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    Elmer's Glue Viscosity
    K-12 Experiments & Background information
    For Science Labs, Lesson Plans, Class Activities & Science Fair Projects
    For Middle School Students & Teachers





    This experiment is courtesy of 

    Elmer's Glue Viscosity Experiments


    Developers:

    Louise A. Pascale
    William Allen Middle School
    Moorestown, New Jersey

    Tammy L. Maver
    Senior Chemist
    Rohm and Haas Company
    Spring House, PA


    Grade
    Level:

    7 and 8


    Discipline:

    Physical Science


    Goal:

    Upon completion of this experiment, the students will:

    1. Incorporate the scientific method within the context of specific content material.
    2. Hypothesize, explore, analyze, and interpret data within a co-operative learning group.
    3. Understand that household products have a scientific basis.


    Specific Objectives:

    Upon completion of this experiment, students will be able to:

    1. Differentiate between high and low viscosity.
    2. Collect, graph, and interpret data.
    3. Quantitatively measure polymer solids.
    4. Experiment with a household example of an emulsion polymer.


    Background:

    Viscosity is defined as the quality of liquid to resist flow. Materials which have a low resistance to flow, or flow quickly, such as water, have a low viscosity. Liquids which flow slowly, such as honey, have a high viscosity. The Elmer's� glue used in this experiment has a high viscosity due to the fact that it consists of a large number of particles dispersed in water. As the glue is diluted with water, the number of dispersed particles decreases, lowering the viscosity of the resulting liquid.

    The particles in Elmer's� glue are polymers. A polymer is a large molecule made up of a large number of smaller molecules (monomers) joined together to form a chain. A few examples of polymers include plastics, protein, nylon, and starch. More specifically, Elmer's� glue is an example of an emulsion polymer where it is prepared by polymerizing an oil-like monomer in water. The actual monomer used is vinyl acetate which after polymerization is known as ploy(vinyl acetate).

    An emulsion is a dispersion of one immiscible liquid in another in the form of fine droplets. Surfactants (surface-active agent) are added to emulsions to provide stability. Surfactants are chemical compounds which contain both a hydrophilic (water soluble) moiety and a hydrophobic (water insoluble) moiety.

    Why does Elmer's� glue dry clear? When the polymer particles are dispersed in water, light striking the glue is reflected by these discrete particle causing the glue to be opaque. (Figure A) As the glue dries, water evaporates forcing the polymer particles closer together. Since the particles are still discrete, they will still reflect light and the glue remains opaque. (Figure B) As the last of the water evaporates the particles are forced together. This can be compared to two balls of clay which when pushed together with enough force will become one. Now as the light strikes the glue there are no longer any discrete particles to reflect it back and the glue is now transparent. (Figure C)


    Vocabulary:

    viscosity
    physical change
    hydrophobic
    polymer
    quantitative analysis
    hydrophilic
    emulsion
    surfactant (surface-active agent)


    Materials:

    funnel
    ringstand
    clamp
    beaker
    droppers
    graduated cylinder -100 ml
    stirring rods
    stop-watch
    graph paper
    watch glass
    Elmer's� glue


     

    Problem:

    PART A: VISCOSITY OF EMULSION POLYMER . . . GLUE

    To determine if the viscosity of Elmer's� glue will change with various dilutions.

    Hypothesis:

     

     


    Procedure:

    1. Pour 50 ml of Elmer's� glue into a 100 ml graduated cylinder.
    2. Set up the apparatus as shown in Figure 1.
    3. Pour glue into funnel. Record the time (sec) it takes for glue to pass through the funnel.
    4. Repeat using the various dilutions.
        4a. 30 ml of glue + 20 ml of water
        4b. 20 ml of glue + 30 ml of water
        4c. 10 ml of glue + 40 ml of water
        4d. 5 ml of glue + 45 ml of water

    Data Table I

    Emulsion Polymer...Glue

    Viscosity Time (sec)


    50 ml (original)

    a. 30 ml of glue + 20 ml of water

    b. 20 ml of glue + 30 ml of water

    c. 10 ml of glue + 40 ml of water

    d. 5 ml of glue + 45 ml of water


    ___________________

    ___________________

    ___________________

    ___________________

    ___________________


    Interpretations:

    1. Graph the results from PART A using viscosity (sec) as a function of water added (ml).
    2. Was viscosity affected by the addition of water? Explain.
    3. Give two examples of liquids that have a high viscosity.
    4. Give two examples of liquids that have a low viscosity.
    5. In a practical sense, why does glue have a high viscosity?


     

    Problem:

    PART B: QUANTITATIVE MEASURE OF SOLID POLYMER

    To determine how the viscosity of Elmer's� glue varies with the quantitative measure of polymer solids.

    Hypothesis:

     

     


    Procedure:

    1. Mass watch glass and add 1g of original emulsion.
    2. Evaporate substance overnight.
    3. Mass watch glass with evaporated emulsion.
    4. Subtract the mass of the watch glass from the total mass to determine how much solid polymer remains.
    5. Determine the % of solid polymer by dividing the final amount by the initial amount of emulsion x 100.
      Example: 0.5g/1g x 100 = 50%
    6. Repeat steps 1-5, using the different dilutions from Part A lab.
    7. Record all data in Data Table II.

    Data Table II

    Dilution

    Initial:

     

     

    Final:

     

     

    Mass of
    Watch Glass

    Mass of
    Emulsion
    Watch Glass

    Initial Mass

    Mass of Dried
    Emulsion +
    Watch Glass

    Final Mass

    Original

     

     

     

     

     

    a. +20 ml water

     

     

     

     

     

    b. +30 ml water

     

     

     

     

     

    c. +40 ml water

     

     

     

     

     

    d. +45 ml water

     

     

     

     

     


    Interpretations:

    1. Calculate the % of solid polymer in each dilution using the following formula:
      % = FINAL MASS/INITIAL MASS X 100
    2. Graph the data of viscosity (sec) from Part A as a function of % solid polymer.
    3. How does the viscosity change as the % solid polymer increases?
    4. Compare and contrast the graphs from Part A and Part B.
    5. Provide an analogy to explain how viscosity is related to the solid polymer content.


    Teacher Hint:

    It is suggested that the class be divided into teams. Each team given the originalsample (50 ml) plus one other dilution to test a minimum of two times. Uponcompletion, all teams will come together to compile data and draw conclusions.


    References:

    1. Becher, Paul, "Dictionary of Colloid and Surface Science", Marcel Dekker, Inc., New York, 1990.
    2. Bennett, H., Bishop J., and Wulfinghoff, M, "Practical Emulsions, Volume II", Chemical Publishing Company, Inc., New York, 1968.
    3. Cooney, T., Pasachoff, J., and Pasachoff, N., "Physical Science", Scott, Foresman and Company, Glenview, Illinois, 1990.
    4. Cuevas, M., Lamb, W., and Lehrman, R., "Physical Science", Harcourt Brace Jovanovich, Publishers, Orlando, 1989.
    5. Eby, D., and Horton, R., "Physical Science", Macmillan Publishing Company, New York, 1988.

    This experiment is courtesy of 



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