The experimental data obtained from fast heating FTIR spectroscopy have confirmed that a conformational change occurs at about 135 ℃ for semicrystalline iPP. Based on the results of density and WAXD measurements, it ...The experimental data obtained from fast heating FTIR spectroscopy have confirmed that a conformational change occurs at about 135 ℃ for semicrystalline iPP. Based on the results of density and WAXD measurements, it can be inferred that the conformational change occurring at 135 ℃ comes from the disordering of helical sequences in non crystalline phase, which is further corroborated by the FTIR study on the chloride polypropylene.展开更多
Isotactic polypropylene(iPP) hollow fiber microporous membranes were prepared via thermally induced phase separation(TIPS)method.The mixture of di-n-butyl phthalate(DBP)and dioctyl phthalate(DOP)was used as diluent.Th...Isotactic polypropylene(iPP) hollow fiber microporous membranes were prepared via thermally induced phase separation(TIPS)method.The mixture of di-n-butyl phthalate(DBP)and dioctyl phthalate(DOP)was used as diluent.The effects of α(DBP mass fraction in mixed diluent)and β(iPP mass fraction in polymer solution)on pore size distribution of the membrane were investigated by N2-liquid displacement measurement.The connectivity of the membrane was evaluated with membrane tortuosity.It is noted that resulting membrane is apt to possess a narrow pore size distribution.For same β,the mean pore size and connectivity of resulting membrane decrease with increasing α.For α=0.20,with increasing β,mean pore size of resulting membrane increases with subsequent decreasing,while resulting membrane connectivity increases slightly.For α=0.35 or α=0.50,the mean pore size and connectivity of resulting membrane decrease with increasing β.It is indicated that the change of connectivity is attributed to the difference of the membrane topology.It is shown that membrane pore size and connectivity can be controlled effectively by choosing proper α and β.展开更多
文摘The experimental data obtained from fast heating FTIR spectroscopy have confirmed that a conformational change occurs at about 135 ℃ for semicrystalline iPP. Based on the results of density and WAXD measurements, it can be inferred that the conformational change occurring at 135 ℃ comes from the disordering of helical sequences in non crystalline phase, which is further corroborated by the FTIR study on the chloride polypropylene.
文摘Isotactic polypropylene(iPP) hollow fiber microporous membranes were prepared via thermally induced phase separation(TIPS)method.The mixture of di-n-butyl phthalate(DBP)and dioctyl phthalate(DOP)was used as diluent.The effects of α(DBP mass fraction in mixed diluent)and β(iPP mass fraction in polymer solution)on pore size distribution of the membrane were investigated by N2-liquid displacement measurement.The connectivity of the membrane was evaluated with membrane tortuosity.It is noted that resulting membrane is apt to possess a narrow pore size distribution.For same β,the mean pore size and connectivity of resulting membrane decrease with increasing α.For α=0.20,with increasing β,mean pore size of resulting membrane increases with subsequent decreasing,while resulting membrane connectivity increases slightly.For α=0.35 or α=0.50,the mean pore size and connectivity of resulting membrane decrease with increasing β.It is indicated that the change of connectivity is attributed to the difference of the membrane topology.It is shown that membrane pore size and connectivity can be controlled effectively by choosing proper α and β.
