Background

Within the past 70 years, over 6 billion tonnes of plastic was generated – 80% being stored in landfills or disposed elsewhere in the environment [1]. The overuse and accumulation of unused plastic has become an environmental issue in recent years.

Plastic is the miracle that turned into environmental risk. Why now plastic is so popular?

lightweight
durable
waterproof
highly versatile
energy effiecient to produce
cheap
slow to degrade (-)
from non-renewable source (-)
difficult to recycle (-)

Biodegradable Polymers

Thus, as an alternative to conventional plastics, biodegradable polymers, which are generally made of polysaccharides like starch and other renewable materials, have been developed [3]. Despite being more readily degradable than conventional plastics, biodegradable plastics are still far from the norm as they are generally not durable, especially when wet. Additionally, they are not easily fabricated and costly to produce. Some biodegradable plastics involve mixtures of starch and some resins, making the plastic only partially degradable. Other strategies utilize prodegradants (additives that promote degradation in the presence of oxygen) mixed into conventional plastics; these are called oxo-degradable plastic. Although the plastic is mixed with prodegradants, oxo-degradable plastic still contributes to plastic pollution as when it breaks down, fragments of microplastic are produced [4]. These microplastics may contain additives (like endocrine disruptors) that are harmful to marine organisms [5]. Regardless of the current state of the art biodegradable plastic, when compared to the superior properties of conventional plastics and their cost-effectiveness it is clear that more research is needed. To alleviate plastic pollution, we attempted to develop a biodegradable plastic made of cellulose designed to be more water-resistant and more durable than other biodegradable polymers with similar method of production. Nata de coco powder was chosen as the source of the cellulose as it is a cheap and widely-available product.

General Procedure

This project is using commercial nata de coco powder. Other materials: Beeswax, carboxymethyl cellulose and glycerol. Tools needed: heat-mixer, petri dish, oven-drier, heat press, tensile test tool.

Nata de coco: Coconut jelly made through the fermentation of coconut water. it forms through the production of microbial cellulose (bacterial cellulose). Composed of cellulose, which can be used for bioplastic production.
Glycerol: Glycerol is a liquid that is commonly used in the food industry which can be used as a sweetener and a plasticizer among other things. Glycerol can be used as a plasticizer to promote flexibility and potentially increase tensile strength in the NDC-based product.
Beeswax: Wax produced by bees. It is made of free fatty acids, hydrocarbons and over 300 other components. It contains hydrophobic properties [8]. Thus, the wax is used to waterproof the NDC sheet.
Carboxymethyl cellulose (CMC): CMC is a water-soluble cellulose derivative often used in the food and beverage industry due to its high-solubility. Made of cellulose and is biodegradable.

Prototype of the Nata-Based Product (Spice Sachet)

Dissolvable spice sachet using NDC + glycerol:

Made with 1% NDC (sourced from commercial NDC powder) and 0.5% glycerol.

To make the sachets, the NDC + glycerol solution was oven-dried and then heat pressed to form a circular sheet. Then the sheet was folded by three sides. Each fold was then heated using an iron to thermally cross-link (form bonds linking polymer chains to each other) parts of the sheet, effectively sealing the sides together. The sachet was filled and then the top was ironed to fully seal the sachet.

Findings:

The NDC + glycerol sheets seem to display thermoplastic properties, making them easily moldable using heat energy.
The sachets can dissolve in water and are safe to consume.

Functionalized Nata Sheets

NDC + Glycerol: NDC + glycerol has theromoplastic properties, making it moldable with heat. NDC + glycerol maintains its shape until submerged in water (thus, it can be used as a dissolvable spice sachet).
NDC + Glycerol + Beeswax: NDC + glycerol + beeswax absorbed the least water of the three variants and is the strongest. It has a smooth surface and can potentially be used as w water-resistant plastic.
NDC + Glycerol + CMC: NDC + glycerol + CMC absorbed the highest amount of water (swelling the most of the three variants). It is not brittle and does not dissolve in water.

Freeze-Dried Nata Sheets

NDC + Glycerol
NDC + Glycerol + Beeswax
NDC + Glycerol + CMC

The freeze-dried samples have a similar texture to tissue. The samples were thin, light and were not textured.

possible applications: bandage, skincare (as glycerol is safe for skin), or thermal insulators.

Conclusion

The product above is just one example of the use of NDC-based products. More prototypes of products made using NDC, beeswax and CMC are being created at present. As nata de coco is a cheap and easily-available product that can be used for a variety of functions due to its water-resistance, durability and thermoplasticity, there is potential for NDC-based polymers to become a sustainable alternative to plastic in the future following further research. Further work is needed to further improve its mechanical properties and water-resistance even more. Future research will also need to include biodegradability tests to assess its environmental footprints when the NDC products are disposed to the environment.

Keshia Widjaja

PUBLICATION AND PRESENTATION

EVENTS ATTENDED