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Basketball By: Barrington Powell Intro to Chemistry: 5 th hour.

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Presentation on theme: "Basketball By: Barrington Powell Intro to Chemistry: 5 th hour."— Presentation transcript:

1 Basketball By: Barrington Powell Intro to Chemistry: 5 th hour

2 How its Made (; hehe Forming the Bladder 1 The making of a basketball begins with the interior bladder. Black butyl rubber in bulk form (and including recycled rubber) is melted in the hopper of a press that feeds it out in a continuous sheet that is 12 in (30.5 cm) wide and 0.5 in (1.3 cm) thick. A guillotine-like cutter cuts the long strip into sheets that are 18 in (45.7 cm) long, and they are stacked up. A hand-controlled machine selects the sheets one at a time and, using a punch press, punches a 1-in-diameter (2.54-cm- diameter) hole that will hold the air tube for inflating the bladder.

3 …….. Shaping the carcass 4 The bladders that withstand the 24-hour inflation test are conveyed from the holding chamber to the twining or winding department. They make this joumey suspended from a conveyor system by their air tubes. Machines loaded with spools of either polyester or nylon thread or string wrap multiple strands at a time around each bladder; this is the same process used to make the inside of a golf ball. The irregularly shaped bladders now begin to take on a better, more rounded shape as the precisely controlled threads build and shape the balls.

4 What its Made of A basketball is made from leather, rubber, or a synthetic composite. Most basketballs have an inflatable rubber bladder inside of this outer shell. Rubber is just a combination of polymers of isoprene units and other natural substances and impurities. It is a build up of the isoprene unit molecules and is not normally made up of other synthetic materials (although sometimes these materials are used to sythesise rubber).

5 More info.. Nearly all basketballs have an inflatable inner rubber bladder, generally wrapped in layers of fiber and then covered with a tacky surface made either from leather (traditional), rubber, or a synthetic composite. As in most inflatable balls, there is a small opening to allow the pressure to be increased or decreased. The surface of the ball is nearly always divided by "ribs" that are recessed below the surface of the ball in a variety of configurations and are generally a contrasting color. An orange surface with black ribs and a possible logo is the traditional color scheme of basketballs but they are sold in various colors.

6 How it works You bounce it.. Rubber elasticity, a well-known example of hyperelasticity, describes the mechanical behavior of many polymers, especially those with crosslinking. Invoking the theory of rubber elasticity, one considers a polymer chain in a crosslinked network as an entropic spring. When the chain is stretched, the entropy is reduced by a large margin because there are fewer conformations available. Therefore, there is a restoring force, which causes the polymer chain to return to its equilibrium or unstretched state, such as a high entropy random coil configuration, once the external force is removed. This is the reason why rubber bands return to their original state.

7 The end…..

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