Reverse Engineering of Rubber Products in Science and Practice

Dear Colleagues,

With the evolution of human beings, their acute interest in the scientific world, made them think deep about the causes and effects of various natural states and happenings. In the process, nature was investigated through the minds of humans as cryptograms to be solved, a very reflection of a reverse engineering process on the existing observable phenomena. The concept has been well practiced in the materials science domain also, to understand the material composition and the processes applied to produce products of commercial and sometimes purely scientific interest.

Ranking amongst the materials as one of the most mysterious to a layman, many of the different rubber products may appear to be completely identical. This impression can be traced back to the fact that rubber products are predominantly of a black colour, and feel almost similar to the touch. However, after little more inspection, substantiated through various analytical techniques, it is quite obvious that each rubber is different. One may be soft, whereas another may be hard, another brittle whereas the next one tough. Some may show incredible flexibility, or conversely, high plasticity. Stated in another way, the spectrum of properties encountered with rubber products far surpasses those of many other materials. However, all the rubbers bear a fact in common. They are irreplaceable in their original applications with other materials due to their ability to show viscoelasticity or damping.

Therefore, they are used especially in cyclically dynamically loaded applications with respect to the required viscoelastic properties. That is why every rubber is unique. Typical examples are synthetic and natural covalently cross-linked rubbers integrated into automobile tyres, or other applications such as driving or conveyor belts, seismic isolators, fuel system hoses, seals, turbo charger hoses, cooling system hoses, engine bushing, spring pads and many more.

Recently, from the environmental point of view, a growing body of scientific research is linking tyre wear to microplastic pollution, and scientists have put forward a relevant question—which components in rubber can prevent wear and increase the life of such a product, while simultaneously reducing pollution?

In principle, it is not possible to produce identical rubber products repeatedly, even if a completely identical composition has been used for its production. Each has its personal fingerprint, and this is non-transferable. In order to be able to decipher this fingerprint, it is necessary to perform a comprehensive analysis by applying reverse engineering.

This is used in both research laboratories and the research and development wings of companies, either to get an idea about specifications or to gain knowledge about compositions of the products in terms of elastomers and other compounding ingredients such as crosslinking agents, accelerators, fillers, antidegradants, plasticizers and miscellaneous chemicals. Scientific principles are developed and followed for the analysis and reconstruction of a specified product, and even to understand the compositions of waste rubber products.

Once a successful reverse engineering has been accomplished, then it can be of great importance in various application fields. For example, the controlled pyrolysis of waste rubber products, such as waste tyres, can be used as a source to obtain high-value-added products such as pyro-oil, carbon black and steel. It can also be helpful in generating heat, which in turn, may be used for the production of electricity. This approach is considered to be economically viable only if the waste rubber product contains more rubber and processing oil over ingredients such as cheapening filler, which includes China clay. Thus, reverse engineering is useful to ascertain the compounding ingredients in such a waste rubber product prior to using it as a feedstock for the production of energy.

In another example, the collected abraded rubber dust worn-off of tyres may be subjected to efficient reverse engineering to understand the amount of unreacted zinc oxide and para-phenylene diamines present as compounding ingredients, thus helping to decide whether such washed away waste satisfies the permissible threshold considered to be safe for marine lives. If not, then stringent measures must be adopted to discard such wastes.

Innumerable examples highlighting the great importance and helpfulness of the reverse engineering of rubber products, assisting in such areas as health and medicine, energy and recycling, and pollution control, are to be found in the various published literature.

In general, the scope lies in understanding existing rubber compounds chemically, with the objective of allowing the estimation of the cost and a tentative alteration in the compounding to produce cost-effective products, satisfying and, if possible, improving upon the already existing required properties of the reverse-engineered products that are targeted for contemplated end use. Additionally, the importance in understanding products from the environmental point of view has already been highlighted. Finally, reverse engineering applied on a failed rubber product in service against a known formulation from where such a product was manufactured can be effectively applied to estimate the redistribution of the non-reactive compounding ingredients present, which may be an operative way to understand the mechanical nature of such a failure.

While experimenting, sometimes disappointing failures may overshadow hope, but that can never stop the desire to start afresh. Great science is often not achieved with the first attempt. Indeed, we learn from our mistakes, and use what we learn to improve, innovate and create.  

This “Special Issue” will highlight original articles and reviews that describe the systematic approach to the chemical reverse engineering of rubber products, using such physical and chemical means as infrared spectroscopy, chromatography, thermal and thermomechanical analysis, and acetone extraction, to name a few. Submissions describing very new analytical techniques and developments on new and unique grounds are also highly encouraged as potential perspectives on future trends and challenges in this field.

Dr. Sanjoy Datta
Dr. Radek Stoček
Guest Editors

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