Politics Don’t compare
Politics Don’t compare apples and organges Using LCA to compare biobased and fossil-based plastics is not that simple By: Constance Ißbrücker Head of Environmental Affairs European Bioplastics e.V. Berlin, Germany Life cycle assessment (LCA) has evolved to be the preferred tool to assess the environmental sustainability of certain products and materials. Recently it has also been used with great enthusiasm to compare biobased with fossil-based plastics. It seems to be an easy instrument to draw conclusions on certain advantages or disadvantages of both material groups. However, there are quite some hurdles to overcome if you do not want to end up comparing apples with oranges again. There are several aspects to which attention must be paid in order to guarantee a fair comparative assessment. Fossil-based plastics have experienced many decades of continuous, often heavily subsidised, process improvements, whereas most biobased alternatives are still at the beginning of their maturity/optimisation curve. Therefore, comparing fossil-based with biobased plastics is comparing mature and immature production systems. Future improvements in terms of feedstock sourcing, production, conversion, and end-of-life options need to be considered and assessed by appropriate assumptions and modelling approaches. Additionally, it is often assumed that the applied inventory data of biobased and fossil-based materials are comparable. That is currently not the case, we have no real level playing field. Fossil- and biobased plastics datasets should be brought to the same level of quality in terms of their completeness, system boundaries, regional scope, and, of course, transparency. It is one of the inherent advantages of biobased materials that they are produced from annually renewable feedstock, such as corn, sugarcane, or wood. Thus, CO 2 is taken up from the atmosphere, and the biogenic carbon is locked up in the biobased product. At the product’s end of life (i.e. when it can no longer be recycled), the carbon re-enters the natural carbon cycle via incineration or composting, thereby closing the material carbon loop. Biobased plastics are independent of fossil resources and do not contribute to harmful environmental effects connected with the exploitation of fossil raw materials such as crude oil. Effects of the latter are, interestingly, hardly considered in LCA data modelling. In contrast to certain possible negative indirect effects connected with the sourcing of renewable feedstock. No doubt, it can make sense to look at factors such as ILUC (indirect land-use change) and gain additional information on this subject. However, for the sake of fair play, indirect effects caused by fossil-absed materials and their production need to be considered as well. Furthermore, LCAs should not only focus on the negative impacts but also account for indirect positive impacts, especially where these are of high relevance to a functioning circular economy (e.g. the beneficial effects on biowaste collection by using industrial compostable bio-waste bags). Biobased plastics offer multiple end-of-life options, depending on the material chosen and the application at hand. For example, biobased drop-ins (e.g. bio-PE or bio- PET) can be mechanically recycled in the existing recovery streams. Industrially compostable materials that are certified in line with EN 13432 can be recovered through organic recycling. Any selected end-of-life option needs to be material and product-specific and reflect reality. Whatever impact categories are considered in a comparative LCA of fossil- and biobased materials, a transparent and acknowledged methodology (like ISO 14040/44, or PEF methodology) must be the basis, without neglecting stakeholder involvement. In the end, the interpretation of the results is a crucial aspect and can, when done frivolously, be harmful to the whole bioplastics sector. Especially in a policy context, proper communication of LCA outcomes is of high importance and should show the necessary sensitivity and expertise. For more information on this topic please also read the EUBP Position Paper [1]. [1] “Sound LCA as basis for policy information” www.european-bioplastics.org 26 bioplastics MAGAZINE [03/21] Vol. 16
Compounding PLA Processing PLA on a production scale Continuous Mixer Processing Farrel Pomini (Ansonia, Connecticut, USA) has completed a second research study on processing Ingeo polylactide (PLA) with Farrel Continuous Mixing Technology. The original study, conducted in 2018, compared the results of processing PLA compounds with various levels of talc mineral filler utilizing the Farrel Pomini CPeX ® , a laboratory-scale continuous technology mixer, and a twin-screw extruder to evaluate the effects on molecular weight retention and melt temperature. The CPeX has a nominal production range of 10–30 kg/h. The original study found that processing with the CPeX resulted in significantly better molecular weight retention with values as high as 95 % depending on the level of filler (Fig. 1). In addition, the trials demonstrated that FCM Farrel Continuous Mixer technology provided distinct advantages over the twin-screw extruder for lower processing temperature (Fig. 2) and specific energy input. In this follow-up study, a production size and scalable CP550 Compact Processor was utilized to confirm the results of talc loading levels on both molecular weight and processing temperatures found with the CPeX ® and determine output rate. The research on the CP550 determined: • The molecular weight retention followed the trend seen with the CPeX. With the addition of 1 % of EBS (ethylene bis stearamide), a common additive used when processing PLA, the molecular weight retention on the CP550 was 84 % at a 60 % talc loading level. The rate is also significantly better than the molecular weight retention on the twin-screw extruder found in the initial study. • Process temperatures on the CP550 were higher than those seen on the CPeX, albeit still lower than temperatures on the twin-screw extruder. However, due to the short residence time provided by continuous mixing technology, molecular weight retention is still maintained to an enhanced level. A more comprehensive white paper is available for download at: www.bioplasticsmagazine.de/202103/white-paper.pdf. AT www.farrel-pomini.com PLA/Talc Processing Temperatures % Mw Retention Effects of Talc Filler on Mw Retention 120.0% 100.0% 80.0% 60.0% 40.0% 20.0% 0.0% 10 20 30 40 50 60 70 80 Percent Talc CPeX CP550 CP550 with 1% EBS TSE Melt Temperature 250 240 230 220 210 200 190 180 170 160 150 10 20 30 40 50 60 70 80 Talc Concentration (%) CPeX CP550 CP550 with 1% EBS Figure 1: Effects of Talc loading level on M w Retention Figure 2: PLA/Talc Melt Temperature as a function of Talc concentration bioplastics MAGAZINE [03/21] Vol. 16 27
