Lesson List
#01 Examination of the Degradation and Weathering of Polymeric Materials
#02 Investigation of Crystallinity in Polymeric Materials
#03 The Study of Molecular Orientation by Linear Dimension Change of Polymeric Films
#04 Simplified Vertical Rebound Testing
#05 Properties and Perfectly Polymeric Sodas
#06 Simple Tensile Testing of Polymeric Films and Sheeting
#07 Water and Polymers
#08 Slime and Intermolecular Attractions
#09 Condensation Polymerization: Preparation of Nylon 6/10
#10 Condensation Polymerization: Preparation of Nylon 6/6
#11 Condensation Polymerization: Preparation of Thiokol (Polysulfide Rubber)
#12 Condensation Polymerization: Preparation of Two Types of Polyesters
#13 Addition Polymerization: Preparation of Polystyrene Using Two Types of Initiators
#14 Determination of Plasticizer in PVC by IR or FTIR and a Precipitation Method
#15 Elastomers: The Best Bungee Cord
#16 How to Clean up an Oil Slick
#17 What Is Special About Polyethylene Food Storage Bags?
#18 Determination of the Set Time for Epoxy Adhesive
#20 The Influence of Initiator Concentration on the Molecular Weight of Polystyrene
#21 Films, Fibers, and Solubility
#22 Chemical Resistance and Synthetic Polymers
#23 Glass Transition in a Rubber Ball
#24 How Much Air Is In Foamed Polystyrene Products?
#25 Investigating the Effect Of Successive Heat and Cool Cycles on a Thermoplastic Material
#26 Intrinsic Viscosity, Evaluating the Polymerization Pattern in Polyvinyl Alcohol
#27 A Search for Automated Plastics Recycling Separation
Lesson Descriptions |
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| #01 Examination of the Degradation and Weathering of Polymeric Materials |
This lab investigates issues of degradation and weathering of polymeric materials during their useful life. The first activity will look at the qualitative changes in film materials when exposed to weathering. This activity will also have students evaluate photodegradable plastics and their viability as an environmental solution for litter. The second activity will have students investigate the qualitative changes in other polymer products when exposed to weather.
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#02 Investigation of Crystallinity in Polymeric Materials
This series of qualitative activities provides a visual introduction to the amorphous and crystalline nature of polymers. Students will observe the inherent crystalline nature of various polymers using polarized light. Students will also compare the degree of crystallinity of low- and high-density polyethylene and polypropylene.
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#03 The Study of Molecular Orientation by Linear Dimension Change of Polymeric Films
This lab will provide students an opportunity to investigate the linear dimension change of heated plastic film and relate the results to processing and service use of the materials. Students will cut samples from film and prepare them for testing. The students will make pre-and post-measurements to calculate percent change in dimension as related to anisotropy (differences in properties according to the direction of measurement) and molecular reorientation.
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#04 Simplified Vertical Rebound Testing
This activity involves rebound testing of elastomers. Students will produce rebound data and determine the kinetic energy transformed by the impact of a free falling ball.
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#05 Properties and Perfectly Polymeric Sodas
The following activities can be used in the instruction of physical properties, chemical properties, interfaces, and forms of plastic. The concepts of thermoplastic and thermosetting materials will also be introduced and related to recycling. Students will use polycaprolactone to demonstrate a thermoplastic material and physical changes. Epoxy putty is used to demonstrate a thermosetting material and a chemical reaction. The students will also create a foam (a "perfectly polymeric soda") to study interfaces and multiple forms of plastics.
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#06 Simple Tensile Testing of Polymeric Films and Sheeting
These activities investigate the tensile strength and percent elongation of various polymer films or sheeting. Student will pull tensile bars applying stress and feeling the differing strain produced. They will also calculate percent elongation of different materials comparing the differences between plastics and elastomers. These are modifications of ASTM D-638 which is the industrial standard for tensile testing.
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#07 Water and Polymers
These activities represent both qualitative and quantitative investigations based on the interaction between water and various polymers. Hydrogen bonding between water and different polymers is the basis of the investigations. Students will determine the percent moisture contained in various plastics along with a qualitative procedure to determine if water is present in a plastic sample. Students will also perform a modified industrial test to determine the percent moisture absorbed by various plastics.
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#08 Slime and Intermolecular Attractions
This is a perennial favorite for students young and old which provides an excellent visual example of the strength of intermolecular attractions. The same type of interactions that causes water absorption in plastics causes liquids to turn into slimy masses. Students will also compare the difference in the physical properties of sheet and powdered polyvinyl alcohol (PVAl) with polyvinyl acetate (PVAc) and relate these to molecular structure and additives.
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#09 Condensation Polymerization: Preparation of Nylon 6/10
One of the classic experiments in the preparation of nylon is the interfacial polymerization. Students produce nylon 6/10 by the reaction between a diacid chloride and a diamine. This reaction occurs at the interface of two solutions. The material is wound up on a spool or other device and at some point it seems that the winding will never end.
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#10 Condensation Polymerization: Preparation of Nylon 6/6
Nylon 6/6 is produced here by the melt method. Students will first produce "nylon salt" from the reaction of hexamethylene diamine (HMDA) and adipic acid. In this particular case, the stoichiometric equivalence of the functional groups is achieved by isolating the 1:1 salt before allowing the condensation to take place. Then the nylon salt is converted, under pressure and heat, to nylon 6/6.
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#11 Condensation Polymerization: Preparation of Thiokol (Polysulfide Rubber)
Students will prepare a synthetic elastomer called Thiokol®. This polysulfide was the first synthetic rubber produced by Dr. Joseph C. Patrick in the 1920s. Students will synthesize this material by combining an alkylene dichloride and sodium polysulfide. This is an interfacial polymer reaction but unlike the nylon 6/10 the polymer forms at the bottom of the beaker.
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#12 Condensation Polymerization: Preparation of Two Types of Polyesters
In this lab, students will synthesize two examples of condensation polymers, a linear polyester and a cross-linked polyester. Both esters are produced by the reaction of an acid anhydride (phthalic anhydride) and an alcohol. Phthalic anhydride is the anhydride of phthalic acid, 1,2-benzenedicarboxylic acid. In the case of the linear polyester, the alcohol is a diol (ethylene glycol). Thus both the alcohol and the acid (anhydride) have two reaction sites and a linear polyester is produced. This polyester is similar to the more familiar Dacron. When more than two functional groups are present in one of the monomers, the polymer chains can be cross-linked to make a three-dimensional network. The alcohol used in the synthesis of the cross-linked polymer is the triol, glycerol. This polyester (Glyptal®) has a structure which is more rigid than the linear structure and therefore has different properties.
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#13 Addition Polymerization: Preparation of Polystyrene Using Two Types of Initiators
This is an excellent lab to introduce students to addition polymerization and to the concept of initiators. Addition polymerization usually must be catalyzed (initiated) by a base, an acid, or free radical. There are three steps that are involved in addition polymerization no matter what initiator is used. These three steps are initiation, propagation, and termination. The students will polymerize styrene using two types of initiators, benzoyl peroxide (free radical) and anhydrous aluminum chloride (cationic). They will then compare the properties of the products.
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#14 Determination of Plasticizer in PVC by IR or FTIR and a Precipitation Method
Students in this experiment will isolate and determine the amount of plasticizer in polyvinyl chloride (PVC). Students will use Infrared Spectroscopy (IR) or Fourier Transform Infrared Spectroscopy (FTIR) and gravimetric techniques in this experiment. Plasticizers are organic compounds added to polymers, like PVC, to facilitate processing and to increase flexibility and toughness of the final product by internal modification of the polymer morphology. Important plasticizers include esters of phthalic acid, and epoxidized soybean oil esters. The most common used plasticizer in PVC is the diester, dioctyl phthalate (DOP).
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#15 Elastomers: The Best Bungee Cord
Students will determine the strength of a single rubber band, the strength of two rubber bands working in parallel, and the strength of three rubber bands working in parallel. A simple tensile strength testing apparatus will be set up using 2 L containers, string, and a sturdy ring stand. The students will use this apparatus to determine the tensile strength, percent elongation, and plot stress vs strain graphs for each experiment. The students will design a small bungee cord, giving a rationale for the design. After submitting their design, the students will take a bungee cord apart and see how their design compares to the bungee cords on the market today.
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#16 How to Clean up an Oil Slick
The task of cleaning up and recovering oil from an oil spill is not easily accomplished. In this laboratory exercise, the students will learn about how an oil spill is contained and cleaned up. They will investigate an oil absorbing polymer that is hydrophobic, absorbs up to 19 times its own weight in nonpolar liquids, floats on water, and can be reused or disposed of by incineration or burial in accordance with local regulations.
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#17 What Is Special About Polyethylene Food Storage Bags?
In this investigation students compare a polyethylene bag designed for recycling or garbage disposal with a polyethylene food storage bag. For food product safety, it is essential that materials in the container not contaminate the food. The bags intended for food storage contain measurably less hexane extractables (low molecular weight oligomers and additives) than the bags intended for waste handling. Bags are cleanly cut into two centimeter squares, weighed and exposed to warm hexane solvent for a specified time. After the time is up, the hexane is removed and allowed to evaporate. (Two rinses of the bag pieces with small amounts of hexane may be performed.) Once the hexane has evaporated, the residue is weighed (ideally at the next laboratory period), and the percent hexane extractables calculated. The procedure is similar to that suggested in the Code of Federal Regulations (see references).
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#18 Determination of the Set Time for Epoxy Adhesive
Most epoxy glues or adhesives, as well as epoxy resins, are produced when the epoxy group reacts with a difunctional backbone monomer producing a thermoset polymer. Thermoset polymers are mostly unchanged when heated after being cured while thermoplastic polymers soften and eventually flow when subjected to increased heat and pressure. The set or gel time of a specific thermoset polymer is important to know. It determines the length of time the material may be worked prior to hardening. Many epoxy glues are sold with specific set times for specific adhesive applications. In chemistry, the set time of an epoxy is similar to the time it takes a reaction to occur. Hence, a study of epoxy set times is very similar to a study of chemical kinetics. The set time may be determined by testing the gel every so often with a stick to observe its tackiness or, possibly more elegantly, by observing the disappearance of the epoxide IR band and the appearance of the IR O-H stretching frequency. The temperature profile of the reaction may also be monitored; however, it, as well as gel time, is dependent upon the volume of material mixed. Reproducible data may be obtained when the tests are performed reproducibly.
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#20 The Influence of Initiator Concentration on the Molecular Weight of Polystyrene
Polystyrene (PS) is a hard, rigid, transparent plastic with good dimensional stability. The material has good chemical resistance to many aqueous solutions but it is soluble in many aromatic and halogenated solvents. It cannot be used at elevated temperatures (maximum 60 °C continuous, 70 °C for short periods) and it may break when subject to mechanical stress. Polystyrene polymerizes with a chain reaction. Chain reactions require initiator molecules, like the free radical formed when benzoyl peroxide breaks up. Free radicals have single electrons, which makes them very reactive. Monomers for chain reactions often have carbon-carbon double bonds, which then are attacked by the initiator molecule to form a reactive molecule. This reactive molecule then attacks another monomer, so the chain gets longer and longer. The total number of polymer molecules formed depends on the number of initiator fragments. The more initiator you use, the more polymer molecules. That is, for the same amount of monomer, you get smaller polymer molecules by using more initiator, because there are more reactive sites competing for monomers. Students will synthesize polystyrene and explore the influence that initiator concentration has on the molecular weight of the product.
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#21 Films, Fibers, and Solubility
These activities will introduce how the differences in solubility of materials are used in the manufacture of fibers and films. The various processes used to make films and fibers will be introduced to the student and completed on a small scale.
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#22 Chemical Resistance and Synthetic Polymers
These activities look at the chemical resistance of synthetic polymers. The activities include immersion, stain resistance, and stress cracking labs and both qualitative and quantitative analysis. Immersion testing is a alternative method for teaching solubility in which the polymer is the solute rather than typical salts and sugar which are often used. Chemical resistance can be used as one method to identify polymers, as well as being used to look at property changes which will effect service performance and aesthetics. The stain resistance lab offers students an opportunity to develop and carry out a procedure of their own design.
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#23 Glass Transition in a Rubber Ball
This experiment provides a dramatic way to illustrate the changes in the properties of a material at its glass transition point. Students gather data which they use to construct graphs to learn about elastic modules versus absorption modulus, tangent delta, and the effect of impact speed on the glass transition temperature.
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#24 How Much Air Is In Foamed Polystyrene Products?
In this experiment students are challenged to come up with a good estimate of the amount of air in foamed polystyrene products. It is ultimately a gas evolution experiment and as such has students measure the gas generated when foamed polystyrene is degassed and dissolved or dispersed in an organic solvent. The volume of the air is measured by water displacement with the twist that the organic solvent utilized is mostly water immiscible and floats on the water but has a vapor pressure significantly greater than water at room temperature and pressure. Gas laws calculations can be utilized in determining the amount of air present in the sample. The vapor of the organic solvent contributes to the total gas pressure so it must be considered in the calculations.
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#25 Investigating the Effect Of Successive Heat and Cool Cycles on a Thermoplastic Material
In this investigation, a mini glue gun is used as both an injection molding simulator and a melt index viscometer. Hot melt glue is squeezed into rubber tubing sections and allowed to cool. A slit in the side of the rubber tubing allows the cooled hot melt glue sections to be removed and remelted in the hot melt glue gun; hence samples of successive heated and cooled thermoplastic can be produced. The samples are then evaluated by weighing the glue extruded over a constant time period.
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#26 Intrinsic Viscosity, Evaluating the Polymerization Pattern in Polyvinyl Alcohol
In this experiment, a high molecular weight polyvinyl alcohol polymer is treated with potassium periodate. Potassium periodate reacts with 1,2 (vicinal) glycols, cleaving the bond between the 1 and 2 carbons and producing two aldehydes. Potassium periodate does not react with 1,3-glycols. The regular repeating unit of polyvinyl alcohol is similar to a 1,3-glycol. Polyvinyl alcohol is usually made by hydrolysis of polyvinyl acetate. Vinyl acetate normally polymerizes head to tail producing the alternating 1,3-acetate and, by hydrolysis, the alternating 1,3-alcohol. Formation of a 1,2-glycol thus represents an abnormal head to head addition of monomer to the growing chain. Treatment of polyvinyl alcohol with periodate ion thus determines the number of abnormal head to head polymerizations. In this experiment, the viscosity of polyvinyl alcohols of varying molecular weights will be measured. From a graph of viscosity versus molecular weight, the approximate molecular weight of the periodate treated polymer can be determined. The number of head to head polymerizations is estimated from the ratio of the average molecular weight of untreated polymer to the average molecular weight of periodate cleaved polymer.
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#27 A Search for Automated Plastics Recycling Separation
Recycling efforts of recent years have been hampered by the high cost of manually separating the materials. This is particularly true of plastics. Students will be challenged to investigate the physical and chemical properties of plastics and use these properties to design a system that could be used to separate them. First-year chemistry students were steered in the direction of using density for separation. They were directed to use information gathered from handbooks and the Internet to prepare a series of solutions with different densities which could be used to separate the plastics. A flow chart was developed to describe and outline this process. Second-year chemistry students were given the problem during a study of infrared spectroscopy. During discussion they were directed to search for absorption peaks unique to each plastic. Again a flow chart was used to summarize the process design. Third-year chemistry students with some limited experience in chemical instrumentation were given the problem as an independent study.