Epoxy glues and the ATLAS project: the biggest experiment ever?

ATLAS is a particle physics experiment that will explore the fundamental nature of matter and the basic forces that shape our universe. The ATLAS detector will search for new discoveries by colliding extraordinarily high-energy protons head on with each other. ATLAS is the largest collaborative effort ever attempted in the physical sciences. Over 1800 scientists from more than 150 universities and laboratories in 34 countries (including the UK) are participating.

Aim

The aim of this activity is to give students some idea of the scale of the projects undertaken in science and to make them aware of how scientists from dozens of different countries can work collaboratively to enhance our understanding of the universe. The activity focusses on one aspect of the ATLAS accelerator/detector – that of the superconducting magnets and, more specifically, the glue which is used to hold them together. Students will develop their own glue to solve a specific problem and then look at how the issue was tackled by the research team at CCLRC (Council for the Central Laboratory of the Research Councils) in Didcot, Oxfordshire.

Background knowledge required

Developing glue is accessible to the majority of students; the rest of the activity may not be. This activity could be carried out as an enhancement activity or as a science club activity. Students will need to have some understanding of the structure of the atom. The video goes way beyond what students will need at this stage. However, with a little background knowledge and interest, they will be able to understand enough to grasp the point of the ATLAS experiment. Students will need some knowledge of organic chemistry, acids and bases.

Developing glue – equipment needed

For making the glue:

• Milk – full fat, semi-skimmmed and skimmed – 100 cm³ of each per group
• Vinegar
• Bases, eg sodium hydrogencarbonate, magnesium carbonate, calcium carbonate, milk of magnesia
• Spatulas
• Stirring rods
• Measuring cylinders (100 cm³ and 25 cm³)
• Beakers (100 cm³ and 250 cm³)
• Bunsen burner, mat, tripod, gauze
• Filter funnel and paper
• Conical flask (100 cm³ or above)
• Universal Indicator paper (some students may request it). 
• Lolly sticks

For testing the glue:

• Weights (the ones on a hook are ideal) to be added, approx 100 g at a time
• Sand tray.

Health and safety

• Eye protection should be worn whilst making the glue. 
• Read our standard health and safety guidance
• To avoid the danger of weights landing on students’ feet, make sure a sand tray is placed underneath the sticks as they are tested.
• If the sticks snap then there is a risk of splinters. Students should wear eye protection during testing.
• Check students’ proposals for testing before they are carried out – pay particular attention to their plans for safety.

Notes on the method

Factors that could be varied in the glue making include: the type of milk – ordinary full fat, semi-skimmed, skimmed milk; the base (eg sodium hydrogencarbonate, magnesium carbonate, calcium carbonate) – carbonates are good as the mixture bubbles when they are added so it is easy to tell when the glue has been neutralised without using an indicator; the pH of the glue (ie vary the amount of base added, from not enough for neutralisation to excess); the acid used to curdle the milk.

Students can make one ‘batch’ with one type of milk and then divide the curd and water mixture into portions and add a different base to each portion. A large number of different glues can then be made without too much effort.

Testing the glue can be awkward as it is so strong that if paper is used, the paper will almost certainly break before the glue does, which would not allow relative strengths of glue to be tested. One alternative is to use two lolly sticks overlapped by about 2 cm and glued down at the overlap. Once the glue is dry, balance the sticks over the gap between two tables separated by a suitable distance.

Place a sand tray underneath and hang weights on the lower of the two sticks until the glue breaks and the sticks come apart. Quite a significant amount of force is required for this – if you are short of weights, make the overlap between the sticks smaller to reduce the force needed.

As the results vary, each glue should be tested at least twice.

Developing glue

It has been known for a long time that glue can be made from milk. A basic recipe for this kind of glue is given below but there are a number of ways it can be varied. Work in a team of 2–5 to develop the strongest glue you can, starting from milk.

Use your glue to stick two lolly sticks together and then test its strength. In order to complete this task in the time available, you will need to share out the work amongst your team.

Basic formula for milk glue

You will need:

• 100 cm³ milk
• 20 cm³ vinegar
• About a spatula of base (write down which base you use)
• Measuring cylinder
• Beaker
• Bunsen burner, mat, tripod and gauze
• Stirring rod
• Filter funnel and paper
• Conical flask.

What to do

1. Measure the milk and vinegar into a beaker. Heat over the Bunsen burner, stirring constantly until small lumps start to form. Stop heating but keep stirring until no more lumps form.
2. Let the lumps settle out, then decant the liquid from the top.
3. Filter the rest of the mixture and keep the solid part (called the curds).
4. Wash up the beaker.
5. Gently squeeze off any excess liquid from the curds and then put them back into the beaker.
6. Add 15 cm³ water and stir until the mixture is smooth.
7. Add about half a spatula of the base and check that the mixture is now neutral. If it is not neutral then add some more base until it is.
8. You have now made your glue.

Things to think about

• How could you vary this basic formula?
• Plan the formulations of glue you will make. Make sure you know which glue is which.
• How will you test your glue? Make sure your method is safe and the experiment is fair.
• Get your method checked by your teacher before you try it.
• Lolly sticks are good for glue testing.
• How will you record your results?