Temperature Effects on the Elasticity of Rubber Bands
By Anna Black, Ellen McKean, and Madison Richardson
Table of Contents
Background Information | Purpose|Hypothesis| Method|Diagrams and Pictures | Dataand Graph | Conclusion | Sources |Go Up
Background Information
First used by Caribbean locals, Christopher Columbus was the first to bringrubber to Europe. Later in 1839, Charles Goodyear discovers heating the heatingprocess of Vulcanization, which stabilized and strengthened rubber’sproperties. The addition of sulfur induces vulcanization, which connects rubbermolecules into a chain, giving rubber bands their elasticity, strength, andmaking it immune to solvents and moderate heat and cold. The method ofvulcanization allowed for the more widespread use of rubber. Synthetic rubberis formed by adding color, sulfur, and other additives to make the materiallast longer. (Rubber World Vol. 214) To make rubber bands, theprevious ingredients are mixed in a container that is heated to 250 degreesFahrenheit until it is a ball of dough. Then it is rolled into sheets, cut intostrips, then molded into the shape of a tube, and later is heated, rinsed,cooled and cut (www.rubber-band.com).Rubber has unique viscoelastic qualities, meaning it has the elastic propertiesof a metal spring, but also has the energy absorbing characteristics of aviscous liquid. These properties allow rubber to maintain its original shapeafter deformation (Rubber World Vol. 210). Also, if rubber is stretched it willactually shrink when heated, but is also less resilient when cooled, becausethe strands become less mobile. It shrinks because as the molecules in therubber become heated, they also become less aligned and contract, causing therubber band itself to shrink. This simple experiment can be performed by usingweights to stretch the rubber band 2-4 times its original length, then heatingit with a hair dryer. The rubber band will shrink, but then will return to itsoriginal length after cooling (http://www.newton.dep.anl.gov).
Purpose
The purpose of this investigation is to determine the correlation betweenthe stretch distance of a rubber band and the temperature to which it issubjected.
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Hypothesis
Heat will affect the stretch distance of rubber bands because it altersthe bonds between the rubber molecules. When the heat increases, the bondsbetween molecules will weaken causing the rubber band to stretch father. Whenthe temperature decreases, the molecular bonds strengthen causing the rubberband to stiffen up and not stretch as far. The time that the rubber bands aresubjected to the varying temperatures, brand of rubber band, and the forceapplied will remain constant while the temperature changes.
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For this experiment there is aseparate set up for both warmer and cooler temperatures. The cold set uprequires a small cooler, which we filled 4.77cm full of ice. We then added 1tablespoon of salt to the ice. A rack on which the rubber bands were placed wassuspended over the ice. For the warm temperatures, a conventional oven was setat a temperature of 350° Fahrenheit. In the oven, a non stick, non metalcooking sheet was placed to separate the rubber bands from the hot metal surfaceof the oven. The rubber bands were then placed in their respective set ups, andremoved when they reached the desired temperature. Temperature was measured byan electronic thermometer. Four cold temperatures were taken, beginning at 65 Fand decreasing by 5°F. The warm temperatures began at 80 °F and varied by 10°F.There were a total of 5 warm temperatures. The was also one room temperaturetest at 70°F. For each temperature, we collected data for two colored rubberbands, and two natural rubber bands. When the rubber bands were removed fromtheir apparatuses, a measurement was taken pre-stretching. The rubber bandswere suspended from a secured pencil, and 400g of weight were hung from thepencil. The length of the stretching pencil was taken, and the original lengthwas subtracted from it to find the stretch distance. All data was converted toCelsius at the end of the experiment.
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Cold Apparatus
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Warm Apparatus
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Heat Effects onRegular Rubber Bands
| Temperature (°C) | Length after Heating (cm) | Length after Stretching (cm) | Stretch Distance (cm) |
| 0.00 | 7.5 | 10.3 | 2.8 |
| 0.00 | 7.5 | 10.2 | 2.7 |
| 7.20 | 7.6 | 10.6 | 3.0 |
| 7.20 | 7.5 | 10.7 | 3.2 |
| 16.10 | 7.8 | 11.0 | 3.2 |
| 16.10 | 7.8 | 11.0 | 3.2 |
| 18.90 | 7.5 | 9.5 | 2.0 |
| 18.90 | 7.7 | 10.9 | 3.0 |
| 21.10 | 7.8 | 13.2 | 5.4 |
| 21.10 | 7.6 | 11.0 | 3.4 |
| 28.20 | 7.5 | 11.2 | 3.7 |
| 28.20 | 7.8 | 11.5 | 3.7 |
| 33.30 | 7.8 | 13.3 | 5.5 |
| 33.30 | 7.7 | 11.6 | 3.9 |
| 38.75 | 7.9 | 10.9 | 3.0 |
| 38.75 | 7.6 | 9.4 | 1.8 |
| 43.89 | 7.8 | 10.1 | 2.3 |
| 43.89 | 7.6 | 9.9 | 2.6 |
| 47.78 | 7.7 | 10.3 | 2.6 |
| 47.78 | 7.8 | 10.4 | 2.6 |
Heat Effects onColored Rubber Bands
| Temperature (°C) | Length after Heating (cm) | Length after Stretching (cm) | Stretch Distance (cm) |
| 0.00 | 7.5 | 13.3 | 5.8 |
| 0.00 | 8.4 | 15.2 | 6.8 |
| 7.20 | 7.6 | 13.9 | 6.3 |
| 7.20 | 8.0 | 14.1 | 6.1 |
| 16.10 | 8.1 | 14.7 | 6.6 |
| 16.10 | 7.6 | 14.5 | 6.9 |
| 18.90 | 8.9 | 20.1 | 11.2 |
| 18.90 | 8.2 | 14.0 | 5.8 |
| 21.10 | 8.0 | 14.6 | 6.6 |
| 21.10 | 8.0 | 13.4 | 5.4 |
| 28.20 | 8.0 | 14.8 | 8.8 |
| 28.20 | 8.0 | 15.8 | 7.8 |
| 33.30 | 8.5 | 15.4 | 6.9 |
| 33.30 | 8.4 | 17.4 | 9.0 |
| 38.75 | 8.3 | 14.3 | 6.0 |
| 38.75 | 8.0 | 16.1 | 8.1 |
| 43.89 | 8.3 | 16.4 | 8.1 |
| 43.89 | 8.3 | 15.4 | 7.1 |
| 47.78 | 7.2 | 13.2 | 6.0 |
| 47.78 | 7.0 | 12.6 | 5.6 |
Data Files: Text | Excel
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The results thatwe got from our experiment were very sporadic, not linear or consistentlycurving. The colored rubber bands in particular had the largest range betweenextreme stretch distances (5.4 cm – 11.2 cm; range of 5.8 cm). This may havebeen caused by an ingredient in the dye, such as water, that altered therubber’s response to vulcanization. We can assume this because of the consistencyof the regular rubber bands whose extreme values (1.8 cm and 5.5cm) where onlyseparated by 3.7 cm. Although the rubber bands used had the same thickness, thecolored rubber bands were less resistant to the weight. The data seems tosuggest that there is no significant variance between the cooled, roomtemperature, and heated rubber bands. This simply reiterates the concept ofvulcanization. The manufactures of these rubber bands used vulcanization toprevent the effect of temperature on their product. Our experiment seems toprove the effectiveness of vulcanization in stabilizing the molecular structureof the rubber bands.
There are severalerrors that may have occurred. First, the thermometer used was a cookingthermometer, so it had difficulty reading the extremely cold temperatures. Italso didn’t show the temperature changing by degree, but rather would show onetemperature and then jump sometimes ten degrees to the next temperature. Thismade data very difficult to collect precisely and hard to duplicate withanother trial. The second error is that we were unable to keep the rubber atthe measured temperature as we measured its length and stretch distance. Theband’s temperature changed immediately as soon as we removed it from the ovenor the cooling box. Unless we preformed the experiment in a room with the sametemperature that we wanted our rubber bands to be at, there isn’t a way toeliminate this error. Our final error is that as we put the rubber bands on thethermometer, we could not keep the tension the same. Because of that, somerubber bands may have stretched more than others before their heating/coolingprocess, making them stretch more with the weight. Again, this is a difficult,if not impossible error to overcome. We were as careful as possible to keep therubber bands loose.
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http://www.rubberband.com/. Aristotle, n.d. Web. 10 Oct. 2010.
This is the Alliance Rubber Company's website. This site was useful for background information concerning the history of commercial rubber use and manufacturing process of rubber bands.
Calder , Vince. "Rubber Bands and Elasticity." http://www.newton.dep.anl.gov.N.p., n.d. Web.
10 Oct.2010. <http://www.newton.dep.anl.gov/askasci/eng99/eng99163.htm>;.
On this site we found a similar experimental method, that helped us to both design our own lab setup, and to avoid previously made errors.
Columbia Electronic Encyclopedia, 6th Edition; 7/1/2010, p1-1, 1p
RubberWorld; May94, Vol. 210 Issue 2, p20, 3p, 1 Black and White Photograph, 1Graph (Rubber World Vol. 210)
RubberWorld; Apr96, Vol. 214 Issue 1, p18, 3p, 1 Black and White Photograph, 1Diagram, 1 Graph (Rubber World Vol. 214)
The above three sources provided information about the process of vulcanization, and the chemical composition of rubber bands.
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