BIOGLUE QUARTERLY
December 2026
Reporting window 1 Sep – 30 Nov 2026 · Research cutoff 14 Oct 2026 · For MID · MIM · MTE · Benchmark: UF
TRIAL / PARTIAL-WINDOW ISSUE — covers 1 Sep – 14 Oct 2026 only. Draft for technical review (reviewer: OPEN); not for circulation.

What changed this quarter

Four laboratory papers moved formaldehyde-free binders closer to panel conditions: a cysteine-lignin plywood glue, a starch–citric acid MDF binder, a lignin–tannin NIPU curing at 130 °C and a veneer-faced spent-grain particleboard. None ran a UF control. No verified industrial bio-binder or bio-acrylic milestone appeared before the cutoff.

Tags: BIO-DERIVED FOSSIL-TYPICAL ORIGIN ND INORGANIC · Strategy A = renewable version of the same chemistry, B = different chemistry · ND = not disclosed

1

Cysteine-grafted lignin bonds plywood without formaldehyde

Change. Bagasse lignin grafted with cysteine self-cures in the press as a 20 wt% aqueous glue. Two-layer poplar plywood reached 4.0 MPa dry [1].

Implication. At 1.96 mPa·s it can be sprayed. Its ‘beats commercial resin’ claim uses PF diluted to 20 % solids, not UF or PF as supplied [1].

Gap. Stable wet strength needed hotter pressing (190 °C, 8 min). Cysteine recovery and cost remain unresolved [1].

Bagasse ligninextracted in cysteine/lactic acidBIO-DERIVEDL-cysteine (grafted)adds -NH2, -COOH, thioetherORIGIN NDLactic acid (residual)mild acid catalystORIGIN NDAq-LCL glue20 wt% in water100 g/m2 wet, one side190 °C8 min, 1 MPapoplar veneer, 3 mmcured network: amide + C-C linksPROPOSED by authors (FTIR/NMR, simulation)poplar veneer, 3 mm2-layer lab specimen · no UF control
Representative motifs, not the lignin polymer:
G-unit motif (coniferyl alcohol) · CID 1549095
L-cysteine · CID 5862
Lactic acid · CID 612
Cysteine-grafted lignin glue cures between veneers; bond chemistry shown as the authors propose it.
Application
2-ply poplar plywood (lab)
Chemistry
Claimed fully bio-based; cysteine and lactic-acid origin ND · B
Geography
China
Scale / TRL
Lab · TRL not reported
Capacity
ND
Cost basis
ND
CO₂e
ND
HCHO / VOC
0.05 mg/L, dryer method GB 17657 · VOC ND
2

Citric acid and urea upgrade starch binder for MDF

Change. Starch with sorbitol, glycerol, citric acid and urea bonded 10 mm lab MDF at 10 % dry resin: IB 0.59–0.86 MPa, 2 h swelling 22.74–24.54 % [2].

Implication. An aldehyde-free MDF route on commodity inputs; urea (8.2 % of solids, computed) makes it hybrid. Press: 180 °C, 7 min (≈42 s/mm, computed) [2].

Gap. No UF control, rheology, pot life or emission test [2].

Dry solids of best binder (SSGUC), computed from Table 1Corn starch 81.6 %Sorbitol 3.1 %Glycerol 3.1 %Citric acid 4.1 %Urea 8.2 %Plant-derivedBIO-DERIVEDOrigin not disclosedORIGIN ND
Citric acid (ester crosslinker) · CID 311
Urea (co-reactant) · CID 1176
Dry solids of the best binder; only starch is stated as plant-derived.
Application
Lab MDF, 10 mm, hardwood fibre
Chemistry
Hybrid (urea, origin ND) · B
Geography
Iran (with Bulgaria)
Scale / TRL
Lab · TRL not reported
Capacity
ND
Cost basis
ND
CO₂e
ND
HCHO / VOC
Not measured
3

Lignin–tannin NIPU cures birch plywood at 130 °C

Change. Diamine-grafted lignin and oxidised, methoxycarbonylated tannin form urethane links without isocyanate. At 130 °C, 10 min: 1.89 MPa dry, 0.85 MPa wet (EN 314-1) [3].

Implication. Brings NIPU cure into plywood press range; the authors' control NIPUs peaked near 180–200 °C [3].

Gap. Wet strength is below 1.0 MPa and passes only via the ≥40 % wood-failure rule. HMDA is fossil-typical; spread 300 g/m² [3].

Hardwood ligninLignova Pure, FibenolBIO-DERIVEDHexamethylenediamineaminationFOSSIL-TYPICALAminated ligninmajor prepolymerCondensed tanninspecies NDBIO-DERIVEDNaIO4oxidant: quinonesINORGANICDimethyl carbonatemethoxycarbonylationORIGIN NDLT-NIPU + 30 % MCC (bio)urethane links, no isocyanate3-ply birch: 130 °C, 1 MPa, 10 min
Hexamethylenediamine · CID 16402
Dimethyl carbonate · CID 12021
Two prepolymers combine in alkaline water; tags show the origin of each input.
Application
3-ply birch plywood (lab)
Chemistry
Hybrid (HMDA; DMC origin ND) · B, isocyanate-free
Geography
Sweden / Spain; lignin from Estonia
Scale / TRL
Lab · TRL not reported
Capacity
ND
Cost basis
ND
CO₂e
ND
HCHO / VOC
Not measured
4

Veneer faces lift spent-grain board to P2 bending

Change. Spent grain bonded with boric-acid-modified soy protein missed EN 312 bending minimums. With 0.64 mm veneer faces, boards met P2 and ANSI H1 flexural minimums [4].

Implication. A residue board with no added formaldehyde, but at about 1000 kg/m³ and a 25 min press at 140 °C [4].

Gap. Internal bond untested on faced boards; no UF control or emission data [4].

Cross-section, not to scaleveneer face 0.64 mm (sliced)core: spent grain + soy proteinveneer face 0.64 mmdark green line = SPC adhesive on faces, 25 g/m2 dryIB tested on unfaced boards onlySoy proteinconcentrateBIO-DERIVEDBoric acid3 % modifierINORGANICPress140 °C · 2.1 MPa · 25 min~1000 kg/m3 · mat MC 40 wt%
Veneer faces carry the bending load; the core and its bond strength are unchanged.
Application
Particleboard, high density (lab)
Chemistry
Bio-based organics + boric acid · no crosslinker
Geography
Argentina
Scale / TRL
Lab · TRL not reported
Capacity
ND
Cost basis
ND
CO₂e
ND
HCHO / VOC
Not measured

vs UF — what the four studies let us compare

1 · Lignin plywoodPress: 80–190 °C, 2–8 minComparator: PF diluted to 20 %UF control: none
2 · Starch MDFPress: ≈42 s/mm at 180 °C (computed)Comparator: other starch mixesUF control: none
3 · NIPU plywoodPress: 130 °C, 10 minComparator: internal NIPU controlsUF control: none
4 · Spent-grain PBPress: 140 °C, 25 minComparator: EN 312 P2 minimumsUF control: none
100 °C120 °C140 °C160 °C180 °C200 °C0 min10 min20 min30 min1: mild window 80–120 °C, 5–8 min (dry strength only)1 Lignin plywood (2-ply): 190 °C, 8 min2 Starch MDF (10 mm): 180 °C, 7 min3 NIPU plywood (3-ply): 130 °C, 10 min4 Spent-grain PB: 140 °C, 25 minW2 Soy-PAE-MUG plywood: 105 °C, 4 minplaten temperature and press time as disclosed; thickness and product differ
Disclosed press cycles of this issue's studies; not a like-for-like comparison and not a UF benchmark.

No UF baselines are imported from other sources. A like-for-like UF comparison needs a matched trial: same furnish, resin load, density and press cycle.

Watchlist

Three follow-up questions

  1. MID Does cysteine-grafted lignin keep its wet strength at ≤130 °C on 3-ply panels, against UF and undiluted PF at equal spread?
  2. MIM What press factor does the starch–citric acid binder need on an MDF line, against UF at equal resin load and density?
  3. MTE Can a bio-based diamine replace HMDA in the lignin–tannin NIPU and keep the 130 °C cure?

Coverage this issue

LEADProteinsL4 · W2LEADLigninL1 · L3LEADStarchL2LEADCarboxylic acidsL2 (citric)LEADTanninsL3 (with lignin)LEADCrosslinkersL3 (NIPU) · W1 · W2SEENSugars / polyolsglycerol PB, not selectedSEENPhenolicLPF plywood, not selectedSEENMelamine-containingMUG in W2 onlyNONECelluloseMCC filler onlyNONEPolylysineno in-window itemNONEPolyketonesno in-window itemNONEAcrylic acidno verified milestoneNONESupply / capacityno verified milestoneWATCHRegulationW3 (US EPA)
Chemistry lanes searched; LEAD = lead story, WATCH = watchlist, SEEN = in-window item not selected, NONE = no qualified update.

Searched against particleboard, MDF/HDF, plywood, LVL, glulam and moulded veneer (Crossref and OpenAlex by date; web and local-language search). No LVL, glulam or moulded-veneer result qualified.

Next issue: March 2027 (window 1 Dec 2026 – 28 Feb 2027). This trial issue will be refreshed after 30 Nov to cover the full September–November window.

References

  1. Zhou X., Wang Y., Hu S., … Ou R. Aqueous lignin adhesive for high-performance wood bonding. Science Advances (2026), published 23 Sep 2026. CC BY-NC 4.0. doi:10.1126/sciadv.aee5160. Accessed 14 Oct 2026.
  2. Mehdinia M., Kamrani S., Ahmadi P., Nabipoor S., … Citric acid–urea modification of dual-plasticized starch adhesives for medium-density fiberboard manufacturing. Polymers 18 (2026) 2400, published 1 Oct 2026. CC BY 4.0. doi:10.3390/polym18192400. Accessed 14 Oct 2026.
  3. Aladejana J.T., Olazabal I., Eceiza A., Hosseinpourpia R. Effective strategy for preparing low-curing-temperature lignin-based non-isocyanate polyurethane wood adhesives. Int. J. Biol. Macromol. 382 (2026) 154455, online 10 Sep 2026. CC BY 4.0. doi:10.1016/j.ijbiomac.2026.154455. Accessed 14 Oct 2026.
  4. Rossi L., Rueda F., Ciannamea E.M., Stefani P.M. Bio-based brewer's spent grain particleboards: effect of rosin coating and wood veneer reinforcement on structure and properties. Polymers 18 (2026) 2303, published 20 Sep 2026. CC BY 4.0. doi:10.3390/polym18182303. Accessed 14 Oct 2026.
  5. Zhang X., Liu Z., Zhou Z., Lynch M., … Strong fully reprocessable engineered wood composites. Advanced Materials (2026), online 7 Oct 2026. Abstract only inspected. doi:10.1002/adma.75232. Accessed 14 Oct 2026.
  6. Chang Z., Liu Y., Wei S., Han S., … A soybean meal-based adhesive with improved hot-pressing efficiency and water resistance fabricated from PAE, low-cost melamine-urea-glyoxal and blocked polyurethane resins. J. Agric. Food Chem. (2026), online 17 Sep 2026. Abstract only inspected. doi:10.1021/acs.jafc.6c12235. Accessed 14 Oct 2026.
  7. US EPA. 2026 Unified Agenda of Regulatory and Deregulatory Actions — Section 610 Review of Formaldehyde Emission Standards for Composite Wood Products (RIN 2070-AL38). Federal Register, FR Doc. 2026-16608, 14 Aug 2026; docket EPA-HQ-OPPT-2025-2433 (comment period 14 Aug – 13 Oct 2026). federalregister.gov. Accessed 14 Oct 2026.

Structures drawn with RDKit from PubChem SMILES (CIDs in captions); schematics drawn for this issue. No third-party figures or photographs are used. Numbers trace to verbatim passages in the issue's source files. Computed values are labelled.