Advancing bio-based laminates: characterization of sorbitol-modified glyoxal-melamine thermoset resins for eco-conscious decor applications

Introduction: In response to growing environmental and regulatory concerns regarding fossil-based resources in conventional melamine–­formaldehyde (MF) resins, developing greener, high-performance alternatives has become a key objective in resin technology. Among potential solutions, glyoxal has emerged as a promising, sustainable crosslinker. This study explored glyoxal–melamine–formaldehyde (GMF) resins for decorative laminate impregnation, focusing on sorbitol as a bio-based modifier. Sorbitol (10 wt.%) was incorporated at various synthesis stages to assess its impact on resin structure and performance.Methods: Analytical techniques – including Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and rheology – were employed, along with industry-relevant penetration and surface property testing.Results: The resulting GMF resins showed significantly improved storage stability while maintaining penetration characteristics comparable to conventional MF resins. Sorbitol addition influenced thermal and structural properties, with the stage of addition playing a critical role. While sorbitol-modified GMF resins showed improved thermal resistance, they underperformed in certain surface durability tests compared to unmodified GMF and MF resins. FTIR analysis elucidated changes in network structure associated with reduced hydrolytic stability and revealed distinct crosslinking mechanisms.Discussion: Importantly, sorbitol acted as a flexibilizing agent, modifying the network architecture to reduce rigidity. While this effect compromised surface durability, it may be beneficial in applications requiring greater flexibility, such as post-forming ­laminates or lacquer-based finishes. These findings highlight the importance of fine-tuning structural modifiers and crosslinking mechanisms to enhance resin performance. With targeted ­structural optimization, particularly regarding hydrolytic stability, GMF resins offer a promising foundation for next-generation eco-conscious impregnation systems.