“I’m swimming on the road!”

I always go out with my friends, either two or four of us together. I am black. I have tattoos around my body. I have only a fatty, round body, with no legs and hands. Guess who am I?

-------- I’M A TIRE

Tire is widely used in the world. It is made up of various components. One of the main components is natural rubber. Do you know rubber consists of a type of organic compound, named latex? Do you know where it comes from?

After 5 years of plantation, rubber trees are ready. Once the bark of the rubber tree is cut, a milk like liquid, latex, flows out. Latex is a mixture of rubber particles and water, produced by some plants in special cells called caticifers. The composition of latex differs from plant to plant. However, most natural rubber comes from a single species of tree, Hevea brasiliensis. Formula of natural rubber is (C₅H₈)n, where n is about 10,000. Monomer of natural rubber is C₅H₈, known as 2-metylbut-1,3-diene (isoprene). Each monomer molecule has 2 double bond and therefore known as –diene. After the collection of latex, ammonia (NH₃) is added to be stabilized and transported to a factory. -OH ions in the ammonia neutralize the acid produced by the bacteria, preventing latex from coagulate along the way to the factory to be processed. From there, acetic acid (ethanoic acid) is added to the latex for coagulation to happen. Hydrogen ions from the acid neutralize the negative charges on the surface of the protein membrane. The neutral particles no longer repel each other. These rubber particles may collide with each other, causing the membrane to break. The rubber polymers are freed and they coagulate by combining together to form large lump of rubber polymer. The latex has coagulated.

Natural rubber is elastic. It can be stretched without breaking and able to return to its original shape. Since rubber is made up of a long chain of alkene polymers, its double bonds can be oxidized by oxygen and ozone. However, oxidation can be prevented by adding antioxidants. Natural rubber is insoluble in water, but soluble in certain organic solvents such as benzene. Besides, it resists to alkalis and weak acids. When natural rubber is put under high temperature, it will become soft and sticky.

Other than rubber, there are a number of organic compounds present in the making of tire such as amines, organic acids and phenol derivatives. Amines such as N-(1,3-dimethylbutyl)-N’-phenylenediamine (6PPD), diphenylbenzenediamine (DPPD), N-isopropyl-N’-phenyl-p-phenylenediamine (IPPD), methyl- and ethyl- substituted diphenyl benzenediamines are present in most of the tires. These compounds are antioxidants possessing antiozonant properties, which help in protecting against stress, heat, oxidation and ozone attack.

Process of making tire:

Compounding and Banbury mixing – Combines rubber stock, carbon black and other chemical ingredients to create a homogeneous rubber material.

Milling – Shaping rubber into flat, long strips by forcing it through two set rolls rotating in different speeds.

Calendering – Consists of one or more (often four) rolls, through which the rubber sheets are forced, continuing the shaping of rubber.

Extruding – Rubber is forced through dies of appropriate shape. The extruder consists of screw, barrel or cylinder, head and die.

Component Assembly and Building - Assembly machine consists of rotating drum, on which the components are assembled, and feeding devices to supply the tire builder with the components to assemble. Tire buildings and other workers in this area of the process are exposed to a number of repetitive motion operations.

Curing & Vulcanizing – Curing press operators place green tire into the curing press or onto press loading equipment. Rubber vulcanization is to transform the tacky and pliable material to non-tacky, less pliable, long-lasting state.

Inspection and Finishing – Performed before the tire is stored or shipped. After finishing, the tire is ready to be stored in a warehouse or shipped from the plant.

Importance of Tires:

Tires are the only contact with the road. That means that your control over your car (acceleration, braking and turning) all depend on the grip that those four little patches of rubber provided. If you compromise on the grip of even one of your tires, you're going to lose stability and maybe crash. Your tires also play a big role in the fuel efficiency of your cars.

In conclusion, constant improvements in rubber chemistry and tire design are creating new tires that offer greater mileage and improved performance in extreme weather conditions. Manufacturers now offer tires estimated to last up to 80,000 miles. Treads, designed and tested by computer, now feature unique asymmetrical bands for improved traction and safety on wet or snowy roads.