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Issue 01/2023

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Automotive Sustainable

Automotive Sustainable banana fibre composites for automotive interior applications According to the EU Climate Package: Fit For 55, Europe aims to become climate-neutral by 2050. The proposed regulations also aim at reducing CO 2 emissions for new passenger cars and light commercial vehicles. Therefore, sustainability has become an important issue for automotive manufacturers and their suppliers. Due to their environmentally friendly properties, low costs, and good specific mechanical properties, plant-based fibres have replaced various synthetic fibres in the automotive composites industry. The Automotive interior composites sector is currently with the highest demand for natural fibre composites, was valued at approximately EUR 8 billion in 2019 and is estimated to grow at a compound annual growth rate of 7.5 % from 2020 to 2027. Possible sources of fibres are flax and hemp, which, however, when grown as a monoculture, can also have negative effects on food production for humans and animals. However, there are other natural fibres, such as banana fibres, which have promising mechanical properties and can be used as an alternative to fibres made from fossil raw materials or non-sustainable natural fibres. The banana is the most widely grown fruit in the world, with an annual production of around 120 million tonnes. However, banana plants can only bear fruits once in their lifetime. Once the bananas are harvested, the plant is cut, and the leaves and stems are considered lignocellulosic biomass. The fruits account for only 25 % of the total weight of the banana plant, while the pseudostem accounts for about 60 %. As a result, around 290 million tonnes of banana stems are discarded unnecessarily each year. India, China, Indonesia, Rwanda, Angola, Brazil, Guatemala, and Ecuador are the main banana-producing countries. Since most of the above countries are still developing countries, a significant amount of banana production waste is either landfilled or incinerated. Burning the waste material produces greenhouse gases (GHGs). Decomposing additionally produces harmful gases such as hydrogen sulfide, ammonia, and methane, which pose a serious threat to the environment. However, banana fibre can be extracted from the stems of banana plants using a simple, environmentally friendly, and costeffective mechanical process. With the support of the Institut für Textitlechnik (ITA) of RWTH Aachen University, Biointerio, a student start-up initiative of RWTH University, has developed a process to produce valuable recyclable and biodegradable composite materials from banana fibres and a biodegradable polymer (polylactic acid) for automotive interior applications. The use of this material leads to a prevention of CO 2 emissions generated by the combustion and decomposition of banana plants as well as from the disposal of end-of-life vehicles. It not only promotes a solution to close the value streams of the composite and banana industries, but also contributes to the UN’s 1 st , 8 th , 9 th , 11 th , 12 th , and 13 th Sustainable Development Goals (SDGs). The unique value proposition (UVP) of the composite developed by team Biointerio compared to natural fibre-reinforced composites available on the market, such as flax and hemp-reinforced composites, is that banana fibres have a lower density (up to 20 %) and comparable tensile strength, cost about three times less than flax fibres and half of hemp fibres, are available in large quantities, and are derived from food industry waste. The team first sourced various types of banana fibres from India with varying levels of fineness. They then identified and optimised a suitable production process and produced hybrid nonwovens from banana fibres and polylactic acid fibres (biodegradable matrix fibre) on lab-scale which were subsequently processed to composite by hot forming (see Figure 1 and Figure 2). The composite material samples produced by Biointerio show a thickness of 1.6 mm while having a density of 1,24 kg/m³. Mechanical tests showed a minimum flexural strength of 50 MPa, fulfilling the requirements of the automotive industry for door panels. However, the tensile strength of the produced composite is slightly below the required minimum value of 25 MPa (Figure 3). Moreover, the results of thermogravimetry showed that the main degradation step starts at an initial temperature of 288°C and a second, smaller step occurs at around 430 °C. The material showed excellent thermal stability up to these temperatures and could therefore be suitable for use as a material in automotive interior applications. Figure 2: Nonwoven-based composite manufacturing process [Source: ITA] 22 bioplastics MAGAZINE [01/23] Vol. 18

ROLL-UP 80X200_22-25 june.indd 1 By: Maryam Sodagar, Carsten Uthemann, Thomas Gries RWTH Aachen Institute of Textile Technology Aachen, Germany DESIGN & materials Automotive smart technology However, further improvements are still required to meet the high standards of the automotive industry. The banana fibre-reinforced composites may also be used in furniture, architecture, and sports applicaions in the future. Sustainability Figure 1: Consolidated composite plates [Source: ITA] Flexural strength [MPa] 50 40 30 20 10 25 20 15 10 5 Tensile strength [MPa] 0 Flexural Strength Tensile strength 0 • Bending test according to DIN EN ISO 14125 • 1 kN XForce HP force transducer • 1 mm/min testing speed • Tensile test according to DIN EN ISO 572-4 • 5 kN XForce HP force trandsducer • 2 mm/min testing speed Figure 3: Flexural and tensile strength of banana fibre-reinforced composites bioplastics MAGAZINE [01/23] Vol. 18 23

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