IMPACT MODIFIERS | ADDITIVES
and toughness in PA and polyester compounds. Better flow properties are required for cycle time reduction across applications, helping to reduce energy consumption,” according to Henschke. “Automotive OEMs have defined ambitious carbon dioxide reduction targets and timelines,” he says. “Bio-based impact modifiers can play an important role to enable lower carbon footprint compounds. Another way of reducing the use of fossil-based materials and related emissions is the addition of recycled polymers in automotive compounds. The 2023 update of the end-of-life vehicle (ELV) directive will likely define mandatory recycled content targets for the near future and hence will ask for new solutions to be implemented in the automotive value chain. When using post- consumer sources for recyclates, impact modifiers often need to act as compatibilisers and flow enhancers as well, so novel materials are needed.” Dow says technical developments for its next
generation of polyolefin elastomer impact modi- fiers will support the continued lightweighting trend with low CLTE PP compounds. Improvements in rubber efficiency, stiffness/toughness/flow balance and cycle time are possible at the same time. Safety requirements in the growing EV segment emphasise the need for plastic compounds with improved CTI and flame-retardant properties. Another topic of interest is the improvement of processability enabling higher flow PA compounds that are required for thinner-walled automotive parts.
Recycling ideas Recycled polymers are finding increasing use in the
automotive interior and exterior space, adds Dow. Typical applications include, for example, rein- forced PP compounds for bumper fascia or door panels. PP recyclates from post-consumer waste often suffer from a limitation in impact performance due to partial degradation of the matrix material during processing and first life. It says Engage poly- olefin elastomer grades can help to compensate for this drop and allow an improvement in impact performance to virgin material level. The latest products from Dow include Engage 11000 polyolefin elastomers, which are PP impact modifiers for lightweighting and enable metal replacement and thin walling in thermoplastic olefin (TPO) compounds. This elastomer range is also used for PP compounds with recycled content from post-industrial and post-consumer waste sources. Engage 11000 allows TPO compounders, part manufacturers and OEMs to develop solutions with reduced part weight and improved system costs through processing advantages. It also enables more complex designs and thinner parts with a higher balance of flow, stiffness and toughness. TPO compounds modified with Engage 11000
are suitable for a range of applications, including instrument and door panels, air bag covers and bumper fascia, rocker panels and tail gates. The additive is said enable the use of recycled PP content and provide features such as low CLTE and improved paint adhesion. Engage 11000 can also act as a compatibiliser in PP compounds with some PE contamination. A recent automotive study carried out by Dow
Figure 1: A recycling study carried out by Dow shows flexural modulus and Charpy impact data for a recycled ‘input’ blend of waste PP battery case and mixed PE/PP film resin converted to a TPO ‘output’ compound suitable for use in an automotive underbody part using its Engage impact modifier Source: Dow
www.compoundingworld.com
looked at the quality of recycled PP from end-of-life vehicles and aimed to determine their ability to be used in an under-the-body part. Trials showed that small amounts of Engage polyolefin elastomers could enable the use of a battery case PP in combination with bumper TPO in a resulting recycled PP formulation. Due to limited availability
April 2023 | COMPOUNDING WORLD 55
Above:
Lightweight, impact resistant
compounds are in demand for both EVs and EV charging equipment
IMAGE: SHUTTERSTOCK
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