Time: Oct 22th 2017   Copy editor: Tyrefull

The very concept of the automobile tyre is getting constantly overhauled. This is gaining accelerated pace with top manufacturers embracing disruptive innovation to keep their market share. Those who shy away from it will soon get deflated. As pneumatic tyres take away almost 30 per cent of the available energy needed to move the vehicle, it is imperative that new types of materials and tread designs are developed to reduce rolling resistance. The only constant that researchers face is the perennial problem of tackling the ‘magic triangle’ as the demand on the tyre is to ensure safety, better wet grip and wear, lower rolling resistance etc. In this interview Dr Aurp Kumar Chandra, a distinguished rubber and tyre technologist, who has made ground-breaking contributions to tyre development, speaks of the science of the tyre and its future developments.

When Elon Musk put on the road Tesla Model 3, it marked one of the greatest technological challenges that have been awaiting OEM suppliers. They will now have to look at various possibilities to develop tyres that will be compatible with electric vehicles (EVs) and emerging autonomous transportation.
In an interview to Tyre Asia Dr Aurp Kumar Chandra, a distinguished rubber and tyre technologist who has made ground-breaking contributions to tyre science and technology, explains the current developments, and shares his thoughts on the disruptive technologies that will change the conventional norms on tyres.
These days, tyres are becoming ‘intelligent’. The ‘cyber’ tyres are becoming ‘sensor agents’ to ensure ride quality and safety, says Dr Chandra, former Head of Global R&D at Apollo Tyres for more than a decade and currently working as its Head of Special projects. During his 35 years of research career in tyre and allied industries, he has received a large number of national and international honours. He has published more than 150 scientific papers in peer-reviewed journals and several books. He has contributed chapters for books by world renowned publishers.
These technological challenges are overwhelming scientists working on tyres, particularly in the emerging class of EVs. In these vehicles, the noisy internal combustion engines that spew smoky pollutants are being replaced by electric- powered drivelines. They are quiet and are designed to extract more miles from every watt. Such vehicles demand tyres that have to meet tough parameters. They need ‘intelligence’ built into them.
Intelligent tyres are the latest development in the tyre industry. They involve the use of systems for communication from tyre to vehicles and power generation for communication. They are the sensors for tyre-road contact monitoring .This type of tyres also requires several speciality chemicals and materials.
The task of tyre researchers is to find the permutations and combinations of more than 200 variables that include rubber compounds, design of sidewall, tread patters, groove width and construction. At the same time the tyre should be able to handle many process parameters of product manufacturing .
“Tyre researchers are continually working on advanced tyre materials and tyre construction,” he says elaborating on how OEMs can remain in reckoning when vehicle electrification gets widespread . As EVs roll out in large numbers, OEMs will force the tyre industry to further improve its product line. Dr Chandra asserts it will need continuing research in new materials too. Of course, performance improvement and cost reduction continue to be on the top of the agenda of tyre developers.

MATERIAL CHALLENGES

Another important challenge is to step up research prompted by the global uncertainties over the supply of natural rubber whose price fluctuations are causing unpredictable market developments. Dr Chandra forecasts dwindling use of NR and greater use of other naturally occurring rubber like guayule and Russian dandelion , synthetic rubbers like polyisoprene, butadiene rubber (BR ) and styrene butadiene rubber (SBR).
He notes that solution SBR, which is widely replacing emulsion SBR in passenger radial tyres, offers lower rolling resistance and better wet grip, which is ideal for EVs. Conventional SBR grades will get replaced slowly and he sees disruptions in elastomers to meet the challenges ahead.
To address the triangulation of qualities that negate each other, researchers keep searching for solutions that would ensure good tread wear, low rolling resistance and superior traction. The thrust is to develop appropriate reinforcing fillers such as improved grades of silica and surface modified carbon black . Biofillers such as corn starch and ground rubber are also opening new avenues .
Application of nanotechnology in tyre development is the top priority of tyre manufacturers, he says. Highly dispersible and high surface area silica offered nearly a 40 per cent reduction in rolling resistance and approximately 30 per cent drop in heat build-up. Researchers are trying to further improve fillers through a combination of carbon and silica to produce tyres that have low rolling resistance with better traction.
Dr Chandra explains that coupling agents have been found to be one of the alternatives to improve reinforcement by silica, a process that researchers are trying to further improve. They are looking at functionalised fillers, which is a new category of fillers in which their surface chemistry is changed for better polymer-filler interactions. This is achieved through several ways including chemical surface modification of fillers.
The widespread use of EVs and autonomous vehicles will trigger development of higher strength reinforcements that will deliver lower weight and reduced tyre thickness for improve d efficiency. Development of reinforcing materials through breakthroughs in carbon fibres to give high strength to the polymer is happening.
“Researchers are constantly improving other reinforcing materials too such as aramid, polyethylene naphthalate (PEN) for future tyres.” He also sees new steel wire geometry and coating composition that will improve rubber to metal adhesion required for enhanced tyre performance.
Tyre developers, who are aware of the tightening environmental regulatory norms worldwide, are working on a series of eco-friendly process oils. In the field of rubber chemicals, technologists have introduced nitrosamine-free vulcanization and vulcanizing agents, several anti-oxidants and anti-ozonants and reversion resistant chemicals.

NANO MATERIALS

A new 3D printed thermoplastic tyre prototype from Michelin

“In this challenging time that the tyre industry faces, it is important to highlight the role of nanocomposites,” says Dr Chandra.
In order to overcome the sustainability issues of the future, we have to reduce materials usage. Nanomaterials and nano-technology promise more for less. It offers ways to create smaller, cheaper and lighter devices that can do more using less energy and materials.
The application of nano-materials/nano-composites in the rubber and tyre industry, including the introduction and usage of nano-silica, nano-zinc oxide, nano-black, etc is set to increase. For tyre performance improvement they will be gaining popularity, Dr Chandra says.
By incorporating relatively small amounts of carbon nano-tubes into the silica filled compound, developers can dream of producing the ‘green’ tyre without the conductivity issue of such tyre. Researchers are developing a new generation nano-fillers: surface modified or plasma treated filler for better filler polymer interaction to improve tyre performance.
“While tyre researchers explore nano composites, plasma surface modified carbon black and new generation functionalised elastomers, they also keep an eye on the disruptions happening in the automobile industry. We also keep a watch on how the nano composites and reinforcing fillers that are being developed impact safety, health and environmental sustainability.”
Looking at the future, Dr Chandra expects higher demand for lower aspect ratio tyres and a reduction in the size of truck tyres that can also handle higher load carrying capacity. Farm and off-road tyres will also see changes that offer higher speeds and improved traction.
Unsymmetrical tread designs that will have different patterns on the outer and inner halves of the tread will become a norm for the PCR-tyre. This will allow the different contact forces on the two halves of the footprint, especially during cornering.
Computer aided design and manufacturing, introduction of automation and higher uses of robots will see manufacturing costs of intelligent tyres dropping. The major trigger for such changes will be EVs that demand not only ride comfort but also more mileage out of each watt.
Every product has a life span. It has been over a century since the air-filled pneumatic tyre was patented. Over the decades, it has undergone many changes in response to rising demands of modern transportation.
Says Dr Chandra: “There is every possibility that the pneumatic tyre will be challenged by thermoplastic-based non-pneumatic tyre that will have eliminated puncture problems, eased manufacturing, including the possibility of 3D-printing and recyclability.”
Once again it will be the customer demand that will drive the future tyre.

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