What is Rubber: Definition and 253 Discussions

Rubber, also called India rubber, latex, Amazonian rubber, caucho, or caoutchouc, as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds, plus water. Thailand and Indonesia are two of the leading rubber producers. Types of polyisoprene that are used as natural rubbers are classified as elastomers.
Currently, rubber is harvested mainly in the form of the latex from the rubber tree (Hevea brasiliensis) or others. The latex is a sticky, milky and white colloid drawn off by making incisions in the bark and collecting the fluid in vessels in a process called "tapping". The latex then is refined into rubber that is ready for commercial processing. In major areas, latex is allowed to coagulate in the collection cup. The coagulated lumps are collected and processed into dry forms for sale.
Natural rubber is used extensively in many applications and products, either alone or in combination with other materials. In most of its useful forms, it has a large stretch ratio and high resilience, and also is water-proof.

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  1. D

    Thermodynamics of Rubber Band

    Homework Statement The equation of state for a rubber band with temperature T is \mathcal{F}=aT\left[\frac{L}{L_0}-\left(\frac{L_0}{L}\right)^2\right] Where \mathcal{F} is the tension, L is the stretched length and L_0 is the unstretched length a) Write the Central Equation for the...
  2. P

    Ant on a rubber string, mathematical series

    Homework Statement Ideal rubber stirng with length L=1km.Ant is takng a walk on the string with speed v=1cm/s After every minute(Δt=60s) ,string is getting longer by ΔL=1km. 1)Will ant get to the end of string? 2)If yes,then how long it will take ? Homework Equations 1) So i used...
  3. G

    'Ant on a rubber rope' Wikipedia page

    Some time ago, I came across this page on Wikipedia. The problem is interesting, and I understood it. There used to be a small part on the bottom that said something like 'One can stack a block, such that it overhangs off the table, and put more blocks on the first one to make the overhang...
  4. Z

    Cloth belt against Rubber coefficient of friction

    Does anyone know where I can get those values? Haven't been able to find them anywhere
  5. NATURE.M

    Solving SHM of Cube Connected By Rubber Bands

    Homework Statement A cube of mass m is connected to two rubber bands of length L, each under tension T. The cube is displaced by a small distance y perpendicular to the length of the rubber bands. Assume the tension doesn't change. Show that the system exhibits SHM, and find its angular...
  6. E

    Heat flow through rubber sample

    I have a rubber sample here, basically it is a slice with a diameter of 45mm and a depth of 3mm. If this sample was at 25 degrees Celsius and I applied 180 degrees temperature all around it (top, bottom faces and outside diameter) how long would it take for the centre point (last point to get...
  7. G

    Rubber ball colliding with steel ball of equal mass

    Homework Statement Suppose a rubber ball collides head-on with a steel ball of equal mass traveling in the opposite direction with equal speed. Which ball, if either, receives the larger impulse? Explain. Homework Equations p = m*v impulse force = change in p The Attempt at a...
  8. D

    Thermodynamics of a Rubber Band

    Homework Statement For the rubber band model, calculate the fractional change in (L-L0) that results from an increase δT in temperature, at constant tension. Express the result in terms of the length and temperature. Homework Equations U=cL0T τ=bT((L-L0)/(L1-L0)); τ=tension, L1=elastic...
  9. Spinnor

    The thermodynamics of stretched rubber, a function of speed?

    By stretching a rubber band slowly and then slowly releasing it can we minimize the energy lost, (minimize the change in entropy?)? If so should a hysteresis curve be a function of the rate at which the rubber is deformed? See, http://en.wikipedia.org/wiki/Hysteresis#Elastic_hysteresis...
  10. D

    Behavior of a Natural Rubber Stud Mount.

    Hello, I am interested in estimating/modelling the behavior of a rubber stud mount (http://image.made-in-china.com/2f0j00nemTaJBgEcbE/Anti-Vibration-Mounting.jpg) when a moment is applied about its radial axis. In my application, I am using it primarily as a spring alternative where it supports...
  11. H

    Properties of Rubber: Resilience & Applications

    Do you know why it's important for rubber to be resilient? and does anybody have an example of an object that is made out of rubber which must be resilient? and does anybody know why it's important why tires and children's play grounds are made from resilient materials? Many thanks,
  12. J

    What Material absorbs shock better? Rubber or plastic?

    For example a phone in a case is dropped, would it suffer more in a plastic case or a rubber case? Thanks
  13. fluidistic

    How Do Thermodynamic Principles Apply to Rubber Band Stretching?

    Homework Statement Hi guys, I'm trying to solve questions from past exams; here comes one. There are 2 possible fundamental equations for the rubber bands: ##S=L_0\gamma \left ( \frac{aU}{L_0} \right ) ^{1/2} -L_0 \gamma \left [ \frac{1}{2} \left ( \frac{L}{L_0} \right ) ^2 + \frac{L_0}{L}...
  14. S

    Equation satisfied by a rubber sheet

    Greetings, How can I derive the equation satisfied by a rubber sheet? I know that it reduces to Laplace's equation when the sheet is quite planar. I found the expression for it on p.113 in Introduction to Electrodynamics by Griffiths. Thanks in advance. Edit: I have attached the expression...
  15. I

    Find work done in stretching rubber band

    Homework Statement Please see attachment. Homework Equations The Attempt at a Solution Not really a homework problem. This is 1 of my exam question which I believe I had the right answer but my professor insists that he has the right one. I started by equating work done, W =...
  16. K

    Rubber Stopper Launcher: How to Launch Over 100m Using a Gas Reaction

    Hello! I'm neck-deep in concept designs, and honestly, I am swamped. I'm participating in an experiment to launch a rubber stopper from a bottle using a gas-producing reaction. My most recent design structure used dry ice, and a chamber made of metal, with the dry ice proportioned out inside...
  17. A

    Engineering Is a Chinook-Style Design the Key to a Successful Rubber Motored Helicopter?

    Homework Statement For a Science Olympiad project I need to make a rubber motored helicopter, and with this I need to find the best design for one. One special rule in this is that Chinook styled helicopters get 3x their original flight time, I was wondering if that would be just to encourage...
  18. B

    Connection to Nature: The Impact of Rubber Soles

    While sitting contemplating life today, I had a thought. Naturally were connected to the earth...The civilizations throughout history had a much deeper profound connection to it as well. The only difference besides technological advances is we wear shoes with rubber soles...Rubber is not...
  19. G

    Where to get really thin rubber sheets?

    Hey guys, I need to get some nitrile, latex, and rubber gum sheets for a project. The problem is, I need them to be really thin - 0.1 mm or thinner. And ideally, I would like to be able to pick what color I get. I spent a few days searching the web and not even Grainger has what I'm...
  20. N

    Does the spring constant of rubber affect the rate at which it cools?

    Does the spring constant of a piece of rubber affect its rate of cooling constant 'k' ? 1) Is there any formula, any proven relationship? 2) If there isn't, would investigating it make any sense? Or would it end up being a waste of time as the two variables are totally unrelated? Is there...
  21. D

    A rubber ball is plugging a whole in bottom of tank. When will it fail

    Homework Statement A 3 cm radius rubber ball weighing 5 g is used to plug a 4cm hole in the base of a tank. The tank is in use and is gradually emptying. At approximately what depth will the plug fail by floating up and out of the hole? Homework Equations Density The Attempt at a...
  22. jedishrfu

    Transforming a Rubber Band into a Trefoil Knot

    Interesting article from SciAm on transforming a rubberband into a trefoil knot and how math in the knot world of zero thickness says no but the real world says yes. http://www.scientificamerican.com/article.cfm?id=mathematical-impressions-can-you-turn-rubber-band-into-knot
  23. N

    Relationship between length of rubber beam and time to come to rest

    Homework Statement Imagine a rubber beam. One en is fixed and the other is pulled down 5cm and released. The beam wobbles until it comes to rest. Independent (what I change): length of rubber beam Dependent (what I measure): time to come to rest Controlled (what stays the same)...
  24. B

    A rubber ball, your family's minivan, and you.

    Just to be clear, this is NOT a homework question. It's honestly a question I have pondered for as long as I can remember sitting on the backseat of my family's minivan with a rubber ball. I'd also like to clear out that you bear with me and if I look unintelligent or questionably retarded...
  25. M

    Moment of Inertia of a hollow beam inside a rubber shell

    Hello guys, I am calculating Bending and Shear stresses in hollow beams. We have a particular kind of shell that we use for impact loading, so we put rubber discs around the steel shell. So my question is, how will it affect the moment of inertia ? Since I know that the rubber discs will...
  26. N

    Calculating Stress Applied to Rubber Band: 1.0 MPa/ unit Strain

    Rubber has roughly a stress of 1.0 MPa per unit strain . how much stress has been applied to the rubber band? Stress = f/a though it was straight forward and used the formula for stress but when I looked at the answer it was 2.0 x 10^6 Pa But why?
  27. R

    Need high-temp rubber coating

    Need high-temp "rubber" coating Hey I'm looking to coat some 0.5" aluminum rods with some sort of coating to increase the friction coefficient ("tackiness" I believe it's called). It will be used in high temperature environments of up to 200C. Does anyone know of such product? I tried...
  28. B

    Physics Lab Questions: Rubber Band & Force Probe

    Okay, I am working on my physics lab, and I have a few questions regarding it. First, we are asked to make a prediction: "Predict how you think the presence of a rubber band will affect the force felt by the force probe from the rubber band compared to masses hung directly from the hook?" My...
  29. M

    Metal Rubber: Exploring the Possibilities of Elastic Metallic Materials

    Hello! Is there a metallic material that can have the elasticity properties of a rubber band? Thanks!
  30. C

    Rubber compression strength question

    Need help in determining the impact force strength of a door stop rubber. It is a urethane rubber formed in a triangular shape. I used a 50t press with a 2" round shaft to compress rubber product and it required 100 lbs of force to compress. I believe this worked out to 18.75 ft lbs to...
  31. V

    Calculating the bounce of a rubber ball off of a domed piston

    Homework Statement I'm supposed to design an "invention" using gas laws, and I've chosen to use Boyle's. But it turns out that a whole bunch of other science is involved, and I just can't handle it all. At it's simplest, this is what the invention is: A giant rubber ball, with a person seated...
  32. P

    Creating a Perfect Fit: Rubber Shims for Saddles and Horses

    Here is the problem: The bars of a saddle, which rest on a horse's back, rarely completely conform to the exact shape of the horse's back. I want to make a rubbery or heavy dense foam shim which will fill in the voids between the saddle bars and the horse's back so there is a perfect fit...
  33. R

    Rubber O-Rings: Hardness, Strength & Compression Stress

    Hi guys I have a general query regarding Rubber O-rings. For an application , say seal between 2 mating flanges of pipes ,with water pressure say about 10bars, How exactly does the hardness of rubber effect the the sealing? Is there a direct relation between hardness & strength ? Can some...
  34. D

    Finding Average Shear Strain in a flexible connection of rubber and steel

    Homework Statement [See Attachment] Given: Thickness, load, G Find:γ and horizontal displacement. Homework Equations τ=γG Angle change should be the shear strain. The Attempt at a Solution I tried plugging 800 into tau and the given value of G to get γ, but that isn't...
  35. X

    Thermodynamics of a rubber band

    Homework Statement For a stretched rubber band, it is observed experimentally that the tension f is proportional tot he temperature T if the length L is held constant. Prove that: (a) the internal Energy U is a function of temperature; (b) adiabatic stretching of the band results in an...
  36. J

    Mounting rubber wheel on motors

    I am trying to mount rubber wheels on a motor to make a paper airplane launcher similar to this: http://www.instructables.com/id/Super-fast-paper-plane-launcher/ only, instead of wheels, I'm using rubber stoppers (for flasks) I've got two questions, 1) how do I attach them to the motor...
  37. L

    Can a Worm Ever Reach the End of a Continuously Stretching Rope?

    Homework Statement Write a Java program to solve the following problem. An elastic rope starts out with length 100 meters. The start of the rope is fixed to a pole and a worm is placed on the rope at the start and the worm starts crawling towards the end. Each day the worm crawls 6 meters...
  38. R

    Natural vs. Synthetic rubber foam ? search project solution help

    Hello everybody I have a mass production project for a new product . The thing is to be made in foam , sheets...it is some material involved . To visualize the idea think about the Yoga mat sort of material but much thick.. Natural or Synthetic ?..provided there is to be found a natural...
  39. N

    Rubber Tyre Gantry: Learn How It Works

    hi all can you please explain to me what a rubber tyre gantry is & how it works
  40. G

    Physics Car Assignment : rubber band car

    1. i have a physics project where we have to make a car that accelerates the fastest during 3.0 m. it also must be accelerating for the whole 3.0m. I am using a simple rubber band car where the rubber bands are attached to both axels and are wound up. i have to make a bunch of calculations but...
  41. D

    Graph plotting, resonant frequency vs tension in rubber cord.

    1. okay, so I'm still struggling on trying to plot a graph for the relationship between the resonant frequency and the tension in a length of rubber cord, using standing waves. I've got that as the tension increases so does the frequency, and as length increases the frequency decreases. and...
  42. J

    Rubber bands and thermodynamics

    Homework Statement Polymers, like rubber, are made of very long molecules, usually tangled up in a configuration that has lots of entropy. As a very crude model of a rubber band, consider a chain of N links, each of length l. Imagine that each link has only two possible states, pointing...
  43. D

    Are Rubber Bands in Parallel Affected by Spring Constant?

    Hey I am doing an experiment, checking how the spring constant of a rubber band relates to the spring constant of rubber bands in parallel. I calculated the gradient of a F vs x, graph i got a -0.0853 for the first rubber band, -0.0791 & -0.088 for the 2nd and the 3rd. Then i did them in...
  44. D

    Exploring the Spring Constant of a Rubber Band

    Hey I am doing a practical on the spring constant of a rubber band, we have studied hooke's law and from that found that the spring constant of a spring is well F = -kx so F is proportional to x. While i did the same experiment with a rubber band, hung it on a clamp connected to a retort...
  45. A

    Exploring the Physics of Stretching a Rubber Band

    Why a rubber band gets warmer when repeatedly stretched and relaxes? Where does the gained ME comes from? Besides, does rubber band obeys Hooke's Law?
  46. R

    Calculating Force Transmitted by Rubber Mountings to Failed Bracket

    I'm having difficulties in finding an answer to the issue show in the attached pic. Fracture surface on the failed bracket! I have the properties of the mild steel, the properties of the rubber mountings, and the number of the cycles per minute. What i can't figure out is the load or the force...
  47. P

    Force/pressure exerted from rubber band

    If you stretch a rubber band around a pole, the band exerts a force onto the surface of the pole (F1 in figure 1). Is it possible to calculate this force if I know the force needed to stretch the rubber band to the same total length as the circumference of the pole? That is to say: 1. I know...
  48. U

    Is Heat the Sole Factor in Rubber Band Strength?

    ive heard somewhere that it is heat that does that, but the effect is supossed to be so small so that one can't even notice. and on the other hand the effect is so large that it resists the motion of your hand for example so something is clearly wrong here it can't be only heat can it it must...
  49. S

    Heating a block of Rubber by passing electricity

    Hi everyone. I want to heat a piece of Rubber by embedding copper strips or wires in it and passing electricity(120V - 2.5Amp) through it. The room temperature is 0(zero) deg Celsius and i want to heat the aluminum block(5" x 5" x 1") to 10 deg Celsius(Not more than 10 deg). Question...
  50. D

    Looking for a high temp rubber

    Can somebody help me out? I a looking for a high temp rubber to use as a lamination press pad. Hopefully something over or around the 700 F (370 C) range. If you know of a material great... if you know of a supplier awesome. Thanks!
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