You have been hired by a local toy company “We ‘R Fun” to help develop a line of slime kits that will compete with a rival company’s line “Toys Toys Toys”. Your employer has determined that the primary characteristic to children’s enjoyment of slime it having the perfect viscosity. Viscosity is the measure of a fluid’s resistance to flow. Although there are many ways to measure this property, you have determined that the “efflux time”, which is the length of time a liquid takes to flow through a hole in a container until the liquid stream stops, is the easiest and most cost-effective method. From analysis of the rival’s kit, you know that their process uses PVA glue (Elmer’s glue), borax (sodium tetraborate decahydrate, ) and water. It is your job to determine the relationship between the concentration of borax in the thickening agent, and the viscosity of the resulting slime. You will accomplish this by graphing increasing concentrations of borax solution added to a constant amount of PVA glue vs the viscosity of the resulting slime. Once you have the graph you will need to determine if there is a relationship between borax concentration and viscosity. Using that relationship you will need to determine based on the viscosity of the rival’s slime, what their recipe is.

Background:

Elmer’s glue uses polyvinylalcohol (PVA) as one of its main ingredients. PVA is a long, straight polymer chain that can easily slide past other PVA molecules, which allows the glue to flow like a liquid. Borax reacts with PVA chains to bind multiple chains together, preventing them from flowing past each other. This process, called crosslinking, is what gives plastics (another polymer) their rigidity. The difference between the plastics you use everyday and slime is the amount of crosslinking that occurs. In the case of the PVA/borax slime that you will make in this experiment there is significantly less crosslinking that would be found in most consumer plastics. However, the more crosslinking that does occur, the more rigid (less viscous) the slime should become.

Procedure:

Prepare a 50/50 mixture by volume, of PVA glue to deionized water by mixing 118 mL of water with the entire contents of a 118 mL bottle of Elmer’s glue. Obtain and label 10 containers and fill each with 20 g of the PVA/water mixture (Solution 1). In 10 separate containers prepare increasing concentrations of borax using the borax stock solution provided and enough water to obtain a total of 20 g of a diluted borax solution (solution 2) (Table 1).

Table 1. Amounts of each component to be used for each trial mixture.

	Solution 1	Solution 2
Trial #	PVA/Water mixture (g)	Borax concentrated solution (g)	Water (g)
1	20	1	19
2	20	2	18
3	20	3	17
4	20	4	16
5	20	5	15
6	20	6	14
7	20	7	13
8	20	8	12
9	20	9	11
10	20	10	10

Pour solution 2 into the container holding solution 1 and mix with a stirring rod for a minimum of 30 seconds or until a consistent thickness is obtained. Repeat for all trial solutions. Next stopper the bottom of a wide mouth funnel and pour the slime mixture into the funnel. Start a stopwatch as soon as you remove the plug from the bottom of the container. Stop the timer once the slime has stopped flowing through the funnel. Record any observations during this process. Repeat the measurement for all the trial slimes and the manufacturer’s sample.

Data analysis:

Tabulate all of your data and graph flow time vs the mass of borax concentrated solution used. Fit a trend-line through the data. Does the graph follow a linear relationship or another relationship? Where does the rival’s slime land on the curve? How much borax concentrated solution is used in their thickening agent solution? Do you think there is a more optimal viscosity for slime? If so, how much borax solution should be added to obtain the result?

Write a formal report for “We R Fun” in which you describe the background information of polymers and how they are formed, any health issues with borax, the method you used in performing this experiment, your results and an interpretation of the results. Include a summary of your method and findings in a conclusion section so they can get a quick overview of your study.