A rubber band (also known as an elastic, gum band or lacky band) is a loop of rubber, usually ring or oval shaped, and commonly used to hold multiple objects together. The rubber band was patented in England on March 17, 1845, by Stephen Perry. They were originally used to hold papers and envelopes. Most rubber bands are manufactured out of natural rubber as well as for latex free rubber bands or, especially at larger sizes, a synthetic elastomer, and are sold in a variety of sizes. Notable developments in the evolution of rubber bands began in 1923 when William H. Spencer obtained a few Goodyear inner tubes and cut the bands by hand in his basement, where he founded Alliance Rubber Company. Spencer persuaded the Akron Beacon Journal as well as the Tulsa World to try wrapping their newspapers with one of his rubber bands to prevent them from blowing across lawns. He went on to pioneer other new markets for rubber bands such as: agricultural and industrial applications and a myriad of other uses. Spencer obtained a patent on February 19, 1957, for a new "Method for Making Elastic Bands" which produced rubber bands in an Open Ring design.
Manufacturing Most rubber, whether it is natural or synthetic, normally arrives at the manufacturing facility in large bales. Rubber bands are made by extruding the rubber into a long tube to provide its general shape. There are a number of different methods that can be applied at this point in the manufacturing process. Originally, and in some instances still today, the rubber tubes will then be placed on mandrels, curing the rubber with heat, and then slicing them across the width of the tube into little bands. This causes the tube to split into multiple sections, creating rubber bands. This is most commonly known as an "off-line" rubber extrusion process. While other rubber products may use synthetic rubber, most rubber bands are primarily manufactured using natural rubber because of its superior elasticity. Natural rubber originates from the latex of the rubber tree, which is acquired by tapping into the bark layers of the rubber tree. Rubber trees belong to the spurge family (Euphorbiaceae) and only survive in hot, humid tropical climates near the equator, so the majority of latex is produced in the Southeast Asian countries of Malaysia, Thailand, and Indonesia. Once the latex has been tapped and is exposed to the air, it begins to harden and become elastic, or rubbery.
Rubber band sizes
Measuring
A rubber band is usually measured in three basic dimensions: the flat length, cut width, and wall thickness. The flat length is the total unstretched length. Perpendicular to the flat length is the cut width. Wall thickness is generally measured using tools such as calipers or pin gauges. The wall thickness determines the band's strength and durability. If one imagines a rubber band during manufacture, that is, a long tube of rubber on a mandrel, before it is sliced into rubber bands, the band's width is decided by how far apart the slices are cut, and its length by the circumference of the tube.
Size numbers
A rubber band is assigned an industry-standard number based on its dimensions. The first use of rubber band size numbers can be traced back to the early 20th century. While it is difficult to pinpoint an exact date, the practice of categorizing rubber bands by size allowed to easily select the appropriate rubber band for their specific needs. Standards for the rubber band were established in the United States in 1925 by the Department of Commerce, Bureau of Standards and is the first known publication to reference rubber band size. Generally, rubber bands are numbered from smallest to largest, width first. Thus, rubber bands numbered 8–19 are all 1⁄16 inch wide, with lengths going from 7⁄8 inch to 3+1⁄2 inches. Rubber band numbers 30–35 are for width of 1⁄8 inch, going again from shorter to longer. For even longer bands, the numbering starts over for numbers above 100, again starting at width 1⁄16 inch.
Thermodynamics
Temperature affects the elasticity of a rubber band in an unusual way. Heating causes the rubber band to contract and cooling causes expansion. Stretching a rubber band will cause it to release heat, while releasing it after it has been stretched will make it absorb heat, causing its surroundings to become a little cooler. This effect is due to the higher entropy of the unstressed state, which is more entangled and therefore has more states available. In other words, the ability to convert thermal energy into work while the rubber relaxes is allowed by the higher entropy of the relaxed state. The result is that a rubber band behaves somewhat like an ideal monatomic gas inasmuch as (to good approximation) that elastic polymers do not store any potential energy in stretched chemical bonds. No elastic work is done to "stretch" molecules when work is done upon these bulk polymers. Instead, all work done to the rubber is "released" (not stored) and appears immediately in the polymer as thermal energy. Conversely, when the polymer does work on the surroundings (such as contracting to lift an object) it converts thermal energy to work in the process and cools in the same manner as an ideal gas, expanding while doing work.
Red rubber bands
In the UK during 2004, following complaints from the public about postal carriers creating litter by discarding the rubber bands which they used to keep their mail together, the Royal Mail introduced red bands for their workers to use: it was hoped that, as the bands were easier to spot than the traditional brown ones and since only the Royal Mail used them, employees would see (and feel compelled to pick up) any red bands which they had inadvertently dropped. As of 2006, some 342 million red bands were being used per year. The Royal Mail no longer uses red rubber bands as of about 2010. The exact date of the expunging of these is uncertain, presumably as different areas used up old stock at varying rates.
Rubber bands in orthodontics
Special rubber bands of medical-grade latex can be used (worn) for orthodontic correction of teeth position together with metal braces or clear aligners to apply additional pressure on the teeth being straightened. These rubber bands are manufactured in different sizes for use in the varying steps of Orthodontic treatment. They are often termed orthodontic elastics.
Ranger bands
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