Week 9

This week was our second and last week of tensile testing. This batch of plastics was our least rigid yet. Unfortunately this caused a great deal slippage within the vice grips of the machine.  In order to minimize this factor, we added tape to the ends of the first few samples. This didn't seem to make a difference so in the end we removed the tape from the samples for all further testing. Because the slipping directly affects the recorded load values, this data set has inaccuracies.

Figure 9.a: Plastic sample with taped ends

Figure 9.b: Tensile machine with taped sample

Another issue we faced in this testing session was the fact that some of the samples did not break in the center. This means that most of the load weight was unevenly distributed across the sample. Because of this, the conclusions we can draw from the collected data have less validity. Ideally, the only section of the sample that should be strained (and therefore broken) should be the middle section. If the samples did not slip it's likely that the testing would have been more uniform and the samples would have compromised in the center.

Figure 9.c: Post-Test samples 

A big thanks to Mr. Steve Pagano, Mr. Brian Wisner and Mr. Satish Rajaram for all their help in our research!

Week 8

This week was very exciting for our team. After 7 long weeks of planning, adjusting and experimenting with the bioplastic material, it was finally time to put it through an ultimate tensile strength test. With help from Mr. Steve Pagano, Mr. Brian Wisner and Mr. Satish Rajaram, our team was able to observe our first tensile test in the Mechanical Engineering and Mechanics laboratory, as well as record the data and graphs displayed on the MARK-10 machines.

Figure 8.b: Preparing the test sample

Figure 8.a: Load weight displayed on MARK-10 screen

Figure 8.c: Slippage is evident through the lines seen on the

Setting up the machine seemed difficult initially, as the software and computer were slow. However, after several minutes of changing settings, we were finally able to place our sample in between the two grips. One of the biggest problems we faced was the slipping of our samples through the grips. When the sample would slip through, even just a little bit, the load value (expressed in Newtons) would be greatly affected. Thus, Mr. Wisner and Mr. Rajaram advised us to find a material to attach our samples to that would prevent them from slipping.

Figure 8.d: Brian and Satish in action

Even though we were not able to test all our samples and our collected data was quite different from what we expected, we were still able to make some good quantitative and qualitative observations. It seems that the less glycerol we mix into the plastic, the more brittle it becomes. The samples with the most amount of glycerol just kept stretching as far as the MARK-10 machine could go, while the ones with less glycerol would snap within seconds.

Figure 8.e: Stress-strain curve seen through the tensile test software

Week 7

During Week 7's lab we tried both methods that we came up with during Week 6. First we tried laser cutting the shape into the sheet of plastic. The result wasn't bad, the shape was quite accurate which was good. However, the edges of the samples ended up being very irregular because of the effects of the laser on the plastic. Later on we tried our second method: cutting the shape with an x-acto knife. This method turned out to be the most ideal one, since the samples cut had the desired shape and their edges were regular and clean.

Figure 7.a: Laser Cutting our New Mold

To follow our new method, we needed to come up with a way to make a regular, flat sheet of each batch of our plastic. To achieve this, we made a new mold with three pieces of acrylic: a simple rectangle that acts as a base, a frame that the plastic will be poured into, and a second smaller rectangle that takes up some of the frame's inner area in order to reduce the volume of plastic that would go to waste after cutting the samples.

Figure 7.c: Plastic in the New Mold

Figure 7.b: Cooking Batch of Plastic

Week 6

Our samples made after the change in the mold during Week 5 were still flawed. During Week 6's lab we went to the lab where we will test our samples planning on testing the samples made during Week 4, which were the closest to the expected shape. However, once we got there, the tensile machine wasn't working properly so we couldn't go through with our testing. We spoke to Brian and agreed on making all of our batches and then testing them all the same day.

Figure 6.b: Tensile Machine

Figure 6.a: Brian setting the machine up

Our next approach for making the plastic will be to pour it into a bigger rectangular mold and then cut the shape of the samples into the dried sheet of plastic with an x-acto knife. This way, warping and flashing won't be a problem.

Background

Majority of our project's techniques and processes come from Green Plastics, by E.S. Stevens. This book was generously lent to us by Dr. Richard Cairncross, of Drexel's Biological and Chemical Engineering department.

The emergence of bioplastics came about due to the fact that regular plastics would use non-renewable sources, or fossil fuel, in their production, such as crude oil. This kind of process would produce a large amount of waste, as well as a huge negative impact on our environment. Bioplastics were created to ensure that we can use plastic to continue to make our lives' easier, without causing so much harm to the environment around us.

Bioplastics are created from renewable biomass sources, such as vegetable oil, starch, vegetable fat, and a lot more other materials. These kinds of "green plastics" can be used in a variety of materials, such as packaging, cutlery, electronics casing, etc. Engineers, as well as ourselves, hope to increase the production of these bioplastics to lessen the damage inflicted by regular plastic production on the world.

Frequently Asked Questions

What do we use to make the plastic?
The ingredients used to make our bioplastic are easy to find products. Our recipe includes water, glycerol and gelatin.
How long does it take to make the plastic?
The preparation of the plastic is relatively quick. Cooking it takes from 10 to 15 minutes, and pouring it in the mold takes about a minute or two. Once the plastic is in the mold, it takes about 5 days for it to dry.
What is the difference between bioplastic and normal plastic?
Bioplastics are made with materials that are easier to break down when they are tossed out than the materials used to make normal plastics. This is because bioplastics use materials that are more natural than plastics.

Week 5

When we looked at the sample made during Week 4's lab we realized that it was flawed. It shrunk to about half its thickness and it had a lot of flashing. The samples also had a lot of bubbles that would affect the breaking point while testing it. These flaws would highly affect our tensile testing, so during Week 5's lab we spoke to Professor Speidel and Mr. Pagano about what changes we could make to our mold in order to get rid of the imperfections. Two more pieces of acrylic were laser cut. They are both the same size as our mold, but they don't have the shape of the sample cut into them. Once we made the new batch of plastic, we put one of the acrylic rectangles underneath the mold, poured the plastic in, put one of the negatives of the original mold (acrylic pieces in the shape of the sample) in each plastic sample and then put the other acrylic rectangle on top of everything. We pressed them together using duct-tape and heavy books. The whole setting is shown in the pictures below. In order to get rid of some of the bubbles formed, we put the mold on an ac unit that constantly vibrates for the first few minutes of the drying process.

Figure 5.a: Mold Arrangement

Figure 5.b: Mold Arrangement

Week 4

On Friday morning we went to the machine shop at 3101 to get our mold cut out. Once we got there we found out that we couldn't use aluminum like we had planned because that would have taken around a week to be ready. Therefore, with Mark's help, we laser cut our mold into acrylic as shown in the picture and video below.

Figure 4.a: Mark working on our mold

Video 1: Mold being laser cut

Since we already had all the materials we need for the project, we were able to make our first batch. These samples were made with the original recipe: 60mL of water, 12g of gelatine and 12g of glycerol. We worked in the hot room mentioned before. The samples are now setting, once they're done we will take them out of the mold and perform our first tensile test.

Figure 4.c: Team members making the plastic

Figure 4.b: Plastic drying

Week 3

During Week 3's lab we had to figure out the exact geometry for the molds that are going to be used to pour the plastic in. Since we are using machines to test our bioplastic, there is a specific shape that the sample is required to have in order to perform the test on it. We designed this shape using a software called PTC Creo. We will order aluminum and email this file to the machine shop in order to get the molds for your project. Once we have these molds, we can begin the process of making the samples. The shape of our samples is shown in the picture below.

Figure 3.a: Calculations of the thickness of our samples

Towards the end of the lab, Mr. Steve Pagano took our team to the shop where the tensile machines are so that we could take a look at where we would be working while testing. This shop is located in the Main Building. The picture below shows the tensile machines that will be used to test our samples.

Figure 3.b: Tensile Testing Machines

Week 2

During the second week's lab we collected some materials, asked our TA about what machines would be useful for testing or product in the Machine Shop, and did some research on the creation of bioplastics. 

The resources collected were a hot plate that will be used to heat the plastic, a nonstick pan, and a spatula required to mix the plastic. The machine needed for our testing is a Tensile Strength Tester for plastic. Through our research we found out the basics of plastic chemistry including how the properties relate to the reactants used. We also found out that there is no reaction in the process of making the bioplastic. 

Figure 2.a: Team 14

Project Overview / Week 1

Since we decided to do a project that was different from the one that's being done by our section, we had already met with Professor Speidel a few weeks before the class. During the lab, our final idea and goal with discussed with the professor and he showed us the Hot Room (with a temperature of 37 °C) that we will work in throughout the course.

Figure 1.a: Collage of Hot Room pictures and Team 14

Our Engr 103 Design Project is called Plausible Plastics and our goal for such project
is to find an alternative to mass produce plastics, which are non biodegradable, and therefore harmful to the environment. This is why we've decided to create our own bioplastic from scratch by testing different samples that we're going to prepare each week. Each sample will have different formulas of the same ingredients and our aim is to observe how the variations affect the plastic's properties.

Figure 1.b: Logo of our project: Plausible Plastics

Who We Are: Plastic Kids

   John H. Speidel - speidel@drexel.edu - Teaching Professor

  Max Beverly - rmb327@drexel.edu - Chemical Engineering

Keagan Clark - ktc44@drexel.edu - Chemical Engineering

Veronica Graterol - vg373@drexel.edu - Chemical Engineering

Isabella Mendoza - mm3977@drexel.edu - Material Science and Engineering

Plastic Kids: Engineering 103, Drexel University