REINFORCEMENT | ADDITIVES
Firms turn to recycled fibres for compounds
Companies are collaborating to find new ways to manufacture and use recycled fibres as a reinforcement material in polymer compounds. Jennifer Markarian finds out more
Trends such as the miniaturisation of electronics and lightweighting of vehicles continue to drive growth in use of fibre-reinforced thermoplastics to replace metals, because thermoplastics provide the ability to create complex geometries and thus add functionalities to moulded parts and to simplify assembly. The largest volume in fibres used for reinforcing thermoplastics is glass fibres (GF), followed distantly by carbon fibres (CF), said Steve Bassetti, Michelman’s Director, Global Marketing, Fibres & Composites. Fibres are coated with a sizing both to bind the
fibres so that they can be fed into the compound- ing extruder and to act as a coupling agent between the fibre and the thermoplastic to improve properties of the final part. Michelman’s sizings are used in in combination with silane- based sizing chemistries in glass fibres, and without silane in carbon fibres. The type of sizing chemistry
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is primarily dependent on the target polymer matrix. A different sizing is used for polyamides than for polypropylene, for example, Bassetti explained.
Michelman also provides sizings for basalt fibres for use in thermoplastics. “Basalt fibres fall between glass fibre and carbon fibre in cost and perfor- mance, and they can be sized with similar chemis- tries to glass fibre,” he said. A recent trend that affects the fibre market is
increasing consideration of the end-of-life of reinforced parts, said Bassetti. Because thermoplas- tics are recyclable, they have an advantage compared to thermosets for circularity. “The challenge is the economic model,” he said.
“For glass fibre it is generally cheaper to use virgin fibre, because of the cost and the need for infra- structure to collect composite parts, recycle to recover the fibres, and ship the material. As carbon
June 2025 | COMPOUNDING WORLD 21
Main image: Johns Manville and PureLoop have developed a recycling process that transforms post-industrial waste filtration media into glass fibre-filled compounds
IMAGE: PURELOOP
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