What is Reverte?
What is an oxo-biodegradable plastic?
Why does Reverte™ produce superior products that are more environmentally friendly?
Why use Reverte? (The 4R Solution: Reduce, Reuse, Recycle, ReverteTM)?
What are the options for dealing with plastic waste?
What is the difference between degradable, biodegradable and oxo-biodegradable plastic?
How does the Reverte™ oxo-biodegradable technology work?
What are the advantages of Reverte™ over other methods of degrading plastic?
How controllable is the process of biodegradation (shelf life and service life)?
Do the Reverte™ additives or finished products need to be stored or handled in any special way?
How does Reverte™ affect product performance of the finished product?
Is Reverte™ safe to be used for food contact applications?
Can Reverte™ based plastics be recycled?
Will Reverte™ products create greenhouse gases such as CO2 and methane in a landfill?
What are the end products of Reverte™ and are there any harmful effects on the environment from the use of this additive?
Why does the Reverte ™ process cost so little?
What products are currently manufactured using Reverte™ ?
 

What is Reverte™?

Reverte™ is an additive that provides programmable degradation of plastics.

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What is an oxo-biodegradable plastic? ?

It is a general understanding that discarded conventional plastic packaging films & carrier bags will endure in the environment for many years. This is clearly an issue in terms of increasing requirements for landfill sites for those items collected as refuse & also the damage to wildlife & the unsightly nature of these items left as litter. To counter these issues, there is a movement to manufacture packaging products which will have significantly reduced lifetimes once discarded as waste.

One approach to this is to incorporate additives into materials such as polyethylene (PE), polypropylene (PP), polystyrene (PS) & polyethylene terephthalate (PET) which will accelerate the degradation of the plastic in the environment.

These additives (pro-oxidants) use a salt of a transition metal such as cobalt (Co), iron (Fe), manganese (Mn) or nickel (Ni) to drive the oxidation process which, under the action of heat or light, will reduce the molecular weight of the polymer to a level where bacteria & fungi in the soil or disposal environment can further reduce the material into water, carbon dioxide & biomass.

These products are known as oxo-biodegradable & their testing requirements are described in the ASTM standard guide number D6954-04: “Exposing & Testing Plastics that Degrade in the Environment by a Combination of Oxidation & Biodegradation” This standard guide consist of three stages or Tiers & can be followed to demonstrate that a material should meet the essential requirements for an oxo-biodegradable plastic, namely fragmentation of the polymer, subsequent biodegradation of the polymer fragments within 24 months & also to show evidence that no harmful residues remain.

Oxo-biodegradation of plastics is defined by TC249/WG9 of CEN (the European Standards Organisation) as "degradation identified as resulting from oxidative & cell-mediated phenomena, either simultaneously or successively."

There is currently a draft British Standard for testing oxo-biodegradable plastics - BS 8472.

The ASTM D6954 standard guide differs from the requirements of D6002 & D6400 in that both D6002 & D6400 relate specifically to compostable materials where there is no heat or photo-oxidation component involved in the degradation process & that the degradation should result in evolution of 60% carbon dioxide within 180 days. Similarly BS EN ISO 13432:2000 – Packaging - Requirements for packaging recoverable through composting & biodegradation – requires 90% conversion to carbon dioxide within 6 months.

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The Tiers are now described in more detail.

Tier one - Abiotic oxidative degradation: Using either accelerated or real-time conditions, samples are subjected to a regime of heat or light exposure in order to determine the time taken for the polymer’s average molecular weight to be reduced to 5000 or less &, for thin films, for the elongation at break value to reach 5% or less. It is also suggested that a sieve test be performed to measure the extent of physical fragmentation or disintegration. Additionally, analysis using infra-red spectrophotometry may also be used to follow the extent of surface oxidation – the Carbonyl Index.

Depending on the polymer type & the conditions of the Tier one testing, there is the possibility that, rather than causing a reduction in the average molecular weight of the polymer, gel formation or cross-linking will occur. Cross-linked polymer is generally not biodegradable, so the extent of any cross-linking will need to be measured. A limit of 10% is given in the guide.

Tier two - Biodegradation: The entire residues from the Tier one tests are subject to biodegradation testing according to one of a number of standard tests according to whether the material is intended for disposal by landfill (anaerobic digestion) or by composting (aerobic digestion). In either case the sample is mixed with a suitable soil sample & the amount & rate of evolution of carbon dioxide, & methane in the case of anaerobic digestion, is measured. The requirement for evolution of carbon dioxide varies from 60% to 90% depending on the polymer type or blend.

It is anticipated by both the Oxo-Biodegradable Plastics Institute (OPI) & the Oxo-Biodegradable Plastics Association that in the environment of a landfill site, the oxo-biodegradable plastics materials will biodegrade near the surface producing only carbon dioxide. Once fully buried, deep in the landfill, the oxo-biodegradation process will cease so that methane will not be produced as a result of anaerobic biodegradation. Both methane & carbon dioxide are greenhouse gasses but methane has approximately 20 times the greenhouse effect of carbon dioxide so is less preferable to be produced from the biodegradation process. it is also expected that some of the carbon from the plastic will be used to produce biomass, thus reducing the levels of carbon dioxide generated.

Tier three - Eco-toxicology: In order to show that the residues form the abiotic & bio-degradation processes are not harmful to the environment a measurement of the effect of the soil, or an appropriate extract of it, from the Tier two test regime on a variety of living organisms is performed. Specifically, the tests performed may include the measurement of germination rates of seeds such as cress, the growth & survival rate of earthworms (OECD Guideline 207)and the rate of growth of a variety of plants(OECD Guideline 208) & also an aquatic toxicology test with a Rotifer, Brachionus (a form of plankton) performed according to ASTM E1440.

Metal content - It is a requirement of European legislation (94/62/EC) that levels of heavy metals (lead (Pb), cadmium (Cd), mercury (Hg) & hexavalent chromium (Cr(vi)) in packaging are not greater than 100ppm. The levels of transition metal salts used as pro-oxidants are thus not affected by this legislation, however the standard for compostable materials (BS EN ISO 13432:2000) does limit the levels of nickel (Ni) to 25ppm.

Food contact – It has previously been reported that oxo-biodegradable plastic packaging is food contact compliant to 2002/72/EC as amended to date. These regulations require that both a review of component materials against the standard & where needed, migration testing be performed. It is important to perform this component review & determine the need for migration testing on the finished product

Recycling – Oxo-biodegradable packaging is recyclable as would be any similar plastic material without the pro-oxidant additive. Care must be taken to ensure that the cleanup of the recyclate will deal with any remaining pro-oxidant either by removal or by the addition of a neutralising agent, otherwise it may result in premature degradation of the products made with the recycled material. There are certain items such as PE pipes for water for human consumption, however, that cannot be produced from recycled material other than process regrind. (BS EN 12201-1)

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Why does Reverte™ produce superior products that are more environmentally friendly?

Reverte™ produces a plastic product with equivalent performance characteristics than the present non-degradables, is cost competitive and results in a product that will totally and harmlessly disintegrate in multiple environments, commencing at a predetermined time.

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Why use Reverte? (The 4R Solution: Reduce, Reuse, Recycle, Reverte™)?

Reverte™ provides the safest, most cost-effective, environmentally safe way to degrade plastic. By far the largest proportion of single use plastics, such as those used in disposable packaging, end their lives in landfills or as litter. At present, conventional non-degradable plastics can persist unchanged for many years.

The unique programmability of Reverte™ technology safely biodegrades plastic waste from within a few months to a maximum of 5 years. In landfills they reduce volume, help maximize capacity utilization and aid in landfill compression.

While not a total solution to littering, degradable plastics help avoid the accumulation of unsightly litter in our environment.

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What are the options for dealing with plastic waste?

There are currently 3 options for dealing with plastic waste:

  • Do Nothing - Continue using plastics as we do now, filling our landfills and waterways with tons upon tons of plastic waste which persist for hundreds of years.
  • Utilize food-based plastics - which are created from crops such as corn and are compostable. While this may seem to be the ideal solution, the price of food has nearly doubled in the last year alone in part as crops are reapportioned to the manufacture of biofuels and bioplastics.
  • Utilize oxo-biodegradable technology - when added to a plastic product at manufacture, allows it to completely and harmlessly break down in a pre-defined programmable manner.

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What is the difference between Degradable, Biodegradable and Oxo-biodegradable plastic?

Degradable and biodegradable plastics are defined by American Society for Testing and Materials (ASTM):

Degradable Plastic: A plastic designed to undergo a significant change in its chemical structure under specific environmental conditions. This change results in a classification determined by the loss of some properties that may vary as measured by standard test methods appropriate to the plastic and the application in a period of time.

Biodegradable Plastic: A degradable plastic in which the degradation results from the action of naturally occurring microorganisms such as bacteria, fungi, and algae.

Oxo-biodegradable Plastic: A two-stage process in which plastic is first converted by reaction with oxygen to molecular fragments that are water wettable. Second, these smaller oxidized molecules are biodegraded and converted into carbon dioxide, water and biomass, by microorganisms. There are 2 main types of biodegradable plastics: oxo-biodegradable and hydro-biodegradable. Both will first undergo chemical degradation by oxidation and hydrolysis for oxo- and hydro-biodegradable plastics respectively. This results in their physical disintegration and a drastic reduction in their molecular weights. These smaller, lower molecular weight fragments are then amenable to biodegradation by microbes.

Hydro-biodegradable plastics tend to degrade and biodegrade somewhat faster than oxo-biodegradables but the end result is the same – both plastics are converted to carbon dioxide, water and biomass. Oxo-biodegradable plastics are generally less expensive, possess better physical properties and are easier to process on current plastic processing equipment than hydro-biodegradable plastics.

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How does the Reverte™ Oxo-biodegradable technology work?

Reverte™ is an additive technology introduced in the manufacturing process of a variety of plastic (polyethylene and polypropylene) packaging and applications. The programmable degradation is triggered by UV and thermo-oxidation, meaning once the additive is activated, the presence of oxygen causes the plastic to have a reduction of molecular weight and become very brittle.

These fragments decompose further into simple elements: carbon dioxide, water and biomass. Heat, sunlight and mechanical stress (i.e. movement) accelerate this degradation process.

As the long carbon and hydrogen chains of plastic become shorter and shorter and are now able to incorporate oxygen into their chemical make-up, it is at this point that the plastic turns into organic functional groups (ketones, carboxylic acids, alcohols etc) that attract water. These transformations (to smaller chains in the presence of oxygen and water) create the conditions for the second stage of biodegradation: microbial digestion.

Once the molecular mass of the plastics are reduced to below 40,000 molecular weight - due to oxidative degradation - the material becomes water wettable and can sustain a biofilm on its surface. This biofilm supports numerous microorganisms that feed off the carbon and hydrogen elements of the oxidizing plastic.

If microorganisms are present (as they are in compost or landfill) these small fragments are included in their tropic chain as food. Biomass is the organic waste of microbe cells. This process is similar to the degradation of lignin in wood.

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What are the advantages of Reverte™ over other methods of degrading plastic?

Advantages when compared to alternative methods or products include the following:

  • Programmable and controlled degradation
  • Avoids the emission of methane
  • Can be made from recyclate
  • Degrades in any environment
  • Requires no fertilizers, pesticides or water
  • Won't hurt forestland and reduce biodiversity
  • Very low cost
  • Degraded plastic can be economically recycled
  • Great tensile strength and leak proof
  • Can be incinerated with high energy recovery
  • Does not use foodstock and has no impact on foodstock prices or availability
  • No specialized storage or handling required

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How controllable is the process of biodegradation (shelf life and service life)?

The speed of degradation can largely be controlled by the additive package used for any particular application. This process is affected by the levels of uncontrollable variables - particularly heat, UV light and stress - to which the plastic is exposed. Higher than planned levels of these will speed up the process and lower levels will slow it down (but not stop it). For this reason, manufacturers typically build a significant safety margin into the planned degradation time assuring that the properties of the plastic remain intact for the full useful life of the product.

Reverte™ has a unique control package with two trigger mechanisms for guaranteed performance. First, a photoinitiator which means that the oxo-breakdown reaction does not significantly begin before the product is discarded and exposed to UV light and/or heat. There is also a built-in time release, which can be programmed to be activated as required by supply chain (‘fit-for-purpose’) requirements. This ensures that customers receive optimum formulations that perform as specified.

Second, Reverte™ has secondary phase biodegradation promoters that assist the growth of microbial colonies. This speeds up and facilitates the ultimate biodegradation of the plastic following the initial oxo-breakdown.

Do the Reverte™ additives or finished products need to be stored or handled in any special way?

A degree of 'common sense' is necessary to ensure that the products are not exposed to excessive heat, UV light or stress. For example, degradable plastics should be stored in a cool/shaded place rather than in the open air or in a hot, sunny space. Beyond this sort of 'common sense', no special requirements apply.

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How does Reverte™ affect product performance of the finished product?

Prior to the onset of degradation and disposal, products incorporating Reverte™ will have virtually identical performance to those manufactured without the additive. Products with Reverte™ are engineered to have a predetermined shelf life and have a designated “use before” date.

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Is Reverte™ safe to be used for food contact applications?

Yes! Reverte™ additives comply with FDA, EU and CFIA standard requirements for food contact and are safe for use in direct food contact applications.

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Can Reverte™ based plastics be recycled?

Yes. In-plant materials (trimmings, scrap, etc.) are normally recycled by manufacturers. The usual amount of recycled materials used is about 20% for degradable and 5% for non-degradable end products. This will ensure that quality of the end products are not compromised. Additionally, post-consumer plastics can also be recycled in existing recycle streams provided they have not already started to degrade.

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Will Reverte™ products create greenhouse gases such as CO2 and methane in a landfill?

Reverte™ does not contribute to methane build up. Methane is a gas that occurs in anaerobic conditions when carbon can only combine with hydrogen. Therefore, if there is no oxygen the Reverte™ product will not degrade.

This is a big advantage over food-based biodegradable materials that, in the absence of oxygen, begin anaerobic decomposition, the product of which is methane – a greenhouse gas 20 times more damaging than CO2. The Reverte™ degradation process is an oxidizing system - if no oxygen is present the carbon and hydrogen remains locked in the remnants of the plastic and methane will not be emitted.

CO2 is unavoidably created in all natural breakdown processes. The alternative is to keep the carbon locked up as plastic but that means the bag lasts hundreds of years - potentially longer.

Reverte™ does not generate methane during degradation. CO2 is produced in small quantities.

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What are the end products of Reverte™ and are there any harmful effects on the environment from the use of this additive?

The end products of biodegradation of plastic are carbon dioxide (CO2), water (H2O) and biomass. Extensive studies and tests already completed ensure that no harmful toxic or hazardous remains are left from the Reverte™ oxo-biodegradable process.

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Why does the Reverte™ process cost so little?

Only a small amount of Reverte™ is added during the process of manufacturing plastic and no additional equipment or skilled labor is required.

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What products are currently manufactured using Reverte™ ?

  • Branded carrier bags - Produced for the North American and European marketplace
  • Checkout bags - Used in supermarkets globally
  • Polyethylene rubbish bags - Formulated to biodegrade after their useful life has been completed
  • Fruit netting - Formulated to provide a long dwell time before the onset of degradation
  • Household garbage bags, which consumers buy in rolls at the market, and use for disposal of their ordinary household waste.
  • Aprons for use in the home, hospitals, restaurants, workshops, etc.
  • Bags to contain dog poop
  • Bin liners
  • Gloves
  • Plastic sheeting for a variety of applications in agriculture and horticulture.
  • Plastic film for wrapping newspapers and magazines.
  • Bread bags
  • Frozen food bags
  • Wrappers for cigarette packets
  • Shrink-wrap and pallet-wrap
  • "Bubble-wrap"
  • Rigid products such as bottles and cups
  • As virtually any product with an expected lifespan of from 2 months to 5 years can be made degradable with Reverte™.

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