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Plastic Surface Competition

Grades: 9-12
Author: Joseph DeAngelis
Source: This material is based upon work supported by the National Science Foundation under Grant No. EEC-1161732.


Abstract

The students will investigate the effect of various treatments on the adhesion of water to common plastic surfaces. The students will compete to make a plastic piece with one side able to retain the most water as possible and the other side as little water as possible. This lesson can be an introduction or review of the six recycled numbered plastics as well as the study of Polymer Engineering and surface science.


Objectives

What should students know as a result of this lesson?

  • The students will infer that surface adhesion is an important property of materials.
  • The students will investigate that chemical and physical changes can be made to the surface of a material to modify its properties.
  • The students will show that the surface properties of a material are an important consideration when designing a product.
  • The students will prove that the amount of adhesion of water to the plastic surfaces is inversely proportional to the mass of water retained on the plastics surfaces.

What should the students be able to do as a result of this lesson?

  • The students will use inquiry to investigate how the surface of a plastic can be modified to change its properties.
  • The students will draw conclusions about what effect various treatments have on the water adhesion of plastic surfaces.
  • The students relate their conclusions to real world situations when one would want high surface adhesion or low surface adhesion.

Materials

  • Plastic Samples from the six recycled plastics
  • Scissors
  • Pennies
  • Markers for plastic
  • Rulers
  • Plastic cups
  • Pipettes
  • Various grades of sand paper
  • A variety of non-polar products, e.g. car wax, oils, rain x, etc...
  • A variety of surfactants, e.g. dish soap, shampoo, laundry detergent, etc...
  • Sensitive electronic balance

Procedures

Engagement

Students complete the Water on a Penny Activity.

Assessment: Class discussion of the Water on a Penny Activity questions.

Exploration

Plastic Surface Competition Activity

Assessment: Students test their team's plastic pieces by counting drops or massing and determine which piece to submit for competition.

Explanation

Class discusses which modifications and to which plastics cause the best results. Have students complete the discussion questions on the Plastic Surface Competition Rubric.

Assessment: Evaluate and total the points on the Rubric. Teacher tests each team's plastic piece and compare the greatest difference in the mass of water held on each side of their plastic samples.

Elaboration

Teacher presentation of The Surface Adhesion and Water Drops Power Point.

Students could test the effects of various amounts of sunlight exposure, or various chemical exposures on the water adhesion of plastic surfaces.

This activity could lead students to a myriad of science fair projects involving surface science, or polymer engineering. Examples include testing cell phone covers, paint adhesion and surface preparation, solar cell surfaces, sterile surfaces, wind-shield cleaners and treatments, contact lenses experiments, eye glass cleaners, the best care of electronic device screens, printing on plastic surfaces etc...


Prerequisites

This lesson will also serve as a review of the following concepts with which the students should already be familiar: the structure of a water molecule, hydrogen bonding, dispersion forces, chemical bonding, physical/chemical changes, and physical/chemical properties.


Best Teaching Practices

  • Inquiry Approaches
  • Hands-on/Minds-on
  • Learning Cycle
  • Authentic Problem Based Learning
  • Questioning

Alignment with Standards

NGSS Standards:

  • HS-PS2-6 Communicate scientific and technical information about why the molecular-level structure is important in the functioning of designed materials.
  • HS-ESS3-1 Construct an explanation based on evidence for how the availability of natural resources, occurrence of natural hazards, and changes in climate have influenced human activity.
  • HS-PS2-4 Use mathematical representations of Newton's Law of Gravitation and Coulomb's Law to describe and predict the gravitational and electrostatic forces between objects.

Common Core Standards:

  • RST.9-10.3 Follow precisely a complex multi-step procedure when carrying out experiments, taking measurements, or performing technical tasks, attending to special cases or exceptions defined in the text.
  • WHST.9-10.2 Write informative/explanatory texts, including narration of historical events, scientific procedures/experiments, or technical processes.

National Standards:

  • Chemistry: Intermolecular Chemical Bonding

Ohio Standards:

  • Identify questions and concepts that guide scientific investigations;
  • Formulate and revise explanations and models using logic and evidence (critical thinking);
  • Design and conduct scientific investigations

Content Knowledge

The Surface Adhesion and Water Drops Power Point


Safety

  • Safety considerations depend on the products made available for the students to treat the plastics. MSDS should be reviewed and on hand for each product, and chemical used. Goggles and gloves would be an option depending upon the products used.

Applications

Real world applications include:

  • Surface preparation for adhesives, paints, or any other coatings
  • Surface engineering smooth surfaces vs. textured
  • Surface engineering for non-stick properties, e.g. cookware, water repellency, fabric treatments, glass treatments, eyeglasses.
  • Automobile applications-any type of surface treatments ranging from waxes for the exterior, window treatments and tinting, upholstery and interior surface considerations, and tire surfaces.
  • Surfactants such as soaps, shampoos, cleaning solutions.
  • Polishing surfaces, and abrasives
  • Wood furniture oils and waxes.
  • Flooring surface choices and treatments

Assessment

Plastic Surface Competition Rubric


Other Considerations

This lesson may be used as part of a larger unit on polymers or as a standalone lesson.


Printable PDF Worksheets

Water Drops on a Penny Activity

Plastic Surface Competition Rules

Plastic Surface Competition Rubric

Plastic Surface Competition Pre-Assessment

Plastic Surface Competition Post-Assessment

The Surface Adhesion and Water Drops Power Point