Chem321:Cellulosic Plastics: Environmental Impact of Celluloid Derivative Polymers

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Cellulosic Plastics: Environmental Impact of Celluloid Derivative Polymers

By Franz M. Galoso
Chemistry 321
Prof. Martin Walker

     Cellulose, a naturally occurring and biodegradable polymer, can serve as a feedstock or additive to bioplastics. The increasing rarity of petroleum, combined with the sustainability of cellulosic feedstocks, has made cellulosicbioplastic increasingly viable. However, the total environmental impact of any plastic must be assessed with its complete lifecycle considered. Most plastics, including cellulosic plastics, are highly variable designer products with its physical properties highly dependent on production method and specific composition. Cellulosic plastics have a sustainable, seemingly eco-friendly, impact in their early life cycle phases because they are derived from sustainable feedstocks. However since all plastics can be heavily modified through chemistry cellulosic plastics have end stage environmental impact that is varied, depending on the application and use of the material.

     Polymers are long molecule chains that are present in all natural life. Their purposes vary in range from energy storage as starches, to information management as in nucleic acids. (Rincones et al, 2009)Cellulosic plastics are largely derived from a naturally occurring polymer called cellulose, which constitutes the structural component molecule of plant material. All plant materials contain a minimum of 25 percent cellulose, while certain plant materials such as tree bark may be as high as 50 percent cellulose (SUNY-ESF, 2006).Since cellulosic plastics are composed of molecule chains that are partly formed inside living plants, cellulosic plastics can be generally defined as bioplastics. Because early chemists were readily able to use these naturally abundant molecules as a foundation, cellulosic plastics were the first synthetic polymers created (Rincones et al, 2009). Quite ironically perhaps, celluloid, a cellulosic and one of the first practical synthetic plastics, was born partly out of a quest for ecological stability:

“The impetus for the synthesis, refinement, and manufacture of celluloid was a great rise in the demand for ivory, tortoise shell, and horn objects while the supply of these materials was fixed and the cost high. The search for an imitation of ivory and other natural materials was prompted by fears that the wildlife populations of the world were being rapidly decimated.”(Reilly, 1991).

     In 1870 John Wesley Hyatt, using Celluloid (a modified form of the cellulosic plastic Parkesine), won a competition in which a $10,000 prize was offered to anyone who could find an adequate substitute for ivory in the manufacture of billiard balls.(Bayley, 1994).Early cellulosic items were made as imitation for small personal effects such as buttons and combs that were usually made of more expensive natural polymers such as horn and ivory. But Celluloid’s versatility led to its use in objects such as dental prosthetics, clothing, and cinematography film. However, it was soon replaced by more durable plastics, since Celluloid was prone to cracking over time; and the fact that celluloid was partly composed of nitrogen and oxygen made the substance very flammable. One of the few modern applications of Celluloid is in ping pong balls and replacement parts for musical instruments and historical objects. (Reilly, 1991). Celluloid showed manufacturers the versatility of artificial polymers. The subsequent industrial drive to overcome and surpass Celluloid led to the development of modern plastics.

     Modern plastics were created to overcome the weaknesses of natural polymers, and it is that artificial strength that creates the primary environmental problem of plastics. Most synthetic plastics have been designed to the point that most will only degrade after hundreds of years of oxidation or burning. (NYT, Stevens). About 90 percent of modern plastics are synthetic in nature, meaning they are manufactured artificially out of monomers into polymer chains. (Rincones et al, 2009). The primary effective difference between synthetic polymers and natural polymers is that synthetic polymers are formed out of hydrocarbons into long polymer chains with carbon to carbon bonds. This is in contrast to most natural polymers, such as cellulose, in which the backbone of the polymer chain is composed of carbon and other atoms, like oxygen; or, the carbon to carbon bonds contain double bonds. These double bonds and other atoms make the polymers more susceptible to oxidation and enzymatic processes. (Rincones et al, 2009). This means synthetic plastics are incredibly durable and usually impervious to biodegrading.

     A significant amount of human waste is plastic and there is growing concern over the environmental disturbance caused by persistent and non-biodegradable plastic waste (Misra et al, 2004). The country of Australia, for example, dumps 4 billion plastic bags into landfill every year; that’s about 7150 bags per minute. (“Plastics”, 2008).The UK on the other hand, consumes thirteen billion plastic bags annually. Some studies show that upward to 7% to 17% of western landfill waste consists of plastic items.(Harold, 2011.“Plastics”, 2008).So a significant portion of landfill globally is taken up by materials that are mostly non-biodegradable. The plastic that does degrade, may release potentially harmful chemicals, such as bisphenol A or styrene monomers (a carcinogen), that can act as harmful contaminants to human beings and the surrounding environment. (“Plastics”, 2008. Barry, 2009). Additionally, landfills are not the only end-state destination for plastic items; an unknown amount remains as litter while vast quantities of plastic material end up in the world’s oceans (“Plastics”, 2008.Barry, 2009).And while the plastic polymers themselves are resilient to degradation, in the ocean reduces plastic objects to debris particles that are mostly a five millimeters or smaller. A recent Japanese study analyzed water samples taken from several sites globally, including the United States, Europe, India, Japan, and found that “All the water samples were found to contain derivatives of polystyrene, a common plastic used in disposable cutlery, Styrofoam, and DVD cases, among other things,” (Barry, 2009). This microdebris phenomenon increases the surface area of the plastic in relation to the ocean, a solvent. This may accelerate the rate of chemical leaching into the water. This in turn can potentially cause a host of problems for ocean life, especially through the process of biomagnification. Pollutants tend to accumulate in higher concentrations within animals higher in the food chain as pollutants are retained in tissue, which then in turn is consumed by other apex predators, such as humans. In addition to plastic microdebris, whole plastic objects constitute a threat to the ocean ecology:

“About 44 percent of all seabirds eat plastic, apparently by mistake, sometimes with fatal effects. And 267 marine species are affected by plastic garbage—animals are known to swallow plastic bags, which resemble jellyfish in mid-ocean, for example—according to a 2008 study in the journal Environmental Research by oceanographer and chemist Charles Moore, of the Algalita Marine Research Foundation.”(Barry, 2009)

     One of the environmental concerns about most synthetic plastics centers on the source of their feedstocks. Currently most plastics are manufactured catalytically out of the hydrocarbon monomers that are found in the by-products of the petroleum industry. (Queiroz et al, 2009). The issue of plastic waste disposal, and the potential harm it may cause, has combined with a rise in oil prices to stimulate the interest in, and demand for, bioplastics and biopolymers, of which cellulosics are an option. (Rincones et al, 2009. Queiroz et al, 2009). Celluloids, which rely on the natural polymer cellulose, can be produced from theoretically sustainable plant-based feedstocks. Although several scientific articles point out that biopolymer technology is a nascent science (Queiroz et al, 2009. Rincones et al, 2009.Harold, 2011),there has been a sharp increase in academic and industrial interest in cellulosic polymers. A trending survey of scientific articles, published between 1997 and 2008 and within the subject of plastics, has seen a dramatic increase in the amount of articles published on biopolymers (polymers that either have a sustainable source, are biodegradable, or both). Starch based plastics and PCL polymers were the top two most popular topics, with cellulosic polymers being third. The study showed that the amount of articles about cellulose derivatives quadrupled in the ten year span of the sample data. There was no similar, dramatic increase of published articles about non-biopolymer plastics. (Queiroz et al, 2009). A similar study was conducted to observe if there was any increase in the amount of patents on biopolymer technology. The study showed that between 1996 and 2004 there was a dramatic increase in patents concerning cellulosic plastics technology. However, the data shows that there was a dramatic drop in cellulosic technology patents between 2004 and 2007. The study concluded this drop may be due to secret patents that have yet to be made public, and therefore cannot be included in the sample data. (Queiroz et al, 2009).

     Despite the inherent weakness of celluloid and its place as an “old” plastics technology,the upsurge in interest in biopolymers seems to have resulted in new practical applications for celluloid derivatives and cellulosic plastics.Recently a Swedish company called Tectubes, announced that it has begun manufacturing the world’s first biodegradable toothpaste tube for a company that specializes in natural toothpastes. Tectubes used a plastic product called Biograde, a cellulose-based resin created by a German company FKuR, specifically for injection molding.(“Toothpaste”, 2011). Since the feedstock biopolymer, Biograde, is available to other manufacturers, it is possible that more applications are soon to follow. Recent scientific articles have also suggested the possible application of cellulosic polymers in certain parts of solar cells. However, the parts that can be built with cellulosics are limited because of the poor electrical properties of celluloid polymers. (Smock, 2011). Ultimately though, both examples show that products that are sustainable in purpose (such as natural toothpastes, solar arrays) will probably increasingly seek celluloid plastics as substitutes to all synthetic plastics to maximize the overall lifecycle sustainability of their products.

     Recent experiments at Michigan State University show that biodegradable cellulosics can be used as potential substitutes to certain synthetic polymers when formed into a polymer-clay nanocomposite (or PCN). (Misra et al, 2004). Interest in PCNs and ‘Polymer-Silica Layered Composites’ have been ongoing for some fifty years, but only recently, driven by a rise in social and environmental awareness, has there been interest in the use of biopolymers to form these matrixes. The Michigan State University experiments tested the physical characteristics of varying combinations of cellulose acetate combined with a lesser amount of triethyl citrate plasticizer and organically modified clay. The study concluded that: “Cellulosic plastic-clay based nanocomposites demonstratepotential for replacing/substituting polypropylene-clay nanocomposites for future ‘green’ automotive parts.” (Misra et al, 2004). Cellulose acetate is biodegradable, and since the aforementioned PCN nanocomposite is 80% aellulose acetate, the whole matrix is expected to biodegradable, though more studies are being conducted. (Misra et al, 2004).

     Since natural, unmodified, cellulosic polymers are themselves relatively weak, they may find their greatest utility as ‘green’ additive biopolymers in combination with other materials to form composites. Research at the State University of New York College of Environmental Studies and Forestry (SUNY-ESF) has shown that cellulose nanocrystals, extracted from plant material, can be introduced to certain polymers to increase the strength of the polymer by a factor of 3,000. (SUNY-ESF, 2006). The nanocrystals can be extracted from natural materials that contain cellulose, and a possible source for this cellulose is the one billion tons of biomass generated by the United States each year. To process the cellulose, first the biomass is purified by removing other compounds such as lignin. Then it is homogenized and finally shredded until it is in nanocrystal form. Normally polymers are strengthened using glass but the cellulose nanocrystals offer a green subsititute since, unlike glass, they biodegrade in approximately ninety days. Possible future applications of the cellulose nanocrystals may include incorporating them into other biopolymers to create strong, lightweight, biodegradable plastics.(SUNY-ESF, 2006).

     Cellulosic biopolymers offer a possible sustainable substitute for synthetic oil-derived polymers but there are several potential ecological ‘pit-falls’ that must be thoroughly investigated by the scientific community before cellulosic biopolymers can be truly called a green technology. For one,in total, only about four to five percent of the world’s oil consumption goes into the manufacture of plastic resins. (Queiroz et al, 2009). Therefore producing celluloid polymers as replacements for synthetic polymers will not significantly reduce the hydrocarbon consumption of any nation. Additionally, persistent, non-biodegradable plastics fix large amounts of carbon in forms that do not end up as green house gases. While biodegradable plastics, on the other hand, may end up contributing as a green house gasses since, their production requires energy and the chemical breakdown of biopolymers release carbon into the ecosystem. (But the net effects of carbon fixing would only be a slight delay anyway if the biopolymers are derived from biomass feedstocks that would normally decompose rapidly.) Finally, though cellulosics polymers are generally derived from sustainable feedstocks, that fact does not automatically imply that the finished product plastic will be biodegradable. Any future drive to produce cellulosics may be driven by oil prices rather than environmental responsibility. Many Celluloid objects produced in since the polymer’s heyday are still relatively intact, and widespread production of non-biodegradable cellulosics will pose similar environmental hazards as permanent synthetic plastics, even though the cellulosics are produced from sustainable feedstocks. However, on a positive note, celluloid polymers don’t require the sugars that other ethylene type bioplastics do, as such, their feedstocks can be derived from waste biomass, rather than sugar feedstock crops that will compete with food crops for agricultural space and resources.

     Ultimately, cellulosic biopolymer technology is both re-emergent, and new in its application to create biodegradable polymers. It shows promise as a sustainable polymer if the technology is developed towards creating biodegradable polymers. The original cellulosic, Celluloid, was developed partly out of environmental concern, and cellulosics may come full circle once again, and rescue us from the environmental dilemmas of a new century.



  Works Cited:

  • Bayley, Stephen. (1994) Pretty Polymers.The Times (London, UK) October 8, 1994.
  • SUNY-ESF. (2006). Cellulose Makes Plastic 3,000 Times Stronger. Press Release published by the SUNY-ESF Office of News & Publications. Press Release No. 18, October 16, 2006.
  • First Biodegradable Toothpaste Tube (2011) Plastics Technology. March 2011. Retrieved from Ebsco Host, June 25, 2011.
  • Harold, Malcolm. (2011) Bioplastics Revolution?TCE: The Chemical Engineer, Institution of Chemical Engineers. April 2011.
  • Misra, M. ; Park, H. ; Mohanty, A. K. ; Drzal, L. T. (2004) Injection Molded ‘Green’ Nanocomposite Materials from Renewable Resources. Paper presented at the 2004 Global Plastics Environmental Conference. February 18-19, 2004. Retrieved from EbscoHost, June 25, 2011.
  • Plastics.(2008). Northern Territory News (Australia). September 9, 2008. Retrieved from LexisNexis Academic, June 26 2011.
  • Queiroz, A. U. B. ;Collares-Queiroz, F. P. (2009) Innovation and Industrial Trends in Bioplastics. Journal of Macromolecular Science. Part C: Polymer Reviews, 49:65–78, 2009.
  • Reilly, Julie A. (1991). Celluloid Objects: Their Chemistry and Preservation. Journal of the American Institute for Conservation.1991, Vol. 30, No. 2, Art. 3 (pp. 145 to 162).
  • Rincones, J. ; Zeidler A. F. ; Grassi, M. C. B. ; Carazzolle, M. F. ; Pereira, G. A. G. (2009) The Golden Bridge For Nature: The New Biology Applied to Bioplastics. Journal of Macromolecular Science R, Part C: Polymer Reviews, 49:85–106, 2009
  • Smock, Doug. (2011) Bioplastics Eye the Sun. Design News. February, 2011.
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