is imperative that chemicals do not migrate across boundary layers in an uncontrolled manner, which could result in changed behaviour or interfacial adhesion failure over time. In order to limit migration, the compatibility, solubility and concentration of chemicals are carefully considered. However, one method of ensuring long-term stability involves chemically binding the additive within the vulcanisation network.

At Schill + Seilacher, we have achieved this degree of crosslinking capability for a number of new-generation Struktol process additives. Their usage allows the compounder to avoid completely the risk of migration and bloom due to additive presence.

Photographs of two vulcanised rubber sheets based on the same formulation. On the left-hand side, evidence of typical surface bloom, which may occur due to migration of a conventional process additive, on the right, containing reactive additive Struktol HT 600 as replacement, it can be seen that bloom was eliminated.

This technology also opens tremendous opportunities to “fix” process additives in place within the respective component, the role of additives withinthe cross-linking mechanism may additionally lead to vulcanisate performance characteristics.

                                                                                  One interesting tyre related example involves the development of a superior tyre curing bladder performance, here we have developed new reactive plasticisers called Struktol HT 815 and Struktol HT 820, their use is directed towards resin-cured butyl rubber. This combination of polymer and curing system provides for superior heat resistance with excellent flex fatigue resistance and is used as the basis for tyre curing bladders. Here the replacement of widely used castor oil as plasticiser with new Struktol HT 800 series product leads to a significantly improved bladder performance life, with greater stability in viscoelastic properties. Reduced stiffening of the bladder, due to lower degree of plasticiser migration translated into a much lower flex-cracking rate, especially after high temperature steam ageing.

Reactive Struktol plasticisers, HT 815 and HT 820 exhibit a significantly reduced flex cracking rate when compared to the widely used castor oil, which readily migrates from the bladder; as a result, significant extension of bladder service life is possible.

New reactive process additives, with tailored functionality to closely match the specific chemistry of polymers, fillers and cure systems are actively developed. These innovative products under the Struktol brand offer tyre compounders a more comprehensive toolkit in order to tailor compound performance to meet tyre performance demands. The conflicts of property versus processability diminish and new possibilities emerge!

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Continental has initiated a strategic consolidation of its operations in the United States, which includes the planned closure of its Aldora Mills textile plant in Barnesville, Georgia, by the conclusion of 2026. This decision, impacting approximately 230 employees, follows an extensive review of the company's long-term competitiveness in the Americas. The facility, which produces textile reinforcement materials, including tyre cord fabric, hose yarn and knitted fabric, for exclusive use within Continental’s Tires and ContiTech group sectors, had faced persistent cost challenges for years, with shifting global market conditions ultimately making its continued operation unviable. The company's immediate priority is to provide comprehensive support to the affected staff through career counselling and local employment resources.

Despite this specific closure, Continental is reinforcing its substantial commitment to the US market through continued and significant capital investment. In the past decade alone, the company has directed around USD 1.5 billion into its American manufacturing footprint. This is evidenced by recent projects, such as a major expansion of the ContiTech plant in Mount Pleasant, Iowa and the construction of a new, company-owned tyre distribution centre in the Dallas-Fort Worth area scheduled to open in early 2026.

The company's enduring presence in the country remains robust, with a workforce of over 8,800 people spread across its Tires and ContiTech sectors. Its tyre manufacturing plants located in Illinois, Indiana, Mississippi and South Carolina possess a combined annual production capacity of more than 16 million tyres. The closure of the Aldora Mills facility is therefore presented as a necessary step to safeguard the overall health and future performance of Continental's broader operations across the Americas.

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In a significant development for environmental science and the rubber industry, Perpetuus Advanced Materials has announced a viable solution for eliminating 6PPD-quinone, a highly toxic byproduct of 6PPD, a chemical commonly used in tyres and synthetic rubbers. This breakthrough is particularly urgent given the established link between 6PPD-quinone and acute mortality in coho salmon, a crisis identified in 2020 that has since spurred global regulatory concern. The company’s innovation provides both a direct manufacturing replacement and a method for environmental remediation.

The core of the solution is an amine functionalised graphene masterbatch, engineered using the company's proprietary plasma-functionalised graphene nanoplatelets. This advanced material operates through a novel mechanism where the amine groups act as radical scavengers, effectively stabilising the rubber and rendering the use of 6PPD entirely obsolete. By preventing the formation of the toxic 6PPD-quinone at its source, this technology addresses the root cause of the pollution. The masterbatches are supplied as pre-mixed sheets or blocks, allowing for straightforward integration into existing manufacturing processes for tyres and a wide array of other synthetic rubber products, including hoses, seals and industrial belts, without requiring any operational changes.

To tackle the existing environmental contamination, Perpetuus has concurrently developed a suite of modular filtration systems designed for stormwater management. These units, which include drain cartridges and bioreactor modules, utilise graphene nanoplatelets to capture pollutants. They are enhanced by a proprietary artificial intelligence platform that provides real-time monitoring of filter saturation and pollutant levels, offering a critical tool for protecting vulnerable waterways and urban runoff zones during the transition to reformed tyres.

Produced on a continuous plasma platform ensuring consistent quality, the masterbatch not only replaces 6PPD but also consolidates numerous other mix ingredients and additives, thereby simplifying production and improving workplace air quality. With over 10 years of specialisation in graphene-enhanced elastomers, Perpetuus is now actively pursuing regulatory approvals and industrial partnerships to accelerate the widespread adoption of this comprehensive environmental solution.

John Buckland, CEO, Perpetuus, said, “This is no longer about mitigation. We’ve replaced 6PPD. Our amine functionalised GNPs deliver the same anti-degradant function as 6PPD but with zero toxic quinone by-products. This isn’t theory. It works in formulation and scales now. This isn't a patch; it’s a permanent replacement. By removing 6PPD at the source, we remove the risk of 6PPD-Q entirely. The science is proven. The solution is scalable. The environmental need is urgent. The only question left is whether regulators and manufacturers are ready to act. This is the moment to eliminate 6PPD for good and replace it with something better.”

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Bekaert and EMSTEEL have forged a strategic partnership centred on the manufacturing and commercialisation of high-value, sustainable steel products utilising steel produced within the UAE by EMSTEEL. The agreement was formally signed at the Middle East Iron & Steel Conference & Exhibition in Dubai, with senior leadership from both organisations in attendance, including Group CEOs Engineer Saeed Ghumran Al Remeithi of EMSTEEL and Yves Kerstens of Bekaert.

The alliance will see the two companies extend their cooperation into several key areas. A major component involves technical collaboration, where Bekaert will provide its expertise and offtake intention to support EMSTEEL's strategic initiative to upgrade and substantially expand its wire rod product portfolio in the near future. Furthermore, the partners will jointly assess opportunities for downstream investments. These potential investments are designed to allow EMSTEEL to diversify its offerings with more advanced, value-added products. For Bekaert, this creates a pathway to manufacture its renowned Dramix steel fibre reinforced concrete solutions using locally sourced UAE steel.

A shared objective of this partnership is to actively promote the advantages of sustainable construction materials and solutions throughout the Gulf Cooperation Council markets, leveraging EMSTEEL's position as the UAE's largest steel manufacturer and Bekaert's global leadership in steel wire transformation and coating technologies.

Yves Kerstens, Group CEO, Bekaert, said, “Today’s MoU is intended to serve various ambitions we have in common with EMSTEEL. This includes focused strategy execution in a region with vast growth opportunities, a strong innovation drive and explicit sustainability excellence.”

Engineer Saeed Ghumran Al Remeithi, Group CEO, EMSTEEL, said “This agreement reflects EMSTEEL’s commitment to advancing the capabilities and global reach of UAE-made steel. By combining our manufacturing strength and sustainability leadership with Bekaert’s world-class expertise in material science and advanced steel solutions, we are creating new pathways for innovation, value creation and low-carbon growth.”

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In a long-term strategic partnership, Solvay and Sapio have committed to a 10-year agreement to advance renewable hydrogen production at Solvay's Rosignano plant. This collaboration – a central pillar of the Hydrogen Valley Rosignano Project aimed at cutting CO2 emissions from Solvay’s peroxides operations – will see Sapio responsible for building and managing a 5 MW electrolysis unit. The required power will be sourced from a new 10 MW photovoltaic installation that Solvay will construct on-site.

With operations scheduled to commence by mid-2026, the project is expected to yield up to 756 tonnes of renewable hydrogen annually. This green hydrogen will be directly used in Solvay's manufacturing of peroxides, essential chemicals for the electronics, water treatment, and solar panel industries. The initiative has secured EUR 16 million in funding allocated by the Tuscan Region through Italy's National Recovery and Resilience Plan (PNRR). This decade-long effort is projected to reduce the site's carbon dioxide emissions by as much as 15 percent, marking a substantial step towards more sustainable industrial processes. The partnership's launch was officially celebrated with a groundbreaking ceremony on 18 November 2025.

Carlos Silveira, President of Solvay’s Peroxides business, said, “Our partnership with Sapio represents a good example in how we enhance our global peroxide operations. This project is a key part of our broader strategy to support essential industries – from electronics and water treatment to energy and food safety – with more sustainable solutions.”

Alberto Dossi, President of the Sapio Group and H2IT, said, "The launch of this important project for the production of renewable hydrogen represents a major step forward in the development of the entire hydrogen value chain. With H2IT, we have set ourselves the goal of creating a collaborative ecosystem in which industry, research, policy and local communities work together for a cleaner and more sustainable future. With this collaboration, Sapio is actively contributing to building a cleaner and more sustainable world."

Mario Paterlini, CEO, Sapio Group, said, "We are extremely proud of our collaboration with Solvay: this project, funded by the National Recovery and Resilience Plan (NRRP), is concrete proof that companies can truly contribute to the decarbonisation of the planet and the growth of our country. In a world of great uncertainty like the current one, it is essential to join forces and be a point of reference for the entire ecosystem."

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