Production of Hydrophobic Bioplastics using Silicon Dioxide

ABSTRACT

Silicon dioxide (SiO₂), also known as silica, is a chemical compound that comes in different forms and has a variety of uses. One form is silica gel, which is used as a desiccant in shoe boxes and bags to prevent rupturing, and to prevent molds in food products.

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Silica is the main material in our project because it has water-repelling properties and our group planned to create hydrophobic bioplastics with these properties. The purpose of this study is to benefit people in many ways. One way is the protection for electronic gadgets from water. Another method is to speed up the cleaning of food containers. With the hydrophobic properties of our plastic, water has less contact with it making washing containers easier.

To test our plastics we produced for hydrophobic properties (or wetability), we used a testing method known as the drop contact method. Twelve pieces of 2cm x 2cm plastic samples were prepared – with 3 pieces per concentration. A graduated dropper was used to drop 1mL of water on each plastic sample over a dish. The amount of water on the dish shows how much water each plastic sample repels.

Our results show that as the concentration of the silicon dioxide increases, the water repelled decreases.

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Background of the Study:

SiO₂ is a substance used to produce modern plastics. The group came up with an idea of making use of the said substance to produce hydrophobic plastics which could be a big help in latest technology and practical activities in our daily lives. Through this, we could also expand the capability of the silicon dioxide which may be used also in different ways.

Research Hypothesis:

If silicon dioxide is added as a material in the production of plastics, then a more hydrophobic plastic will be produced.

Objectives of the Study

General Objective:

This study was conducted to test the effectiveness of silicon dioxide in producing hydrophobic plastics.

Specific Objectives:

1. Produce an inexpensive and durable hydrophobic bioplastic material.
2. Test the hydrophobicity of the bioplastic produced using the drop contact testing method.

Significance of the Study

The researchers chose the topic because of the advantages that could be given to us people not only in our homes but on other fields of industries by the product. Plastics are widely used all over the world; it is the main reason why the researchers would like to introduce new technology in the form of hydrophobic plastics. If the project would be successful, hydrophobic plastics would be a big help in cleaning surfaces of plastics. For instances, dusts on plastics could be easily washed away by pouring water into the surface of the plastic. Hydrophobic plastics could also be alternative casings to our gadgets and appliances. It could protect our modern technologies from water penetration. It would also bring advantages in storing food products in the refrigerator like meats and fishes. The product will also be a good container for soaps, toothbrushes, plates and other household materials.

Scope and Limitations

1. The research shall only focus in the ability of plastic to repel water.
2. Other characteristics of a plastic shall be maintained.
3. In the production of the plastic, silicon dioxide will be the only addition to the regular raw materials of the process.

Review of Related Literature

Repellant Plastics

GE accomplished this by modifying a material that’s a mainstay of its plastics business. And they took their inspiration from the leaves of the lotus plant, which is naturally super hydrophobic; microscopic inspection of lotus leaves reveals their nanocrystalline wax structure. The lotus leaf surface has cells 5-10 micrometers wide, on top of which are tiny wax crystals that are tens of nanometers wide. On a lotus leaf, water beads look almost like perfect spheres.

GE set out to mimic this pattern on the surface of its polycarbonate material, essentially by “roughening” the surface in a specific way. Tao Deng, materials scientist at GE, is tight-lipped about the process, but says it was done with a “chemical treatment of the surface.”GE succeeded with its prototype last summer, but only began discussing the advance in recent weeks. One of the significant downsides is that the process leaves the plastic opaque, not transparent. That means it would not work for plastic windows or clear food containers. But a clear version is not far off. “That’s coming,” Deng says.

Even getting the opaque versions into real products will take some time. GE estimates it will be at least five years before commercialization, once the manufacturing issues are resolved. Five years isn’t that much time, though – about how long it takes for all the ketchup to drip out of today’s plastic bottles.

Hydrophobic Glasses

BalcoNano stated that there are two categories of what is known in the market as “self-cleaning” glass. These two categories are: glass coated or applied with hydrophilic layer that uses photo catalytic decomposition, and glass coated or applied with a hydrophobic protective coating.

The microscopically rough surface of glass is what makes it hard to clean. Dirt, bacteria and other particles can get deep into the glasses that it cannot be removed with any cleaning material.

To solve this problem, we can make the surface of the glass very water repelling or hydrophobic. Applying a hydrophobic coating to the glass gives it a sort of shield. Dirt particles are picked up by water droplets due to the surface created by the hydrophobic coating. This form of glass works in a similar way to “Teflon” works on a frying pan. It produces a non-stick surface and water will run off of this surface quickly and not streak. The coating or applications of this type are silica based and create a nano-scale film that covers the microscopic valleys and peaks on the surface of glass. This type of self-clean coating prevents the contamination, dirt and grime from clinging onto the glass or fixing to the surface.

There are advantages and disadvantages of hydrophobic coated glass. An advantage is that everything that gets put on the glass can be easily removed with water. Dirt, graffiti, and paint can get washed off with just a splash or two. A disadvantage is that coatings may differ from manufacturer to manufacturer, and that application is not easy. Factory applied coatings, depending on the exact product, have a life span of 3 to 10 years in external conditions. Cost wise the hydrophobic coatings and applications are usually about half the cost of the hydrophilic type glasses.

Many industries and manufacturers commonly use silica powders alone or in combination with other ingredients. The mineral has moisture absorbing and thickening properties. These characteristics make silica useful in construction materials, cosmetics, and some foods.

Silica is one of the most common minerals on the planet. It is a component of sand and quartz along with other minerals. Manufacturers obtain natural silica by mining and grind the substance into granules or fine powders. Some companies make synthetic silica, but both types commonly start with silica sand. Both natural and synthetic silica powders are frequently found in non-food products.

Microscopic diatoms, which are hard-shelled skeletal remains of single celled plants, also contain silicon dioxide. These remains exist in salt and fresh water beds. These types of silica are frequently referred to as amorphous silica. They are frequently ground into granules or a fine powder, sometimes called silica flour. Diatomaceous earth silica may be used in food or non-food products.

Quartz powders or glass powders are silica sand heated to extreme temperatures and melted. Artisans and manufacturers mold and shape the molten material. When cooled, the substance becomes glass. Paints, plastics, polyvinyl chloride glue, and corrosive resistant coatings all contain silica powders. In some of these products, the silica acts as a thickening or hardening agent.

Some cleansers and detergents contain silica powders. The granulated mineral scrubs surfaces by means of mechanical abrasion. Silica detergents might be used for washing clothes, dishes, or be found in general powdered cleaners. Abrasive action is also desired in some toothpastes, which contain diatomaceous earth silica as one of the ingredients. When used in hand cleaners, the abrasive nature of silica may cause rashes or other skin irritations.

Silica cosmetics contain the silky translucent powder to absorb skin oils. The mineral is thought to be hypoallergenic and some believe the substance reduces the visibility of facial lines and wrinkles. Consumers may purchase silica powders and add the substance to lawns or soil to increase moisture retention. Some believe the powdered form also deters or eliminates insect pests, though inhaling the product may lead to serious lung inflammation or possibly cancer.

Food and pharmaceutical industries commonly use silica powders for the mineral’s ability to absorb up to 50% of its weight in moisture. Food grade, or the diatomaceous earth form of silica powders, is commonly used as an anti-caking agent in coffee creamers, powdered foods, and seasonings. The self-contained gel packs frequently found in medications and over-the-counter supplement bottles usually contain some form of silica.

Bioplastics

Bioplastic isnotmade from petroleum, which is a non-renewable resource. Bioplastics come fromsustainable & renewable resources. Corn regrows in a year. They arenon- toxic:no harmful toxins will leak into the food compostable. Best case scenario it ends in a commercial compost facility where it composts, and is used to feed the soil and grow more plants.

Biodegradable Bioplastic takes longer to biodegrade in home composts, where conditions are uncontrolled and are rarely optimal. If it does end up in a landfill it will biodegrade if it is exposed to bacteria, moisture and heat.

There are different biodegradable plastics available, each with their own properties:

PLA is made from fermented corn starch, and is a great alternative to conventional petroleum based plastic in many applications. PLA is transparent and heat sensitive to 40 C. It’s used on its own, or as a thin sheet over bagasse or cardboard to act as a moisture or grease barrier. It is used to make our bags, bowls, cupsand lids.

CPLA is a combination of PLA, chalk and other biodegradable additives and can withstand temperatures of up to 95°C without deforming. It is usually opaque in colour and is used for making our disposable cutlery and coffee cup lids.

Definition of Terms

For this research study, one must know and understand the following terms:

Plastics are one of class of organic compounds made from hydrocarbons, proteins, cellulose, or resins that can be molded, extruded, cast, or otherwise fabricated into various shapes. In this study, we use bioplastics which are just plastics developed from cornstarch.

Hydrophobicity is a characteristic of a material to repel water.

Drop contact is a testing method to determine the hydrophobicity of the material. It is done by dropping a constant amount of water on a sample material over a dish. The amount of water on the dish shows how much water the sample repels.

METHODOLOGY

Procedure

1. Preparation of materials

The researchers prepared the various raw materials that make up the bioplastic: powdered silica, starch, vinegar, glycerin and water. Three different 7 cm x 7cm x 1 cm containers were also prepared and were labeled A, B and C. The materials and then placed in different containers, grouped as: ‘A’ for 0% concentration, ‘B’ for 1% concentration, ‘C’ for 2% concentration, and ‘D’ for 3% concentration.[Sir Jay1]

2. ­­Production of the Plastic

The materials mentioned above are mixed then heated until the mixture boils and creates a clear substance. After heating, the mixture is placed on a flat surface depending on the desired thickness. The mixture was set aside to dry until it produced a durable plastic.

For the constant group; the researchers mixed 48g of cornstarch, 314ml of water, 8ml of vinegar, and another 8ml of glycerin. Thus 330 ml of mixture is produced which is divided into three making it 110 ml for each plastic sample. For 1% concentration; 3.3 ml of the 330 ml mixture is removed and replaced with 6.3g of powdered SiO2. The 330 ml with 1% concentration is also divided into three making it 110 ml of 1% concentration for each plastic sample. For 2% concentration; 6.6 ml of the 330 ml mixture is removed and replaced with 12.6g of powdered SiO2. The 330 ml with 2% concentration is also divided into three making it 110 ml of 1% concentration for each plastic sample. For 3% concentration; 9.9 ml of the 330 ml mixture is removed and replaced with 18.9g of powdered SiO2. The 330 ml with 3% concentration is also divided into three making it 110 ml of 1% concentration for each plastic sample.

3. Testing and Data Gathering

The produced plastic is tested on its hydrophobic properties by comparing the amount of water repelled by each of the concentrations (using the drop contact testing method). The dimensions of the sample material for each concentration that we used are 2 cm by 2 cm. The statistical test we have selected for this study is one-way ANOVA with Tukey’s multiple comparisons test.

4. Analysis

If the silica-concentrated group shows a noteworthy distinction to the control, we can conclude that SiO₂ is effective in making hydrophobic plastic.

RESULTS AND DISCUSSION

TABLE 1 Amount of water repelled by the produced bioplastics with different silica concentrations

Reflected in Table 1 the evidence showing variability in the amount of water repelled by the plastics produced using different concentrations of silica. The minimum mean (0.63 mL) is in the control and the maximum (0.78 mL) is shared 2% and 3% concentration.

FIGURE 1 Line graph showing the correlation between the values of the amount of water repelled

Then, the researchers tested the data obtained using one-way ANOVA with Tukey’s multiple comparisons test to see if there is a significant difference among the control and independent variables. According to the results of the test, there is a very significant difference (0.0002) on 0% vs 1% and extremely significant differences on 0% vs 2% and 0% vs 3%. However, the 1%, 2% and 3% concentrations show no significant differences when compared with each other. Furthermore, there is positive correlation (0.9012).

CONCLUSION

The purpose of this study is to determine the effect of silicon dioxide (SiO2) powder to the production of hydrophobic bioplastics. According to the results of our experiment, adding silicon dioxide to the contents of a bioplastic evidently makes it more hydrophobic. However, varying the concentration does not affect the hydrophobicity of the plastic.

RECOMMENDATION

The research group recommends adding more variations to the concentrations to give a better comparison of the experiment. Adding more trials to each concentration is also recommended to make the results more accurate. Also, using Tapioca starch is a great alternative for making the bioplastic. Remember to make the right calculations for the concentrations. Maintain the same shape, area, and weight for all trials of the plastic so that the comparison is accurate.

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BIBLIOGRAPHY

BalcoNano™. (n.d.). Hydrophobic Glasses. Retrieved from BalcoNano: http://www.balconano.com/HydrophobicGlass.aspx

Craig Freudenrich, P. (n.d.). How Plastics Work. Retrieved from Howstuffworks: http://science.howstuffworks.com/plastic5.htm

Hall, M. J., & Barwick, S. (2013, April 10). What Are the Different Uses of Silica Powders? Retrieved from wiseGEEK: http://www.wisegeek.com/what-are-the-different-uses-of-silica-powders.htm

Mempro Materials. (n.d.). Silicon Dioxide Nanofiber Materials. Retrieved from Mempro: http://mempro.com/products/ceramic-nanofiber-materials/silicon-dioxide-nanofiber-material/

Rice University News Release. (2010, September 1). Silicon oxide circuits break barrier. Retrieved from Understanding Nano: http://www.understandingnano.com/silicon-oxide-nanowire-memory.html

Talbot, D. (2006, February 23). Super-Repellent Plastic. Retrieved from MIT Technology Review: http://www.technologyreview.com/news/405378/super-repellent-plastic/ http://www.greenhome.co.za/raw-materials/plant-starch/

APPENDICES

Appendix A

Total Cost of the Project

Total project cost: â±£ 863.00

APPENDIX B

Ordinary One-Way ANOVA

(at α = 0.05)

APPENDIX C

Tukey’s Multiple Comparisons

(at α = 0.05)

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