Make Sustainable Fabrics from Seaweed

Creating Your Alginate Biofabric

In this experiment, you will investigate how the properties of your biofabric change when you add different concentrations of glycerin. The three different biofabric recipes you will make are provided in Table 1. Follow the written procedure below or watch the alginate biofabric video to view each step of the procedure.

1. Prepare your alginate biofabric mixture. If you purchased three wooden hoops and have enough other materials, you can make all three recipes at once. If you do not have enough materials, start with recipe #1.
   1. Fill the measuring cup with 200 mL of water. Optionally, you can add food coloring to the water to dye your biofabric.
   2. Add 4 grams of sodium alginate to the liquid and mix thoroughly with an immersion blender, as shown in Figure 3.
   3. Add the glycerin and mix again. For recipe #1, add 8 g of glycerin; for recipe #2, add 4 g of glycerin; and for recipe #3, do not add any glycerin (see Table 1).
   4. Place the alginate mixture in the refrigerator for several hours or overnight to get rid of the bubbles.
   
   Figure 3. The alginate mixture is mixed with an immersion blender.
2. Prepare the calcium chloride solution.
   1. In a cup or small bowl, mix 10 g of calcium chloride with 100 mL of water. This makes a 10% calcium chloride solution.
   2. Stir the solution with a spoon until all the calcium chloride has dissolved.
   3. Pour the solution into a spray bottle. The solution can be stored at room temperature for several weeks.
3. Take your sodium alginate mixture out of the refrigerator. It should be bubble free. Use a spoon to carefully scoop out any foam from the liquid’s surface.
4. Cut a piece of canvas that fits your wooden hoop. Place the cut canvas piece in your wooden hoop as shown in Figure 4. Pull it straight and secure it tightly. This is the mold for your biofabric.
   
   Figure 4. Prepared biofabric mold consisting of a wooden embroidery hoop and canvas.
5. Shake the spray bottle with the calcium chloride solution, then spray the canvas in your prepared mold with calcium chloride. The canvas should be wet but not soaked. Use a paper towel to remove excess chloride solution from the canvas’s surface.
6. Pour the alginate mixture into the biofabric mold.
   1. The alginate mixture in the mold should be about 3–4 mm thick. Let the mixture spread out in the mold. You can use a spoon to distribute it evenly.
   2. Carefully move the spoon across the canvas surface and around the wooden hoop to ensure good contact of the alginate mixture with the canvas surface. This helps the biofabric stick to the canvas, which will reduce the shrinking of the fabric while drying.
   3. Remove any larger air bubbles on the surface of the alginate mixture with a spoon.
7. Spray the surface of the alginate mixture with calcium chloride solution, as shown in Figure 5. The solution should cover the whole surface of the alginate mixture. Let the solution sit on the surface for 10 seconds, then remove the excess liquid with a paper towel. Note: When spraying the alginate solution with calcium chloride, calcium alginate is formed, which creates a membrane-like layer on the surface of the alginate mixture. If the alginate mixture does not stick well to the wooden hoop or canvas, the mixture could shrink and detach from the sides of the hoop. If this happens, make a note in your data table. You can still use your fabric for the remainder of the project.
   
   Figure 5. Spray enough calcium chloride on the alginate mixture so that the whole surface is covered.
8. Place the biofabric on an oven rack and let it dry. There should be airflow from below. Drying can take several days. You can either let it air dry or dry over a radiator or in a dehydrator to accelerate the drying process. Note: The biofabric will shrink during the drying process as it loses water. It will get thinner and, if the mixture doesn’t stick well to the canvas, will shrink in size. As it shrinks in size, the fabric can curl on its sides. If you see this happen, you can either alternate drying and pressing the biofabric under a stack of books or dry the biofabric on a rack with a weight on top to keep it flat.
9. When the biofabric is dry, remove the canvas from the wooden hoop and carefully peel the biofabric off the canvas, as shown in Figure 6.
   
   Figure 6. Be careful not to break the biofabric when peeling it off the canvas.
10. Repeat steps 1, 3, and 5–9 for the two remaining recipes. Don’t forget to change the amount of glycerin in each recipe (see Table 1). You can reuse your fabric mold. If necessary, prepare more calcium chloride solution by following step  2.

Testing Your Alginate Biofabric

To assess which of your biofabric recipes would be most suitable for a textile replacement, you will do several tests to determine various mechanical properties of your different biofabrics. Follow the written procedure below or watch the material testing video to view each testing step.

1. Qualitative description. Before you start cutting your biofabric for testing, look at each of your fabrics closely and make notes about how the material looks, feels, etc. Record your observations in a data table like Table 2.

   Sample	Qualitative description of biofabric
   8 g glycerin
   4 g glycerin
   0 g glycerin

   Table 2. Data table to record the qualitative features of the different biofabrics.

2. Tensile test. In this test, you will investigate how your different biofabrics behave when they are stretched by measuring their tensile strength. Tensile strength is the load or force at failure divided by the cross-sectional area of the sample. Its unit is pascals (Pa) or megapascals (MPa).Equation 1:$$Tensilestrength=\frac{Force\left[N\right]}{Cross\text{–}sectionalarea\left[m^2\right]}$$To measure the tensile strength, make a data table like Table 3 in your lab notebook and follow steps a–g for each of your three biofabric materials.
   1. Cut one 0.5 cm × 4 cm strip of your biofabric. Don’t cut it from the very edges, as these tend to be thinner. Choose a section that is free of defects such as small tears, bubbles, or ridges.
   2. Measure the thickness and width of your strip using a caliper, as shown in Figure 7. Convert your measurements to meters and record the results in your data table. Then calculate the cross-sectional area of your test sample. Record the result in your data table.
      
      Figure 7. Thickness and width measurements with a caliper.
   3. Place each end of one strip into one of the clamps. The end of the sample strip should line up with the end of the metal clamp. Make sure to secure the strip tightly in the clamp.
   4. Do the tensile test. There are two ways to stretch the materials.
      1. Option A. If you have a spring scale, attach a string to one clamp, as shown in Figure 8.
         
         Figure 8. Instructions on how to attach a string to one of the compressor clamps.

         Attach the hook of the spring scale to the string loop. Hold the other clamp with one hand upright on the table. Do NOT move the clamp during the test. The test setup should look like in Figure 9.

         
         Figure 9. Tensile test setup using a spring scale.

         Then very slowly pull the spring scale straight away from the clamp so that your sample gets stretched. Be careful not to bend or twist the sample. While pulling, make sure to monitor the readings on the spring scale. Pull until the sample strip breaks. Make sure that the sample broke somewhere in the middle and did not just slip off the clamp. Record the force (in newtons) that made the sample break in your data table. If your scale measures in pounds or kilograms, convert the force to newtons (1 lb = 4.448 N, 1 kg = 9.81 N—but only if you’re in Earth’s gravity!) Reset your scale to zero if you are using a trigger scale.

      2. Option B. Attach a string to both clamps as shown in Figure 10.
         
         Figure 10. A string attached to each compressor clamp holding the biofabric sample.

         Use the string to attach one clamp to a door handle or other sturdy object. The clamps should hang freely in the air. Use the string on the other (bottom) clamp to attach a container, like a cup or small bucket. Make sure that the container is close to the ground. This avoids spillage of its contents if your sample breaks. The test setup should look like Figure 11. Gradually add weight (e.g., metal or sand) to the container until the sample strip breaks.

         
         Figure 11. Tensile test setup with a cup and weight.

         Again, make sure that the sample broke somewhere in the middle and did not just slip off the clamp. When the sample fails, weigh the filled container and record the weight that caused the sample to break in your data table. If needed, convert the weight to newtons first. (1 lb = 4.448 N, 1 kg = 9.81 N—but only if you’re in Earth’s gravity!)

      Sample	Thickness [m]	Width [m]	Cross-sectional Area [m²] (Thickness × width)	Maximum applied force [newton]	Tensile Strength [MPa]
      Biofabric recipe #1 with 8 g glycerin
      #1
      #2
      #3
      Average
      Biofabric recipe #2 with 4 g glycerin
      #1
      #2
      #3
      Average
      Biofabric recipe #3 with 0 g glycerin
      #1
      #2
      #3
      Average

      Table 3. Data table to record your data from the tensile strength test.

   5. Use equation 1 and your data to calculate the tensile strength of your test sample. You might want to convert your result from pascals to megapascals (1 Pa = 1 × 10⁶ MPa). Record your result in your data table.
   6. Repeat the tensile test with the remaining two material strips.
3. Torsion test. In this test, you will investigate how your different biofabrics behave when they are twisted. To do the torsion test, make a data table like Table 4 in your lab notebook and follow steps a–d for each of your three biofabric materials.
   1. Cut one 0.5 cm × 4 cm strip of your biofabric. Don’t cut it from the very edges, as these tend to be thinner. Choose a section that is free of defects such as small tears, bubbles, or ridges.
   2. Place each end of one strip into one of the clamps. The end of the sample strip should line up with the end of the metal clamp. Make sure to secure the strip tightly in the clamp.
   3. Hold each clamp in one of your hands with the screws both facing up, as shown in Figure 12. To twist your sample, keep one clamp still and rotate the other clamp so its screw is facing down. Now you have rotated the clamp halfway. Rotate the same clamp in the same direction so the screw is facing up again. This makes one rotation. Continue rotating the clamp in the same direction, half a rotation at a time, until the sample breaks. Record the number of rotations until the sample broke in your data table.
      
      Figure 12. Torsion test setup.
   4. Repeat the torsion test with the remaining two material strips.

   Trial	Biofabric recipe with 8 g glycerin	Biofabric recipe with 4 g glycerin	Biofabric recipe with 0 g glycerin
   #1
   #2
   #3
   Average

   Table 4. Data table to record the number of rotations until the sample breaks from the torsion test.

4. Flexure test. In this test, you will investigate how your different biofabrics behave when they are bent. To do the flexure test, make a data table like Table 5 in your lab notebook, and follow steps a–d for each of your three biofabric materials.
   1. Cut three 1 cm × 4 cm strips of your biofabric. Don’t cut it from the very edges, as these tend to be thinner. Choose a section that is free of defects such as small tears, bubbles, or ridges.
   2. To bend your sample, fold it in half, as shown in Figure 13. Then slide your finger along the fold with some pressure as if you were folding a paper airplane. Remove your finger and observe what happens. Did the sample break? Did the material spring back into its original flat state, or did it stay folded? Can you see a fold line in the material? Record your observations in your data table.
      
      Figure 13. Folding the sample strip in half.
   3. Repeat the flexure test with the remaining two material strips.

   Trial	Did the sample break?	Does the material spring back into its original flat state?	Do you see the fold line?
   Biofabric recipe #1 with 8 g glycerin
   #1	yes  no	yes  no	yes  no
   #2	yes  no	yes  no	yes  no
   #3	yes  no	yes  no	yes  no
   Totals	__ yes  __ no	__ yes  __ no	__ yes  __ no
   Biofabric recipe #2 with 4 g glycerin
   8 g glycerin	yes  no	yes  no	yes  no
   4 g glycerin	yes  no	yes  no	yes  no
   0 g glycerin	yes  no	yes  no	yes  no
   Totals	__ yes  __ no	__ yes  __ no	__ yes  __ no
   Biofabric recipe #3 with 0 g glycerin
   8 g glycerin	yes  no	yes  no	yes  no
   4 g glycerin	yes  no	yes  no	yes  no
   0 g glycerin	yes  no	yes  no	yes  no
   Totals	__ yes  __ no	__ yes  __ no	__ yes  __ no

   Table 5. Data table to record your data from the flexure test.

5. Sewing test. In this test, you will investigate whether your biofabrics can be sewn easily, which is crucial for most textile applications. To do the sewing test, make a data table like Table 6 in your lab notebook, and follow steps a–d for each of your three biofabric materials.
   1. Cut two 3 cm × 3 cm square pieces of your biofabric. Don’t cut it from the very edges, as these tend to be thinner. Choose a section that is free of defects such as small tears, bubbles, or ridges.
   2. Place one biofabric square on top of the other.
   3. Use a sewing needle and sewing thread and try to sew the biofabric squares together. Make a single straight stitch along the edges of the square using a backstitch. If you don’t know how to backstitch, you can review this backstitch tutorial (Method 1).
   4. How easy or difficult is it to sew the material? Does the material break? Record your observations in your data table. Then rank your materials from easiest to sew (1) to hardest to sew (3) in your data table.

   Sample	Can you sew your biofabric without breaking it?	Rank from easiest to sew (1) to hardest to sew (3)
   Biofabric recipe #1 with 8 g glycerin	yes  no
   Biofabric recipe #2 with 4 g glycerin	yes  no
   Biofabric recipe #3 with 0 g glycerin	yes  no

   Table 6. Data table to record your data from the sewing test.

Analyzing your Data

In this section, you will analyze your data and come up with a conclusion about which biofabric recipe makes the best textile replacement.

1. Tensile strength data.
   1. For Table 3, calculate the average tensile strength for each glycerin concentration. Record the results in your data table.
   2. Make a bar graph of your data. Put the glycerin concentration on the x-axis and the average tensile strength on the y-axis.
2. Torsion test data.
   1. For Table 4, calculate the average number of rotations that made the sample break for each glycerin concentration.
   2. Make a bar graph of your data. Put the glycerin concentration on the x-axis and the average number of rotations that made the sample break on the y-axis.
3. Flexure data.
   1. Review your Table 5 and for each question count the total number of yes and no responses for each sample. Record the results in your data table.
4. Look at your Tables (2–6), graphs, and observations and try to draw conclusions from your results about which biofabric recipe makes the best textile replacement. Try to take the following questions into consideration.
   1. What similarities or differences do you see among the different biofabrics?
   2. How did the amount of glycerin change the material properties of the different biofabrics?
   3. What function do you think glycerin has as an additive in your biofabric recipe?
   4. Can you explain your results?
   5. Which of the tests you conducted are the most relevant for a textile material?
   6. Is there a possibility that other factors could have affected your test results? If yes, which ones?
5. Based on your results, which biofabric recipe do you think is best suited as a textile replacement?
6. Do you think the biofabrics you made in this project are more or less sustainable than conventional fabrics? You might want to review the 12 principles of green chemistry to answer this question.

Optional: Making Alginate Biofabrics with Food Waste

This section is optional and shows how you can recycle food waste to make alginate biofabrics.

1. Prepare the food waste that you want to add to your biofabrics recipe. There are several food wastes that you might want to try. Some suggestions are eggshells, coffee grounds, or orange peel.
   1. Collect about 30–50 grams of your chosen food waste and place it on a baking tray.
   2. Place the tray in an oven set to 300–350°F (150–180°C) and let the food waste dry completely. This can take up to several hours. Remove the dried food waste from the oven and let it cool.
   3. Use a blender or a mortar to grind the dried food waste into a powder.
2. To make your food waste biofabrics, follow steps 1–9 in the Creating Your Alginate Biofabric section above. Use the recipe in Table 7 for your biofabric. Add the food waste powder together with the glycerin.

   Ingredients	Recipe #1
   Liquid	200 mL
   Sodium Alginate	4 g
   Glycerin	8 g
   Food waste powder	10 grams

   Table 7. Biofabrics recipe with added food waste powder.

   Note: Sodium alginate reacts with calcium to create calcium alginate, which makes the liquid become thick and gelatinous. Take this into account when experimenting with calcium-rich food waste, such as fruit. In addition, biofabrics with food waste tend to be thicker in general and shrink more than biofabrics with just liquid.

3. Once your biofabric has dried, you can follow the steps in the Testing Your Alginate Biofabric section to assess its material properties.