Studies in preparation and characterization of polyesteramide based hot melt adhesive from dimer acid, ethanolamine and ethylenediamine: Effect of ethanolamine concentration

Polyesteramide based hot melt adhesives were synthesized from high purity dimer acid (composition: ∼1% trimer acid, ∼98% dimer acid and ∼1% linoleic acid), ethylenediamine and ethanolamine. The effect of ethanolamine content on the properties of polyesteramide, such as thermal properties: glass transition temperature (T_g), melting temperature (T_m), enthalpy of melting (H_m), crystallization temperature (T_c), enthalpy of crystallization (H_c) and softening point (T_s); mechanical properties: tensile strength, elongation at break and°Shore hardness; adhesion properties: lap shear strength (LSS) and T-Peel strength (TPS); crystallinity and rheological properties were investigated. Ethanolamine was added as a partial replacement of ethylenediamine. Ethylenediamine was replaced by 10, 20 and 30% (molar basis) of ethanolamine. It was found that T_g, T_m, H_m, T_c, H_c, T_s, LSS, TPS, tensile strength,°Shore D hardness, crystallinity and viscosity, all decreased with increased concentration of ethanolamine. This was due to the decrease in the crystallinity of the polyesteramide caused by conversion of certain amide linkages to ester linkages, which increased with increased concentration of ethanolamine, decreasing crystallinity and thus the above-mentioned properties.