MATERIALS | REINFORCEMENTS
during processing, according to Sumika. Sumika says its Thermofil HP and recycled
Right: Sumika says its Thermofil HP short glass reinforced compound outperforms LFT in this Stellantis tailgate application
polypropylene (GF-rPP) Thermofil Circle com- pounds offer carmakers the performance equiva- lent to incumbent engineering plastics such as PA, but with sustainability benefits. “Our Thermofil short glass-fibre reinforced PP compounds offer equivalent performance to traditional engineering plastics while providing a much lower carbon footprint, which makes them highly suitable to meet design challenges that sustainable eMobility brings,” said Bruno Pendélio, Marketing Manager for SPC Europe. While glass reinforced parts offer many benefits in terms of performance, one potential disad- vantage is an increased tendency to warp during the injection moulding process. Japanese company Nittobo has developed a line of chopped glass fibre strand with a modified cross section using its proprietary FlatFiber (FF) technology. In contrast with conventional
fibres, which have a round cross section, the company’s FF products feature an oval cross section. Tests show that the physical properties of FF are greater than those of conventional fibres, while other advantages of the flatter profile include lower warpage and improved dimensional stability. The company says these qualities simplify process- ing and can increase resistance to impact and heat. Japan has also been a longtime user of Fleka
and Fineflake glass flakes, which are manufactured by NSG Group and distributed in the US by Dreytek. The flakes are said to improve strength and stiffness in injection moulded parts and extrud- ed sheet, while minimising shrinkage and warpage issues. This is attributed to the tendency of the glass flakes to orient parallel to the resin surface, meaning they provide a level of dimensional changes not only in the flow direction (MD direc- tion) but also in the transverse direction (TD direction). Dreytek says the MD shrinkage/TD shrinkage is close to one.
Warpage control Warpage can be controlled using standard glass fibres in combination with mineral fillers, but this can lead some loss in mechanical properties, according to Dreytek. “By utilising Fleka and Fineflake, the need to make this common trade-off between mechanical properties and part warpage/
64 COMPOUNDING WORLD | June 2023
shrinkage is eliminated. These glass flake reinforce- ments are truly a problem solver,” says Liz Gershon, North American Business Manager for Dreytek. Fleka and Fineflake are produced using NSG’s
proprietary manufacturing technology to control the thickness of the glass flake (Fleka at 5.0 µm and Fineflake at 0.7 um). They are typically used in applications where a mixture of dimensional stability and mechanical properties is required, including small components such as electronic connectors where precise mating is critical especially when the connectors are exposed to thermal cycling. Other applications include large, thin wall flat parts. Speciality chemical manufacturer Michelman, which develops sizing products to improve the interfacial adhesion between polymer matrices and reinforcing fibres such as glass, reports some major development trends in the industry. “Two emerging areas of development are occurring in parallel and helping to drive innovations throughout the composites industry,” says Steve Bassetti, Global Marketing Director, Composites. “They include the emergence of
processes enabling the use of continuous fibre technologies for thermoplastic composites as well as an expanding pool of fibres, includ- ing basalt and natural fibres,” he says. “Together, these developments create new opportunities to grow the composite market and meet society’s
growing interest in sustainability. Continuous fibre formats, such as thermoplastic unidirectional tapes and organo-sheets, enable precise targeting for structural reinforcement [and] allow designers to meet the demanding challenges of applications while providing for potential recycling at end-of-life.” Production of glass fibres is a relatively energy intensive process but the industry has been working to minimise that. A life cycle assessment (LCA) covering production of continuous glass fibre published earlier this year by producer association Glass Fibre Europe, showed that between 2015 and 2021 the European industry reduced the primary energy consumed to produce 1kg of continuous filament glass by an average of 8.1% and greenhouse gas emissions by an average of 3.2%. The report, based on 2021 manufacturing data from 11 plants across the EU, UK, and Norway, went on to state that 44% of the industry’s produc- tion waste was recycled in 2021, a 26% rise compared to 2015.
www.compoundingworld.com
IMAGE: SUMIKA
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