Biodegradable Films: Types, Applications and Benefits

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There has been an increasing interest in the use of biodegradable polymers as an alternative solution to the environmental problems caused by the accumulation of non degradable synthetic containers. 

As a result, much effort has been made to replace plastic films with biodegradable plastic films, an effective measure to solve the plastic film residue pollution.

What are biodegradable films?

Biodegradable films are plastic-based films that have additives included during the manufacturing process. These additives, usually enzymes, enable the plastic to break down.

It can be decomposed by living organisms, such as bacteria or fungi, with or without oxygen without any environmental impact. 

These films can be prepared using proteins, polysaccharides, or lipid materials. Among these innovative strategies is the incorporation of antimicrobial or antioxidants agents in films, which can be used as packaging. These compounds are incorporated into or coated onto food packaging materials to improve food safety and shelf life.

When the biodegradable film breaks down, it turns into smaller pieces of plastic. That is why it requires specific conditions to break down, such as sunlight or certain temperatures to fully biodegrade. 

Types of biodegradable films

Polyethylene will naturally fragment and biodegrade, but it can take many decades to do this, and can in the meantime cause an environmental problem. There are two methods to resolve this problem. One is to modify the carbon chain of polyethylene with an additive to improve its degradability and then its biodegradability. 

The other is to make a film with similar properties to polyethylene from a biodegradable substance such as starch.

Starch-based biodegradable films

Starch-based biodegradable films are made from corn, potatoes or wheat. This form of biodegradable film meets the ASTM standard (American Standard for Testing Materials) and European norm EN13432 for compostability as it degrades at least 90% within 180 days or less under specified conditions.

Examples of polymers with which starch is commonly used

The heat, moisture and aeration in an industrial composting provide the required conditions  for this type of film to biodegrade. 

Pros & cons of starch based film

Pros

  • Residual material is biodegradable and compostable. 
  • Reduced fossil fuel content (depending on loading of filler)
  • Faster degradation of litter
  • No net increase of carbon dioxide in the global ecosystem

Cons

  • Source of starch can be problematic (competition against food use, rainforests being cleared to grow crops for bioplastics)
  • Poorer mechanical strength than additive based – filling a starch bag with wet leaves and placing it curbside can result in the bottom falling out when a haulier picks it up. 
  • Degradation in a sealed landfill takes at least six months.
  • They have a limited Shelf life.
  • Some starch-based film needs to be composted in industrial facilities because the temperature of the compost needs to be at 58°C. 
  • If mixed with other plastics for recycling, the value of recycling is reduced.
  • For plastic recycling, resin identification code 7 is applicable.

Typical applications

  • Carrier bag
  • Refusal sacks
  • Vegetable bags 
  • Food films 
  • Agricultural films 
  • Mailing films 

However, these applications are still very limited compared to those of petroleum-based plastic films.

Additive based biodegradable films

Additives can be added to conventional polymers to make them either oxodegradable or more hydrophilic to facilitate microbial attack.

Oxodegradable

These films are made by incorporating an additive within regular polymers to provide an oxidative and then a biological mechanism to degrade them. This typically takes six months to 1 year in the environment with adequate exposure to oxygen. 

Degradation is a two-stage process; first, the plastic is converted by reaction with oxygen (light, heat or stress accelerates the process) and then these smaller oxidised molecules are biodegraded by naturally occurring microorganisms.

Commercial competitors and their trade associations allege that the process of biodegradation stops at a certain point, leaving fragments, but they have never established why or at what point. 

OXO-degradation of polymer material has been studied in depth at the Technical Research Institute of Sweden and the Swedish University of Agricultural Sciences. A peer-reviewed report of the work showed 91% biodegradation in a soil environment within 24 months, when tested in accordance with ISO 17556.

OXO-degradation has been studied at the Eurofins laboratory in Spain, where on 25 July 2017 they noted 88.9% biodegradation in 121 days. 

The EU has however disputed the statements about biodegradation of oxo-degradable plastics. In a 2017 report, it was stated that the biodegradation of the fragmented pieces is only partially supported.

Enhancing hydrophilicity of the polymer

These films are inherently biodegradable over a long period. Enhancement of biodegradability of the polymer by adding in additives to change the hydrophobic nature of the resin to slightly hydrophilic allows microorganisms to consume the macromolecules of the product.

Enhancing the hydrophilicity of the polymer allows fungus and bacteria to consume the polymer at a faster rate utilising the carbon inside the polymer chain for energy. These additives attract certain microorganisms found in nature.

Pros and cons of additive based film

Pros

  • Much cheaper than starch-based plastics.
  • Can be made with standard machinery, and can be used in high-speed machines.
  • Materials are well known.
  • Does not compete against food production.
  • These films look, act and perform just like non-degradable counterparts, during their service-life but then break down if discarded.
  • They can be recycled with regular plastics.
  • Like regular plastics, they are made from a by-product of oil or natural gas.
  • They are certified non-toxic, and safe for food-contact.

Cons

  • Degradation depends on access to air.
  • They are not designed to degrade in landfill. 
  • European (EN13432) or American (D6400) Standards on compostable products are not appropriate, as they are not designed for composting. They should be tested according to ASTM D6954.
  • They are not suitable for Polyethylene Terephthalate (PET) or Polyvinyl Chloride (PVC).
  • The precise rate of degradation/biodegradation cannot be predicted.

Typical applications

  • Trash Bags
  • Garbage Bags
  • Compost Bags
  • Carrier bag
  • Agricultural Film
  • Mulch Film

Benefits of biodegradable films

Biodegradable films are material that will decompose naturally when introduced in the environment. The end result of biodegradable films is less harmful to the environment as compared to regular plastic bags.

  • Reduction in Carbon Emission

One of the main benefits of using biodegradable films is a significant reduction in the carbon emissions that happen during the manufacturing process. Not just that, since the materials used to create biodegradable films are plant-based, minimal carbon is emitted during the composting process.

  • Lesser Energy Consumption

While the initial investment might be slightly higher, in the long run, biodegradable films require lesser amounts of energy.

  • Eco-Friendly Disposable Solution

Biodegradable films require composting or recycling to ensure proper breakdown of the plastic pieces to enable the natural composting process.

  • Recyclable Material

Apart from taking a significantly lesser time to breakdown as compared to regular plastic, biodegradable films can also be further recycled to create more plastic by-products.

  • Lower Petroleum Consumption

Oil is a significant ingredient in the manufacturing of traditional plastics. Petroleum is known to have negative impacts on the environment. Biodegradable plastics use natural products; therefore, the use of bioplastic can profoundly reduce the amount of petroleum used and consequently lessen its environmental hazards.

Are biodegradable films food grade?

Plastics are widely used for the manufacturing of packaging materials because of their performance and ease in production. 

Food packaging plays an important role in maintaining the quality of packaged food. It prevents the food getting impacted by any chemical, physical and environmental damage. 

Conventionally, plastic material is commonly used in the food industry due to large availability and excellent mechanical performance at a low cost. However, increased usage of plastics has created serious ecological problems to the environment because of their resistance to biodegradation. 

This has gained high interest for researchers to develop new materials that meet food protection and preservation requirements. 

The addition of a natural bioactive compound such as antioxidant, antimicrobial and pigment also increases the functionality of the film and provides intelligent communication with the consumer. 

Biodegradable films are good systems for the improvement of food quality, shelf life, safety and functionality. 

They can be used as individual packaging materials, food coating materials, active ingredient carriers and to separate the compartments of heterogeneous ingredients within foods. 

There are certain biodegradable films in which the oxygen concentration is reduced and carbon dioxide concentration is increased to reduce the overall metabolic processes, thereby extending the shelf life of the product. 

It is an economical and straightforward technique for extending the shelf life by preserving the quality of fruits and vegetables.

Antimicrobial properties are more essential to regulate unwanted microorganisms on food products by infusion of dynamic molecules, such as antimicrobial compounds. 

Antimicrobial compounds have also been incorporated into films for use in active packaging. These films are considered dynamic because they rely on diffusion through the packaging medium as opposed to a triggered release of antimicrobials via responsive materials.

Applications of biodegradable films

  • Food Industry: In the last decade, there has been an increased interest from the food, packaging and distribution industry toward the development and application of bioplastics for food. Applications of biodegradable films in the food industry include; edible coating, paper boards, egg trays, carry bags, wrapping films and food packaging.
  • Agriculture : The use of biodegradable films for soil mulching and low tunnel covering is seen as a sustainable solution for the disposal and management of agricultural plastic waste.  Furthermore, there is no indication of ecotoxicity or reduced soil quality from using biodegradable films.
  • Cosmetic & Personal Care Products Packaging: Much of the conversation around environmental sustainability in the beauty industry is about post-consumer packaging waste to which only biodegradability seems to be a feasible way of managing post-consumer product waste.  Idealpak, an ISO 9001:2015 certified manufacturer of primary packaging for cosmetics and personal care industry, offers biodegradable packaging.
  • Hospital food service ware: Disposable food service ware is widely used in hospitals. Disposable products provide some benefits to hospitals – ease of use, minimal maintenance and reduced dishwashing needs.

Currently, biodegradable alternatives exist that can reduce human and environmental health degradation. Biodegradable food service ware is made from a renewable resource and can be composted at end life. It also doesn’t leach chemicals during use.

Global market trends and future of biodegradable films

The global biodegradable films market size is estimated to be USD 1.1 billion in 2020 and projected to reach USD 1.5 billion by 2025, at a CAGR of 6.6%

The growing awareness regarding plastic waste and its adverse impact on the environment is one of the primary factors driving the market growth. 

Moreover, factors like growing demand from the food packaging industry, and high demand from the agriculture & horticulture sector are also contributing toward the market growth of biodegradable films.

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