In short: Two changes are coming to thermoset resins. Bio-based resins replace part of the fossil feedstock with renewable carbon; published glass-fiber laminates made with a bio-based polyester resin have matched conventional laminates in strength, but often with a lower glass transition temperature. Recyclable thermosets are built so the resin can be dissolved or reprocessed at end of life; Siemens Gamesa has used one in commercial wind blades since 2021, and vitrimers are still mostly at research and early industrial stage. Neither is a drop-in swap for corrosion-grade vinyl ester yet. Our standard products use proven resins; trial parts in a resin you specify are custom / available on request.
How this guide fits with our others
This guide looks forward: what new resin chemistry is coming. For what can be done with today's FRP at end of life, read can FRP be recycled?. For how to compare carbon footprints, read FRP vs steel carbon footprint: how to read an EPD. For how resin quality is checked in the factory, read our companion guide on FRP quality control: Barcol hardness and traceability. Background on today's resin families is in polyester vs vinyl ester vs phenolic resin and what is FRP.
Why thermosets are hard to recycle
FRP grating, profiles and tanks use thermoset resins: polyester, vinyl ester, epoxy or phenolic. When they cure, the molecules link into one network. A 2022 review in Materials Advances (Schenk and co-authors) puts it simply: thermosets dominate composites because of their stiffness to weight ratio and fatigue resistance, but recycling them is limited "due to the irreversible chemical bonds created during the curing process".
The review lists the routes available today:
- Burning off the resin (pyrolysis) to recover fibers.
- Chemically dissolving the resin (solvolysis) to recover fibers.
- Grinding (mechanical recycling) into filler, covered in our recycling guide.
Each route recovers fibers or filler, but rarely the resin as a resin. That is the gap the new chemistry tries to close. The same cross-links are what make FRP strong and chemically resistant, so any change to them has to keep those properties.
Trend 1: bio-based resins
A bio-based resin is made partly from renewable raw materials, such as plant-derived acids and diols, instead of petroleum.
What the research shows
A 2022 paper in Composites Part A described a glass-fiber laminate made by vacuum infusion with a bio-based unsaturated polyester resin, "with more than 50 wt% of its content derived from renewable raw materials". The authors compared it with an equivalent laminate made with conventional petroleum-based polyester and the same fiber layup. They reported that the bio-based laminate met or exceeded the conventional one in mechanical properties. They also reported a glass transition temperature (Tg) of 64 °C, measured from the onset of storage modulus decay, which they said enables outdoor use.
The same research group's resin paper in ACS Sustainable Chemistry & Engineering explains why bio content drops in the finished resin. The polyester backbone itself was almost fully bio-based, about 99.7% biobased carbon in the best case. But a polyester resin is thinned with a reactive diluent, usually styrene, which is not bio-based. After dilution, the resins reached roughly 50–60% biobased content.
What that means for FRP buyers
- Partial, not full, bio content. Expect a percentage, and ask what it is a percentage of.
- Heat matters. A Tg of 64 °C is fine for many outdoor uses, but our corrosion and process equipment often runs hotter. Check the resin's heat rating against your service before anything else. See our temperature limits by resin type guide.
- Chemical resistance must be tested. Research papers focus on mechanical properties. Corrosion-grade service needs immersion data for your chemical.
How bio content is measured
Bio content is measured by radiocarbon. ASTM D6866 uses carbon-14 analysis to report the biobased or biogenic carbon content of a sample. ASTM revised it in 2024 and notes it is used by the US Department of Agriculture to certify products by biobased content. Plant carbon contains carbon-14; fossil carbon has none.
The ACS paper reported values to ISO 16620-4, which can express biobased content as carbon content or as mass content. The two numbers differ, so ask which one a supplier is quoting. A study in SpringerPlus also warns that fillers and additives in a composite can carry biobased carbon and shift the result, so the resin should be tested separately from fillers.
Trend 2: recyclable thermosets
Dissolvable resin: the wind blade example
The first commercial use at scale is in wind energy. On September 7, 2021, Siemens Gamesa launched the RecyclableBlade, which it called the world's first recyclable wind turbine blade ready for commercial offshore use. The first six 81-meter blades were made in Aalborg, Denmark.
According to Siemens Gamesa's 2022 presentation to Sandia National Laboratories:
- The blade uses Aditya Birla Chemicals' Briozen resin, based on Recyclamine technology.
- The only change from its standard blade design is the resin; the manufacturing process is the same.
- At end of life the blade is cut up and immersed in a mild acidic solution at elevated temperature. The resin dissolves after a few hours.
- The resin is filtered and coagulated, and the glass fiber is rinsed and dried. Glass fiber, resin, wood and metal can be reused in other industries.
This shows that a recyclable thermoset can pass a full structural qualification. It also shows the conditions: a qualified resin system, a planned recycling process, and a dedicated supply chain.
Vitrimers: thermosets that can be reshaped
Vitrimers are a newer class. The Materials Advances review describes them as materials that "combine the mechanical resilience of thermosets with reprocessability of glass at high temperatures". Their cross-links can exchange partners when heated, so the network can be reshaped, repaired or reprocessed while staying connected.
A 2022 review in RSC Advances adds that this bond exchange allows self-healing and recycling, and that fiber reinforcement is being used to raise strength without losing the exchange behavior. A 2025 review in Materials concludes that vitrimer composites offer clear benefits for life extension (repair and reshaping), but that their recycling sustainability "needs to be directly compared" with conventional composites through life-cycle analysis.
In short, vitrimers are promising, but most published work is on carbon-fiber epoxy at lab or early industrial scale. They are not yet a standard option for pultruded grating or corrosion tanks.
Where this could matter for FRP products
| Product | What a new resin could change | What must be proven first |
|---|---|---|
| Pultruded profiles and grating | Lower fossil content, end-of-life recovery | Heat rating, fire behavior, UV, pultrusion speed and cure |
| Corrosion tanks and pipes | End-of-life recovery | Chemical resistance for the stored medium, long-term creep |
| Covers, trays, non-critical parts | Lower fossil content | UV and outdoor durability |
Fire behavior deserves special mention. Fire-retardant grating and tray are usually made with resin systems tested to standards such as ASTM E84. Any new resin needs its own fire tests; results from the old resin do not carry over. See FRP grating fire rating: ASTM E84.
How to check a supplier's claim
Use these questions on any "bio-based" or "recyclable" resin:
- Bio content of what? Carbon content or mass content, of the resin or of the whole laminate? To which standard: ASTM D6866 or ISO 16620?
- Recyclable by which route? Name the process (solvolysis, reprocessing, pyrolysis, grinding), the conditions, and who runs it at scale.
- Is there an actual take-back route in your region, or is recyclability only proven in a lab?
- Same properties? Ask for test data against the resin you use today: strength, modulus, Tg or heat distortion temperature, and chemical resistance in your medium.
- Fire and UV. Ask for fire test results on the new laminate, not on a different product.
- Footprint. Ask for an EPD or LCA that covers the whole life, not just raw materials. Our EPD guide explains how.
Need a quote or a drawing check?
FIBROVX manufactures FRP products in our own factory in China and builds every item to order: sizes, resin system, color, molds and OEM branding. Send your application, dimensions or drawing, quantity and destination port.
Request a QuoteHow we approach new resins
Our standard products are made with proven polyester, vinyl ester and other established systems, matched to the job. We build to order, so resin choice is already part of every quote. For new resins we work like this:
- You name the resin, or ask us to look at options with resin suppliers.
- We check processability for the product type: pultrusion, molding or filament winding each place different demands on viscosity and cure.
- Trial parts and test coupons in that resin are custom / available on request, so you can run your own tests.
- We report honestly what was tested and what was not. A trial is not a qualification.
Tell us the product, the service conditions, and your reason for the change: lower fossil content, end-of-life recovery or a customer requirement. Tell us too which projects or sectors you have in mind; our industries page and emerging industries page show where FRP is used today.
What stays the same
New chemistry does not change the basics of building good FRP. Siemens Gamesa's message on its blade was "same means same": the same design criteria, product quality and service process, with only the resin changed. That is the right test for any resin switch in grating, profiles or tanks.
In practice, a part made with a new resin should go through the same checks as today:
- Cure checks such as Barcol hardness against the resin maker's value, explained in our quality control guide.
- Glass content checks by ignition loss.
- Dimensional and visual checks against the drawing.
- Traceability of the resin batch to the finished part, which matters even more when a resin is new.
The design rules also stay. Load tables, deflection limits and safety factors are based on tested properties. If a new resin changes stiffness or heat rating, the tables must be checked again for that resin.
What to expect in the next few years
Based on the sources above, a realistic view:
- Partially bio-based polyester and epoxy resins exist, but corrosion-grade data is limited, so expect them first in non-critical parts.
- Dissolvable thermosets are proven in wind blades with a planned recycling route. Use in other products depends on whether a recycling route exists.
- Vitrimers are moving from lab to early industry, led by carbon-fiber epoxy. Repair and reshaping may come before large-scale recycling.
- Proof will rest on standards and data: ASTM D6866 for bio content, EPDs for footprint, and the usual mechanical, chemical and fire tests for performance.
FAQ
Are bio-based resins as strong as conventional ones?
In the Composites Part A study, a bio-based polyester laminate met or exceeded the conventional laminate's mechanical properties. Heat and chemical resistance must be checked separately.
Can a bio-based resin be 100% bio-based?
The polyester backbone can be almost fully bio-based, but the styrene diluent is not; the ACS study reported about 50–60% for the finished resins.
Is a recyclable resin the same as a recyclable product?
No. Recycling needs a working process and a collection route. Siemens Gamesa planned both for its blades.
Are vitrimers available for FRP grating?
Not as a standard option. Published work is mostly on carbon-fiber epoxy at lab or early industrial scale.
Can you make parts in a resin I choose?
Trial parts and coupons in a specified resin are custom / available on request, subject to a processability check.
Related: Custom FRP Manufacturing: Sizes, Resins, Colors, Molds and OEM Explained.
Sources
- Schenk et al. (2022), Vitrimer composites: current status and future challenges, Materials Advances: https://pubs.rsc.org/en/content/articlehtml/2022/ma/d2ma00654e
- Self-healable fiber-reinforced vitrimer composites: overview and future prospects (2022), RSC Advances via PMC: https://pmc.ncbi.nlm.nih.gov/articles/PMC9661690/
- Conventional thermoset composites and their sustainable alternatives with vitrimer matrix (2025), Materials: https://www.mdpi.com/1996-1944/18/2/351
- GFRP biocomposites produced with a novel high-performance bio-based unsaturated polyester resin (2022), Composites Part A: https://doi.org/10.1016/j.compositesa.2022.107098
- Hofmann et al., Biobased thermosetting polyester resin for high-performance applications, ACS Sustainable Chemistry & Engineering: https://doi.org/10.1021/acssuschemeng.1c06969
- ASTM, Revision of D6866 biobased testing standard (2024): https://www.astm.org/news/press-releases/astm-international-revises-key-biobased-testing-standard
- Biobased carbon content of resin extracted from polyethylene composite (SpringerPlus, via PMC): https://pmc.ncbi.nlm.nih.gov/articles/PMC4320129/
- Siemens Gamesa, launch of the RecyclableBlade (2021): https://www.siemensgamesa.com/global/en/home/press-releases/launch-world-first-recyclable-wind-turbine-blade.html
- Siemens Gamesa, RecyclableBlade presentation to Sandia (2022): https://www.sandia.gov/app/uploads/sites/273/2022/11/SGRE_RecyclableBlade_Sandia2022_LHv1.pdf