Synthesis of polyhydric alcohols derived from limonene glycol and its application to polyurethane networks

Abstract

Biobased polyhydric alcohols (bis-LG, tri-LG, tetra-LG) with different numbers of hydroxy groups (n=4,6,8, respectively) were synthesized using limonene glycol (LG). Cross-linking reaction of polyhydric alcohols and methylenediphenyl 4,4'-diisocyanate (MDI) with [OH]₀/[NCO]₀=1/1(mol/mol) afforded the corresponding polyurethane networks in 40%, 60%, and 92% yields, respectively. Thermal resistance of the network polymers increased with increasing number of hydroxy groups in polyhydric alcohols. Metal-tometal adhesive using bis-LG and tetra-LG was evaluated by lap shear test, resulting in 2.7 MPa and 5.9 MPa, respectively. When polyurethane foam was prepared by PPG (polypropylene glycol) (90%) and bis-LG (10%), the 5% thermal decomposition temperature and tensile strength of the corresponding polyurethane foam was 16 °C higher and 4 times stronger, respectively, compared to that derived from PPG only. (Received March 22, 2023; Accepted April 5, 2023) Key-words : limonene glycol, polyhydric alcohols, polyurethane networks, polyurethane foams Biobased polyhydric alcohols (bis-LG, tri-LG, tetra-LG) with different numbers of hydroxy groups (n=4,6,8, respectively) were synthesized using limonene glycol (LG). Cross-linking reaction of polyhydric alcohols and methylenediphenyl 4,4'-diisocyanate (MDI) with [OH]₀/[NCO]₀=1/1(mol/mol) afforded the corresponding polyurethane networks in 40%, 60%, and 92% yields, respectively. Thermal resistance of the network polymers increased with increasing number of hydroxy groups in polyhydric alcohols. Metal-tometal adhesive using bis-LG and tetra-LG was evaluated by lap shear test, resulting in 2.7 MPa and 5.9 MPa, respectively. When polyurethane foam was prepared by PPG (polypropylene glycol) (90%) and bis-LG (10%), the 5% thermal decomposition temperature and tensile strength of the corresponding polyurethane foam was 16 °C higher and 4 times stronger, respectively, compared to that derived from PPG only. (Received March 22, 2023; Accepted April 5, 2023) Biobased polyhydric alcohols (bis-LG, tri-LG, tetra-LG) with different numbers of hydroxy groups(n=4,6,8, respectively) were synthesized using limonene glycol (LG). Cross-linking reaction of polyhydric alcohols and methylenediphenyl 4,4'-diisocyanate (MDI) with [OH]₀/[NCO]₀=1/1(mol/mol) afforded the corresponding polyurethane networks in 40%, 60%, and 92% yields, respectively. Thermal resistance of the network polymers increased with increasing number of hydroxy groups in polyhydric alcohols. Metal-tometal adhesive using bis-LG and tetra-LG was evaluated by lap shear test, resulting in 2.7 MPa and 5.9 MPa, respectively. When polyurethane foam was prepared by PPG (polypropylene glycol) (90%) and bis-LG (10%), the 5% thermal decomposition temperature and tensile strength of the corresponding polyurethane foam was 16℃ higher and 4 times stronger,respectively,compared to that derived from PPG only.