A bioactive approach

Materials World magazine
3 Jul 2015

Biobased materials are making waves in the packaging industry. Natalie Daniels reports. 

Advances in biomaterials for the packaging industry are growing, as companies and scientists are discovering more ways to create biodegradable, eco-friendly and longer lasting packaging. It all started in 1907, when Leo Baekeland added phenol to formaldehyde to form Bakelite – an inexpensive, nonflammable, versatile plastic that marked the beginning of the industry. 

Now, it is bioplastics capturing headlines for meeting many modern green targets. They are made partly or fully from sustainable plant sources, and often biodegradable. It is estimated that the manufacturing capacity of bio-based materials and biochemicals, including those going into bioplastics, will increase to around 14,000Mt by 2017. 

And it seems that consumers are partly responsible – a recent report by Stora Enso revealed that 59% of millennials, the generation born in 1980–2000, consider packaging sustainability to be important. This increased awareness of bioplastic packaging’s benefits is contributing to the growing market. 

All this means bioplastic materials are gaining attention in the packaging industry. For example, polylactic acid (PLA), is becoming a popular alternative to petroleum-based plastics in agriculture and food packaging, as it is both biodegradable and carbon neutral. The drive towards using renewable sources has produced plastics using renewable crops such as corn, tapioca roots, starch or sugarcane.

However, biomaterials are not yet as cheap as their competitiors, so researchers are turning their attention to this area. Scientists at the University of Illinois, USA, have developed a hydrolysable polymer designed to degrade over time for compostable packaging materials, which could make biomaterials cheaper. The team discovered how to reverse the characteristics of a key bonding material – polyuria – by developing a class of hindered urea bond-containing polymeric materials or poly(hindered urea)s (PHUs). The urea bond is inert, keeping the polymer stable for long-lasting applications. 

The PHUs can be hydrolysed within a few days and the team demonstrated that degradable polymeric materials could be easily synthesised by mixing multifunctional bulky amines and isocyanates, expanding the family of hydrolysable polymers. These new types of polymers require short functioning time and are degradable, making them ideal for environmentally friendly packaging materials. 

Another noticeable example of research containing a high-level of renewable and compostable materials is biopolymers that are extracted from plantations and do not exploit virgin or deforested land. Novamont is using cornstarch, cellulose, and glycerine obtained from various crops and other raw materials extracted from renewable sources. Fossil-derived polymers are only used when a renewable equivalent is not available on an industrial level.

It is estimated that the use of bio-based polymers will grow 18% a year to 2017 because of an increased need for eco-friendly packaging, according to the report Global Bioplastic Packaging Material Market 2015–2019. Other biopolymers, including polyhydroxyalkanoates (PHAs), made by fermentation, using renewable carbon-based feedstocks have also seen a rise, due to their high biodegradable properties. 

Biopolymers designed for packaging have become an ideal solution for the industry due to the need to reduce its environmental impact. To create flexible films and coatings for products, Biome has designed the BiomeEP bioplastics range based on either a potato-starch based polymer or a cornstarch-based polymer. These are 100% biodegradable and compostable according to EN 13432, ASTM D6400 and Vincotte OK compost guidelines. Research has also begun into a fully bio-based polyester with the aim to create bio-based chemicals from lignin, suitable for the production of plastics.

Innovating with biomaterials 

Novamont technology has created Mater-Bi, a family of compostable bioplastics made from renewable plant materials such as sunflowers and GMO-free cornstarch. These are biodegradable in composting soil and salt water, and are designed for food and industrial packaging industries. Like traditional plastics, biodegradable polymers can be transformed using blow moulding, casting, extrusion and injection moulding machines to create traditional plastics.

In today’s market polylactic acid (PLA) is also transforming the food packaging industry. In 2010, PLA had the second highest consumption of any bioplastic of the world. It is derived from corn and used as a natural substitute for petroleum-based plastics and polyester products. When PLA is exposed to an excessive amount of heat or moisture, the polymer chains that make the substance begin to break down, making it useful for hot food and beverage packaging. The Knowledge Transfer Partnership, with the University of Sheffield, have combined their efforts to develop a plant-based polymer – Floreon, by adding a formulated compound to make bioplastics four times tougher than a standard PLA. It is 100% renewable and works as feedstock recovery, converting back the product to lactic acid, which can then be purified and used to make virgin polymers again.

Bioplastics Timeline

1862 – Alexander Parkes creates the first man-made plastic from an organic material derived from cellulose

1907 – Leo Baekeland invents Bakelite, which transforms the packaging industry

1939 – The outbreak of war leads to stockpiling, as the military substitutes plastics for metals and rubber

1953 – The commercialisation of polyester fibres introduces the concept of ‘drip-dry’ and ‘non-iron’ fabrics

1976 – Available in a wide variety of forms, plastic becomes the most used material in the world

1990 – Commercial demand for bioplastics starts to develop, driven by oil price volatility and environmental concern. A British company, Imperial Chemical Industries, developed a bioplastic.

2000–2008 – The consumption of biodegradable plastics based on starch, sugar, and cellulose has increases by 600% worldwide.