The colored poly(m-phenylene isophthalamide)(PMIA)spinning solution was prepared by wet spinning and the die-swell of the colored PMIA spinning solution was done when it was extruded from a die in this experiment.The ...The colored poly(m-phenylene isophthalamide)(PMIA)spinning solution was prepared by wet spinning and the die-swell of the colored PMIA spinning solution was done when it was extruded from a die in this experiment.The properties and structures of colored PMIA fibers were characterized by scanning electron microscopy(SEM).The colored PMIA spinning dopes were first commixed in a pressurizer and then spun into a coagulation bath.The effect of die swell on the colored PMIA solution was resulted from the viscoelastic properties of the colored PMIA solution in the spinning process.The results showed that the die-swell ratio of the colored PMIA solution increased linearly with increasing the pressure and die length/diameter ratio(L/D).At the same pressure and L/D,the die-swell ratio decreased with the increase of filter layers and temperature.Also,optimized spinning parameters of the dopedyed PMIA fiber were obtained.展开更多
A series of flexible poly(m-phenylene isophthalamide)(PMIA)-based composites with different sizes and mass fractions of hexagonal boron nitride(hBN)were successfully manufactured for the first time via the casting tec...A series of flexible poly(m-phenylene isophthalamide)(PMIA)-based composites with different sizes and mass fractions of hexagonal boron nitride(hBN)were successfully manufactured for the first time via the casting technique.The effects of modified hBN particles on microstructure,mechanical properties,dielectric properties and thermal conductivities of fabricated composites were investigated.The results indicate that modified hBN particles manifest good compatibility with the PMIA matrix.The Young's modulus and Theat-resistance index of PMIA-based composites are increased with increasing the mass fraction of hBN particles.Due to additional thermal conductive paths and networks formed by nano-sized hBN particles,the K-m/n-hBN-30 composite displays the thermal conductivity of 0.94 W·m^-1·K^-1 higher than that of the K-m-hBN-30 composite(0.86 W·m^-1·K^-1),and more than 4 times higher than that of neat PMIA.Moreover,the obtained PMIA-based composites also show low dielectric constant and ideal dielectric loss.Owing to the excellent comprehensive performance,hBN/PMIA composites present potential applications in the broad field of electronic materials.展开更多
文摘The colored poly(m-phenylene isophthalamide)(PMIA)spinning solution was prepared by wet spinning and the die-swell of the colored PMIA spinning solution was done when it was extruded from a die in this experiment.The properties and structures of colored PMIA fibers were characterized by scanning electron microscopy(SEM).The colored PMIA spinning dopes were first commixed in a pressurizer and then spun into a coagulation bath.The effect of die swell on the colored PMIA solution was resulted from the viscoelastic properties of the colored PMIA solution in the spinning process.The results showed that the die-swell ratio of the colored PMIA solution increased linearly with increasing the pressure and die length/diameter ratio(L/D).At the same pressure and L/D,the die-swell ratio decreased with the increase of filter layers and temperature.Also,optimized spinning parameters of the dopedyed PMIA fiber were obtained.
基金the Natural Science Foundation of Shanghai(Grant No.17ZR1401100)the National Natural Science Foundation of China(Grant No.51473031).
文摘A series of flexible poly(m-phenylene isophthalamide)(PMIA)-based composites with different sizes and mass fractions of hexagonal boron nitride(hBN)were successfully manufactured for the first time via the casting technique.The effects of modified hBN particles on microstructure,mechanical properties,dielectric properties and thermal conductivities of fabricated composites were investigated.The results indicate that modified hBN particles manifest good compatibility with the PMIA matrix.The Young's modulus and Theat-resistance index of PMIA-based composites are increased with increasing the mass fraction of hBN particles.Due to additional thermal conductive paths and networks formed by nano-sized hBN particles,the K-m/n-hBN-30 composite displays the thermal conductivity of 0.94 W·m^-1·K^-1 higher than that of the K-m-hBN-30 composite(0.86 W·m^-1·K^-1),and more than 4 times higher than that of neat PMIA.Moreover,the obtained PMIA-based composites also show low dielectric constant and ideal dielectric loss.Owing to the excellent comprehensive performance,hBN/PMIA composites present potential applications in the broad field of electronic materials.
