Friday, May 25, 2012
Tuesday, September 13, 2011
Friday, April 22, 2011
How Green is your Green Packaging
Types of green packaging
by: Rod Alire, Chief Scientist
by: Rod Alire, Chief Scientist
Manufacturers Focus on Green Packaging
Green is in, not only in terms of energy, financial products and food articles, but also in packaging, and packaging materials are increasingly being labelled as green. The research agency Global Industry Analysts estimates the worldwide market for sustainable packaging will be more than 149 billion dollars in 2015. Various businesses are anticipating this market change and are focusing on green packaging. Sometimes prompted by the conviction that better solutions are really necessary, sometimes purely as a marketing instrument. The question therefore arises of actually how green is green packaging? A good example is set by packaging specialist FP International, a company which has been inextricably connected with environmentally-friendly packaging since its founding in 1967, and which adheres to a notable sustainability model in this regard.
The rise of green products can be logically explained if we remember that sustainable development has been a topic of discussion since the end of the 1980s. An oil crisis was enough to make consumers and industry realize that every natural resource is finite. The interest in sustainable development and treating the environment and natural resources responsibly has grown, not least because of the increasingly emphatic role claimed by national and international governments.
Europe Leads Way in Waste Legislation
Due to social, economic, space limitations, and legislation the European standards for waste and recycling are far reaching, and a model for the United States and other countries to achieve. The European Waste Directive 2008/98/EC addresses in detail the effects of waste generation and management on human health and the environment. In this context, the waste management policy is aimed at reducing the use of natural resources, and favors compliance with the so-called waste hierarchy.
This waste hierarchy shows what consecutive measures can be taken to minimize the negative effects of generating waste as much as possible. The hierarchy has the shape of an inverted pyramid (Illustration 1), whereby prevention of waste is of course at the top of the pyramid. The following measures are proposed, in the order given: reduction, reuse, recycling, processing (incineration), treatment and finally, dumping in landfill. This last step is notable since, in many European countries, waste no longer ends up in landfills but is incinerated.
Many manufacturers currently claim they are "green" by focusing on degradable packaging. With this, attention is focused on the final element of the waste hierarchy, while the legislative authorities have in mind a "total approach" to the generation and management of waste.
Illustration 1: Waste hierarchy
This hierarchy facilitates waste collection, reuse and processing, which includes recycling, as much as possible.
Becoming Green
Against this background of rules and the way in which waste can best be combated, it is striking that many businesses use the term "green" or "sustainable" for their efforts. The label "green" is used for various environmentally-friendly solutions. In general terms, there are four types of green packaging solutions.
1. Packaging Based on Renewable Resources, for Example PLA
The first possibility is packaging based on starch-derived PLA (lactic acid). Consequently, the packaging is biodegradable. This biodegradable plastic packaging satisfies the EN 13432 standard, which states that 90% of the packaging must be degraded in 9 months. To meet this standard, an industrial composting facility is required in most cases, which are not generally available in most areas in the United States. PLA is derived from starch (for example, corn, potatoes, sugarcane), which is renewable, but at the same time also draws on resources of items that can be used such as foods, soil, water, energy, minerals and nutrients.
2. Packaging with Additives
There is also packaging to which additives are added in order to make the packaging degradable. On the current packaging market, we come across two types of additives:
A) OXO Additive
The OXO additives are formed by heavy metals that react under the influence of UV rays and - somewhat like rust - break down the plastic. OXO plastic is polyolefin plastic to which has been added amounts of metal salts. These catalyze the natural degradation process to speed it up so that the OXO plastic will degrade resulting in microfragments of plastic and metals which will remain in the environment but will not be seen as a visual contaminant. OXO plastic degrades in the presence of UV and heat but cannot be recycled with normal plastic. OXO plastics will not degrade in a landfill environment due to insufficient oxygen present below a depth of approximately 6 inches (15 cm). The duration and residues of this degradation process vary depending upon environmental conditions. Some regions have banned OXO based products.
B) BIO Additive
Packaging may also contain BIO additives. As soon as this packaging unexpectedly ends up in the environment and comes into contact with microorganisms, the additive stimulates the growth of microorganisms on the packaging accelerating the degradation. The microorganisms adapt to use the plastic as food and then ensure that the packaging is broken down into water, inert compost and CO2. FP International's products will degrade in the presence of microorganisms in one to five years or more depending on conditions. Since end of life conditons vary, it is impractical to state specific times for degradation. The more microbial activity, the faster the products degrade. This additive does not affect the performance or the shelf life of the product, because biodegradation only occurs in the presence of microorganisms which are present in landfills, home and commercial composting, and other areas where they exist in nature. These eco-friendly packaging products will biodegrade in aerobic (with air) and anaerobic (without air) conditions.
3. Use of Recycled Material
Another - much more obvious - method for making the packaging more sustainable is the use of recycled resources. This approach is higher in the waste hierarchy (see the pyramid in Illustration 1). Recycled resources can come from waste from the production process (pre-consumer recycling) or from plastic already used by the consumer and then disposed of (post-consumer recycling). The plastic waste once again becomes a resource, which means fewer new sources are needed and less CO2 emission takes place. This packaging is once again recyclable.
4. Optimization of Packaging
Finally, the environment can benefit by optimization or prevention of packaging. The reduction of packaging is an area where many companies are focusing their efforts. However, the elimination of packaging is rare, because the actual function of packaging is to protect products during storage and/or transport.
Sustainability Model
As stated, the waste hierarchy makes it clear that sustainable packaging can be achieved not only by making packaging degradable, but that different activities are possible that jointly determine how sustainable and green packaging actually is. Packaging manufacturer FP International uses a notable model in this, which seems to bring together all aspects. In the sustainability model (Illustration 2), sustainability cannot be seen in isolation from social, environmental and economic aspects of a packaging product. In summary, sustainable packaging is a product that is friendly to the environment, socially acceptable and economically appealing for both manufacturer and user.
Illustration 2: Sustainability model
The company's sustainability philosophy is focused on providing products that deserve a position high on the inverted waste pyramid. All of FP International's biodegradable products (both the loosefill and air cushion film) have been especially developed according to EU regulations which are set at a higher standard than that of the United States.
As such, sustainability is deeply rooted in the company. The company has its origin in Redwood City, California, where the production waste of paper drinking straws was reused and recycled as packaging material. After being the first company to make packaging from 100% recycled material, the company has recycled more than 145 million pounds of EPS since 1990. It is clear that there is a vision on the generation and management of waste in which the analysis of products' lifecycle always plays a major role. In this, attention is not only focused on the various waste stages (recycling, reuse, etc), but also on the energy that is needed to make a product, and to recover or renew resources. With modern recycling facilities, the company saves energy, minimizes waste and uses sustainable products (such as water-based ink). Moreover, the company provides products that consist 98% of air.
Our SUPER 8® green loosefill (packing peanuts) is made from 100% recycled materials, is reusable and recyclable, and contains the addition of a BIO additive. The BIO additive is used as a backup solution in the event the product is disposed. The BIO additive ensures no harmful substances are left behind and does not use natural sources such as starch. Air cushion films from FP International that contain this additive are also reusable and 100% recyclable, thus making them more sustainable. Initially, air cushions based on renewable materials such as PLA were considered. Even though the product would be degradable, under limited conditions, the company decided that this type of packaging is not consistent with its sustainability philosophy for environmental, socio economic and practical reasons. The reasons are simple: in order to obtain the PLA derived from starch, food must be sacrificed, similar to the case with biofuels. A careful lifecycle analysis should be performed on PLA products taking into consideration the cost and energy required to grow, fertilize, maintain, harvest and process these materials. There is also the concern that PLA products, which are compostable, will be inserted into our recycle stream contaminating that channel for reusing valuable resources. PLA products lack the performance characteristics that FP Internationals customers require.
The packaging market calls for products that are recycled and recyclable, but which also provide a solution if the product ends up somewhere as litter in the environment. When determining the type of packaging to use, it is always important to investigate a lifecycle analysis. Ask yourself, how is the product made, where is it made, what types of materials does it incorporate, is it reusable, it is easily recyclable, and how is it disposed? Look beyond the convenience, price and the labelling to determine how green your product really is.
http://www.fpintl.com/
About the Author
Rod Alire is Chief Scientist for FP International. Mr. Alire carries more than 20 years experience in polymer processing with particular expertise in polymeric foam and film extrusion processes. His projects have emphasized environmental impact mitigation and sustainability through new product design and manufacturing technologies.
Wednesday, March 10, 2010
FP INTERNATIONAL INTRODUCES BIODEGRADABLE PILLOW PAK®
AIR CUSHIONS FOR INTERIOR PACKAGING
Eco-Friendly Superior Protective Packaging
Redwood City, CA -- (MARKET WIRE) - March 8, 2010 -- FP International, a leading manufacturer of sustainable packing solutions, introduces Biodegradable PILLOW PAK® Quilt Medium air cushions, the latest edition to the Green Family™ line of environmentally friendly packaging products. Biodegradable PILLOW PAK® Quilt Medium air cushion material is made from 100 percent recyclable material. Should Biodegradable PILLOW PAK air cushion material end up in a landfill or in soil it will biodegrade in the presence of microorganisms within nine to 60 months. Microorganisms commonly found in soil help Biodegradable PILLOW PAK film break down.
Unlike traditional bubble, which is made in a factory and shipped, Biodegradable PILLOW PAK air cushion material is made on-site. One pallet of Biodegradable PILLOW PAK film is the equivalent of one 53’ truckload of traditional bubble material. No more bulky bundles of bubble to transport, handle and take up valuable storage space. Plus, by producing on-site, Biodegradable PILLOW PAK reduces the greenhouse gas emissions from shipping bundles of bubble. Simply make the air cushion material as you need it! Lower shipping costs, save money and use Biodegradable PILLOW PAK air cushion material as a cost-effective, eco-friendly packaging option.
Each roll of Biodegradable PILLOW PAK Quilt Medium film makes two-1,000 square feet bundles of 48” air cushion material, which is perforated every six inches, for maximum packing flexibility. The PILLOW PAK’R machine makes cushions fast; a 1,000 sq. ft. bundle in under 8½ minutes! The Biodegradable PILLOW PAK air cushion material uses FP International’s patented air transfer technology. This technology allows air to move (transfer) between connected cells. Unlike traditional bubble material, Biodegradable PILLOW PAK film doesn’t “pop” and lose its cushioning properties.
Thursday, September 17, 2009
The MINI PAK’R® Bubble Wrapping Machine is Now Mountable to a Wheeled Cart for added portability.
Innovative Cart with Storage Bin Allows an Entire Packing Station
to be Quickly Moved for Extra Convenience.
to be Quickly Moved for Extra Convenience.
The MINI PAK’R® Inflatable Packaging Machine is now available with a cart for added mobility and convenience for retailers that need to protect items they pack-and-ship. The MINI PAK’R can now simply be attached to a wheeled cart with a large storage bin. The MINI PAK’R creates bubble wrapping void fill which is stored in the bin for removal. A sensor automatically starts and stops the MINI PAK’R to create inflatable packaging on demand. See a product demo now of our Portability Cart.
The lightweight cart system enables employees to easily move the MINI PAK’R bubble wrapping machine to workstations throughout a warehouse. The versatile MINI PAK’R can be placed on a table or mounted to a wall or cart. It’s easy to operate since the 13 pound machine “reads” an RFID tag in the film roll and automatically sets the air fill amount and seal temperature. See our Facebook page for exclusive photos and become a Fan!
One of the first companies to test the MINI PAK’R machine was Makes Scents of Columbus, Texas www.makes-scents.com. Makes Scents Owner, Joanne Klauber started her fragrance lamps, candles and reed diffuser oil business from her dining room, today she operates a store. Klauber was immediately impressed with the MINI PAK’R machine. Klauber said, “there was no need to monitor the machine. The MINI PAK’R air cushions immediately gave my company a professional image. Professional packaging tells your customers you have a business. I no longer looked like someone doing business from my dining room”. For more information about the MINI PAK’R and its innovative new portable cart system please contact us at www.minipakr.com.
Tuesday, September 8, 2009
The Reality Behind Biodegradable Plastic Packaging Material
The Science of Biodegradable Plastics
Rod R. Alire, Chief Scientist
FP International
Interest in biodegradable disposable plastic items has steadily grown over the last decade. Disposable packaging materials used to ship and protect purchased items as well as disposable containers used for food and drink are of special interest. The idea that one time use items can be disposed of with the peace of mind, that they will not remain for centuries in a landfill, or as litter, is one of the tenets driving the recent interest in “green” technologies and lifestyles. With packaging materials, the reduction in usage of raw materials, re-use and recycling is of course the best route to sustainable lifestyle. However, for various reasons, in practice, much of the material ends up being discarded to a landfill or accidentally shows up as litter. For these instances, it is advantageous to have a plastic material that would biodegrade when exposed to environments where other biodegradable materials are undergoing decay.
What is Biodegradable?
Biodegradation is degradation caused by biological activity, particularly by enzyme action leading to significant changes in the material’s chemical structure. In essence, biodegradable plastics should breakdown cleanly, in a defined time period, to simple molecules found in the environment such as carbon dioxide and water. The American Society of Testing and Materials (ASTM) defines ‘biodegradability’ as:
“capable of undergoing decomposition into carbon dioxide, methane, water, inorganic compounds, or biomass in which the predominant mechanism is the enzymatic action of microorganisms, that can be measured by standardized tests in a specified period of time, reflecting available disposal conditions.”
During this process of biodegradation, the large molecules of the substance are transformed into smaller compounds by enzymes and acids that are naturally produced by microorganisms. Once the molecules are reduced to a suitable size, the substances can be absorbed through the organism cell walls where they are metabolized for energy. Most naturally occurring materials such as yard waste, food scraps, etc., contain these large molecules and biodegrade in this way.
Aerobic and Anaerobic Biodegradation
Aerobic biodegradation is the breakdown of an organic substance by microorganisms in the presence of oxygen. Almost all organic materials can be metabolized in an oxidative environment by aerobic organisms. The organism has secreted enzymes that breakdown substances into smaller organic molecules which are then absorbed into the cells of the microbes and used for cellular respiration. During the respiration process, the organic molecules absorbed into the cells are broken down in steps, where a molecule known as adenosine-5’- triphosphate (ATP) is used to store and transport energy for cells, for life processes such motility and cell division. In biochemistry this chemical reaction sequence is known as Electron Chain Transfer. In the case of aerobic metabolism, oxygen is used at the end of the chain as the final electron acceptor, producing the main byproducts of carbon dioxide and water.
Composting is a well known and common use of aerobic biodegradation, during which the volume of organic material is typically reduced by about 50%, where the remaining, slow-decaying humus material left over can be used as a rich planting medium. The ASTM defines a compostable plastic material as being:
“capable of biological decomposition in a compost site as part of an available program, such that the plastic is not visually distinguishable and break down to carbon dioxide, water inorganic compounds and biomass at a rate consistent with known compostable materials (e.g. cellulose).”
The biomass material referred to here is humus. The bioactivity in active compost will generate heat that further enhances the rate of microbial growth and metabolism. However, for the purpose of the ASTM definition, the available program is an industrial compost facility where heat and moisture are artificially added to the mass to maximize the degradation rate. As we will see, this artificial environment becomes critical for degradation of some biodegradable plastic materials.
Anaerobic biodegradation occurs in the absence of oxygen where anaerobic microbes are dominant. In the absence of oxygen the organism must use some other atom as the final electron acceptor. Hydrogen, methane, nitrogen and sulfur are common along with oxidizing minerals. Thus, the effluent from anaerobic digestion is biogas, consisting of mostly methane and carbon dioxide, with trace gasses such as ammonia and hydrogen sulfide. Often, the complete digestion will require several different types of bacteria where one type partially processes the waste to a point where another bacterium strain takes over (4). Most biodegradation of solid waste in landfill occurs under anaerobic conditions by design because it is typically much slower than aerobic degradation.
Most biodegradable substances come from plant and animal matter, or from artificial materials that are very similar in molecular structure to these naturally occurring substances. As the naturally occurring substances evolved, microorganisms also evolved to use the substances as a food source: the carbon in particular, used as a building block for life-sustaining compounds. Simple sugars are readily absorbed into the cell to be metabolized. However, larger and more complex molecules such as starches, proteins and cellulose, require enzymes and acids to reduce their size enough to be absorbed. Living organisms have developed the ability to secrete specific digestive compounds so as to best utilize the available food supply. For example, the enzyme amylase, found in human saliva, is used to breakdown long-chain starch molecules into and smaller simple sugars.
For microorganisms, this adaptive process can be applied to other, more complex carbon containing compounds in crude oil. This type of microbial biodegradation has been demonstrated for hydrocarbons derived from petroleum (10)
Biodegradable Plastic Materials
Currently available degradable plastic materials can be broken down into two main groups:
1. Polyester Polymers
2. Synergistic and Hybrid Polymers
The Polyesters
When one thinks of polyesters in general, the polymers that come to mind are very durable with good physical and mechanical properties. A good example is polyethylene terephthalate (PET). This polymer is strong, abrasion and stain resistant, so it can be a good choice for carpeting and clothing. It also has good gas barrier properties which make it ideal for soda bottles. These polymers, which are also resistant to biodegradation, typically contain a large number of six-carbon rings in their molecular structure. In chemistry, compounds containing these rings are known as aromatic compounds.
Biodegradable polyesters which do not contain six-carbon rings are known as aliphatic polyesters. They will typically react with moisture at elevated temperatures to breakdown the long polymer chains. This process, called chemical hydrolysis, reduces the higher molecular weight polymer to much smaller hydrocarbon compounds. The resulting molecules can then be absorbed by microorganisms and metabolized for energy. Since it is a chemical reaction, the hydrolysis occurs at a much higher rate than one would expect for a purely biological process, and as a result, relatively quick degradation is observed.
Aliphatic polyesters have attracted interest as biodegradable plastic materials; however they typically have poor physical and mechanical properties (3) like strength, flexibility, heat resistance, etc. Some common biodegradable polyester polymers in commercial use include poly(caprolactone) (PCL), poly(glycolic acid) (PGA) and poly(butylene succinate) (PBS). These are synthetic polymers, made from petroleum-based, raw materials, and like most biodegradable polyesters have inferior mechanical properties e.g. low heat deflection temperature and low elongation failure (brittle). They will also begin to hydrolyze at modest temperatures in the presence of moisture, rapidly losing molecular weight and further decreasing mechanical properties. Although expensive to make, these biodegradable polymers are ideal for use in specialized, high margin applications such as medical devices (e.g. dissolving, drug delivery systems, tissue engineering scaffolds and bone repair etc.).(2)
Another well known aliphatic polyester is poly(lactic acid). PLA is a synthetic polymer made from fermented sugars extracted primarily from food crops such as corn, beets or sugarcane. The resulting lactic acid monomer is chemically processed and then polymerized, in the presence of a metal catalyst, to form the high molecular weight plastic material. Like the petroleum-based biodegradable polyesters, PLA has many of the same undesirable mechanical properties, such as low heat deflection temperature. Figure 1 shows the affects of 170oF water on cup made from PLA. The polymer is also very brittle and has a low-melt strength leading to difficulty in processing. Consequently, most commercial applications using PLA require a synthetic rubber and/or acrylic additive to compensate for these deficiencies.
Degradation of PLA occurs quickly through a multistep process (4) of chemical depolymerization, followed by dissolution of the intermediate lactic acid in the presence of moisture, and the absorption into the cells of microorganisms with subsequent metabolization. Initiation of this chain of events typically occurs at elevated temperatures (above heat deflection temperatures), such as conditions existing in an industrial compost operation. The relatively fast chemical reaction at the beginning of the chain of events explains the surprisingly quick degradation of polymer in an industrial compost environment. This mechanism of chemical attack followed by cell metabolism does not meet the true definition of a biodegradable material inasmuch as biological activity is not required for the initial breakup of the material. In low temperature aerobic or anaerobic environments where initial hydrolysis occurs slowly, biodegradation of PLA also proceeds very slowly if at all.
Another family of biodegradable polyesters, which could in a way be viewed as more complex extensions of the molecular structure of PLA, is known as polyhydroxy alkanoates (PHA’s). Intriguingly, PHA’s are natural polymers also derived from plant sugars but are synthesized within the bacteria themselves. The PHA’s are manufactured and used as carbon storage in the cells(6), similar to the way the human body stores fat to be used as an emergency food source.
One of the more notable polymers in this class is polyhydroxy butyrate (PHB), and like the synthetic aliphatic polyesters, it has the same poor physical and mechanical properties, and an additional disadvantage of being quite expensive. A cousin to PHB, which is actually a copolymer, was developed to help improve these deficient properties. This co-polyester is known as polyhydroxy butyrate-valarate (PHBV) and has much better, and more useful, thermoplastic properties that are similar to polypropylene(5). Since these materials are produced by microorganisms as an emergency food source, they are, by design, easily biodegradable by direct enzymatic action of microorganisms, and don’t necessarily require the chemical hydrolysis reaction step first. It has been shown that bacterially produced PHB/PHV (92/8 w/w) deteriorated nearly to completion within 20 days of cultivation by anaerobic digested sludge, while synthetic aliphatic polymers such as PLA, PBS, and poly(butylene succinate adipiate) (PBSA) did not degrade at all in 100 days (1).
For degradable polyesters, the best improvement in physical properties is obtained by synthetically creating a polyester copolymer using both aliphatic and aromatic groups. These are typically derived from oil-based raw materials such as 1,4-butanediol, adipic acid, and terephthalic acid (7). Using this technique, the polymer can be tailored to balance the excellent physical and mechanical characteristics of the aromatic polyester groups with the degradation and subsequent mineralization of the aliphatic groups. These polymers are also readily mixable with pure aliphatic polyesters like PLA, or natural polymer like cellulose, to form a hybrid, degradable polymer with improved performance.
Synergistic or Hybrid Polymers
Synergistic polymers are typically intimate mixtures of oil-based and naturally occurring polymers where the two have some chemical affinity for each other. When mixed, there is intimate contact between the two polymer chains so as to create a homogenous single phase. In other words, once mixed they could not be mechanically separated. This is somewhat akin to mixing gelatin powder with hot water to form a single uniform substance, once cooled.
A good example of a commercial, synergistic, biodegradable material is Thermoplastic Starch (TPS). The key to this blend of the two natural starch polymers, amylose and amylopectin, and the synthetic polymer, polyvinyl alcohol (PVOH), is their natural affinity to each other, due to the large number of hydroxyl (OH) groups present in the compounds. This hybrid can be made into foamed articles, plastic films or molded parts such as cutlery. Generational adaptations that occur during the digestion of the familiar starch groups quickly begin to breakdown the synthetic PVOH chains.
The intimate mixing of the natural and synthetic polymers can be taken one step further: where the attraction of the synthetic and natural polymers is enhanced by grafting other chemically compatible groups along the chains of the natural and/or synthetic polymers. As with the PVOH, this technique enhances biodegradation through generational adaptation which can be initiated with relatively small additions of natural polymers. To illustrate how this could be possible, it has been shown that polyethylene will biodegrade via a monooxygense enzyme pathway (9). Initiation of the process begins with the formation of a biofilm on the surface of the polymer, which is facilitated by the inclusion of the compatible natural polymers. These films of microorganisms have been shown to efficiently biodegrade petroleum based polymers (8).
Low-level synergistic enhancement does not materially impact the physical and mechanical properties of the original synthetic polymer. Therefore, the product applications are not restricted beyond what would normally be expected for the un-amended polymer. Since the additive itself will not degrade the polymer or affect processing, the ability for recycling or reuse of the plastic article will be unaffected. Unintended degradation will not occur since the initial colonization requires an environment where existing biodegradation is occurring or would normally be expected to occur, either aerobic or anaerobic. Additional heat is not required, and no chemical, polymer-chain weight reduction process is needed beyond the enzymatic action of the microorganisms.
Figures 2 – 6 illustrate a short period, pictorial history of the biodegradation of polystyrene loosefill particles containing this kind of synergistic additive. Figures 7 – 10 show a similar history for polyethylene film containing the additive taken from a back yard compost environment.
Polyethylene Film Biodegradation
Synergistic Additive
Compost History
Conclusion
For the choice of materials to be used in the manufacture of a more environmentally friendly packaging material, the criteria needs to take into account business considerations and strategies, while addressing environmental concerns related to the life cycle of the packaging. The primary purpose of the packaging material is to protect the items being shipped from damage via impact or abrasion, and therefore protection should be the first consideration. The material will also need to perform in largely uncontrolled, ambient conditions of heat and humidity; thus, the next consideration should be given to the products’ possible end-of-life scenarios. The scenarios include disposal in landfills, litter, recycle, etc. Finally, material costs need to meet market criteria.
Conventional polymer technologies have been able to tailor materials that can meet the market need of both cost and performance. There is infrastructure in place for recycling and/or re-use of many of these materials, which is the most desirable destination in the life cycle of the packaging product. With inclusion of a synergistic additive, such as that used by FP International, the materials would also be well-suited for the less desirable destinations, such as landfills.
The other biodegradable polymer options have no recycle infrastructure, and could possibly be viewed as having been designed to be thrown out. However, the fact that many of these polymers, like PLA, are limited to biodegradation in only commercial compost facilities, further decreases the potential for a desirable end-of-life scenario. Moreover, while the bacterially produced polyesters (PHB/PHV) would biodegrade in a more general disposal scenario, they are particularly cost-prohibitive for most packaging applications.
In addition to sustainable choices in materials for FP International’s products, FP has ongoing programs for reduction of raw material and energy usage, recycling, increased production efficiencies, efficient product design and increased recycled, raw material usage.
About the Author
Rod Alire is Chief Scientist for FP International. Mr. Alire carries more than 20 years experience in polymer processing with particular expertise in polymeric foam and film extrusion processes. His projects have emphasized environmental impact mitigation and sustainability through new product design and manufacturing technologies. By Mr. Alire’s development of a theoretical model for mass transport phenomena and foam expansion behavior in polystyrene packaging material production, FP International was able to reduce the usage of raw materials and density of the products being produced.
In order to replace the use of CFC’s – chlorofluorocarbon, (known to be harmful to the ozone and environment), Mr. Alire designed and built a high pressure, foaming agent metering and delivery system for polymer foam extrusion. Also, he developed polyolefin polymer blends and a blown film process for production of PMOS (products manufactured on-site) air bag materials. These airbags are 99% air, since they can be manually deflated or popped, they also reduce the size of materials produced for recycling. Also, the size of the film air cushion materials takes less space to ship, thus less cost and lowers the use of trucks (lowering gas use and truck emissions). Currently, Mr. Alire is working to increase the strength and mechanical property of the film itself, in order to produce film which uses less material.
References
1. Shin et al. in Nolan – ITU; ‘Environment Australia, Biodegradable Plastics – Developments and Environmental Impacts’ (2002)
2. Yoshito Ikada, Hideto Tsuji, ‘Biodegradable polyesters for medical and ecological applications’, macromol. Rapid Commun. Vol. 21, (1999).
3. Yiwang Chen, Licheng Tan, Lie Chen, Yan Yang and Xiaofeng Wang, ‘Study on biodegradable aromatic/aliphatic copolyesters’, Brazilian Journal of Chemical Engineering, Vol. 25, No. 2 (2008).
4. Dunja Manal Abou Zeid, ‘Anaerobic Biodegradation of Natural and Synthetic Polyesters’, Dissertation, Von der Gemeinsamen Naturwissenschaftlichen Fakultat der Technisschen Universitat Carolo-Wilhemina zu Braunschweig (2001).
5. Yon Jia, Wei Yuan, Jola Wodzinska, Chung Park, Anthony J. Sinskey, JoAnne Stubbe, ’Mechanistic Studies on Class I Polyhydroxybutyrate (PHB) Synthase from Ralstonia eutropha: Class I and III Synthases Share a Similar Catalytic Mechanism’, Biochemistry, (2001), 40.
6. Sung-Eun Lee, Qing X.Li, Jian Yu, ‘Diverse protein regulations on PHA formation in Ralstonia eutropha on short chain organic acids’, International Journal of Biological Sciences, (2009), 5.
7. Ilona Kleeberg, Claudia Hetz, Feiner Michael Kroppenstedt, Rolf-Joachim Muller, Wolf-Dieter Deckwer, ‘Biodegradation of Aliphatic-Aromatic Co-polyesters by Thermomonaspora fusca and Other Thermophilic Compost Isolates’, Applied and Environmental Microbiology, Vol. 64, No. 5, (1998).
8. Gamini Seneviratne, N.S. Tennakoon, et al. ‘Polyethylene biodegradation by a developed Penicillium-Bacillus biofilm’, Current Science, Vol. 90, No 1, (2006).
9. van Beilen in Seneviratne
10. Okerentugbea in Seneviratne
Rod R. Alire, Chief Scientist
FP International
Interest in biodegradable disposable plastic items has steadily grown over the last decade. Disposable packaging materials used to ship and protect purchased items as well as disposable containers used for food and drink are of special interest. The idea that one time use items can be disposed of with the peace of mind, that they will not remain for centuries in a landfill, or as litter, is one of the tenets driving the recent interest in “green” technologies and lifestyles. With packaging materials, the reduction in usage of raw materials, re-use and recycling is of course the best route to sustainable lifestyle. However, for various reasons, in practice, much of the material ends up being discarded to a landfill or accidentally shows up as litter. For these instances, it is advantageous to have a plastic material that would biodegrade when exposed to environments where other biodegradable materials are undergoing decay.
What is Biodegradable?
Biodegradation is degradation caused by biological activity, particularly by enzyme action leading to significant changes in the material’s chemical structure. In essence, biodegradable plastics should breakdown cleanly, in a defined time period, to simple molecules found in the environment such as carbon dioxide and water. The American Society of Testing and Materials (ASTM) defines ‘biodegradability’ as:
“capable of undergoing decomposition into carbon dioxide, methane, water, inorganic compounds, or biomass in which the predominant mechanism is the enzymatic action of microorganisms, that can be measured by standardized tests in a specified period of time, reflecting available disposal conditions.”
During this process of biodegradation, the large molecules of the substance are transformed into smaller compounds by enzymes and acids that are naturally produced by microorganisms. Once the molecules are reduced to a suitable size, the substances can be absorbed through the organism cell walls where they are metabolized for energy. Most naturally occurring materials such as yard waste, food scraps, etc., contain these large molecules and biodegrade in this way.
Aerobic and Anaerobic Biodegradation
Aerobic biodegradation is the breakdown of an organic substance by microorganisms in the presence of oxygen. Almost all organic materials can be metabolized in an oxidative environment by aerobic organisms. The organism has secreted enzymes that breakdown substances into smaller organic molecules which are then absorbed into the cells of the microbes and used for cellular respiration. During the respiration process, the organic molecules absorbed into the cells are broken down in steps, where a molecule known as adenosine-5’- triphosphate (ATP) is used to store and transport energy for cells, for life processes such motility and cell division. In biochemistry this chemical reaction sequence is known as Electron Chain Transfer. In the case of aerobic metabolism, oxygen is used at the end of the chain as the final electron acceptor, producing the main byproducts of carbon dioxide and water.
Composting is a well known and common use of aerobic biodegradation, during which the volume of organic material is typically reduced by about 50%, where the remaining, slow-decaying humus material left over can be used as a rich planting medium. The ASTM defines a compostable plastic material as being:
“capable of biological decomposition in a compost site as part of an available program, such that the plastic is not visually distinguishable and break down to carbon dioxide, water inorganic compounds and biomass at a rate consistent with known compostable materials (e.g. cellulose).”
The biomass material referred to here is humus. The bioactivity in active compost will generate heat that further enhances the rate of microbial growth and metabolism. However, for the purpose of the ASTM definition, the available program is an industrial compost facility where heat and moisture are artificially added to the mass to maximize the degradation rate. As we will see, this artificial environment becomes critical for degradation of some biodegradable plastic materials.
Anaerobic biodegradation occurs in the absence of oxygen where anaerobic microbes are dominant. In the absence of oxygen the organism must use some other atom as the final electron acceptor. Hydrogen, methane, nitrogen and sulfur are common along with oxidizing minerals. Thus, the effluent from anaerobic digestion is biogas, consisting of mostly methane and carbon dioxide, with trace gasses such as ammonia and hydrogen sulfide. Often, the complete digestion will require several different types of bacteria where one type partially processes the waste to a point where another bacterium strain takes over (4). Most biodegradation of solid waste in landfill occurs under anaerobic conditions by design because it is typically much slower than aerobic degradation.
Most biodegradable substances come from plant and animal matter, or from artificial materials that are very similar in molecular structure to these naturally occurring substances. As the naturally occurring substances evolved, microorganisms also evolved to use the substances as a food source: the carbon in particular, used as a building block for life-sustaining compounds. Simple sugars are readily absorbed into the cell to be metabolized. However, larger and more complex molecules such as starches, proteins and cellulose, require enzymes and acids to reduce their size enough to be absorbed. Living organisms have developed the ability to secrete specific digestive compounds so as to best utilize the available food supply. For example, the enzyme amylase, found in human saliva, is used to breakdown long-chain starch molecules into and smaller simple sugars.
For microorganisms, this adaptive process can be applied to other, more complex carbon containing compounds in crude oil. This type of microbial biodegradation has been demonstrated for hydrocarbons derived from petroleum (10)
Biodegradable Plastic Materials
Currently available degradable plastic materials can be broken down into two main groups:
1. Polyester Polymers
2. Synergistic and Hybrid Polymers
The Polyesters
When one thinks of polyesters in general, the polymers that come to mind are very durable with good physical and mechanical properties. A good example is polyethylene terephthalate (PET). This polymer is strong, abrasion and stain resistant, so it can be a good choice for carpeting and clothing. It also has good gas barrier properties which make it ideal for soda bottles. These polymers, which are also resistant to biodegradation, typically contain a large number of six-carbon rings in their molecular structure. In chemistry, compounds containing these rings are known as aromatic compounds.
Biodegradable polyesters which do not contain six-carbon rings are known as aliphatic polyesters. They will typically react with moisture at elevated temperatures to breakdown the long polymer chains. This process, called chemical hydrolysis, reduces the higher molecular weight polymer to much smaller hydrocarbon compounds. The resulting molecules can then be absorbed by microorganisms and metabolized for energy. Since it is a chemical reaction, the hydrolysis occurs at a much higher rate than one would expect for a purely biological process, and as a result, relatively quick degradation is observed.
Aliphatic polyesters have attracted interest as biodegradable plastic materials; however they typically have poor physical and mechanical properties (3) like strength, flexibility, heat resistance, etc. Some common biodegradable polyester polymers in commercial use include poly(caprolactone) (PCL), poly(glycolic acid) (PGA) and poly(butylene succinate) (PBS). These are synthetic polymers, made from petroleum-based, raw materials, and like most biodegradable polyesters have inferior mechanical properties e.g. low heat deflection temperature and low elongation failure (brittle). They will also begin to hydrolyze at modest temperatures in the presence of moisture, rapidly losing molecular weight and further decreasing mechanical properties. Although expensive to make, these biodegradable polymers are ideal for use in specialized, high margin applications such as medical devices (e.g. dissolving, drug delivery systems, tissue engineering scaffolds and bone repair etc.).(2)
Another well known aliphatic polyester is poly(lactic acid). PLA is a synthetic polymer made from fermented sugars extracted primarily from food crops such as corn, beets or sugarcane. The resulting lactic acid monomer is chemically processed and then polymerized, in the presence of a metal catalyst, to form the high molecular weight plastic material. Like the petroleum-based biodegradable polyesters, PLA has many of the same undesirable mechanical properties, such as low heat deflection temperature. Figure 1 shows the affects of 170oF water on cup made from PLA. The polymer is also very brittle and has a low-melt strength leading to difficulty in processing. Consequently, most commercial applications using PLA require a synthetic rubber and/or acrylic additive to compensate for these deficiencies.
| Figure 1 – Poly (lactic acid) Cup Before and After Adding Hot Water |
Degradation of PLA occurs quickly through a multistep process (4) of chemical depolymerization, followed by dissolution of the intermediate lactic acid in the presence of moisture, and the absorption into the cells of microorganisms with subsequent metabolization. Initiation of this chain of events typically occurs at elevated temperatures (above heat deflection temperatures), such as conditions existing in an industrial compost operation. The relatively fast chemical reaction at the beginning of the chain of events explains the surprisingly quick degradation of polymer in an industrial compost environment. This mechanism of chemical attack followed by cell metabolism does not meet the true definition of a biodegradable material inasmuch as biological activity is not required for the initial breakup of the material. In low temperature aerobic or anaerobic environments where initial hydrolysis occurs slowly, biodegradation of PLA also proceeds very slowly if at all.
Another family of biodegradable polyesters, which could in a way be viewed as more complex extensions of the molecular structure of PLA, is known as polyhydroxy alkanoates (PHA’s). Intriguingly, PHA’s are natural polymers also derived from plant sugars but are synthesized within the bacteria themselves. The PHA’s are manufactured and used as carbon storage in the cells(6), similar to the way the human body stores fat to be used as an emergency food source.
One of the more notable polymers in this class is polyhydroxy butyrate (PHB), and like the synthetic aliphatic polyesters, it has the same poor physical and mechanical properties, and an additional disadvantage of being quite expensive. A cousin to PHB, which is actually a copolymer, was developed to help improve these deficient properties. This co-polyester is known as polyhydroxy butyrate-valarate (PHBV) and has much better, and more useful, thermoplastic properties that are similar to polypropylene(5). Since these materials are produced by microorganisms as an emergency food source, they are, by design, easily biodegradable by direct enzymatic action of microorganisms, and don’t necessarily require the chemical hydrolysis reaction step first. It has been shown that bacterially produced PHB/PHV (92/8 w/w) deteriorated nearly to completion within 20 days of cultivation by anaerobic digested sludge, while synthetic aliphatic polymers such as PLA, PBS, and poly(butylene succinate adipiate) (PBSA) did not degrade at all in 100 days (1).
For degradable polyesters, the best improvement in physical properties is obtained by synthetically creating a polyester copolymer using both aliphatic and aromatic groups. These are typically derived from oil-based raw materials such as 1,4-butanediol, adipic acid, and terephthalic acid (7). Using this technique, the polymer can be tailored to balance the excellent physical and mechanical characteristics of the aromatic polyester groups with the degradation and subsequent mineralization of the aliphatic groups. These polymers are also readily mixable with pure aliphatic polyesters like PLA, or natural polymer like cellulose, to form a hybrid, degradable polymer with improved performance.
Synergistic or Hybrid Polymers
Synergistic polymers are typically intimate mixtures of oil-based and naturally occurring polymers where the two have some chemical affinity for each other. When mixed, there is intimate contact between the two polymer chains so as to create a homogenous single phase. In other words, once mixed they could not be mechanically separated. This is somewhat akin to mixing gelatin powder with hot water to form a single uniform substance, once cooled.
A good example of a commercial, synergistic, biodegradable material is Thermoplastic Starch (TPS). The key to this blend of the two natural starch polymers, amylose and amylopectin, and the synthetic polymer, polyvinyl alcohol (PVOH), is their natural affinity to each other, due to the large number of hydroxyl (OH) groups present in the compounds. This hybrid can be made into foamed articles, plastic films or molded parts such as cutlery. Generational adaptations that occur during the digestion of the familiar starch groups quickly begin to breakdown the synthetic PVOH chains.
The intimate mixing of the natural and synthetic polymers can be taken one step further: where the attraction of the synthetic and natural polymers is enhanced by grafting other chemically compatible groups along the chains of the natural and/or synthetic polymers. As with the PVOH, this technique enhances biodegradation through generational adaptation which can be initiated with relatively small additions of natural polymers. To illustrate how this could be possible, it has been shown that polyethylene will biodegrade via a monooxygense enzyme pathway (9). Initiation of the process begins with the formation of a biofilm on the surface of the polymer, which is facilitated by the inclusion of the compatible natural polymers. These films of microorganisms have been shown to efficiently biodegrade petroleum based polymers (8).
Low-level synergistic enhancement does not materially impact the physical and mechanical properties of the original synthetic polymer. Therefore, the product applications are not restricted beyond what would normally be expected for the un-amended polymer. Since the additive itself will not degrade the polymer or affect processing, the ability for recycling or reuse of the plastic article will be unaffected. Unintended degradation will not occur since the initial colonization requires an environment where existing biodegradation is occurring or would normally be expected to occur, either aerobic or anaerobic. Additional heat is not required, and no chemical, polymer-chain weight reduction process is needed beyond the enzymatic action of the microorganisms.
Figures 2 – 6 illustrate a short period, pictorial history of the biodegradation of polystyrene loosefill particles containing this kind of synergistic additive. Figures 7 – 10 show a similar history for polyethylene film containing the additive taken from a back yard compost environment.
Polystyrene Loose-Fill Biodegradation
Synergistic Additive
Compost History
| Fig. 2 – Amended, Unexposed Loosefill |
| Fig. 3 – Uniform Foam Cells; Amended, Unexposed Loosefill Magnification 18X |
| Fig 4 – Amended Exposed 3 Months in Compost |
| Fig 5 – Degraded Foam Cells and Pits, Amended Exposed 6 Months, Magnification 18X |
| Fig 6A – Amended Exposed 6 Months in Compost |
| Fig 6B - Amended Exposed 9 Months in Compost (left) vs. Original Sample (6A) |
Polyethylene Film Biodegradation
Synergistic Additive
Compost History
| Fig 7 – Amended, Unexposed Film |
| Fig 8 – Amended Exposed 3 Months in Compost |
| Fig 9 – Amended Exposed 6 Months in Compost |
| Fig 10 – Amended Exposed 6 Months, Magnification 20X Fungus Colonies |
Conclusion
For the choice of materials to be used in the manufacture of a more environmentally friendly packaging material, the criteria needs to take into account business considerations and strategies, while addressing environmental concerns related to the life cycle of the packaging. The primary purpose of the packaging material is to protect the items being shipped from damage via impact or abrasion, and therefore protection should be the first consideration. The material will also need to perform in largely uncontrolled, ambient conditions of heat and humidity; thus, the next consideration should be given to the products’ possible end-of-life scenarios. The scenarios include disposal in landfills, litter, recycle, etc. Finally, material costs need to meet market criteria.
Conventional polymer technologies have been able to tailor materials that can meet the market need of both cost and performance. There is infrastructure in place for recycling and/or re-use of many of these materials, which is the most desirable destination in the life cycle of the packaging product. With inclusion of a synergistic additive, such as that used by FP International, the materials would also be well-suited for the less desirable destinations, such as landfills.
The other biodegradable polymer options have no recycle infrastructure, and could possibly be viewed as having been designed to be thrown out. However, the fact that many of these polymers, like PLA, are limited to biodegradation in only commercial compost facilities, further decreases the potential for a desirable end-of-life scenario. Moreover, while the bacterially produced polyesters (PHB/PHV) would biodegrade in a more general disposal scenario, they are particularly cost-prohibitive for most packaging applications.
In addition to sustainable choices in materials for FP International’s products, FP has ongoing programs for reduction of raw material and energy usage, recycling, increased production efficiencies, efficient product design and increased recycled, raw material usage.
About the Author
Rod Alire is Chief Scientist for FP International. Mr. Alire carries more than 20 years experience in polymer processing with particular expertise in polymeric foam and film extrusion processes. His projects have emphasized environmental impact mitigation and sustainability through new product design and manufacturing technologies. By Mr. Alire’s development of a theoretical model for mass transport phenomena and foam expansion behavior in polystyrene packaging material production, FP International was able to reduce the usage of raw materials and density of the products being produced.
In order to replace the use of CFC’s – chlorofluorocarbon, (known to be harmful to the ozone and environment), Mr. Alire designed and built a high pressure, foaming agent metering and delivery system for polymer foam extrusion. Also, he developed polyolefin polymer blends and a blown film process for production of PMOS (products manufactured on-site) air bag materials. These airbags are 99% air, since they can be manually deflated or popped, they also reduce the size of materials produced for recycling. Also, the size of the film air cushion materials takes less space to ship, thus less cost and lowers the use of trucks (lowering gas use and truck emissions). Currently, Mr. Alire is working to increase the strength and mechanical property of the film itself, in order to produce film which uses less material.
References
1. Shin et al. in Nolan – ITU; ‘Environment Australia, Biodegradable Plastics – Developments and Environmental Impacts’ (2002)
2. Yoshito Ikada, Hideto Tsuji, ‘Biodegradable polyesters for medical and ecological applications’, macromol. Rapid Commun. Vol. 21, (1999).
3. Yiwang Chen, Licheng Tan, Lie Chen, Yan Yang and Xiaofeng Wang, ‘Study on biodegradable aromatic/aliphatic copolyesters’, Brazilian Journal of Chemical Engineering, Vol. 25, No. 2 (2008).
4. Dunja Manal Abou Zeid, ‘Anaerobic Biodegradation of Natural and Synthetic Polyesters’, Dissertation, Von der Gemeinsamen Naturwissenschaftlichen Fakultat der Technisschen Universitat Carolo-Wilhemina zu Braunschweig (2001).
5. Yon Jia, Wei Yuan, Jola Wodzinska, Chung Park, Anthony J. Sinskey, JoAnne Stubbe, ’Mechanistic Studies on Class I Polyhydroxybutyrate (PHB) Synthase from Ralstonia eutropha: Class I and III Synthases Share a Similar Catalytic Mechanism’, Biochemistry, (2001), 40.
6. Sung-Eun Lee, Qing X.Li, Jian Yu, ‘Diverse protein regulations on PHA formation in Ralstonia eutropha on short chain organic acids’, International Journal of Biological Sciences, (2009), 5.
7. Ilona Kleeberg, Claudia Hetz, Feiner Michael Kroppenstedt, Rolf-Joachim Muller, Wolf-Dieter Deckwer, ‘Biodegradation of Aliphatic-Aromatic Co-polyesters by Thermomonaspora fusca and Other Thermophilic Compost Isolates’, Applied and Environmental Microbiology, Vol. 64, No. 5, (1998).
8. Gamini Seneviratne, N.S. Tennakoon, et al. ‘Polyethylene biodegradation by a developed Penicillium-Bacillus biofilm’, Current Science, Vol. 90, No 1, (2006).
9. van Beilen in Seneviratne
10. Okerentugbea in Seneviratne
Subscribe to:
Posts (Atom)