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Issue 06/2017

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  • Bioplastics
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Polyurethanes /

Polyurethanes / Elastomers Biobased EP(D)M Focus on sustainability ARLANXEO Netherlands has made a pioneering move towards exploring a future based on renewable resources, by developing the world’s first biobased EP(D)M elastomers commercialized under the tradename Keltan ® Eco. Keltan Eco is produced from biobased ethylene supplied by Braskem which originates from sugar cane (Figure 1). The sugar from sugar cane is converted to ethanol, which is then dehydrated to ethylene by Braskem in their Brazilian Triunfo plant. This biobased ethylene is transported via a pipeline to the neighboring Arlanxeo EP(D)M polymerization plant. Depending on the ethylene content of the particular grade, the bio-carbon content of Keltan Eco elastomer ranges between 48 and 70 wt-%. Translating this to final rubber articles produced from EP(D)M compounds, a bio-carbon content of 15-20 wt-% can be achieved, if Keltan Eco is the only biobased ingredient of the compound (Figure 1). Keltan Eco gives the following benefits: • reduced dependence on fossil resources; • reduced carbon footprint due to use of sugar cane; • truly sustainable as validated by a Life Cycle Assessment performed by Thinkstep; • biobased content up to 70% measured and traced back by ASTM D6866 carbon-14 test performed by Beta Analytic. Figure 2 shows the Global Warming Potential of Keltan Eco. Depending on ethylene content the EP(D)M carbon footprint is reduced up to 82 % for Keltan Eco 5470 (70 wt-% biobased ethylene) and up to 54 % for Keltan Eco 8550 (55 wt‐% biobased ethylene). Figure 2 - Global Warming Potential of Keltan Eco 5470 and 8850 compared to crude oil-based Keltan 5470 and 8550, all produced in Triunfo plant (kg CO2-equiv. per ton polymer) (Data by Thinkstep). In essence Keltan Eco elastomers look, feel and behave like conventional crude oil-based EP(D)M, which show exceptional elasticity, flexibility, weather ability and durability. It can be mixed, moulded, extruded and calendared to produce rubber articles with excellent aesthetics. Arlanxeo has six Keltan Eco elastomers commercially available in its portfolio (Table 1). Typically, rubber articles not only consist of elastomer(s), but also of (reinforcing) filler(s), plasticizer(s), crosslinking agents and other additives. EP(D)M products may contain higher than 400 phr of compounding ingredients incorporated into 100 phr of EP(D)M elastomer. Carbon black is produced via incomplete combustion of a hydrocarbon feed with natural gas. Silica is produced via precipitation from a silicate salt solution. Inert white fillers, such as clay, talc and chalk are extracted from the ground in open mines and milled to fine powders. Traditional extender oils for EP(D)M are refinery fractions of crude oil. All of these ingredients, lack sustainability. In further efforts to increase the sustainability of EP(D)M rubber products based on Keltan Eco, the potential of using sustainable alternatives for traditional plasticizer oils and (reinforcing) fillers have been explored. Typical issues encountered when exploring relatively polar and unsaturated natural oils and fats in EP(D)M compounds are: • a lack of compatibility (mixing issues and oil bleeding); • competition for sulfur vulcanization (reduced crosslink density, inferior vulcanization properties). Modified natural oils, such as hydrogenated coconut oil or trans-esterified mono-esters have improved compatibility and/or vulcanization performance. Squalane (EPM hexamer) provides the best biobased alternative for mineral oil plasticizer, since it is as apolar as EP(D)M and is fully saturated. As far as sustainable fillers are concerned, pyrolysis black was shown to have a reinforcing efficiency 90 % of that of furnace N550 black. Rice husk ash and micro-cellulose do not show reinforcing properties, but can still be used as inert, white fillers, substituting certain traditional, mineral white fillers. Combining these sustainable plasticizer oils and (reinforcing) fillers has resulted in automotive solid seal EP(D)M compounds based on Keltan Eco with more than 85 % sustainable content and properties comparable to the reference EP(D)M compounds, including heat ageing resistance up to 125 ºC. The final step towards a fully sustainable EP(D)M rubber compound would require the development of biobased rubber additives and curatives, which considering their chemical structure will be a long and challenging development. Aside improving sustainability of EP(D)M rubber products by compounding sustainable plasticizer oils, (reinforcing) fillers, another approach would be to develop a second generation Keltan Eco EP(D)M based on bio-ethylene ánd bio-propylene, which would bring the total biocarbon content of the EP(D)M elastomer, and sustainable compounds directly, to ~95 %. 14 bioplastics MAGAZINE [06/17] Vol. 12

Polyurethanes / Elastomers By: Joyce Kersjes Technical Manager Global M&S/TSAD Keltan EPDM Arlanxeo High Performance Elastomers Geleen, The Netherlands Table 1 - Keltan Eco EP(D)M portfolio and key properties For the future Arlanxeo and its raw material suppliers are assessing routes to increase the biocarbon content of the EP(D)M elastomer to a maximum attainable, amongst others via: • production of methanol from wood, followed by conversion of methanol to propylene; • sugar-based routes either via ethanol to ethylene and then via metathesis to propylene or via isopropanol to propylene; • direct fermentation of glucose using genetically engineered micro-organisms to a mixture of olefins, including propylene. The finishing touch to 100 % bio-carbon EP(D)M elastomer would be a biobased diene. As an example to stimulate interest, it can be mentioned that first experiments with an amorphous EP(D)M with 6 wt% 2,4-dimethyl-2,7-octadiene (natural terpene) as the diene, showed reasonable sulfur vulcanization characteristics and corresponding vulcanization properties, similar to a medium ENB- EP(D)M. Up till now Keltan Eco has received a positive response in the market and commercialization at customers is on-going in different application segments, like automotive and construction window and door sealing systems, as well as in hoses, innertubes, (bio-)plastics impact modification, TPE-V production, sport surfaces and sports goods. Some examples are displayed below. In conclusion: The broad portfolio of Keltan Eco EP(D)M elastomers offers the unique opportunity to industries to develop sustainable and bio-carbon based compounds and TPE-Vs for many applications. | [kg CO 2 -Equiv] Sugar cane Crude oil Figure 2: Global Warming Potential of Keltan Eco 5470 and 8850 compared to crude oil-based Keltan 5470 and 8550, all produced in Triunfo plant (kg CO 2 -equiv. per ton polymer) (Data by Thinkstep) 3,500 3,000 2,500 2,000 1,500 1,000 500 0 Grades Raw materials Ethanol Viscosity ML(1+4) (@ shown °C) [MU] Figure 1 - Route to biobased EP(D)M 100% bio-based Ethylene 0% bio-based C2 [wt%] 50-70% bio-based Keltan-Eco® EPDM ENB [wt%] Keltan Eco 0500R 11 g/10 min. (MFI) 49 - Keltan Eco 3050 51 (@ 100°C) 49 - Keltan Eco 5470 55 (@ 125°C) 70 4.6 Keltan Eco 8550 80 (@ 125°C) 55 5.5 Keltan Eco 6950 65 (@ 125°C) 48 9.0 Keltan Eco 9950 60 (@ 150°C) 48 9.0 15-20% biobased 0% bio-based End products K5470 Triunfo K5470 Eco K8550 Triunfo K8550 Eco bioplastics MAGAZINE [06/17] Vol. 12 15

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