Synthesis of aromatic polyamides based on reaction of terephthalic acid and isocyanate
A series of new aromatic polyamide(PA)was successfully synthesized based on the polymerization between toluene diisocyanate(TDI),4,4′-diphenyl diisocyanate(MDI)and terephthalic acid(TPA),and the structure and properties synthesized PA were systematically characterized.The molecular weight(Mn)of the synthesized polyamides increases with the increase of the proportion of TDI,which ranges from 3.18×104 g·mol-1 to 7.81×104 g·mol-1.The breaking strength and tensile modulus of the PA films are 98-127 MPa and 3.33-3.95 GPa,respectively,and the elongation at break is higher than 20％.The elongation at break of the PA films can be modified by changing the TDI/MDI molar ratio,which can reach over 50％,indicating an excellent toughness behavior of the films.The glass transition temperature(tg)is higher than 290℃,and the temperatures of 10％weight loss of the films in nitrogen are 431-447℃,demonstrating a certain thermal stability of the films.The cutoff wavelength of the PA film is lower than 383 nm,and the transmittance at the wavelength of 530 nm is more than 80％,which exhibits a certain degree of transparency.
aromatic polyamideterephthalic aciddiisocyanatestructure and property
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