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The lucrative demand for rubber is taking a toll on forest areas in Asia. But tyre and car makers are taking action by developing the rubber-yielding potentials of plants and renewable materials,in this report.
Land conversions add on to problems
The global consumption for natural rubber is expected to reach 19.4 million tonnes by 2020, according to the Singapore-based International Rubber Study Group (IRSG). As the natural rubber demand continues to be a brisk business, the multiplication of rubber plantations has permeated forest reserves, which are the natural habitat of many species of flora and fauna and wildlife.
This is especially prevalent in Southeast Asia, purportedly the cradle of rubber production, accounting for 97% of the world’s natural rubber supply and, thus, the risks to habitat displacement are continuously increasing.
A 2014 report by the US-funded independent, non-profit organisation East-West Centre disclosed that more than 1 million ha of land has been converted to rubber plantations. By 2050, it projects that the area under rubber trees in the regions of Cambodia, Laos, Myanmar, Thailand, Vietnam, as well as China’s Yunnan Province would increase fourfold.
These land conversions have several environmental ramifications such as animal species being displaced. In a new study, Remotely Sensed Data Informs Red List Evaluations and Conservation Priorities in Southeast Asia, published recently, over 200 species of mammals, birds and amphibians have been newly identified as being at high risk in remote mountainous forests near India, Singapore and China. These are currently listed as threatened or endangered by the International Union for the Conservation of Nature (IUCN). Additionally, the study says that close to 40% of the species have less than 10% of their habitats protected from future development or deforestation. The displacement is also spurred by the conversion of some forest land into rubber and palm oil plantations in Southeast Asia.
The high levels of carbon emissions are also perpetuated by land conversions. The East-West centre research suggests that when primary or secondary forests are converted to rubber, carbon emissions are likely to increase.
Thus, encroaching forest reserves for commercial plantations not only results in deforestation, it also releases greenhouse gas (GHG) emissions. Forests are the largest terrestrial stores of carbon, according to Switzerland-headquartered conservation organisation World Wide Fund for Nature (WWF). Likewise, deforestation is the largest source of carbon dioxide emissions after fossil fuel burning, causing 15% of GHG emissions.
Tyres tread on sustainability
Flagging threats to biodiversity has resulted in industries to consider other plant-based rubber alternatives that can be cultivated locally. Two industries: tyres and automotive sectors are large consumers of rubber. Tyres represent 70% of world rubber consumption; and the growth of the automotive industry increases demand for tyres.
An analysis from industry information provider IHS Markit credits the shift to radial tyres as a significant contributor to the rise in natural rubber consumption over the past three decades or so. Radial tyres use a higher percentage of natural rubber than bias-ply tyres.
While natural rubber from para rubber trees remains a key ingredient in tyres, stakeholders are, however, adopting sustainable rubber initiatives in the supply chain. With a primary goal to promote sustainably produced rubber, the IRSG, via its Sustainable Natural Rubber Working Group, has drawn out sustainability standards. The group has created the Sustainable Natural Rubber Initiative (SNR-i), which has set guidelines and criteria for best practices that organisations can choose to adopt.
Working along the same line, US tyre maker Bridgestone and speciality materials company Yulex have also ventured into projects to drive sustainable alternatives to rubber since 2013.
Tapping other sources for rubber
In the quest for other plant sources of rubber, the dandelion and guayule plants stand out. Taraxacum kok-saghyz, also known as Russian dandelion, has fortunately a distinct edge as an alternative source. Unlike the para rubber tree, which can only be tapped for latex once it reaches about seven years of age, dandelions have the advantage of growing annually.
Researchers from the Fraunhofer Institute for Molecular Biology and Applied Ecology IME have established the basis for the large-scale production of high quality rubber with Russian dandelion. They are also able to achieve this without genetic modification. The roots of the Russian dandelion, also known as Buckeye Gold, contain 10-15% natural rubber. A researcher at the Ohio State University (OSU), studying the dandelion variety says that one of the goals is to develop it into an industrial rubber crop. Plus, growing the crop locally can reduce transportation costs.
Germany-headquartered Continental Tire, working with Fraunhofer, Julius Kuehn-Institute and EKUSA, has produced and tested the first tyres with tread that is made 100% from dandelion rubber. The company plans to begin manufacturing dandelion-derived rubber consumer road tyres in five to 10 years, it says.
The flowering shrub, guayule (Parthenium argentatum), has also been found to be a viable biorubber source. Tyre makers Cooper Tire, Pirelli, and Bridgestone have trialled the use of guayule in prototype tyres. Michigan-headquartered automotive maker Ford has been working with two Arizonabased guayule producers, Yulex and PanAridus, for its biorubber-based parts.
Moreover, Ford has collaborated with the OSU, the Ohio Agricultural Research & Development Centre (OARDC) and industrial members to develop sustainable materials to replace traditional rubber.
At the same time, it is continuing its research collaboration with the United Soybean Board (USB) on the use of soybean oil for automotive rubber applications. Soy-based rubber parts such as radiator deflector shields, air baffles, cup-holder inserts and floor mats are under consideration for future Ford vehicle programmes, says the car maker, which is also a member of OSU’s Programme of Excellence in Natural Rubber Alternatives (PENRA).
PENRA was created “to integrate and accelerate the incubation, demonstration, market entry, and growth of a domestic natural rubber industry”. It focuses on the creation of the science and technology and the private partnerships needed to support the introduction and scale-up of natural rubber alternatives.
Way forward with synthetic biorubbers
Italy’s elastomers producer Versalis (Eni), and Genomatica, a US bioengineering solutions firm, have successfully advanced to pilot-scale production of bio-butadiene (bio-BDE) from fully renewable feedstock. The bio-BDE is used to make bio-polybutadiene (bio-BR). Butadiene is one of the most widely used chemicals in the world, with a production of 10 million tonnes/year.
According to the partners, the success of this innovative undertaking results from a newlydeveloped process for the on-purpose production of butadiene that uses various types of sugars as feedstock, rather than the traditional use of hydrocarbon feedstocks. The project started with the establishment of a technology joint venture between Versalis, holding a majority stake, and Genomatica in early 2013. The joint venture has developed a complete process to make bio-BDE and plans to license the resulting technology.
Versalis and Genomatica determined that 1,3-butanediol (1,3-BDO) was the most suitable intermediate to produce bio-BDE. Genomatica applied its ‘whole-process’ systems approach to bioengineering to develop a microorganism that produces 1,3-BDO in a way that enables costefficient, scalable fermentation and subsequent process operations.
Versalis leverages its industrial process engineering and catalysis capabilities, as well as expertise in overall polymer production, to purify the 1,3-BDO, dehydrate it and then purify the resulting butadiene. Versalis has produced several kg of butadiene from 1,3-BDO made in 200 l fermenters at its research centres at Novara and Mantova in Italy, and then made bio-polybutadiene, at the Ravenna R&D centre, using both anionic and Ziegler-Natta catalysis.
Initial testing of the bio-BDE and bio-BR demonstrates good compatibility with industry standards, the companies explained. Versalis is continuing to test the bio-BDE within its other proprietary rubber and plastics downstream technologies such as SBR (styrene butadiene rubber), SBS (styrene butadiene styrene rubber) and ABS (acrylonitrile butadiene styrene).
Other automotive makers getting on the bandwagon
Meanwhile, Japanese automotive manufacturer, Toyota, has also embarked on biobased rubber alternatives to reduce its carbon footprint across its vehicle line, having endorsed a commitment to sustainable rubber by becoming the first car manufacturer to sign a partnership agreement with WWF.
In May this year, Toyota has claimed its locus as the world’s first automotive maker to use biohydrin, a newly-developed biosynthetic rubber product, in the engine and drive system hoses.
The biohydrin rubber is jointly developed with Japanese chemicals manufacturer Zeon Corporation, and another Japanese company that produces rubber and synthetic resin, Sumitomo Riko. It is manufactured using plant-derived bio-materials instead of epichlorohydrin, a commonly-used epoxy compound. Since plants absorb CO2 from the atmosphere during their lifespan, such biomaterials achieve an estimated 20% reduction in material lifecycle carbon emissions (in comparison to conventional petroleum-based hydrin rubber), explained Toyota.
The first vehicles to use vacuum sensing hose made from biohydrin rubber were produced in May, with usage expected to be rolled out to all Toyota automobiles manufactured in Japan by the end of this year.
Engine and drive system hoses require a particularly high level of oil and heat resistance. Since epichlorohydrin offers exceptional oil resistance, heat resistance, heat ageing resistance, ozone resistance, and gas permeability, it is currently commonly used as a key compound in the production of rubber for components such as hoses.
Production of biohydrin rubber uses a variety of compound technologies for bonding plant-derived materials with petroleum-derived materials at the molecular level. These technologies ensure that biohydrin rubber provides the levels of oil resistance, heat resistance, and durability required for vacuum sensing hoses in engines and drive systems.
Additionally, biohydrin rubber is similar to conventional petroleum-based hydrin rubber in terms of quality and mass production, enabling large-scale use in commercial vehicles. Toyota says that it plans to expand the usage of biohydrin to other highperformance rubber components, such as brake hoses and fuel line hoses.
The company’s impetus towards developing biorubber is part of the Toyota Environmental Challenge 2050, its roadmap for contributing to global environmental sustainability.