Citric Acid–Urea Modification of Dual-Plasticized Starch Adhesives for Medium-Density Fiberboard Manufacturing
9 affiliations
- 1Wood and Forest Products Science Research Division, Research Institute of Forests and Rangelands, Agricultural Research, Education and Extension Organization (AREEO), Tehran 14968-13111, Iran
- 2Department of Wood and Paper Science and Technology, Faculty of Natural Resources, University College of Agricultural & Natural Resources, University of Tehran, Karaj 77871-31587, Iran
- 3Department of Chemistry, Faculty of Science, Tonekabon Branch, Islamic Azad University, Tonekabon 46841-61167, Iran
- 4School of Chemistry, College of Science, University of Tehran, Tehran 14179-35840, Iran
- 5Department of Mechanical Wood Technology, Faculty of Forest Industry, University of Forestry, 1797 Sofia, Bulgaria
- 6Department of Nanotechnology, Faculty of Engineering Modern Technologies, Amol University of Special Modern Technologies (AUSMT), Amol 46156-64616, Iran
- 7Faculty of Chemical Technologies, University of Chemical Technology and Metallurgy, 1757 Sofia, Bulgaria
- 8Department of Wood Industry, Faculty of Applied Sciences, Universiti Teknologi MARA Pahang Branch Jengka Campus, Bandar Tun Abdul Razak 26400, Pahang, Malaysia
- 9Institute for Infrastructure Engineering and Sustainable Management (IIESM), Universiti Teknologi MARA, Shah Alam 40450, Selangor, Malaysia
Abstract
Formaldehyde-free starch adhesives offer a renewable alternative to conventional binders used in medium-density fiberboard (MDF), but their application remains limited by poor moisture resistance and insufficient mechanical performance. The aim of this research work was to investigate and evaluate the combined effects of sorbitol and glycerol plasticizers, citric acid modification, and urea addition on the properties of starch-based adhesives and the resulting MDF panels. Five adhesive formulations were prepared and characterized using Fourier-transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). Laboratory MDF panels were manufactured and evaluated for thickness swelling (TS), water absorption (WA), internal bond strength (IB), modulus of rupture (MOR), and modulus of elasticity (MOE). Among the tested formulations, the hybrid adhesive system, composed of sorbitol/starch/glycerol/urea/citric acid (SSGUC), provided the best overall performance. Panels bonded with SSGUC exhibited the lowest TS and WA after both 2 and 24 h of water immersion, with TS2 values of 22.74 to 24.54% and WA2 and WA24 values of 91.16–101.43% and 132.11–141.29%, respectively. The same panels achieved IB, MOR, and MOE values of 0.59–0.86 MPa, 24.95–26.17 MPa, and 2413–2632 MPa, respectively. FTIR spectral changes were consistent with citric-acid-mediated esterification and modified hydrogen-bonding interactions in the urea-containing formulations, while DSC revealed formulation-dependent differences in thermal behavior. The FTIR interpretation was based primarily on comparative band development and intensity changes rather than on marginal peak-position shifts. Overall, the results indicate that combining sorbitol and glycerol with citric acid and urea can improve the moisture resistance and mechanical performance of starch-bonded MDF. Further optimization, including rheological characterization and comparison with commercial binders, is required to assess industrial applicability.
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BibTeX
@article{mehdinia2026citric,
title = {{Citric Acid–Urea Modification of Dual-Plasticized Starch Adhesives for Medium-Density Fiberboard Manufacturing}},
author = {Meysam Mehdinia and Saeed Kamrani and Peyman Ahmadi and Sara Nabipoor and Sogand Ghafari Movahed and Petar Antov and Ali Dorieh and Viktor Savov and Stoyko Petrin and Lee Seng Hua},
journal = {Polymers},
year = {2026},
month = oct,
doi = {10.3390/polym18192400},
url = {https://europepmc.org/article/PMC/PMC13667178},
note = {CC BY},
}
RIS
TY - JOUR
TI - Citric Acid–Urea Modification of Dual-Plasticized Starch Adhesives for Medium-Density Fiberboard Manufacturing
AU - Meysam Mehdinia
AU - Saeed Kamrani
AU - Peyman Ahmadi
AU - Sara Nabipoor
AU - Sogand Ghafari Movahed
AU - Petar Antov
AU - Ali Dorieh
AU - Viktor Savov
AU - Stoyko Petrin
AU - Lee Seng Hua
PY - 2026
DA - 2026/10/01
JO - Polymers
DO - 10.3390/polym18192400
UR - https://europepmc.org/article/PMC/PMC13667178
AB - Formaldehyde-free starch adhesives offer a renewable alternative to conventional binders used in medium-density fiberboard (MDF), but their application remains limited by poor moisture resistance and insufficient mechanical performance. The aim of this research work was to investigate and evaluate the combined effects of sorbitol and glycerol plasticizers, citric acid modification, and urea addition on the properties of starch-based adhesives and the resulting MDF panels. Five adhesive formulations were prepared and characterized using Fourier-transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). Laboratory MDF panels were manufactured and evaluated for thickness swelling (TS), water absorption (WA), internal bond strength (IB), modulus of rupture (MOR), and modulus of elasticity (MOE). Among the tested formulations, the hybrid adhesive system, composed of sorbitol/starch/glycerol/urea/citric acid (SSGUC), provided the best overall performance. Panels bonded with SSGUC exhibited the lowest TS and WA after both 2 and 24 h of water immersion, with TS2 values of 22.74 to 24.54% and WA2 and WA24 values of 91.16–101.43% and 132.11–141.29%, respectively. The same panels achieved IB, MOR, and MOE values of 0.59–0.86 MPa, 24.95–26.17 MPa, and 2413–2632 MPa, respectively. FTIR spectral changes were consistent with citric-acid-mediated esterification and modified hydrogen-bonding interactions in the urea-containing formulations, while DSC revealed formulation-dependent differences in thermal behavior. The FTIR interpretation was based primarily on comparative band development and intensity changes rather than on marginal peak-position shifts. Overall, the results indicate that combining sorbitol and glycerol with citric acid and urea can improve the moisture resistance and mechanical performance of starch-bonded MDF. Further optimization, including rheological characterization and comparison with commercial binders, is required to assess industrial applicability.
SN - 2073-4360
ER -