Adesivos de poliuretano para a madeira baseados em uma mistura simples de óleo de mamona e glicerina loira

Abstract

This research thoroughly explores the effects of incorporating crude glycerol in different proportions to castor oil during the production of polyols for polyurethane (PU) adhesives intended for wood bonding. The addition of crude glycerol is investigated to understand its impact on the properties of polyols and, consequently, on the characteristics of the resulting adhesives. Modified polyols showed a substantial increase in hydroxyl content, viscosity, and moisture, with a noticeable alteration in their physical appearance. The produced adhesives exhibited variations in reaction times, indicating a direct influence of the presence of crude glycerol. FTIR spectroscopy provided insights into the formation of the PU polymer, revealing differences in unreacted NCO groups among the adhesives. Furthermore, crude glycerol impacted the thermal stability of the adhesives while increasing surface and volumetric hydrophobicity, providing greater resistance to degradations caused by different means. All adhesives fully met the adhesive strength requirements according to ASTM D905 standards. The addition of crude glycerol to castor oil emerges as a highly promising strategy to enhance not only the mechanical properties but also the durability of PU adhesives for wood bonding. However, careful consideration of the impact of this modification on the thermal stability of adhesives is emphasized.