含有石墨烯和纳晶纤维素的聚氨酯复合纳米纤维

以N,N-二甲基甲酰胺/丙酮(DMF/CP)为混合溶剂,纳晶纤维素(NCC)辅助还原的氧化石墨烯(r GO)和热塑性聚氨酯(TPU)为原料,采用静电纺丝法制备了rGO/TPU复合纳米纤维,通过扫描电子显微镜、透射电子显微镜、激光粒度仪观察了rGO、NCC、复合纳米纤维膜的尺寸和形貌结构,并测试分析了纳米纤维膜的力学性能、热性能和亲水性。结果表明,当m(rGO)/m(TPU)=1.5/100时,复合纳米纤维表面光滑、直径均一,相应的复合纳米纤维膜断裂强度最大(31.98MPa),比纯TPU纳米纤维膜断裂强度(7.92 MPa)提高了303.79%。此外,随着rGO和NCC的加入,复合纳米纤维膜的热稳定性和亲水性增强。     

二醋纤纺丝液性能对静电纺纤维的影响

为优化二醋酸纤维素的纺丝加工成型工艺,研究了二醋片特性黏度、浓度和溶剂配比对纺丝液性能的影响,并探索了纺丝液性能与所纺纤维形貌和直径之间的关系。结果表明:随着特性黏度和浓度的增大,纺丝液黏度增大,流动性能变差,所纺纤维直径增大;当混合溶剂中丙酮含量低时,纺丝液因黏度和表面张力大,电导率小而无法纺丝只能收集到珠状液滴;逐渐增加丙酮含量,黏度和表面张力减小,电导率增大,所纺纤维直径增大;当使用丙酮/N,N-二甲基乙酰胺的体积比为3∶2时,可以收集到光滑无缺陷的纳米纤维;当丙酮含量较高时,纺丝液因溶剂挥发速率快而凝固从而无法纺丝。     

静电纺丝制备聚苯乙烯/纳米纤维素晶体纳米复合薄膜及其性能表征

采用静电纺丝法成功制备出聚苯乙烯(PS)/纳米纤维素晶体(CNCs)纳米复合薄膜,并对复合纤维薄膜的形貌、热学性能、力学性能和疏水性能进行了表征。结果表明,随CNCs添加量的增加,静电纺PS/CNCs纳米复合纤维表面逐渐光滑,且纤维平均直径呈先增大后减小趋势;纳米复合薄膜呈两阶段热分解方式,其最大热解温度由415.2℃升高到421.4℃;纳米复合薄膜的拉伸性能也随CNCs的增加而有所提高,CNCs添加量为m(CNCs)/m(PS)=7/100时得到纳米复合薄膜的最大拉伸应力为(0.4±0.02)MPa,为电纺PS纳米纤维薄膜拉伸应力的5.7倍,而断裂伸长率则呈逐渐减小趋势。亲水性CNCs的加入,并未降低PS本身疏水特性,其接触角先增大至139°后减小到130°,接触角总体呈增大趋势。     

电纺聚酰亚胺/氧化石墨烯复合纳米纤维膜的制备及性能研究

采用静电纺丝技术制备了氧化石墨烯(GO)不同含量的聚酰亚胺/氧化石墨烯(PI/GO)复合纳米纤维膜,并研究其结构、表面润湿性、热氧化特性、力学性能和过滤性能。结果表明,添加GO有利于纳米纤维的直径分布趋于均匀,在GO用量为0.5%(wt,质量分数)条件下,PI/GO复合纳米纤维膜平均纤维直径最小为(231±36)nm,孔隙率高达89.61%,拉伸强度为14.43MPa,杨氏模量为1.36GPa,断裂伸长率为10.84%,热氧化稳定性较纯PI纳米纤维膜提高了15℃,过滤效率最高达到96.5%,较纯PI纳米纤维膜提高了8%。添加GO能有效提高PI/GO复合纳米纤维膜的疏水性、力学性能及热氧化稳定性。     

静电纺丝法制备PLA/CNCs纳米复合薄膜及其性能研究

采用静电纺丝法成功将纳米纤维素晶体(CNCs)植入聚乳酸(PLA)基体中,制备出网状结构的绿色纳米复合材料,并探讨了PLA/CNCs薄膜的微观形貌、结晶度、热学性能和机械性能随CNCs添加量的变化趋势。结果表明,随着CNCs添加量的增加,静电纺PLA/CNCs纳米复合材料薄膜珠状纤维减少,纤维直径增大;纳米复合纤维薄膜的结晶度提高了87.9%;纳米复合纤维薄膜的最大热解温度由369.36℃提升到380.02℃;纳米复合纤维的拉伸性能随CNCs添加量的增加而显著提高,CNCs添加量为11%(质量分数)时得到的最大拉伸力和拉伸强度最大分别为3.76N和4.58MPa,与纯PLA薄膜相比分别提高了289%和159%。     

静电纺丝法制备聚偏二氟乙烯-六氟丙烯共聚物锂离子电池隔膜及性能

以N,N-二甲基甲酰胺(DMF)和丙酮的混合溶液为溶剂,通过静电纺丝技术制备了聚偏二氟乙烯-六氟丙烯共聚物(PVDF-HFP)纳米纤维膜,并对纺丝工艺及纤维膜的性能进行了详细研究。结果表明:PVDF-HFP纤维膜的最佳纺丝工艺条件为:纺丝液浓度为0.26g/mL、溶剂DMF与丙酮的体积比为7∶3、纺丝电压为20kV、纺丝温度为30℃。制备的PVDF-HFP纤维膜中纤维直径主要分布在150～300nm,膜的熔点为157.94℃,拉伸强度为10.09MPa,断裂伸长率为74.34%,孔隙率达84%,吸液率达到570%。     

浓度及溶剂配比对PVDF静电纺纳米纤维膜的影响

以聚偏氟乙烯(PVDF)为纺丝溶质，N,N-二甲基甲酰胺(DMF)与四氢呋喃(THF)为混合溶剂，配制不同浓度和不同溶剂配比的纺丝溶液，利用静电纺丝技术制备了PVDF纳米纤维膜。通过扫描电子显微镜(SEM)、光学接触角测量仪、ImageJ软件对所制纳米纤维膜的微观形貌、疏水性能、纤维直径等进行分析，研究了不同浓度和不同溶剂配比对纳米纤维膜的影响。结果表明：当溶液浓度为10%(PVDF质量分数),DMF/THF溶剂配比为3/2时静电纺丝制备的纳米纤维膜纤维形貌良好，直径分布均匀，具有良好的疏水效果。     

静电纺丝制备定向排列聚酰亚胺基炭纳米纤维

均苯四甲酸二酐和二氨基二苯醚溶解在N,N-二甲基乙酰胺中,室温下聚合为聚酰胺酸。以聚酰胺酸溶液作为前驱体,在20 k V电压下静电纺丝,然后进行350℃热亚胺化处理可得到定向排列的聚酰亚胺纳米纤维,再于900℃炭化、3 000℃石墨化,得到均匀连续、定向排列的聚酰亚胺基炭纳米纤维,纤维直径约100 nm。结果表明,聚酰胺酸质量分数为20%的溶液电纺性能最佳,3 000℃石墨化处理后的炭纳米纤维具有典型的石墨结构。     

亚胺化时间对电纺聚酰亚胺纳米纤维结构和性能的影响

通过两步法制备聚酰亚胺(PI)纳米纤维,首先采用高压静电纺丝技术制备聚酰胺酸(PAA)纳米纤维,然后在高温下通过不同的亚胺化时间获得PMDA-ODA型PI纳米纤维。利用红外光谱仪、X射线衍射仪、扫描电子显微镜、热重分析仪和力学性能测试仪研究了不同亚胺化时间对PI纳米纤维微观形貌、化学结构、热稳定性以及断裂强度等的影响。结果表明,当亚胺化时间较短时,聚酰胺酸纳米纤维亚胺化并不完全;亚胺化时间达到30min左右时,聚酰胺酸的亚胺化基本完成;随着亚胺化时间的延长,纳米纤维结晶度逐渐增加,纤维变得更细也更加均匀,热稳定性也随之提高,断裂强度和断裂伸长率也有所提高。通过对聚酰亚胺纳米纤维膜进行透气性测试发现,随亚胺化时间延长纤维膜透气性有所提高。     

凝固浴条件对聚酰亚胺纤维形貌和性能的影响

采用湿法纺丝获得聚酰胺酸(PAA)初生纤维,以水和N,N-二甲基乙酰胺(DMAc)的混合溶液作为凝固浴,通过热酰亚胺化制备了均苯四甲酸二酐/4,4’-二氨基二苯醚(PMDA/4,4’-ODA)-聚酰亚胺(PI)纤维。系统研究了阱深长度、凝固浴温度及浓度对PI纤维形貌和性能的影响。结果表明:PAA纤维截面在阱深长度较小、凝固浴温度较低、DMAc浓度较低时呈不规则的腰形,随着阱深长度不断增加,凝固浴温度和浓度的增加,纤维截面都会逐渐趋于圆形。在阱深长度为50cm,凝固浴温度40℃,以3%(体积分数)DMAc作为凝固浴时,所得PAA纤维截面形貌较圆整,且PI纤维性能较好。     

同质纳米纤维增强制备透明低膨胀系数聚酰亚胺

应用于柔性显示的聚酰亚胺(Polyimide,PI)膜要求高透明性和低热膨胀系数C_TE,而目前高透明聚酰亚胺的C_TE普遍高于40×10?6/℃。本研究采用同质增强法,将高强度的纳米PI纤维与无色透明热塑性含氟聚酰亚胺(PI-F)复合,得到的纳米PI纤维增强PI-F基复合薄膜不仅保持PI-F的高透明,同时具有更低的C_TE和优异的拉伸性能。研究结果表明:纳米尺寸的纤维可减少光透过时发生的散射,使复合薄膜维持了较高的透明性。当纳米PI纤维质量分数为10%时,在可见光区其透光率达到80.5%,与纯PI-F薄膜相比,复合薄膜的C_TE值降低了40.3%,为28.3×10?6/℃。其拉伸强度提高了132.9%,达到107.6 MPa,拉伸模量增大了89.5%,达到1152.2 MPa。      

High performance polyimide composite films prepared by homogeneity reinforcement of electrospun nanofibers

Highly aligned polyimide (PI) and PI nanocomposite fibers containing carbon nanotubes (CNTs) were produced by electrospinning. Scanning electron microscopy showed the electrospun nanofibers were uniform and almost free of defects. Transmission electron microscopy indicated that the CNTs were finely dispersed and highly oriented along the CNT/PI nanofiber axis at a relatively low concentration. The as-prepared well-aligned electrospun nanofibers were then directly used as homogeneity reinforcement to enhance the tensile strength and toughness of PI films. The neat PI nanofiber reinforced PI films showed good transparency, decreased bulk density and significantly improved mechanical properties. Compared with neat PI film prepared by solution casting, the tensile strength and elongation at break for the PI film reinforced with 2 wt.% CNT/PI nanofibers were remarkably increased by 138% and 104%, respectively. The significant increases in the overall mechanical properties of the nanofibers reinforced polyimide films can be ascribed to good compatibility between the electrospun nanofibers and the matrix as well as high nanofiber orientation in the matrix. Our study demonstrates a good example for fabricating high performance and high toughness polyimide nanocomposites by using this facile homogeneity self-reinforcement method.     

Electrospun nanofiber belts made from high performance copolyimide

Electrospun nanofibers based on copolyimides were made, aiming at finding a promising method for improving the mechanical properties of electrospun polyimide nanofibers. The copolyimide had a backbone consisting of 3,3',4,4'-biphenyl-tetracarboxylic dianhydride (BPDA), biphenylamide (BPA) and 4,4'-oxydianiline (ODA) residues. The structure and composition of the copolyimide was controlled by the ratio of rigid BPA and flexible ODA moieties. The electrospun copolyimide nanofibers were collected in the form of a belt using a rotating disc with a rim of 8?mm width. Scanning electron microscopy (SEM), infrared (IR) spectroscopy, x-ray scattering and tensile testing, dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) were used to characterize the nanofiber belts. The nanofibers had a diameter range from 80 to 300?nm and were well aligned in the belts. The thermal stability of the nanofiber belts was over 460?°C. The tensile test showed that the copolyimide nanofiber belts had much better mechanical properties than either of the flexible and rigid homo-polyimide (homo-PI) nanofiber belts. The tensile strength, modulus and elongation to break of the copolyimide nanofiber belt with BPA/ODA ratio of 40/60 are respectively 1.1 ± 0.1?GPa, 6.2 ± 0.7?GPa and 20.8 ± 1.2%, compared to 459 ± 36?MPa, 2.1 ± 0.3?GPa and 41.3 ± 2.2% for BPDA/ODA homo-PI as well as 384 ± 18?MPa, 11.5 ± 0.6?GPa and 3.9 ± 0.1% for BPDA/BPA homo-PI. The important feature is that the electrospun polymer nanofibers can be made very strong by using copolyimides as spinning materials.     

极端湿热环境下隔热的超疏水聚偏氟乙烯/聚酰亚胺纳米纤维复合气凝胶

优异的隔热材料在建筑、航空航天和体育设备等领域有着广泛的应用需求.然而,在实际应用中,隔热材料在不同温度和湿度条件下,其性能往往会恶化.因此,构建在极端湿热环境下仍具有出色的隔热性能的块状材料是非常重要的.在本工作中,我们构思了一种绿色制备策略,即通过静电纺丝和冷冻干燥技术来制备超疏水且可压缩的聚偏氟乙烯/聚酰亚胺(PVDF/PI)纳米纤维复合气凝胶. PVDF纳米纤维和PI纳米纤维分别充当疏水性纤维骨架和机械支撑骨架,形成具有良好机械柔韧性的坚固的三维框架. PVDF/PI气凝胶在室温下具有出色的超疏水特性(水接触角为152°)和低导热性(31.0 m W m^-1K^-1).同时,在100%湿度(80℃)下, PVDF/PI气凝胶仅显示出48.6 m W m^-1K^-1的低热导率,其性能优于大多数商业绝热材料.因此,新型的PVDF/PI复合气凝胶有望成为高温和高湿环境中应用的优良隔热材料.     

Fabrication and evaluation of polyamide 6 composites with electrospun polyimide nanofibers as skeletal framework

In this study, two types of polyimide (PI) nanofiber mats, including (1) the mats consisting of (almost) randomly overlaid PI nanofibers and (2) the mats consisting of highly aligned PI nanofibers, were prepared by the materials-processing technique of electrospinning. The nanofiber mats were subsequently used to develop composites with polyamide 6 (PA6) via the composites – fabrication method of polymer melt infiltration lamination (PMIL). Owing to superior mechanical properties (i.e., the tensile strength and modulus were 1.7 GPa and 37.0 GPa, respectively) and large specific surface area of electrospun PI nanofibers, the PI/PA6 composites with PI nanofiber mats as skeletal framework demonstrated excellent mechanical properties. In particular, the PI/PA6 composite containing 50 wt.% of aligned PI nanofibers had the tensile strength and modulus of 447 MPa and 3.0 GPa along the longitudinal direction, representing ～700% and ～500% improvements as compared to neat PA6.     

短切聚酰亚胺纤维增强可瓷化三元乙丙橡胶复合材料的制备与性能

以三元乙丙橡胶(EPDM)为基体,高岭土(Kaolin)和滑石粉(Talc)为功能填料,Al(OH)_3为阻燃剂,短切聚酰亚胺纤维(PI Fiber)为增强材料,制备了不同PI纤维含量的可瓷化PI Fiber-Kaolin-Talc-Al(OH)3/EPDM(PKTA/EPDM)复合材料。研究了短切PI纤维对复合材料拉伸性能、热稳定性和微观形貌的影响,分析了短切PI纤维增强复合材料的陶瓷化机制。研究表明,短切PI纤维含量增加会导致可瓷化PKTA/EPDM复合材料拉伸性能下降,当纤维含量与EPDM质量比低于10∶100时,复合材料力学性能良好。可瓷化PKTA/EPDM复合材料在800~1 100℃热解后均发生陶瓷化反应。当PI纤维与EPDM质量比为4∶100~8∶100时,可以有效保持复合材料高温热解后的形状尺寸稳定,并且热解产物弯曲强度在6~18 MPa之间。热分析结果表明,加入PI纤维可以提高可瓷化PKTA/EPDM复合材料的热稳定性。结合热分析和断面SEM分析表明,PI纤维热解、炭化后贯穿在EPDM裂解后的炭层中形成纤维增强炭层结构。这种纤维增强结构在复合材料热解过程中有助于获得尺寸稳定、形状完整的陶瓷产物。     

In vitro evaluation of electrospun gelatin–glutaraldehyde nanofibers

The gelatin–glutaraldehyde (gelatin–GA) nanofibers were electrospun in order to overcome the defects of ex-situ crosslinking process such as complex process, destruction of fiber morphology and decrease of porosity. The morphological structure, porosity, thermal property, moisture absorption and moisture retention performance, hydrolytic resistance, mechanical property and biocompatibility of nanofiber scaffolds were tested and characterized. The gelatin–GA nanofiber has nice uniform diameter and more than 80% porosity. The hydrolytic resistance and mechanical property of the gelatin–GA nanofiber scaffolds are greatly improved compared with that of gelatin nanofibers. The contact angle, moisture absorption, hydrolysis resistance, thermal resistance and mechanical property of gelatin–GA nanofiber scaffolds could be adjustable by varying the gelatin solution concentration and GA content. The gelatin–GA nanofibers had excellent properties, which are expected to be an ideal scaffold for biomedical and tissue engineering applications.     

熔体微分电纺PLA/OMMT可降解纳米纤维膜制备及污染处理

采用无溶剂的熔体静电纺丝技术制备可降解聚乳酸(PLA)纳米纤维,是一种很有前景和挑战性的绿色制备技术。其制备的纳米纤维膜孔隙率高、吸附能力强,可高效地处理环境污染问题。借助自制的熔体微分电纺装置,在PLA中引入了有机改性蒙脱土(OMMT),在260℃下制备了PLA/OMMT纳米纤维膜。探究了OMMT含量对PLA纤维形貌、吸油性能、空气过滤性能及降解性能的影响,并获得了最佳的OMMT配比含量。研究表明:加入OMMT后PLA热稳定性提高,结晶度大幅降低。OMMT质量分数为2%时制备的纤维,其直径为450nm。该纤维膜吸油倍率为133.5g/g,是市售PP无纺布的4~5倍,保油倍率为84.2g/g,具有良好的重复使用性能。针对粒径≥0.3μm尘埃粒子的空气过滤效率为99.31%,达到欧标H11过滤等级。且相比于纯PLA纤维膜降解性能提高,减少了二次污染,符合工业化绿色环保要求。     

溶剂对静电纺丝聚氨酯纤维仿生涂层的影响

为了有效预防心血管支架植入后的再狭窄病征,在不锈钢支架表面构建仿生细胞外基质结构的纳米纤维涂层是提高支架生物相容性的有效方法.本文通过静电纺丝技术,在316L不锈钢基底上制备出纳米聚氨酯纤维涂层,研究溶剂对聚氨酯纤维形貌的影响.实验证明溶剂的性质对T80A型聚氨酯的可纺浓度范围有显著影响.在本实验装置下,以THF为溶剂,可纺浓度范围为4%～15%,以DMF为溶剂范围增大为8%～22%.以THF为溶剂,在6%～12%最佳纺丝范围内,随着浓度的增大,纤维直径先减小后增大.采用适宜比例的THF和DMF混合溶剂可获得比单一溶剂更好的纤维形貌,制备出直径分布均匀(平均为350nm)、连续致密的聚氨酯纤维涂层,并找出最佳溶剂配比随浓度的变化规律.     

利用静电纺丝技术制备纳米黏土/聚乳酸复合纳米纤维与其表征

利用静电纺丝技术制备了纳米黏土/聚乳酸(PLA)复合纳米纤维,并将该复合纳米纤维收集成无纺布薄膜,采用SEM和TEM观察了复合纳米纤维的微观形貌和结构,分别利用XRD和TGA测试了复合纳米纤维的结晶行为及热学行为,并分析了复合纳米纤维薄膜的拉伸力学性能随纳米黏土含量的变化关系。结果表明:当PLA含量为10wt%、纳米黏土含量为1wt%、CHCl3与DMF体积比为3∶1溶剂条件下,所制备的纳米黏土/PLA复合纳米纤维的细度和均匀性均得到改善;XRD测试结果表明,纳米黏土成功附着在PLA中。TGA和力学测试结果表明,纳米黏土/PLA复合纳米纤维的热稳定性和力学性能相对于纯PLA纤维有较大幅度提高,当纳米黏土含量为1wt%时,其初始分解温度提高了60℃,拉伸强度、断裂伸长率和弹性模量分别提高了111.3%、74.9%和20.0%。