What is Compostable Plastic and How is it Made?

There are multiple types of bioplastic available on the market right now. Each one is manufactured differently. Factories can use their existing plastic manufacturing facilities to create bioplastics too. Bio PE, bio-PP, and bio-PET can all be made via the same process of PP, PE, and PET. 

Other bioplastics are created from the ground, using a manufacturing process that’s bio-based. Nanotechnology synthesis, such as epitaxial growth and microbial reactions can be used to create a variety of bioplastics, suited to different purposes. 

Bioplastics can also be made by extracting polymer from microorganisms. Centrifugation is used to isolate microorganisms before press-filtering the bioplastic. Bacteria can be used in this method to metabolize feedstocks while boosting conversion efficiency. PHA is one of the most researched bioplastics that uses this technique.

Raw Materials Used when Manufacturing Compostable Plastic 

Some of the most common raw materials used when manufacturing bioplastics, can be found below.

Corn Starch

Corn starch is extracted from corn kernels and combined with a glycerol solution. Corn starch accounts for over 85% of starch across the world, meaning the availability is high, and the price is low. The production is simple and the final product is high-performance with biodegradability. Corn plastics only break down in commercial facilities, and require high humidity levels.

 

 

Potato Starch

Potato starch is used to create PLA. This is often used in food packaging. This starch is extracted from potatoes and then mixed with a glycerol solution. The mixture can then be heated to form different shapes. Potatoes are widely available and sustainable, and on top of this, the plastic breaks down naturally over time. Half of the bioplastics on the market right now, are starch-based. 

Sugarcane

Sugarcane is another raw material used when manufacturing bioplastic. Sugarcane is processed to extract the sugar, which is then used to create ethanol. Ethanol is used as a feedstock for plastic. Sugarcane plastic is often used to create medical gadgets as well as culinary utensils. Sugarcane bioplastic can be recycled and it can also absorb CO2. Bagasse, a waste product, can also be used to create electricity, sustaining the production of bioplastics.

Cellulose

Cellulose is an organic substance and after it’s been extracted, it can be mixed with colorants, plasticizers, and additives to create bioplastic. Cellulose bioplastic can be used in disposable cutlery and even to create clothing. With an annual production of 180 billion tons, cellulose is the most abundant organic compound. It can improve water permeability in bioplastics and it can also increase the potential for eutrophication.

Algae

Algae is widespread within the bioplastic sector due to its low nutritional requirements. Algae bioplastics are still in their early stage of development but they do have the potential to be a sustainable alternative. They are used in numerous applications, including electronic displays and greenhouse films.

How Much Does it Cost to Create Bioplastic?

Bioplastics remain to be a viable solution for planet decarbonization. The cost of manufacturing bioplastic can vary, as a lot of it comes down to the process, feedstock, and waste materials generated. In terms of energy, however, it’s estimated that bioplastic is 20% more efficient to create when compared to standard plastic.

What Happens to Bioplastics When They’re Composted?

Biodegradation happens under anaerobic conditions. This can take between 6 and 12 weeks, with the process being dependent on bacteria, fungi, and enzymes. The resulting end mass from the process includes Co2, water, and biomass. Temperatures for biodegradation often have to be between 50-70°C, with water being essential to the process. 

Compostable plastic degrades in a compost site.  Microorganisms work to break it down at the same rate as normal, organic materials, leaving no toxic chemicals or residue behind. Although all plastics are biodegradable, the process takes many years. Plastics, including PET, can’t readily biodegrade. Both processes, for plastic and biodegradable plastic, depend on bacteria that consume the waste, breaking it down into simple matter. The issue is that PET is made with chemicals that bacteria is unable to consume. A plastic bottle for example, takes 450 years to decompose. 

When you look at biodegradable plastics, such as PHA or PLA, they break down naturally. PLA, which is derived from corn sugar, sugarcane, or potatoes, uses far less fuel during the manufacturing process when compared to traditional plastic. Bioplastics also use less than 0.02% of agricultural land, with the most complex bioplastics taking a maximum of six months to decompose. This is far faster than the hundreds of years associated with normal plastic. 

So even though the process of degradation is similar for plastics and bioplastics, the fact that bioplastics don’t contain anything that bacteria can’t consume, makes them much faster to degrade. This translates to environmental benefits, as well as cost and energy savings.  The main difference between compostable bioplastic and plastic is that compostable bioplastic has to break down within a specific time frame, and cannot release anything harmful to the environment. Standard bioplastics don’t have to meet such stringent requirements. The standards for compostable bioplastics are outlined by AS 5810 and BPI regulations.

Exploring AS 5810 and BPI Standards

Australian AS 5810 standards specify that any products listed as being home compostable, need to break down fully, under organic composting conditions. The standard looks at the biological treatment and the effect on home compost. Although a home composting system is very different from an industrial system, the core requirements for AS 5810 remain the same. For a plastic to be registered under this standard, it has to undergo stringent testing, which is usually carried out by a third party. The testing period is usually 12 months. Bioplastics that meet this requirement have to be 90% biodegradable, have no toxic effects, and also need to be safe for compost, plants, and worms. 

They should also contain over 50% organic material. If a bioplastic is successful at meeting these requirements then the applicant will be granted a license, meaning that they can use the home composting logo on their packaging. The logo helps the end consumer, or the customer to recognize that the packaging is biodegradable so that they can dispose of it appropriately.

So as you can see, compostable plastic is the future of our planet. It can be biodegraded faster, provides the same benefits as plastic, and doesn’t pollute the ocean with harmful chemicals. It’s cheaper to manufacture and is slowly becoming a prominent material within the industrial sector.

 

Check out our several Compostable Kitchen Products  and make the switch!