ADDITIVES | REINFORCEMENT
Proper sizing selection provides benefits including optimising interfacial adhesion and compatibility to the matrix resin, resulting in improved mechanical properties
fibre is more expensive than glass fibre, and [carbon fibre also] offers better composite proper- ties, the economics to recover and recycle provide a more robust business case. It remains to be seen how end-of-life concerns will affect the market, but it is a growing question.”
Michelman is actively working with companies in
recycled CF. “Without adding sizing it is very difficult to reuse recycled carbon fibre,” Bassetti said. “The majority of the carbon fibre market uses epoxy chemistry for sizing, but to optimise perfor- mance, we need to ‘oversize’ the epoxy sizing with one that is compatible with thermoplastics. The epoxy sizing has enough reactivity for the new sizing to attach to.” One source of CF used by companies making
recycled CF is the post-industrial collection of spools or bobbins of continuous CF fibres. “Pro- cesses that use continuous carbon fibre are often set up to use full bobbins, so the carbon fibre remaining – which could be 30% of the spool, for example – can be oversized, chopped, and used in thermoplastics,” he explained. Other post-industrial CF sources used by the industry add sizing as a ‘glue’ that holds the fibre bundles together so that they can be fed into a compounding extruder.
Fibre markets Bassetti sees growing markets for glass and carbon fibre. “While the glass-fibre reinforced thermoplas- tic (GFRT) market is relatively mature, the level of adoption is high and continues to grow at higher than GDP-growth rates due to these advantages over metal,” he said. CF has been traditionally used more in thermosets, so there is room for growth and innovation in thermoplastics. “Carbon fibre has
22 COMPOUNDING WORLD | June 2025
Source: Michelman
better performance than glass fibre and so you can make thinner parts when using carbon-fibre reinforced thermoplastics (CFRT), but the weight reduction is offset partly by the higher cost of carbon fibre. We do see growing adoption of CFRT at two or more times GDP.” He added that this strong growth in fibres is occurring in a hyper-competitive market with a significant overcapacity in GF, due primarily to capacity expansion in China, which has led to recent changes in fibreglass market players. One of the more recent announcements was in
February 2025, when US-based Owens Corning said that it was selling its glass reinforcements business to India-based Praana Group. Owens Corning said that it would focus on its building products in North America and Europe and would retain its integrated glass nonwovens business. Praana Group’s portfolio currently includes 3B Fibreglass, which offers chopped strand and direct roving for thermoplastics, as well as other products.
Recycled CF US-based Vartega says that recycled carbon fibre (rCF) is a lower carbon-footprint alternative to virgin carbon fibre and that it can be made cost- effectively, which makes it an alternative to glass fibre for lightweighting high-performance thermo- plastics. The company reclaims carbon fibre from post-industrial dry fibre and prepreg scrap sources and uses this rCF to manufacture the company’s proprietary EasyFeed Bundle technology, which is designed for thermoplastic compounding. “The majority of the manufacturing waste we use becomes waste prior to being put on a spool and does not otherwise have an outlet other than
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