Key Advancements in Rubber Disposal by Teresa Clark ENSO Plastics, L.L.C

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www.rubbernews.com Rubber & Plastics News ● December 2, 2013 15 Technical Key advancements in rubber disposal By Teresa Clark ENSO Plastics, L.L.C. The author In recent years, the waste disposal Executive summary problem has spurred mounting interest The international environmental movement has not left the latex/rubber in- Teresa Clark is the co-founder and in the biodegradability of polymers, es- dustry untouched, and disposal considerations are becoming more scrutinized. vice president of ENSO Plastics, pecially when the public is voicing Most of these products are disposed of through incineration and landfill disposal. L.L.C. greater concern about protecting human For products disposed of in landfills, the persistence of these products is a point Clark is an avid environmentalist health and preserving the quality of our of concern, and a means to induce biodegradation of these materials in anaerobic with experience in microbiology, environment. conditions is necessary. chemistry, biodegradation and relat- Plastics, for instance, which became Discussed are recent advancements in technology that promote biodegradation ed environmental fields. an integral part of contemporary life, al- to assimilate these products back into the natural cycle and compare these prod- She was a featured educational ready formed a significant part of ucts to the biodegradation of natural rubber. The environmental impact of biode- speaker during wastes in municipal landfills. grading these materials (landfill gas and residual chemicals) is reviewed, as well the eighth an- as the impact of using these novel materials on a products shelf stability, nual LAPET strength and physical properties. 2010 conference TECHNICAL NOTEBOOK and 2011 Inter- Edited by Harold Herzlich national Plas- are either landfilled or are illegally more than 100,000 articles that use rub- timagen. Concerns regarding the environmen- dumped. According to a recent report of ber as a raw material.2 Clark was an tal impact of solid wastes, recycling and the U.S. Environmental Protection With the increase in demands, the instructor for composting options are expected to in- Agency (U.S EPA), this has resulted in a manufacturing and use of rubber and the College of crease as landfill capacity decreases. national stockpile of more than 2 billion the rubber products has increased Engineers in 2 Puerto Rico, Managing waste is thus a challenge fac- waste tires. tremendously both in the developed and Clark ing the global community.10 Aside from tires, rubber in its many less developed countries. The use of rub- teaching a con- This report reviews previous work on forms is used for many, many other ap- ber in so many applications results in a tinuing education class in plastic natural rubber biodegradation and a re- plications. Rubber is used in radio and growing volume of rubber waste.2 biodegradation. She also developed cent technological advancement in the television sets and in telephones. Med- The waste comes not only from dis- an educational program for middle biodegradation of synthetic rubber ma- ical and multipurpose gloves made of carded used product but also from man- school children to educate them on terials in an effort to address the ever- rubber provide a safe barrier to chemi- ufacturing. plastics and the environment, which increasing demand rubber waste puts cals and infection. For example, the latex industry ex- has been used in several private on the environment. Electric wires are made safe by rubber panded over the years to meet the world schools. insulation. Rubber forms a part of many demand for examination gloves, con- Clark has held positions within Rubber waste mechanical devices in the kitchen. doms, latex thread, etc. Due to strict sales, human resources, billing, In 2011, newspaper/mechanical pa- It helps to exclude drafts and to insu- specifications for latex products, as health care, management, restau- pers recovery was about 73 percent (7 late against noise. Sofas and chairs may much as 15 percent of the products are rant services, financial analysis and million tons), and about 57 percent of be upholstered with foam rubber cush- sometimes rejected, and these rejects staffing. She has founded several yard trimmings were recovered (Fig. 3). ions, and beds may have natural rubber create a major disposal problem for the businesses. Total MSW generation in 2011 was 250 pillows and mattresses. Clothing and rubber industry. million tons. footwear may contain rubber: e.g., elas- At the same time, there is a world- Organic materials continue to be the ticized threads in undergarments or wide demand to reduce landfill buildup emissions. largest component of MSW. Paper and shoe soles. and environmental pollution.2 Others have focused marketing efforts paperboard account for 28 percent, and Most sports equipment, virtually all The environmental movement of rub- on promoting the value of renewable yard trimmings and food waste account balls and many mechanical toys contain ber has focused in areas outside of dis- natural rubber and claims of its “inher- for another 28 percent. rubber in some or all of their parts. Still posal. Some companies, such as Styron ent biodegradability.” Plastics comprise about 13 percent; other applications have been developed Emulsion Polymers, have focused on uti- Ultimately, having an environmental- metals make up 9 percent; and rubber, due to special properties of certain types lizing renewable energy during manu- ly-sound product is becoming an impor- leather and textiles account for 8 per- of synthetic rubber, and there are now facturing to reduce greenhouse gas tant factor for an increasing number of cent. Wood follows at around 6 percent consumers; the hard part is deciding the and glass at 5 percent. best choice for your company’s needs, 13 Other miscellaneous wastes make up Fig. 1. Total municipal solid waste generation 2011 U.S. budget and planetary commitment.5 approximately 3 percent of the MSW generated in 2011.13 Waste management of rubber The figure for rubber, leather and tex- The specific focus of this paper is the tile may not seem significant, as 8.2 per- disposal and ultimate integration of rub- cent seems fairly inconsequential. How- ber materials into the natural cycle of ever, given the tremendous amount of biodegradation, an important aspect of waste produced in general, 8.2 percent any environmental approach to waste is a significant burden on the environ- disposal as it is becoming more critical ment when considered in measurements to address our solid waste as society more equitable to the impact—tons of grows and our use of rubber products ex- rubber discarded into landfills yearly. pands. Given the unique properties of rubber There are two major categories of rub- materials, the overall use of rubber for a ber: natural and synthetic. large number of applications is con- Natural rubber is extracted from rub- stantly on the rise and becoming an ber producing plants, most notably the ever-increasing focus of concern. tree Hevea brasiliensis, which origi- Rubber materials also are of increas- nates from South America. ing concern, not only in industrialized Nowadays, more than 90 percent of all countries but also in less developed na- natural rubber comes from these trees tions. in the rubber plantations of Indonesia, Rubber products are everywhere to be the Malay Peninsula and Sri Lanka. found, though few people recognize rub- The common name for this type of rubber in all of its applications. ber is Para rubber.1 Since 1920, demand for rubber manu- Synthetic rubbers are produced pri- facturing has been largely dependent on marily from petrochemicals. There are the automobile industry, the biggest several synthetic rubbers in production. consumer of rubber products.2 These are produced in a similar way to Most often the image that comes to plastics, by a chemical process known as mind when the words “environment” polymerization. They include neoprene, and “rubber” are spoken together con- Buna rubbers and butyl rubber. jures the thought of automotive tires. Synthetic rubbers usually have been About 242 million tires are discarded developed with specific properties for every year in the U.S. alone. Less than 7 specialist applications. percent are recycled. The synthetic rubbers commonly used Eleven percent are incinerated for for tire manufacture are styrene-butadi- their fuel value, and another 5 percent ene rubber and butadiene rubber (both are exported. The remaining 78 percent See Rubber, page 16 P016_RPN20131202.qxp 11/26/2013 3:36 PM Page 1

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posing of in the open environment) of tresses occupy up to 23 cubic feet of biodegradation. They pose threats to the rubber; however in most societies, this is landfill space for each mattress. All nat- ecosystems they contaminate and accu- Rubber not an acceptable or legal means to dis- ural latex mattresses are made of 100 mulate within the environment. pose of any waste materials, percent plant derivatives, which make Biodegradative activities in natural Continued from page 15 Rubber recovery for recycling can be a them biodegradable.5 material and energy cycling constitute members of the Buna family). Butyl rub- difficult process. There are many rea- • Very thin rubber products, such as one of the most important processes in ber, since it is gas-impermeable, is com- sons, however, why rubber should be re- balloons and condoms, will degrade nat- water, sediment, soil and other ecosys- monly used for inner tubes.1 claimed or recovered:1 urally, especially if they are subjected to tems in processing waste materials, or- With the significant volume of rubber • Recovered rubber can cost half that natural sunlight. As is evident from the ganic recycling. Non-biodegradable mate- waste, it is critical to identify proper of natural or synthetic rubber. problems that are associated with seal- rials prevent this natural cycle and the means of handling the waste. • Recovered rubber has some proper- ing rings, natural rubber is capable of process of environmental detoxification. There are three methods considered ties that are better than those of virgin being biodegraded. It should be possible The emergence of various elastomeric appropriate in the environmental sense, rubber. to compost thin rubber articles.8 materials had posed an environmental to dispose of various rubber wastes: recy- • Producing rubber from reclaim re- Biodegradation of rubber has been problem for many years. Their growing cling, incineration and biodegradation. quires less energy in the total produc- studied for close to 100 years, yet until use is expected to raise concerns about Historically there has been some in- tion process than does virgin material. today, very little was understood about their environmental impact as a result terest in addressing the littering (dis- • It is an excellent way to dispose of the breakdown mechanism, microorgan- of their disposal.10 unwanted rubber products, which is of- isms and enzymes involved. Most commonly-used natural poly- ten difficult. The study of rubber biodegradation mers and fibers (e.g., natural rubber, • It conserves non-renewable petrole- must be prefaced with a clear under- starches, gelatin, wood and cotton) are um products, which are used to produce standing of what biodegradation is and inherently biodegradable under proper synthetic rubbers. the factors affecting it. conditions, although the extent of degra- • Recycling activities can generate dation decreases with increasing molec- work in developing countries. Understanding biodegradation ular weights of the polymers. • Many useful products are derived Microbial degradation is a natural Natural rubber is often considered an from reused tires and other rubber prod- process by which organic compounds, in- environmentally degradable material; ucts. cluding rubber polymers, are converted however, in nature it is expected to de- Recycling of rubber waste can pose a by the action of bacteria to simpler com- grade very slowly in comparison with challenging environmental, economical pounds, mineralized and redistributed other natural polymers. Natural rubber and social problem, and the primary through the elemental cycles.15 Biodeg- degrading bacteria are distributed wide- product available for recycling is rubber radation is the biological breakdown of ly in soil, water and sewage.10 tires.2 organic compounds by microorganisms This leaves an obvious gap in the life into cell biomass and less complex com- Studies on the biodegradation of cycle of non-tire rubber products. If not pounds, and ultimately to water, and ei- natural rubber available for recycling, what means are ther carbon dioxide (aerobically) or Over the years, there have been con- available to address the waste of these methane (anaerobically). certed efforts to investigate microbial products? The primary disposal methods The extent and rate of this natural rubber degradation. It became obvious of rubber products are: incineration and process depend on interactions between that bacteria as well as fungi are capa- landfill. the environment, the number and type ble of degrading rubber. It is assumed Combustion of natural rubber latex is of microorganisms present and the that degradation of the rubber backbone quite clean, although some hydrocar- chemical structure of the compound(s) is initiated by oxidative cleavage of the bons, minute quantities of unreacted ni- being degraded. Microorganisms secrete double bond.15 trogen-based chemicals and sulfur diox- the enzymes that catalyze the degrada- Most studies have been performed us- ide may be produced at low incineration tion of polymers. Oxygen, nutrients and ing isolated strains of bacterium. Early temperatures. microorganisms are very often the limit- studies showed that pure strains of Nitrogen-based reaction products are ing factors in soils.10 some bacteria caused up to a 55 percent released minimally during incineration While microorganisms can degrade loss in weight of thin rubber sheets in 70 of nitrile; the other chemical by-prod- most natural compounds, they often days. Thin films from a latex glove were ucts are similar to those produced by lack the appropriate enzymes to degrade rapidly degraded, and weight losses natural latex. many synthetics including synthetic reached 75 percent after a two-week cul- Polychloroprene releases hydrochloric rubbers. tivation period. acid gas, carbon monoxide and dioxide, Compounds having a molecular struc- Pure isolated strains of bacteria in various hydrocarbons and partially oxi- ture to which microorganisms have not batch cultures, using laboratory fer- dized hydrocarbon and partially oxi- been exposed to (i.e. synthetic rubbers menters, completely degraded latex dized organic compounding chemicals and polymers) are usually resistant to glove films after 45 days. After eight during incineration.

Incineration methods and differing 2 technologies can reduce the environ- Fig. 2. Natural rubber mechanism of breakdown, Malaysian Rubber Board. mental pollutants and provide a theoret- ical value in energy production.6 Ultimately, the most interesting av- enue of disposal is in landfill disposal and biodegradation of unwanted rubber materials. Given that a very large por- tion of discarded rubber articles ultimately are disposed of within municipal landfills, the ability to biodegrade the wasted material effectively is of para- mount importance.

Industry stance on natural rubber biodegradation There has been significant research on the microbial assimilation of rubber into the natural environment, (i.e. aerobic and soil degradation of natural latex rubber). It is generally noted that natural latex rubber is biodegradable as is claimed by numerous products and manufacturers: • Natural rubber latex gloves can be disposed of by either landfill or incineration without environmental damage.4 • Since ordinary aerobic or anaerobic decomposition processes in gloves will not form any toxic products, gloves may be disposed of in any landfill. Break- down in landfill will be very slow except for products made of natural rubber.6 • You have a pretty big landfill problem when it comes to mattresses. Mat- P017_RPN20131202.qxp 11/27/2013 2:39 PM Page 1

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weeks, about 28 percent of a tire strip gi-toxic rubbers. were reported among the degradation natural products all gradually and com- disintegrated into very small particles There are, however, slowly emerging products in several studies. Carboxylic pletely will biodegrade eventually, so with a 51 percent loss of initial weight.10 data about the susceptibility of nitriles acids usually were formed after the for- you don’t have to worry about filling up More recent research has found that a to biodegradation in pure cultures. mation of alcohols and aldehydes ac- landfills. Our mattresses will last up to crude enzyme from a bacterium is able Miller & Gray isolated a species of bac- cording to the degradation pathway of n- 25 years and then biodegrade. All our to biodegrade natural rubber in the la- teria from garden soil that could hy- alkanes.16 products will naturally biodegrade in tex state. This work has uncovered evi- drolyze a number of amides and nitriles This brings an interesting observa- the landfill. From cradle to grave, we dence for the existence of an extracellu- (acetonitrile, acrylonitile, propionitrile tion: it appears the mechanisms behind have an all-natural solution.”9 lar enzyme capable of degrading natural and n-butyronirile) to ammonia. More re- microbial rubber degradation are often Notwithstanding the question of oxi- rubber.10 cently, simple nitrile compounds were oxidation and chain scission of the poly- dization, it is accepted within the indus- Research also has shown that overall shown to be degraded by specific species.10 mer. The oxidation seems primarily try the natural rubber will biodegrade. biodegradation rate is influenced by en- Polychloroprene and nitrile gloves through environmental exposure rather We look to answer the questions: Can vironmental factors. buried in amended compost and tropical than solely microbial activity. This synthetic rubbers be made to biodegrade Biodegradation rate was studied by soils remained intact after 40 weeks, breakdown process is illustrated in Fig. similar to natural rubber in landfill en- burying natural rubber latex gloves in while plasticized PVC gloves showed 2, as provided by the Malaysian rubber vironments as an effective means of tropical soils amended with nitrogen small weight losses due to plasticizer board.2 waste management? And, can this be and phosphorus, and in a composting and other additive losses.3 This finding raises significant ques- done without jeopardizing the value environment created from dried grass tions when one considers the common proposition the synthetic rubbers offer? clippings, cattle manure and soil. Mechanism of breakdown disposal method of rubber articles and The test involved manipulating soils As seen above, the biodegradation of the environment they will be exposed to. Developing biodegradable to favor microbial growth enhanced natural rubber has been evaluated in In researching the disposal and bio- synthetic rubbers biodegradation compared to natural at- several studies, as has the biodegrada- degradation of natural and synthetic To develop biodegradable synthetic tenuation processes in unamended soils. tion of synthetic rubbers. The presence rubbers, it seems common for brands to materials, one must understand the mi- The mean specific degradation rate of of rubber degrading microorganisms is claim biodegradability of natural rub- crobiological reason synthetic and natu- natural rubber glove pieces in a high soil well documented. ber, not only in native soil, but within ral products are assimilated differently. nutrient treatment was three times One study evaluated 33 different sam- the anaerobic environment of municipal The variation in biodegradation abili- higher than in the unamended controls.3 ples from different ecosystems and the landfills as is demonstrated in the fol- ty between natural and synthetic mate- In a composting environment, biodeg- ability of the soils to biodegrade natural lowing excerpts: rials is primarily because they have not radation rates of greater than 24 weeks rubber. All soil samples showed rubber • “Natural rubber latex is also been available for a long enough time in were twice that compared to the fertil- degrading bacteria except three: Asian biodegradable, and Doyle is a big propo- natural evolution for microorganisms to ized treatment in soils. river sediment, one soil sample and the nent of keeping the environment clean develop degradative enzymes that will Degradation of natural rubber condoms commercial compost sample. and healthy. A balloon that is made out utilize the compounds. in soil was slower compared to gloves During the testing, more than 50 of natural rubber latex, or Vytex, would Microorganisms will have to evolve with 42 percent of the initial weights re- species were isolated with the ability to have the same staying power in a land- new genes and genetic functions that maining after 48 weeks. In contrast, the degrade natural rubber and concluded fill as an oak leaf, so it’s going to de- encode catabolic enzymes to degrade manufactured polyurethane condoms that natural rubber degrading bacteria grade about the same time as a leaf that new chemicals generated by the chemi- hardly were biodegradable.3 are distributed widely throughout na- falls off of a tree,” Doyle said. “Whereas cal industry. Gene exchanges among mi- ture.14 if you put something like a mylar bal- croorganisms can give rise to a particu- Studies on the biodegradation of In these tests, degradation is not ex- loon into a landfill, chances are it’s going lar degradative pathway.10 synthetic rubbers clusively microbiological (i.e., purely en- to be there during the next Ice Age.”7 Various molecular mechanisms exist to Unlike natural rubber, synthetic rub- zymatic process) but include other com- • “It easily decomposes in landfills be- enable microbes to recruit genes from pre- ber compounds have been reported to be plex physicochemical actions of the soil cause it is a natural product.” existing genes of related catabolic path- more resistant to microbial attack than environment, usually the auto-oxida- • “When latex is properly encased, it ways and to modify the nucleotide se- natural rubber compounds, and studies tive-progressive aging effect, which can should last decades. By properly en- quences in the structural and regulatory show a variety of results depending on make the material more amenable to cased we mean minimal exposure to air, genes to enhance expression and to use the period and mode of tests. Cundell & microbial action.10 sunlight and other elements. Latex synthetic compounds as substrates. Mulcock investigated the microbial re- The mechanism involved in the degra- cores covered by quilted cases have Thus microbes occasionally have resistance of isobutene-isoprene (butyl), dation of natural rubber may be the ox- proven to last 25 years. In some cases, sponded to synthetic chemicals by produc- chloroprene and acrylonitrile-butadiene idative cleavage that is very well reflect- after eight years, exposure to elements ing degradative enzymes, although the (nitrile) in pure culture. ed in the reduction of double bond has caused the sides/edges to begin pathways may not be optimally regulat- After 18 months, the losses in weight character and in the presence of alde- crumbling when covered by just a sim- ed.10 of the rubber strips generally were hydes. The formation of acids was also ple cotton case. The key to synthetic material biodegra- small, and they reasoned that such dete- clear from the results of TLC, which also The point to remember is these all See Rubber, page 18 riorations may be at the expense of the was supported by FTIR data. This also compounding ingredients in the rubbers supported the oxidative cleavage of nat- e.g., 5.3 percent (NR), 10.8 percent ural rubber latex during biodegradation. Fig. 4. Anaerobic biodegradation of nitrile treated with 1 percent ENSO Restore RL. (chloroprene rubber), 1.6 percent (buta- Previous studies on natural rubber diene rubber), 2.2 percent (acrylonitrile- biodegradation with various microor- butadiene), 0 percent (butyl rubbers) ganisms indicated that during rubber and 2.4 percent (styrene-butadiene).10 degradation, oxidative cleavage of the In a review, Zyska wrote that only double bond in the poly cis1, 4 isoprene raw and unvulcanized chloroprene and backbone occurred as the first step. nitrile may be classified as inert or fun- Presence of aldehydes and ketones

Fig. 3. Anaerobic biodegradation of untreated nitrile. P018_RPN20131202.qxp 11/27/2013 2:41 PM Page 1

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not contribute directly to any degrada- ments. It is common to see quicker percent in extended testing. tion of the rubber, thus leaving the shelf degradation results in the BMP test due The most rapid biodegradation was Rubber life of the rubber article intact. to the smaller sample size (larger sur- 16.9 percent in 20 days. Longer term It is interesting to note that the inert- face area to mass) and more optimized testing under ASTM D5511 shows a Continued from page 17 ness of the ENSO Restore RL material conditions. clear biodegradation curve developing dation is utilizing this natural process of within the rubber not only relates to the The rate of biodegradation fluctuates with continued biodegradation in both microbial acclimatization in somewhat of degradation, but also to the physical within the test as it would in a natural tests. There was no plateau observed in a “fast track” method to enhance the rate properties of the material. environment. This is normal and is ex- any of the test samples. of biodegradation. Biodegradation occurs Products made using various synthet- pected. There are also periods of more When compared together (as seen in primarily through degradative enzymatic ic rubbers were found to have the same and less rapid biodegradation during a Fig. 5) it is clearly apparent the acceler- activity. These enzymes, produced by mi- chemical resistance, strength, flexibility test as microorganisms go through stan- ated degree of biodegradation between croorganisms, either can be intra-cellular and appearance as those using untreat- dard periods of activity and transition. treated and untreated samples. or extra-cellular. ed rubbers. Tests were performed at Eden Re- Additionally, although the untreated To biodegrade high molecular weight ENSO Restore RL is an additive used search Laboratory and NorthEast Labo- samples show limited initial biodegra- synthetic materials, it is critical to utilize during the manufacturing of rubber ar- ratories to ensure third party as well as dation, in the more extended testing extra-cellular enzymes and to optimize ticles in such a way as to disperse the peer comparative testing. biodegradation ceases, and a plateau is the production of these enzymes. additive throughout the matrix of the Inoculum for the testing was prepared clearly seen. This initial biodegradation It is also critical to validate that these rubber. as per ASTM D5511 protocol. may be due to impurities and additives microorganisms involve and the result- It is also important to note that each within the samples rather than a ing enzymes are adaptable (or naturally Biodegradation test parameters sample (referenced in charts as Sample change in the nitrile itself. occurring) in the appropriate environ- Testing was performed on several syn- ID or by material name) contains tripli- Similar testing was performed on ments. For rubber disposal, this envi- thetic materials, including nitrile, poly- cate samples and the results listed are polyurethane, polychloroprene and PVC ronment is the anaerobic municipal chloroprene, polyurethane and PVC. the average of the three results. These with very similar results. Treated landfill. The material evaluated to in- Comparative testing also was performed tests have not concluded as of the time polyurethane showed 162 percent increase the rate of biodegradation was using natural rubber gloves as well as of writing and are ongoing so future crease in the rate of biodegradation in ENSO Restore RL. The testing was per- untreated gloves of the same correspon- data will include biodegradation over 30 days with 11 percent biodegradation, formed in two separate laboratories us- ding materials. longer periods of time. whereas the untreated polyurethane ing landfill simulated environments. Tests performed were the ASTM Specific samples were tested simulta- biodegraded only 4.2 percent. D5511 and biomethane potential (BMP) neously: Biodegradation of polychloroprene ENSO Restore RL: A novel approach testing, both of which validate biodegra- 1. Untreated No. 1 and Untreated No. when untreated showed 0.7 percent ENSO Restore RL is a unique materi- dation using gas production in an anaer- 2. biodegradation and treated demonstrat- al designed not only to attract specific obic environment as would be found in a 2. Untreated No. 2, Treated No. 2 and ed biodegradation of 15 percent, an in- naturally occurring microorganisms, but landfill. All treated samples were manu- Treated No. 3. crease of more than 21,000 percent. also to induce rapid microbial acclimati- factured using 1 percent ENSO Restore 3.Untreated No. 3, Treated No. 4, Similarly the biodegradation seen in zation to synthetic rubbers and result- RL. Natural Rubber, polychloroprene (treat- treated PVC was 13 percent whereas ing biodegradation. Biodegradation percentages were cal- ed and untreated), PVC (treated and un- the untreated material showed no The method of biodegradation caused culated by gas production as identified treated). biodegradation at all. is strictly enzymatic and is designed to in ASTM D5511 test method. The bio- 4. Untreated No. 4, Treated No. 5, The results very clearly show an im- utilize naturally occurring microorgan- methane potential testing is carried out Treated No. 6, polyurethane (treated pressive increase in the rate of biodegra- isms within waste environments, in- in the same manner as the ASTM and untreated). dation when treating the material with cluding landfills. D5511, with using smaller sample sizes ENSO Restore RL. ENSO Restore RL does not involve an to conserve laboratory space and more Biodegradation test results initial abiotic breakdown as is seen with optimal conditions (temperature and Untreated nitrile showed little if any Comparing treated synthetics with degradable products in other industries. moisture rates). biodegradation and was shown to occur natural rubber A novel aspect of this material is its in- The optimized conditions are more within any of the test samples. The most The increase in biodegradation with ertness to the host rubber resin; it does similar to bioreactor optimized environ- biodegradation seen was 4 percent, how- all the tested materials demonstrates ever the mean percent of biodegradation the ability of ENSO Restore RL to accli- was minimal even over testing exceed- mate the flora within the test inoculum Fig. 5. Comparative between treated and untreated nitrile biodegradation. ing 300 days. The lack of biodegradation to utilize synthetic rubber as the sole is consistent with research done in pre- carbon source and effectively biodegrade vious article and supports the belief that the material. untreated nitrile is not biodegradable. However, the critical question re- Using the inoculum from the same mained of whether synthetic rubbers source and testing under the same con- could biodegrade at the rate of natural ditions, a marked change is seen in the rubber in landfill environments. test results of treated nitrile. Once Natural rubber gloves were tested treated with 1 percent ENSO Restore alongside various treated synthetic RL, the nitrile showed significant accel- gloves to determine the ability of treated eration of biodegradation; more than 18 synthetics to biodegrade comparable to

Fig. 6. Anaerobic biodegradation of treated and untreated polychloroprene, polyurethane and PVC. P019_RPN20131202.qxp 11/27/2013 2:42 PM Page 1

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natural rubber. fill waste as a green energy proposition to degrade materials through oxygen Hyde unveils cut-off blades The testing again utilized the same in their overall environmental portfolio. and/or UV exposure, which would risk inoculum and test conditions with the The rubber industry is no exception. the stability of a rubber product. to make dimple-free tubes only variable being that of the test ma- Styron Emulsion Polymers is one such It was interesting, and somewhat Hyde Industrial Blade Solutions has terial. Fig. 7 shows the comparative be- company: shocking, to see that in landfill replica- unveiled new, tube cut-off blades de- tween the treated synthetic and un- “As we continue to focus on developing tion natural rubber showed no biodegra- signed to produce dimple-free tubes. treated natural rubber. innovative solutions to address the dation. This questions the theory of in- Hyde said these blades remain sharp While the treated materials showed earth’s energy challenges, Styron Emul- herent biodegradability and opens for extended life on the most produc- significant increase in the rate of sion Polymers business has created Lo- opportunity to use products such as tion lines to increase yield and reduce biodegradation, the comparative data max Technology. ENSO Restore RL in natural rubber to waste. They are made from high-speed for natural rubber was completely unex- Lomax Technology uses renewable en- restore biodegradability within the con- steels and pected. ergy (currently landfill gas) to manufac- fines of a municipal landfill. are vacu- During the 105 days of biodegradation ture our latex carpet backings, which re- It also brings to question other natu- um heat testing, the natural rubber demonstrat- duces greenhouse gas emissions and ral materials that have by default due to Products treated. A ed zero biodegradation. Contrary to pop- assists customers in developing high their occurrence in nature, been as- variety of ular belief and industry claims, the nat- performance products with sustainable sumed biodegradable within landfills. vertical and horizontal blades is avail- ural rubber material showed absolutely attributes.” Additionally, the resulting methane able, as well as with or without coat- no biodegradation in landfill environ- Within the U.S., all municipal land- production during the anaerobic biode- ings such as TiN, TiCN and TiAIN. ments. fills are required to manage methane gradation of these materials is common- Hyde, which produces industrial emissions and more than 500 of these ly used for energy production to offset knives and blades for a wide variety of Landfills—A unique environment landfills currently utilize methane to en- traditional energy sources, such as coal markets including tire and rubber, In closer consideration it should not ergy methods. burning. hose and tube, food processing, cloth be so surprising. Natural rubber under- Two-thirds of all municipal waste is This provides a method for reducing and textile and leather, manufactures goes a two-step degradation with the placed in landfills that effectively man- waste volume through biodegradation blades for machine brands including initial step being primarily an abiotic age methane emissions. These emis- as well as benefiting environmentally Alpha, Haven, Eagle and Yoder. oxidization and then secondarily the ac- sions and the resulting energy production for the byproduct of that biodegradation. For more information, go to www.hy- tual biodegradation of the degraded ma- provide a solid path for environmental For manufacturers and brands utiliz- deblades.com. terial by microorganisms. disposal of biodegradable materials. ing rubber materials, this presents an Within the anaerobic environment of opportunity to provide environmentally a municipal landfill, it may be unlikely Conclusion focused waste management for the fore- to have sufficient oxygen present, with- In conclusion, there is a tremendous seeable future, in a way that requires out biotic oxidization, to initiate the first need to address the ever-growing issue very little direct action or input other stage necessary for natural rubber. of rubber waste, and focus must be put than a slight change in materials. In contrast, the synthetic rubber treat- on remediation of these wastes. ed with ENSO Restore RL is solely a bio- Complete biodegradation of these ma- References tic process, and all degradation occurs terials may be the suitable answer, pro- 1. Recycling Rubber-Practical Action. enzymatically through extra-cellular and vided we are able to control the 2. Recent advances in the recycling of rubber waste- biodegradation in such a way that it Eldho Abraham. intra-cellular enzymes, thus requiring no 3. Natural rubber biodegradation in soil in relation direct free oxygen involvement. does not impact the service life of rubber to the waste disposal of used latex products Additionally, most testing of natural products. Malaysian Rubber Board, Kuala Lumpur, Malaysia. rubber biodegradation involved isolat- There has been substantial focus in 4. What is Latex? Ansellhealthcare.com. the past as to the inherent (or suggested 5. The Eco-Conscious Choice of a Natural Latex ing microbial species to utilize for the Mattress - Amber Merton. testing. inherent) biodegradation of natural rub- 6. Nitritex.com. Natural and landfill environments ber; and the focus here was to determine 7. Rubber Investor William Doyle Discovers Safer seldom will have the concentration of the ability of products such as ENSO Alternative to Generic Natural Latex. Restore RL to create synthetic biode- 8. Natural rubber as a green commodity-Part II - only one type of microbial flora; instead Kevin P. Jones. there will be millions of different species gradable rubber materials. 9.Organicmattressshop.com. in varying concentrations. Testing clearly shows drastic increas- 10. Environment Friendly Natural Rubber Gloves - Dow thermal adhesives. Testing using isolated species in en- es in the rate of biodegradation in vari- Malaysian Rubber Board. Dow Corning Corp. has released ous synthetic rubbers when treated with 11. Rubber in the Environmental Age - Rapra Tech- hanced environments does not necessar- nology. two thermally conductive adhesives ily correlate with the real world. ENSO Restore RL, and with the biodeg- 12. Styron.com. that it said enables the design of more Within the confines of a municipal radation being in anaerobic environ- 13. US EPA. compact, reliable and higher perform- landfill, oxygen is scarce, moisture is ments offers a unique waste disposal so- 14. Bacterial Degradation of Natural Rubber-Dieter ing automotive electronics assemblies. lution. Jendrossek. limited, and biodegradation takes a very 15. Studies on microbial degradation of natural rub- The new silicone technologies in- different course than in natural soil. The purpose of the ENSO Restore RL ber using dilute solution measurement and weight clude TC-2030, for traditional automo- The bacteria and fungus dwelling in the is to impart biodegradability without af- loss techniques - G.N. Onyeagoro. tive electronics applications, and TC- landfill also can be very different than fecting the physical characteristics or 16. Microbial Degradation of Natural Rubber Latex 2035, a high-performance thermal shelf stability of the treated rubber arti- by a novel species of Bacillus sp. SBS isolated from those inhabiting aerobic soils. soil - E. Cherian. interface material for high-heat auto- The bi-products of landfill biodegrada- cles. 17. Biodegradation of Natural and Synthetic Rub- motive applications, such as next-gen- tion, due to the lack of oxygen, are also This is in contrast to other approaches bers - Alexander Linos. eration power electronic modules. different than compost or soil biodegra- Both materials are part of Dow’s dation, primarily being that the anaero- Fig. 7. Biodegradation of natural and treated synthetic materials. portfolio of thermal management solu- bic process is less efficient and produces tions. Dow, which specializes in sili- methane gas as opposed to the carbon cones, silicon-based technology and in- dioxide released in aerobic processes. novation, said that TC-2030, a two-part, heat-cured silicone technology, reduces Landfill biodegradation—A value thermal resistivity with a high thermal proposition conductivity and improves elongation Anaerobically biodegradable waste performance for a material of such high materials offer a unique value proposi- thermal conductivity. tion when assessing waste management Dow said its TC-2035 withstands heat of landfilled materials and most rubbers in next-generation automotive applica- (with the possible exception of rubber tions, including power electronics for tires) are either landfilled or incinerat- electric and hybrid electric vehicles. The ed. The biodegrading material reduces two-part, heat-cured silicone bonds to a in mass—freeing up valuable space in variety of thermal substrate types, in- overflowing landfills. cluding direct bonding copper, high-den- The resulting products of biodegrada- sity interconnect, low-temperature co- tion, (water, carbon dioxide, methane, fired ceramic and printed circuit board. inert humus, etc.) are non-toxic and re- For silicone applications, visit vert to the natural cycle. www.dowcorning.com/electronics. And, the methane produced is a high- ly valuable energy resource that is Master Bond Inc. has released quickly gaining favor globally. MasterSil 153 and MasterSil 153Med, There is tremendous push from waste addition-cured systems that offer one- management companies as well as mu- to-one mixing ratios, by weight, very nicipalities to increase the use of low exotherm and releases no by-prod- methane to energy. ucts, according to the company. Many companies and municipalities MasterSil 153Med meets USP Class are utilizing the energy produced from VI requirements and ISO 10993-5 methane created by biodegrading land- specifications for cytotoxicity.