The morphology of PPTA pulp is investigated by means of optical microscope and scanningelectron microscope (SEM). It shows that PPTA pulp has feather-like branch, needle point-likeend, and irregular cross-section, whi...The morphology of PPTA pulp is investigated by means of optical microscope and scanningelectron microscope (SEM). It shows that PPTA pulp has feather-like branch, needle point-likeend, and irregular cross-section, which are very important for PPTA pulp as a reinforcer. Theseparation limitation of PPTA pulp is also investigated from both torn and brittle break cross-sec-tion. A packing mechanism is proposed to illustrate the microfibril packing in the gel system.展开更多
Poly(p-phenylene terephthalamide)(PPTA)pulp was prepared by polycondensation of the p-phenylene diamine(PPDA)with terephthaloyl chloride(TPC)in the completely anhydrous solvent system of N-methyl pyrrolidone(NMP)havin...Poly(p-phenylene terephthalamide)(PPTA)pulp was prepared by polycondensation of the p-phenylene diamine(PPDA)with terephthaloyl chloride(TPC)in the completely anhydrous solvent system of N-methyl pyrrolidone(NMP)having calcium chloride,in the presence of poly(vinyl pyrrolidone)(PVP)having a viscosity average molecular weight lower than 40 000.It was confirmed that the polycondensation could be accelerated,the inherent viscosity of the polymer could be increased,and the polymers could be fibrillated more easily by the addition of the PVP.FTIR and X-ray spectra proved that PVP had not combined into molecular chains of the resultant PPTA pulps.The morphology of the resultant pulps,the effect of viscosity average molecular weight,amount and adding mode of PVP on inherent viscosity,specific surface area,and mean length of the resultant pulps were discussed in detail.And the friction and wear properties of the compound reinforced by the resultant pulps were simply investigated.展开更多
文摘The morphology of PPTA pulp is investigated by means of optical microscope and scanningelectron microscope (SEM). It shows that PPTA pulp has feather-like branch, needle point-likeend, and irregular cross-section, which are very important for PPTA pulp as a reinforcer. Theseparation limitation of PPTA pulp is also investigated from both torn and brittle break cross-sec-tion. A packing mechanism is proposed to illustrate the microfibril packing in the gel system.
文摘Poly(p-phenylene terephthalamide)(PPTA)pulp was prepared by polycondensation of the p-phenylene diamine(PPDA)with terephthaloyl chloride(TPC)in the completely anhydrous solvent system of N-methyl pyrrolidone(NMP)having calcium chloride,in the presence of poly(vinyl pyrrolidone)(PVP)having a viscosity average molecular weight lower than 40 000.It was confirmed that the polycondensation could be accelerated,the inherent viscosity of the polymer could be increased,and the polymers could be fibrillated more easily by the addition of the PVP.FTIR and X-ray spectra proved that PVP had not combined into molecular chains of the resultant PPTA pulps.The morphology of the resultant pulps,the effect of viscosity average molecular weight,amount and adding mode of PVP on inherent viscosity,specific surface area,and mean length of the resultant pulps were discussed in detail.And the friction and wear properties of the compound reinforced by the resultant pulps were simply investigated.
