Nanoclay Research Takes a Leap
By TA News Bureau
Researchers have discovered a novel carbon black and nanoclay filled system in natural rubber matrix for steel cord tyre ply compound that could deliver better performance properties. What they have done was to partially replace carbon black with two different kinds of nanoclay. This nanocomposite has demonstrated improved adhesion properties between the steel cord and rubber. The lead researcher, who worked on this experiment, is Dr Arup Kumar Chandra, a 33-year tyre and rubber technology veteran and Head of Special Projects of Apollo Tyres. He told Tyre Asia about the exciting possibilities that his research team has come up in the use of nanoclay
Worldwide researchers are continually grappling with various challenges to make the tyre safer, fuel efficient, durable and competitively priced to offer higher customer satisfaction. In this journey, they have come up with innovative ways that would make the tyre perform well. One of the leading figures in this effort is the research team headed by Dr Arup Kumar Chandra. He says in an interview that a carbon black and nanoclay-filled system in natural rubber matrix could improve steel cord adhesion.
He says partial replacement of carbon black by organoclay in the control formulation of steel cord ply compound for a truck-bus-radial (TBR) tyre has lead to an all round improvement, specially the pull out adhesion force and other related properties.
Tyre is a highly engineered product that consists of several different components. This complex composite consists of several types of rubbers, fillers in the rubber formulations and other ingredients like reinforcing fibres and steel cords. The major reinforcing material in building the tyre is the steel cord especially for carcass and belt of a radial tyre.
The challenge before researchers is to ensure high adhesion among these various components. Ensuring good adhesion between the rubber skim compound and brass-plated steel cord is essential since this plays a crucial role as the tyre has to bear the load that comes on it for several millions of cycles under different weather conditions.
It is in this light that Dr Chandra’s research team has developed a novel carbon black and nano-clay-filled system in natural rubber matrix for steel cord tyre ply compound. “Here, for obtaining the optimised performance properties, we studied the effect of partial replacement of CB (N-220)by two different kinds of nanoclay (Cloisite-20A and Cloisite-30B) on the adhesion properties,” he said.
The study found that the addition of nanoclay at lower loading (up to 3 phr) has resulted in an increase in the overall performance of the rubber compound. Due to nano filler reinforcement, the cohesive strength of the nanocomposites is found to have increased. The adhesion improvement is more significant in the case of 3phr Cloisite 30B.
Dr Chandra says that the major strength of a tyre comes from the body ply or carcass. In tyres the materials used for reinforcement in the ply are mainly steel cords or organic textile cord.
“With growing demand for better tyre performance, which includes better fuel-efficiency, greater load carrying capacity, durability, low rolling resistance and puncture proofing, tyre manufacturers globally are looking for various types of reinforcing materials for tyres. To address these diametric demands the world attention was on steel cord as a major reinforcing material,” he says.
Good adhesion between the rubber skim compound and brass-plated steel cord plays a very crucial role in order to absorb the impact properly and to bear the load that comes on the TBR-tyre.
He said for the past two decades nanoclays have been used as reinforcing agent for various elastomers. Nanoclays with high aspect ratio offer a wide range of property enhancement at very low level of loadings, owing to the nanometric dimension and dispersion. Most researchers have mainly studied the usage of nanoclays on the mechanical, thermal and physical properties of various polymers.
“We launched the research on the effects of nanoclays on rubber adhesion behaviour as there were only limited studies on this,” Dr Chandra says. “So we took up the research work with the objective to study the effect of nanoclay on the adhesion behaviour of NR based CB-NC hybrid composite and its implementation as a steel cord ply compound.”
His team focussed its attention at the effect of partial replacement of CB (N220) in the control formulation of steel cord ply compound for a truck-bus-radial tyre by two different types of organoclay (Cloisite-20A and Cloisite-30B).
The result showed all round improvement, especially the pull out adhesion force. It was found that the addition of nanoclay at lower loading was found to increase the rubber reinforcement and cohesive strength of the nanocomposites, he points out.