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rCF-UD-Tapes in thermoplastic composite materials: From recycled fibers to structural applications

How rCF-UD-Tapes are produced, where the fibers come from, how they compare to primary fibers, and where they can be used in structural thermoplastic composites. [Photo: fenix composites]
August 23, 2026 by
Alformet GmbH, Lucas Ciccarelli

The carbon fiber waste problem — and a structural answer

Every year, tens of thousands of tons of carbon fiber reinforced plastic waste (CFRP waste) are generated worldwide — from manufacturing scraps in aviation, decommissioned aircraft parts, retired wind turbine blades, and sports equipment. Until recently, the majority of this material ended up in landfills or was downcycled into low-quality filler applications. The intrinsic properties of carbon fiber — properties that require 198 to 595 MJ/kg of energy to produce — were simply discarded.

The question that the composite industry has been grappling with for over a decade is: Can recycled carbon fibers (rCF) be used again in structural applications? And more specifically: Can a semi-finished product be made from them that can compete with primary fibers in automated manufacturing processes?

The answer is increasingly: Yes — and the crucial key to this is the rCF unidirectional tape (UD-Tape).

Where the fibers come from: Recycling processes and raw materials

Before an rCF-UD-Tape can be produced, the fiber must first be recovered from its original composite matrix. There are three main recycling processes that significantly differ in their impact on fiber quality:

Pyrolysis is the most widely established thermal process in industry. The CFRP waste is heated in a controlled atmosphere (typically 450–600 °C), causing the polymer matrix to burn off and leaving the carbon fibers behind. Pyrolysis can retain 80–90% of the original tensile strength and modulus of elasticity and is suitable for both thermosetting and thermoplastic waste. The process consumes about 30–49 MJ/kg — a fraction of the 262–464 MJ/kg required for the production of primary fibers. Industrial providers like CarboNXT operate at this level.

Solvolysis uses chemical solvents — often subcritical or supercritical water, alcohols, or glycols — to dissolve the matrix at lower temperatures. Fiber retention can be high (up to 90–95% tensile strength in certain solvolysis routes), and the process is gentler on the fiber finish. However, solvolysis is associated with a significantly higher environmental impact due to solvent chemistry and health effects compared to pyrolysis.

Mechanical recycling (shredding, grinding) produces the shortest fibers with the greatest loss of properties. It is the least suitable method for producing structural UD tapes and is typically used for non-structural injection molding compounds.

A crucial factor for the quality of the raw material is the origin of the waste: Manufacturing scraps (so-called dry fiber waste or prepreg trimmings) tend to provide longer, cleaner fibers with better finish retention than end-of-life composite components, which may contain multiple resin systems and contaminants.

How rCF-UD tapes are produced: Transforming chaos into structure

The fundamental challenge with recycled carbon fibers is that they emerge from the recycling process in a tangled, disordered state — far from the perfectly parallel, continuous roving yarn of a primary fiber spool. The conversion of this disordered material into a high-performance UD tape requires a multi-stage textile engineering process.

Research institutions such as the German Institutes for Textile and Fiber Research Denkendorf (DITF) and the Technical University of Dresden (TU Dresden) have spent over 15 years developing and refining this process chain. The approach, which was demonstrated in the BMBF-funded project Infinity typically includes the following steps:

  1. Opening and Mixing: The rCF is mechanically opened and mixed with thermoplastic matrix fibers (often polyamide 6, PA6) in a defined ratio to achieve the desired fiber volume content.

  2. Carding: A modified carding machine aligns the mixed fibers into a fiber band — a continuous, loosely oriented bundle of fibers.

  3. Stretching: The fiber band passes through a series of stretching roller pairs that gradually align the fibers in the longitudinal direction. A hot air blower partially melts the thermoplastic component, allowing for consolidation between the roller stages.

  4. Tape formation and fixation: The stretched, oriented fiber tape is consolidated into a flat tape. The thermoplastic fibers melt and solidify again, fixing the rCF in a highly oriented configuration.

  5. Edge trimming: The tape edges are trimmed to achieve a uniform width — a critical feature for downstream automated processing.

The result is a thermoplastic UD semi-finished product that is entirely made from recycled raw material. Practitioners like Philipp Huber from Fenix Composites (Flensburg) have significantly contributed to demonstrating the practical use of such tapes — among other things in wound thermoplastic pipes for bicycle frames — and documenting the real engineering challenges in processing rCF in structural applications.

Quality assurance: The central challenge with rCF tapes

Unlike primary fiber tapes, which come from a single, strictly controlled raw material, rCF tapes inherit the variability of their raw material. This makes quality assurance not only important — it is the defining engineering challenge of this material.

Essential quality parameters are:

  • Fiber length distribution: Recycling inevitably shortens fibers. The carding and stretching process additionally affects the final fiber length. Longer fibers (>20 mm) are crucial for effective load transfer in structural applications.

  • Consistency of fiber volume content (FVG): Fluctuations in the FVG over tape width or length directly affect the dispersion of mechanical properties. Nonwovens made from rCF typically achieve FVG values of up to about 35%; highly oriented rCF tapes can exceed this value but require demanding process control.

  • Fiber orientation / Orientation distribution: The degree of fiber orientation — quantifiable through methods such as micro-CT or image analysis — is the most important influencing factor on the stiffness and strength of rCF tapes in the plane.

  • Residual matrix contamination: Incomplete pyrolysis leaves soot deposits on the fiber surfaces, which reduce interfacial adhesion. The fiber sizing is often lost or damaged during recycling, which must be compensated for by re-sizing or surface treatment.

  • Uniformity of width and thickness: Essential for automated tape laying or tape winding processes.

Research groups have developed inline quality measurement systems — including novel optical testing devices developed as part of the German research project rCF-Tape — to assess tape quality against primary material benchmarks under production-like conditions. The standardization of quality levels for rCF tapes remains an open task for the industry.

Performance compared to primary fibers: What the data actually shows

The honest answer is: rCF-UD tapes do not reach the level of primary fiber composite materials — but the gap is smaller than generally assumed, and it is getting smaller.

The Infinity-Tape from the DITF achieved 88 % of the tensile strength and the tensile modulus of a comparable primary fiber product. This is a significant result: It shows that highly oriented rCF tapes are no longer limited to non-structural applications. Further studies report:

  • Pyrolytically recovered fibers retain 80–90 % of the tensile strength and modulus of primary fibers at the single fiber level.

  • Composite laminates made from solvolytically recovered fibers achieve up to 93 % of the property level compared to virgin CFRP.

  • rCF-UD tapes processed by AFP show tensile and bending properties that improve with each process improvement iteration.

The main causes of performance decline are:

  • Shorter fiber length → reduced stress transfer efficiency

  • Degraded or missing sizing → weaker fiber-matrix interface

  • Misalignment of the fibers → lower stiffness in the plane

  • Higher porosity or void content → stress concentration points

Crucially: Stiffness (modulus) is better preserved than strength. For applications where deformation control and the stiffness-to-weight ratio are the primary design drivers — pressure vessel windings, structural pipes, stiffening profiles — rCF-UD tapes are a technically credible option. For applications requiring maximum tensile strength at the laminate level, the performance gap must be compensated through careful design.

Impact on component design: Constructing with rCF from the outset

The use of rCF-UD tapes is not a simple material substitution — it requires a change in construction philosophy. Philipp Huber from Fenix Composites refers to this as End-of-Life appropriate design: the idea that recyclability and the use of recycled materials must be considered in the earliest phases of product development — and cannot be retrofitted only at the end of the component's life.

In practice, designing with rCF-UD tapes means:

  • Applying reduction factors: Design limits must reflect the reduced and more variable mechanical properties of rCF. Safety margins should be defined based on rCF-specific test data — not by simply scaling primary fiber data sheets.

  • Utilizing the thermoplastic matrix: The thermoplastic nature of rCF-UD tapes allows for welding, reshaping, and end-of-life recycling — a closed loop that thermoset-based rCF products cannot offer. This is a real design advantage.

  • Layer structure: Since rCF tapes contain shorter, discontinuous fibers, load paths must be designed conservatively. Quasi-isotropic or multi-angle layer structures can compensate for the lower unidirectional strength compared to continuous fiber tapes.

  • Hybrid approaches: The combination of rCF-UD tape layers with continuous fiber tapes made from primary material in critical load zones is a pragmatic strategy that reduces material costs and CO₂ footprint while maintaining structural integrity where it is most needed.

  • Joining and assembly: The sleeve frame approach demonstrated by Fenix Composites — rCF-thermoplastic pipes combined with topology-optimized, 3D-printed titanium sleeves — shows how modular construction strategies can make rCF-based structures both repairable and recyclable.

Where rCF-UD tapes can be used — and why

The applications that are best suited for rCF-UD tapes share a common profile: stiffness-critical, moderate loads, high quantities or cost-sensitive, with sustainability as a procurement driver.

Structural components in automotive construction: Seat structures, floor panels, B-pillar reinforcements, and door impact beams are strong candidates. The automotive industry is subject to legal recycling quotas of 95%, creating a regulatory incentive for rCF-based solutions. Press-molded organo sheets made from rCF staple fiber yarns have already been demonstrated for this segment at TU Kaiserslautern.

Bicycle frames and sports equipment: Fenix Composites has demonstrated a fully recyclable

racing bike frame made from rCF-thermoplastic pipes that

were woven from rCF/PA6 tapes — a direct application of the

pipe manufacturing process relevant to Alformets' LATW process. The frame

was awarded the JEC Innovation Award — a signal of industry recognition.

Industrial pressure vessels and windings: The tape winding of rCF thermoplastic tape over a liner — as demonstrated by Fraunhofer IPT in the context of hydrogen pressure tank recycling — represents a direct application of LATW-like processes. The modular retention of rCF tapes makes them suitable for area-dominant winding patterns.

Rotor and stator wraps: In electric motor applications where the primary load is circumferential tension (inclusion of rotating magnets), the module retention of rCF tapes is sufficient — and the cost and sustainability advantages are commercially convincing.

Prototypes and small series profiles: For high-mix/low-volume applications where cost sensitivity and delivery time flexibility are more important than maximum performance, rCF-UD tapes offer a viable alternative to primary fibers — especially when the component is designed from the outset with appropriate safety margins.

Commercial availability: No mass market yet

Despite scientific progress, an important limitation must be stated here: rCF-UD tapes in thermoplastic form are currently not commercially available — at least not in a form that allows for industrial series processing. What exists are research samples, project demonstrators, and small-scale development batches from university and institutional process chains. Providers like V-Carbon (Taufkirchen) are working on industrialization, and projects like Infinity (DITF/BMBF) have impressively demonstrated technical feasibility — but a standardized, rollable rCF-UD thermoplastic tape with defined material data sheets and quality guarantees is still sought in vain today.

This is not a niche detail — it is the central hurdle for any OEM or Tier-1 supplier looking to integrate rCF-UD tapes into their process chain. Without reliable material supply, without reproducible batch quality, and without a certification basis, the use remains limited to R&D contexts. The industry is watching the development closely — but the step from the lab to the supply chain is still pending.

Conclusion: A material whose time has come

rCF-UD tapes are no longer laboratory rarities. The process chain — from pyrolytically recovered fiber through carding and stretching to tape consolidation — is mature enough to produce thermoplastic semi-finished products for structural applications. The performance gap compared to primary fibers is real, but quantifiable and manageable through intelligent design.

What makes rCF-UD tapes particularly attractive in the context of thermoplastic composite manufacturing is the alignment of two trends: the growing availability of high-quality rCF raw materials from maturing recycling industries and the inherent recyclability of thermoplastic matrices. Together, they create the conditions for a truly circular material system — one in which the fiber can be recovered, realigned, consolidated into a tape, wound into a structural component, and recovered again at the end of its life.

For manufacturers and OEMs evaluating rCF-UD tapes, the crucial first step is not a material test — but a design conversation. The potential of the material can only be fully realized if end-of-life thinking is embedded in the design from the very beginning.

Would you like to explore how thermoplastic composite pipes and profiles can be made from recycled fiber semi-finished products? Talk to Alformet about your application.


📚 SOURCES USED:


Continuous fiber reinforcement, many ways: Which manufacturing process fits which application?
Pull winding, braiding, CCM, tape laying or LATW – a technical comparison of the main manufacturing processes for continuous fiber reinforced thermoplastic composite components.