Polyamides derived from piperazine and used for hot-melt adhesives: synthesis and properties

The polyamides, used for hot-melt adhesives, were synthesized from dimer acid, sebacic acid, ethylenediamine and piperazine. The effect of the content of piperazine and sebacic acid on properties of the polyamides, such as glass transition temperature, crystallinity, softening point, mechanical properties and low-temperature properties, was investigated. The adhesion strength of the resultant hot-melt adhesives was also studied. DSC thermograms of the polyamides showed that the glass transition temperature (Tg) and crystallinity of the polyamide decreased as the molar fraction of piperazine increased; Tg almost did not change as the mole fraction of sebacic acid increased from 6.2% to 12.2%, while crystallinity of the polyamide increased. Softening point, mechanical properties, low-temperature properties and adhesion properties were also, to some extent, changed as the content of piperazine and sebacic acid varied. The polyamide had the best properties in all aspects when the molar fraction of piperazine was about 25% and the mole fraction of sebacic acid, about 8.2%.