Bioplastic from Strach - Phase 2 : The making of Bioplastic

 

Phase 2:

Theory:

We used potato starch for our research because we reflected about a sustainable use of potato peel, which is often degraded to waste and potato starch is easily accessible in every grocery. Plants store starch in special organelles called amyloplasts which are present in the cells in form of granules to save the energy produced by photosynthesis. 

The glucose produced by photosynthesis forms bonds to grow to a macromolecule following the equation: 

n(C6 H12O6) →(C6H10O5)n+(n-1)H2O

There are two products which can form: amylopectine and amylose. For amylopectine „n“ in the above equation can vary between 2 000 and 200 000, which means that the amylopectine chains are formed by between 2 000 and 200 000 glucose units, which form branchings every 24 to 30 glucose units. For amylose, „n“ varies between 300 and 3000 and there are no branchings in the chain ,in contrary to amylopectine, and, as a consequence, amylose is less soluble in water than amylopectine because its molecules do not link to water molecules via hydrogen bonds. In the image below, the structures of amylose and amylopectine are respresented. The branchings of amylopectine are visible.

 

The potato starch we used contains 70 % amylopectine and 30% amylose.

Glycerin (Propan-1,2,3 triol):

Glycerin is a hygroscopic liquid with a high viscosity. It has 3 hydroxyl groups which make it be soluble in water.

Glycerin makes the biolastic more flexible.

Water: 

Water plays an important role in the production of bioplastic. First, it acts as a solvent to dissolve the starch. Secondly, it helps the starch molecules to stay disrupted after heating.

Acid (Vinegar): Vinegar, a 6% in volume solution of acetic acid liberates acetate ions and hydrogen ions in solution. This is important, because ions react with the starch polymers and make them be disordered more easily in the solution. This disorder, resulting from the disruption by the water and the ionization by the acetic acid, makes the resulting cast film more homogenous. 

Determination of the best water/starch ratio :

We did some tests to find out in which proportion we have to mix water to starch in order to receive a plastic which conforms to our criteria. The plastic has to be flexible, but not too soft.

Solution number	Mass of Water in %	Mass of Starch in %
1	82	18
2	55	12
3	61	13.5

Plastics produced with solution 2 seemed to fit the best to our conditions, so we continued with this proportion for further experiment.

Experimental Procedure:

Aim: To prepare bioplastic sheet from the starch extracted from a specified amount of potatoes.

Materials Required: Extracted starch,glycerine,glacial acetic acid,distilled water,beaker,heating pan,spatulla,measuring flask,aluminium foil.

Procedure: 

1. Weigh 50 gm of starch from our extracted sample.

2. Add it to 250 ml of water with continuous stirring so that no lumps are formed.

3.Add 25 ml of glycerine drop by drop with continuous stirring.

4. Heat the mixture with a heating pan until a dense paste of the above mixture is formed .

5. Spread the mixture on aluminium foil and allow it to dry for 2-3 days.

6. Carefully Peel off the prepared bioplastic from the aluminium foil in order to reduce the wear and tear.

Result : We got a piece of bioplastic of required strength which can be used for our daily purpose. 

Precautions:

1. Addition of starch to water must be done with continuous stirring so that no lumps forms.

2. Glycerine should be added drop by drop otherwise a homogeneous mixture will not be formed.

3. Spread the prepared paste carefully and uniformly over the aluminium foil in order to get bioplastic of constant thickness.

4. Handle the heating pan carefully and the heat provided to the solution must be in a controlled amount.

Conclusion:

All in all, we can say that our produced plastic satisfied our expectations. Now, we are looking for a practical application of this material. Further, we are going to analyze the biodegradability and its strength must be tested to know how much load it can bear before commercial use.

To conclude, the production of starch based plastic film is a viable industry even though for the time ,it will be dependent on petroleum product such as energy resources for the machine operation. However ,the increased  influence of environment concern, use of renewable resources such as starch based plastic products. will be an obligation across the world.

References:

Video sources:

• https://youtu.be/5M_eDLyfzp8

• https://youtu.be/nr6Ks4R3aAM

• https://youtu.be/y1joh_t1thc

• https://youtu.be/nr6Ks4R3aAM

Article sources:

• https://www.academia.edu/27856907/Production_of_bioplastics_using_potato_starch

• Production of Bioplastic by Matthieu Schon and Pit Schwartz.

• https://aaas.confex.com/aaas/2017/webprogram/Paper20402.html

• http://www.mhhe.comnot

• http://green-plastics.net