Laboratory Activity - Bioplastics

Laboratory Activity 1: Synthesis of Plant Based Polymers In this experiment, you will use starch, citric acid, and glycerol in various combinations to synthesize larger molecular mass bioplastic polymers. Plant starches (Figure 1) that have been isolated from biomass sources such as corn, potato, and tapioca root, citric acid (Figure 2), a natural preservative present in citrus fruits and glycerol (Figure 3), the backbone of all fats and oils and is a common food additive will be the reagents used to prepare you bioplastics. Vinegar will be used in the synthesis of polymers 1 & 2, but not 3. It is not one of the three mentioned monomers. Polymers 1 & 2 have starch as one of their reagents. As illustrated in Figure 1, starch exists in two forms, amylose (straight chain) and amylopectin (branched chain). The amylose form of starch is required in this synthesis, so to ensure all starch molecules are in the amylose form, vinegar is added to the mixture. Vinegar aids in the converting amylopectin to amylose. A) B) Figure 1. General representations of plant starches (polysaccharides) comprised of glucose molecules (represented by hexagons). A) Amylose (straight chain) B) Amylopectin (branched chain). Figure 2. Citric Acid Materials and Equipment • soluble starch • glycerol • citric acid • deionized (DI) water • white vinegar Figure 3. Glycerol several small beakers 3 glass stir rods parchment paper squares small aluminum pan food coloring (erioglaucine dye) *Procedures *Virtual lab: these procedures have been recorded. Please go to video folder. **Record observations and measurements of reagents used to prepare the three bioplastics polymers on provided worksheet. Polymer 1: Starch and Citric Acid Polymer: 1. Measure 10.0 mL of DI water with a graduated cylinder and add it to a 100-150 mL beaker. 2. Place beaker on a hot plate and set to a low setting. NOTE: Set the blue hot plates on 2-4 of 10 and set the yellow hot plates on 1-2 of 10. 3. Mass 3.20 g of soluble starch on weigh paper, record exact amount, and add it to the beaker while stirring. 4. Mass 0.50 g of citric acid on weigh paper, record exact amount, and add it to beaker. 5. Measure 1.0 mL of white vinegar with a graduated cylinder and add it to the beaker. 6. Add a few drops of food coloring/dye solution. 7. Stir contents of beaker on hot plate with a glass stir rod to mix completely (~5-10 minutes) - Do not overheat or mixture will get clumpy. If it clumps form, remove from heat, and stir vigorously. 8. Once the mixture is heated for 10 minutes or has become thick, remove the beaker from the hot plate. 9. Transfer the mixture to the center of a piece of parchment paper and spread out in an even layer. Label paper with type and group name. 10. Store it in your drawer to dry until the second portion of the experiment. Polymer 2: Starch and Glycerol Polymer: 1. Mass 1.1–1.5 g of glycerol directly into a 100-150 mL beaker and record exact amount. 2. Place beaker on a hot plate and set to a low setting. NOTE: Set the blue hot plates on 2-4 of 10 and set the yellow hot plates on 1-2 of 10. 3. Mass 2.00 g of soluble starch on weigh paper, record exact amount, and add it to the beaker while stirring. 4. Measure 10.0 mL of DI water with a graduated cylinder and add it to the beaker. 5. Measure 1.0 mL of white vinegar with a graduated cylinder and add it to the beaker. 6. Add a few drops of food coloring/dye solution. 7. Stir contents of beaker on hot plate with a glass stir rod to mix completely (~5-10 minutes) - Do not overheat or mixture will get clumpy. If it clumps form, remove from heat and stir vigorously. 8. Once the mixture is heated for 10 minutes or has become thick, remove the beaker from the hot plate. 9. Transfer the mixture to the center of a piece of parchment paper and spread out in an even layer. 10. Store it in your drawer to dry until the second portion of the experiment. Label paper with type and group name. Polymer 3: Glycerol and Citric Acid Polymer: 1. Mass 2.00 g of glycerol directly into a 50 mL beaker. 2. In a separate 50 mL beaker, mass 2.00 g of citric acid directly into the beaker. 3. Measure 2.0 mL of DI water and add to the beaker. 4. Add a few drops of food coloring to the citric acid solution and stir with a glass stir rod to mix completely. 5. Add the citric acid solution to the glycerol and stir with a glass stir rod to mix completely. 6. Be sure to grease an aluminum pan and label it with the lab day/time, group number, and sample name. 7. Pour the solution into the center of the aluminum pan and place in a 115 °C oven for 7 days. Lab Activity 2: Investigating the Physical of Bioplastics Background Information The properties that have made polymers essential to modern society are strength, resistance to temperature change, flexibility, and the ability to be molded into various shapes. The polymers that were synthesized in last week’s lab will have different properties, due to differing interactions/bonds within each polymer. These molecular level interactions manifest in the macroscopic world as polymer properties, such as rigidity, flexibility, transparency, durability, and others. Part 1: Physical properties of bioplastics • In this experiment, you will be determining the physical properties of flexibility, rigidity, elongation, bounce/recoil, and transparency for the bioplastic samples you prepared through visual and manual inspection. Materials & Equipment • The three bioplastic polymers that were prepared in laboratory Activity 1. • Ruler *Procedures *If virtual these experimental activities have been recorded to view via Videos **Record observations of the polymers on provided worksheet. Polymer Observations and Properties: 1. Remove your polymer samples from the drawer or oven. 2. Remove the samples from the parchment paper or aluminum pan. 3. Examine the samples and record your observations on provided worksheet. Lab Activity 3: Investigating the Degradation (i.e., durability) of Bioplastics You will examine the durability of your samples by monitoring degradation of the polymer under various conditions or in various solutions. Materials and Equipment: test tubes in rack hot plate deionized water polymer samples dropper bottles of 1.0 M HCl dropper bottles of 1.0 M NaOH assorted beakers label tape & markers digital thermometer Vernier meter *Procedure *Virtual lab: these experimental activities have been recorded to view. Please go to video folder. **Record observations of the polymers on provided worksheet. Polymer Observations: Degradation 1. For each of the three prepared bioplastics label four test tubes NaOH, HCl, water and hot bath water. 2. Mass ~0.10 g of each polymer, for each test tube, and record the exact mass of the sample used. 3. In the appropriate labeled test tube, place a piece of the polymer and add enough of the respective reagent to cover the polymer. a. Record the initial observations of the polymer sample. b. Some degradation processes can happen quickly so be sure to record your observations of the polymers at various times, making sure to mix the samples regularly. 4. Fill either a 250- or 400-mL beaker ¾ with tap water and place on a hot plate. Turn on hot plate to heat water. 5. Place the test tubes labeled “hot bath water” in in a hot water bath and record if there is a difference in the degradation of your samples. a. Record the initial observations of the polymer sample. 6. Waste and Clean up: a. All degraded materials are common, non-toxic chemicals and can be disposed of in the trash (i.e., bioplastic solids, paper, etc.) or down the sink (NaOH, HCl, water) with water. NOTE: If dye is placed in polymers, some dye will leach out into the solution. Make sure you observe how the polymer itself degrade.