why do rubber bands break?

As you know, when you stretch a rubber band too much, it suddenly snaps. A rubber band, although it may not seem so, is not exactly the same thickness or width all the way around the loop. Therefore, it is important to note that rupture of the rubber band will break at it's weakest point or the point where pressure is most directly exerted.

When an object such as rubber is stretched, stress is put upon the object, resulting in 'microtears' along the stretched part. THis is why when you strech a rubber band, there are very small 'wrinkly' lines in the band. The more stress is exerted, the more likely the rubber band will break. Eventually the rubber band will break.



TO

Intro (2)- BAckground research on Rubber

Taking off from before...

It was only an accident when Charles Goodyear (yes, the person who made the tyres on your car) mixed sulfur, lead and rubber on a hot surface that the formerly- natural rubber acquired a more usable consistency and texture. Goodyear dubbed this process 'vulcanization'. Vulcanization can be defined as the process of treating rubber with sulfur with a high heat using sulfur/ other 'curatives' to improve elasticity, strength and/or durability of the rubber.

Today, most of the rubber in this world is used for commercial/ domestic purposes and is produced synthetically. There are about 20 types of synthetic rubber, all classified according to their intended use and thus, their quality, and only one type of natural rubber.

Rubber bands are simply short lenghts of rubber, calcium carbonate, carbon black, clay, sulfur, stearic acid, zinc oxide, wax and oil formed into a loop (mentioned in previously in another post). These ingredients are put into a tube and mixed in a pressurized steam tank through the process of 'vulcanization'. When this is done, the tube is cut into rings to form the rubber bands that we know.

References:

• http://science.jrank.org/pages/7266/Vulcanization.html, vulcanization- rubber as a natural product, Date accessed [30th March 2010]
• Mark,J.E., Erman B. and Eirich F.R. (1994), Science and Technology of Rubber: 2nd edition, Academic Press Limited, London
• http://www.essortment.com/all/historyofrubbe_rcml.htm, history and development of rubber, Date accessed [30th March 2010]
• http://www.enotes.com/how-products-encyclopedia/rubber-band, history and development of rubber bands, Date accessed [31st March 2010].
  

Introduction (1)- Background about Rubber

Before the process of curing/ vulcanizing rubber was discovered, rubber was a product with much potential to be improved as it was extremely unreliable and temperamental according to the weather i.e. when it was humid, the rubber would 'follow' and turn warm and sticky, when it was cold, the 'unvulcanized' rubber would turn soft and fragile. This made the rubber unreliable for practical use.

Rubber originally and nuturally derives from plants which grow in the equitorial regions of the globe, particulary East Asia. It was initially used by the Mayans (for who knows how long) by extracting latex found in tree sap of rubber trees and combining it with the liquids of a nearby vine, resulting in a black substance with basic waterproofing qualities.

Since the mid 1700s when CHristopher Columbus discovered the Mayan's incredulous invention and introduced it to other 'developed' countries such as Europe and America, there has been many attempts to develope the natural rubber until it could hold it's shape and be sutiable for commercial use.

To be continued...

waiting

well hi there,
i still haven't gotten miss Zhang's approval yet so i'm just going to type this to fiill in some space. Actually, i'm not being that pointless, but until official approval from the 'one above' is handed down, i'll keep the research on rubber bands etc. until next time.
By the way, is it just me or is everything so ambiguous...

EVERYTHING

VARiables/ Research ETc. etc. etc. Hello again! AS i have previously mentioned before, i am doing my experiment on-

'DOES TEMPERATURE AFFECT THE FORCE A RUBBER BAND CAN WITHSTAND BEFORE RUPTURE?'

The variables are:
INDEPENDANT VARIABLE: Temperature
DEPENDANT VARIABLE: Elasticity of a rubber band (The force the rubber band can withstand before it breaks)
CONTROLLED VARIABLES: Size of the rubber band, brand of rubber band, spring scale used, same fridge and oven.

EQUIPMENT NECESSARY (MAY CHANGE LATER) - spring scale -protective gloves (optional) - pack of rubber bands -same oven and fridge - safety goggles

METHOD (SUBJECT TO CHANGE):

1) Hang the spring balance from a secure post vertically.

2) Heat 15 of the same type of rubber band in the oven at 70 degrees celcius for 2 hours.

3) Take the rubber bands out of the oven and pull on spring scale with rubber band. Record results (force exerted before rupture of elastic band in a table).

4) Repeat steps 1-3, instead using 15x rubber bands at room temperature left for 2 hours, and 15x rubber bands at 0 degrees celcius for 2 hours.

5) Record and tabulate results.

For my other project ideas:

- does the design of a bridge affect the weight it can carry?

INDEPENDANT VARIABLE: Design of bridge

DEPENDANT VARIABLE: weight it can support/ carry

CONTOLLED VARIABLES: Material the bridges are made of, the length and size of the bridges, same weights used

-Does fertiliser actually affect the rate of plant growth?

INDEPENDANT VARIABLE: type of fertiliser

DEPENDANT VARIABLE: rate of plant growth

CONTROLLED VARIABLES: plant type, position and location of the plants, water and amount of fertiliser gaiven to each plant

Rubber band research

RUBBER BAND RESEARCH:
I found that rubber bands are short loops of rubber and latex, calcium carbonate, carbon black, clay, sulfur, stearic acid, zinc oxide, wax and oil. The rubber band can be classified into classes according to its- length, width and thickness.

The rubber band is made with the ingredients above through a process called 'vulcanization.' I shall conduct further research on the process of vulcanization later on.

An important note i found is that ELASTICITY (defined as the tendency of a body to return to its original shape after it has been stretched or compressed) is different to stretching the rubber band till it breaks and meausuring the force exerted on the rubber band just before it breaks. I think the correct term is rupture, that is, where an object suddenly breaks, but confirmation would be grealty appreciated... Miss Zhang...
As a result of this finding, i have decided to change my experiment aim to:

Does temperature affect the force that a rubber band can withstand before rupture?

Bibliography/ sources:
- http://en.wikipedia.org/wiki/Rubber_band, what are rubber bands made of?, Date accessed[6/03/10] (research was conducted before posting)
-taken from wordnetweb.princeton.edu/perl/webwn, elasticity, DAte accessed [10/03/10]

BINGO!

to everyone who actually reads this:

after careful consideration, i have come to the conclusion that my SRP will be on:

' Does temperature affect the elasticity of a rubber band?'

it's a experiment which i find fairly interesting and do-able but just case this falls apart, i have come up with a few other ideas:

- does design of bridges affect the weight it can carry

- do plants grow in accoradance with gravity

- does fertiliser actually affect rate of plant growth

these however are all pretty boring and/or complex (to me) and i hope to start researching rubber bands real soon....

Brainstorming

Hi again! I've been brainstorming what my brilliant experiment should be on... but so far there have only been many questions as to how i'm going to actually do the experiment :( . I've been thinking... maybe something to do with whether bridge designs influence how much weight it can carry. Or maybe something to do with plants, but that sounds cliche. Don't you agree? Hmm... but that can be my backup plan i guess.
Golly! This is harder than it seems.

Post 1

Hello World.