Biodegradable Packaging

From corn to resin

What you need to know about Biodegradable Packaging

For the past five decades, the packaging industry has witnessed several generations of plastics that have evolved into a variety of packaging materials such as polystyrenes, polyethylenes and polypropylenes. With every passing day, an increasing awareness of these products and the impact humans have on our planet has created the "Green & Environmental Movement". The packaging industry's term for this movement has become known as "Sustainability".

The following is a brief overview of the various product production methods employed in the packaging industry today. We feel that through understanding these production options, you will be able to better appreciate the superior aspects of the Nviroplast line of packaging solutions and their positive impact on our environment vs. the petrochemical based product widely used in today's marketplace.

Types of Biodegradable Plastics

Normal plastics derived from petroleum are made from synthetic polymers. However, polymer chains are also found in nature. These chains are common in cellulose, lignin, and starch. Cellulose is abundant in all plants, although some plants produce more than others. Lignin is typically found in wood, and starch is common in plants such as corn, potatoes, and wheat.

The reason traditional plastics are not biodegradable is because their long polymer molecules are too large and too tightly bonded together to be broken apart and assimilated by decomposer organisms. However, plastics based on natural plant polymers derived from wheat or corn starch have molecules that are readily attacked and broken down by microbes.

There are two main types of biopolymers: those that come from living organisms; and those which need to be polymerized but come from renewable resources. Both types are used in the production of bio-plastics.

1) Biopolymers From Living Organisms

These biopolymers are present in, or created by, living organisms. These include carbohydrates and proteins and can be used in the production of plastic for commercial purposes. Following are examples:

Cellulose- Wood, cotton, corn, wheat, and others: This polymer is made up of glucose. It is the main component of plant cell walls.

Soy Protein- Soybeans: Protein which naturally occurs in the soy plant.

Starch- Corn, potatoes, wheat, tapioca, and others: This polymer is one way carbohydrates are stored in plant tissue. It is a polymer made up of glucose. It is not found in animal tissues.

Polyesters- Bacteria: These polyesters are created through naturally occurring chemical reactions that are carried out by certain types of bacteria.

2) Polymerizable Molecules

These molecules come from renewable natural resources, and can be polymerized to be used in the manufacture of biodegradable plastics.

Following are examples:

Lactic Acid- Beets, corn, potatoes, and others: Produced through fermentation of sugar feedstock's, such as beets, and by converting starch in corn, potatoes, or other starch sources. It is polymerized to produce polylactic acid -- a polymer that is used to produce plastic.

Triglycerides- Vegetable oils: These form a large part of the storage lipids found in plant and animal cells. Vegetable oils are one possible source of triglycerides that can be polymerized into plastics.

How are Biopolymers and Bio-plastics Made?

There are two methods being researched and used to produce plastics from plants. The first uses fermentation and the second rely on the plant to become the factory for plastic production. These two methods are outlined below.

1. Using Fermentation to Produce Plastics

Fermentation, used for hundreds of years by humans, is even more powerful when coupled with new biotechnology techniques. Fermentation is the use of microorganisms to break down organic substances in the absence of oxygen. Today, fermentation can be carried out with genetically engineered microorganisms, specially designed for the conditions under which fermentation takes place, and for the specific substance that is being broken down by the micro-organism. There are two ways fermentation can be used to create biopolymers and bio-plastics:

      A). Bacterial Polyester Fermentation

- Bacteria are one group of microorganisms that can be used in the fermentation process. Fermentation, in fact, is the process by which bacteria can be used to create polyesters. Bacteria called Ralstonia eutropha are used to do this. The bacteria use the sugar of harvested plants, such as corn, to fuel their cellular processes. The by-product of these cellular processes is the polymer. The polymers are then separated from the bacterial cells.

      B). Lactic Acid Fermentation

- Lactic acid is fermented from sugar, much like the process used to directly manufacture polymers by bacteria. However, in this fermentation process, the final product of fermentation is lactic acid, rather than a polymer. After the lactic acid is produced, it is converted to polylactic acid using traditional polymerization processes.

2. Growing Plastics in Plants

Plants are becoming factories for the production of plastics. Researchers created an Arabidopis Thaliana plant through genetic engineering. The plant contains the enzymes used by bacteria to create plastics. Bacteria create the plastic through the conversion of sunlight into energy. The researchers have transferred the gene that codes for this enzyme into the plant. As a result, the plant produces plastic through its cellular processes. The plant is harvested and the plastic is extracted from it using a solvent. The liquid resulting from this process is distilled to separate the solvent from the plastic.

Application of Biodegradable plastics

As with conventional plastics, bio-plastics have a very broad application spectrum. Initial applications have already established themselves successfully in important markets. Commercial success occurs above all when the particular properties can be transformed into useful product functionality and added value.

Many bio-plastics products are still being used in areas where compostability represents a significant benefit. This is particularly the case for segments which are closely linked to biological recycling e.g. collection bags for compost, agricultural foils, or nursery products. Other applications such as packaging and technical applications are gaining importance. This is an area where functionality factors influence the decision for bio-plastics.

Processing of Bioplastic

Bio-plastics can be processed into a vast number of products using all the conventional plastics processing technologies. The process parameters of the processing equipment have to be adjusted to the individual specification of each polymer. This is usually not a complex procedure. Machine and plant manufacturers are also getting involved in processing bio-plastics on their equipment. They are searching for optimization possibilities. For this reason, several manufacturers have joined the European Bio-plastics association.

Numerous individual production steps are often necessary prior to achieving the finished product. Depending on the requirements, basic materials are modified through compounding with the result that there are different formulations for film or injection moulding types. If it is important that the biodegradability or compostability is maintained, this must be taken into account during the selection of the type of processing and materials. This concerns not only polymers and all additives, but also colorants and labels and stickers on the final product, as well as the contents in the case of packaging. The Certification of compostable products is undertaken by an independent body using strict criteria.

Compostable Standards

There are currently few international organizations which have established standards and testing methods for compostability, namely:

The ASTM, CEN and DIN standards specify the criteria for biodegradation, disintegration and eco-toxicity for a plastic to be called compostable.

Certification of compostable Biodegradable Products

Certification links the EN 13432 testing standard to the protected quality label that allows the identification and proper handling of compostable plastic products on the market. It ensures that the product can be composted. Product certification guarantees that not only the plastic is compostable but also all other components of the product, e.g. colors, labels, glues and - in case of packaging products - residuals of the content. The protected "compostability label" (called "seedling") may only be used for certified products. The logo as well as the number of the certificate printed on the product allows the producer to identify the product and show proof of conformity: The product marketed must match the product tested.

It is recommended to commercial users or retailers of compostable bio-plastic products to ask distributors about their product certification and to demand the certification number. Even if it is not intended to compose the product, certification guarantees a high product safety. Certification, moreover, distinguishes between bio-plastic and conventional plastic and offers marketing and communication possibilities.

The certification program for compostable plastic products has been set up by experts responsible for waste-management recycling and compost quality assurance.

The members are as follows:

The composition of the certification committee ensures broad acceptance of the certification system; for this reason, it also enjoys high prestige in other countries. Leading resin producers have committed themselves voluntarily to apply product certification - the self-commitment has been officially acknowledged by the EU Commission. Harmonization of Certification and Labeling. European Bio-plastics promotes the use of product certification and the use of a single label in Europe. The association further collaborates with leading organizations in Asia and USA within the International Compostable Product Certification Network. Agreements and memorandums of understanding have been signed with BPI (USA), BPS (Japan) and BMG (China), e.g. on acceptance of testing laboratories and certificates. This approach aims at facilitating international trade of high quality products. Background information on the procedure of certification is given the certification agencies.

Reference: www.european-bioplastics.org