Síntese e caracterização de poliamida termofundível

Abstract

Hot melt adhesives have the advantage that don t release volatile organic compounds as solvent-based adhesives. Polyamides containing dimer fatty acid in their structure can be used as hot melt adhesives. In this work polyamides with different compositions of dimer fatty acid, primary amines and secondary amines and their proportions were synthesized, the effect of these changes were evaluated in physical, chemical and mechanical properties. In relation to primary amines, ethylenediamine and hexamethylenediamine were used and it was found that a smaller chain gives an increase in the softening point, a higher elongation, lower Tg and a higher crystallization. The variation of secondary amines (DIPIP, piperazine, and aminoethylpiperazine) didn t affect the softening point. The piperazine based polyamide promotes better crystallization compared to the other structures of the amines (DIPIP and aminoethylpiperazine), because piperazine can promote higher organization of the chains. The methylenes groups from DIPIP and aminoethylpiperazine provide higher elongation of polyamides, increasing mobility of the chains. Increasing the content of ethylenediamine provides increased intermolecular interactions, giving a rise in the softening point, crystallization, viscosity and mechanical strength of the polyamide. Different compositions of dimer fatty acids were evaluated and was observed that the higher content of monomers, the lower molecular weight of the polyamide were achieved, consequently lower viscosity and more brittle polymers. Higher purity of dimer fatty acid promotes the formation of only one fraction of crystallization and melting. Performance bonding is usually associated by molecular weight of the polyamide and intermolecular interactions between substrate and polyamide chains.