Die-Swell Performance of Colored Poly(m-phenylene isophthalamide)(PMIA)Fiber Prepared by Wet Spinning

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.

Comprehensively-modified polymer electrolyte membranes with multifunctional PMIA for highly-stable all-solid-state lithium-ion batteries

Polyethylene oxide(PEO)-based electrolytes have obvious merits such as strong ability to dissolve salts(e.g.,LiTFSI)and high flexibility,but their applications in solid-state batteries is hindered by the low ion conductance and poor mechanical and thermal properties.Herein,poly(m-phenylene isophthalamide)(PMIA)is employed as a multifunctional additive to improve the overall properties of the PEO-based electrolytes.The hydrogen-bond interactions between PMIA and PEO/TFSI-can effectively prevent the PEO crystallization and meanwhile facilitate the LiTFSI dissociation,and thus greatly improve the ionic conductivity(two times that of the pristine electrolyte at room temperature).With the incorporation of the high-strength PMIA with tough amide-benzene backbones,the PMIA/PEO-LiTFSI composite polymer electrolyte(CPE)membranes also show much higher mechanical strength(2.96 MPa),thermostability(4190℃)and interfacial stability against Li dendrites(468 h at 0.10 mA cm-2)than the pristine electrolyte(0.32 MPa,364℃and short circuit after 246 h).Furthermore,the CPE-based LiFePO4/Li cells exhibit superior cycling stability(137 mAh g^-1 with 93%retention after 100 cycles at 0.5 C)and rate performance(123 mAh g^-1 at 1.0 C).This work provides a novel and effective CPE structure design strategy to achieve comprehensively-upgraded electrolytes for promising solid-state battery applications.

Fabrication of asymmetric poly(m-phenylene isophthalamide)nanofiltration membrane for chromium(VI) removal

The feasibility of employing nanofiltration for the removal of chromium（VI） from wastewater was investigated. Poly （m-phenylene isophthalamide） （PMIA） was used to fabricate asymmetric nanofiltration membrane through the phase-inversion technique. Scanning electron microscopy （SEM） and atomic force microscopy （AFM） were used to characterize the obtained membrane, and the both confirmed a much smoother surface which could reduce membrane fouling. The PMIA membrane showed different rejections to electrolytes in a sequence of Na2SO4 〉 MgSO4 〉 NaC1 〉 MgC12, which was similar to the sequence of the negatively charged nanofiltration membranes. Separation experiments on chromium（VI） solution were conducted at various operating conditions, such as feed concentration, applied pressure and pH. It is concluded that chromium（VI） could be effectively removed from chromiumcontaining wastewater by the PMIA nanofiltration membranes while maintaining their pollution resistance under alkaline condition.

Poly(m-phenylene isophthalamide)-reinforced polyethylene oxide composite electrolyte with high mechanical strength and thermostability for all-solid-state lithium metal batteries

Polyethylene oxide(PEO)-based solid polymer electrolytes(SPEs)with flexibility,easy processability,low cost and especially strong ability to dissolve lithium salts have been regarded as promising alternatives to traditional flammable liquid electrolytes in next-generation highsafety and high-energy-density lithium metal batteries.However,the inferior mechanical strength and thermostability of PEO-based SPEs will raise the lithium dendritic penetration issue,further leading to the short circuit in batteries.In this work,aiming at enhancing the interfacial stability against Li dendrites of PEO-based SPEs,poly(mphenylene isophthalamide)(PMIA)is introduced as a reinforcing phase for the rational design of PEO/PMIA composite electrolyte.Impressively,PMIA chain with meta-type benzene-amide linkages significantly improves the mechanical strength(1.60 MPa),thermal stability(260℃)and ability to inhibit the growth of lithium dendrites(>300 h at 0.1 mA·cm^(-2))of SPEs.Meanwhile,allsolid-state LiFePO_(4)‖PEO/PMlA‖Li cell demonstrates superior electrochemical performance in terms of high specific capacity(159.1 mAh·g^(-1)),remarkable capacity retention(82.2%after 200 cycles at 0.5 C)and excellent safety characteristics.No burning or explosion occurs under pressing,bending and cutting conditions.This work opens a new door in developing high-performance PEObased electrolytes for advanced all-solid-state lithium metal batteries.

芳纶1313纤维的特点及其在个体防护服装领域的应用

对芳纶1313纤维的发展历程、性能特点、生产加工、产品应用等各个方面进行了详细的阐述。芳纶1313纤维是一种性能优异的阻燃耐热纤维,在安全生产领域有着广阔的应用前景。自问世以来历经半个多世纪的发展,其在安全生产领域的应用价值已经得到广泛的认可。由于芳纶1313纤维具备一系列的突出优点,同时也存在某些缺陷,因此建议扬长避短,充分发挥这种纤维的种种优点,同时通过纤维改性、改进和优化生产工艺等方法,充分发挥其在安全生产领域的应用,使之产生应有的社会效益和经济效益。

叔胺作为HCl吸收剂对间苯二胺与间苯二甲酰氯缩聚反应的影响

研究了各种叔胺作为聚间苯二甲酰间苯二胺 (PMIA)合成反应中HCl的吸收剂对PMIA分子量的影响 .结果表明 ,在PMIA树脂合成中加入添加剂α -甲基吡啶 ,对提高PMIA分子量作用明显 .探索了高分子量PMIA树脂稳定的生产工艺 ,并用红外光谱。

聚间苯二甲酰间苯二胺干-湿法及干法纤维静电成形研究

通过聚间苯二甲酰间苯二胺(PMIA)/甲基咪唑四氟硼酸盐([bmim]BF4)和聚间苯二甲酰间苯二胺(PMIA)/N,N-二甲基乙酰胺(DMAc)两个体系,采用干-湿法以及干法静电纺丝的方法,制备出了直径在300nm^3μm之间的亚微米尺度的纤维,并比较了PMIA干-湿法及干法静电纺丝的成纤工艺.利用光学显微镜、扫描电镜比较了两种方法所得电纺纤维的形态,并通过纤维结晶度测试比较了两种纤维的结晶结构,从而研究了新型溶剂离子液的使用对高聚物纤维静电成形的影响.

Improved thermal conductivity and dielectric properties of flexible PMIA composites with modified micro-and nano-sized hexagonal boron nitride

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.