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《合成纤维工业》2016,(6):46-49
采用溶液喷射纺丝技术制备间位芳纶/多壁碳纳米管(PMIA/MWNTs)纳米纤维,探讨了不同工艺参数下纳米纤维表观形貌和直径分布的变化,研究了MWNTs对PMIA纳米纤维膜结晶性能和力学性能的影响。结果表明:在拉伸风压为0.12 MPa、喷丝孔内径为0.4~0.5 mm时,可以制得形貌较好的PMIA/MWNTs纳米纤维;随MWNTs负载量的增加,制得纳米纤维的平均直径变粗,结晶度变大,纤维膜拉伸强度增大,断裂伸长率则下降;MWNTs的最佳负载量为0.3%,此时可制得形貌结构均匀,直径较细的PMIA/MWNTs纳米纤维,纤维平均直径为372 nm,纤维膜拉伸强度达到41.85 MPa,较纯PMIA纳米纤维膜提高了86%以上。 相似文献
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以聚乙烯醇(PVA)为原料、去离子水为溶剂,通过静电纺丝制备PVA纳米纤维膜,利用正交实验探讨静电纺丝过程中纺丝液PVA浓度、纺丝距离、纺丝电压和注射速度对PVA纳米纤维膜形貌及纤维直径的影响,得出制备纤维膜的较佳工艺条件,并分析了纺丝液PVA浓度对纤维膜的力学性能和亲水性能的影响。结果表明:随着纺丝液PVA浓度的增加,PVA纤维的直径逐步变小,直径分布变窄;当纺丝液PVA质量分数为7%、纺丝电压为14 kV、纺丝距离为14 cm、注射速度为0.5 mL/h时,纤维膜的纤维直径最小,为203 nm;正交实验中PVA浓度、纺丝电压、纺丝距离、注射速度4个因素的极差值分别为87.00,49.67,18.33,11.67;纺丝液PVA质量分数从5%增加到7%,纤维膜的断裂强度从2.21 MPa提高至2.81 MPa,断裂伸长率从31.63%提高至56.39%,水接触角从37.7°提高至48.7°。 相似文献
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采用静电纺丝技术,以特殊设计的金属丝螺旋盘绕滚筒作为接收装置,制备了具有一定取向的丝素蛋白(SF)-聚乙烯醇(PVA)共混纳米纤维材料。利用扫描电子显微镜(SEM)对纤维形貌进行观察,并通过Image-Pro Plus软件对纤维细度进行测试,探讨了SF与PVA的配比以及纺丝电压、接收距离等静电纺丝参数对所得纳米纤维形貌、细度及其分布的影响。结果表明:将质量浓度为25 kg/L的SF与质量分数为8%的PVA以质量比15∶3.2共混,并采用20 kV的纺丝电压和13 cm的接收距离静电纺时,所得纳米纤维的平均直径约为238 nm,且直径分布较为均匀。采用该法制得的纳米纤维材料具有一定的纤维取向,有利于细胞生长,可应用于生物医药领域。 相似文献
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《化学与生物工程》2017,(4)
将CdTe量子点(QDs)与聚乙烯醇(PVA)通过溶液共混,利用静电纺丝技术制备出CdTe QDs/PVA复合纳米纤维,通过扫描电子显微镜(SEM)、能量色散X-射线光谱(EDX)、分子荧光分光光度计和倒置荧光显微镜对复合纳米纤维进行微观形貌和荧光性能的研究。结果表明:当PVA含量为10%、CdTe QDs浓度为1.5mmol·L-1时,所制备的CdTe QDs/PVA复合纳米纤维的荧光性能最佳,且纳米纤维表面光滑、尺寸均匀,直径为200nm左右。与溶液浇铸法制得的CdTe QDs/PVA复合薄膜相比,该复合纳米纤维膜的荧光性能有所提高,说明CdTe QDs在复合纳米纤维中具有更好的稳定性和分散性。 相似文献
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以聚苯硫醚(PPS)、聚酰胺6(PA6)为原料,采用共混熔融纺丝法制备出PPS/PA6共混海岛纤维,用甲酸溶解剥离基体相PA6,制得纳米PPS纤维;研究了PPS/PA6共混体系的流变性能以及PPS含量、螺杆转速对共混物及PPS纳米纤维的结构、性能的影响。结果表明:PPS/PA6共混物的纺丝温度为290℃;随着PPS含量增加,共混物中PPS岛相直径增加,分布变宽,PPS质量分数应小于60%;当共混物中PPS质量分数由20%增至55%时,PPS纳米纤维平均直径由104 nm升至150 nm;加工过程中,适当提高螺杆转速有利于PPS纳米纤维直径细化和均匀化,当螺杆转速由20 r/min增至60 r/min时,其平均直径由180 nm降至122nm;PPS与PA6共混后,两种聚合物结晶速率均提高,且得到的PPS纳米纤维结晶度约22%,高于纯PPS纤维的结晶度。 相似文献
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将水性聚氨酯(WPUR)与聚乙烯醇(PVAL)按照不同质量比制备质量分数为8%的纺丝溶液,通过静电纺丝制备WPUR/PVAL复合纳米纤维。运用扫描电子显微镜、傅立叶变换红外光谱仪和X射线衍射仪对WPUR与PVAL质量比不同的纺丝溶液制备的复合纳米纤维的微观形貌和结构进行分析。实验结果表明,PVAL的含量对复合纳米纤维的形成和形貌起着决定性的作用,随着溶液中PVAL含量的增加,纺丝过程中纺丝液逐渐从不连续复合纳米纤维转变为连续均匀的复合纳米纤维,纤维直径逐渐增大,当纺丝液中WPUR与PVAL的质量比为30∶70时,得到的复合纳米纤维形貌最佳,其平均直径为330.8 nm,具有最小标准差,为22 nm,同时随着纺丝溶液中PVAL含量的增加,所得复合纳米纤维的结晶性能增强。 相似文献
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苯乙烯是重要的石油化工原料。本文介绍了国内外苯乙烯生产的发展概况,合成乙苯,苯乙烯所用的催化剂种类,并就苯乙烯生产及催化剂的发展趋势提出了自己的观点。 相似文献
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Synthesis and characterization of homopolymers and copolymers of various acrylates and acrylonitrile
Various homopolymers and copolymers of methyl acrylate, ethyl acrylate, butyl acrylate, and acrylonitrile in different feed ratios were synthesized. These were characterized by IR, 13C-NMR, DSC, DTA, and TGA. Spectroscopic characterization helped in differentiating copolymers of different mol ratios. Thermal analysis revealed different degradation patterns for homopolymers and copolymers. The temperature and energy changes associated with various phase transitions were dependent on the chemical composition of homo- and copolymers, as expected. © 1993 John Wiley & Sons, Inc. 相似文献
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G. R. Hamed 《The Journal of Adhesion》1983,16(1):31-39
A substantially greater detachment energy is required to strip a polyethylene tereph-thalate (Mylar) film from a styrene-butadiene-styrene (SBS) triblock copolymer compared to that for peeling from a random styrene-butadiene (SBR) copolymer. This is true even though the intrinsic interaction between the Mylar and each elastomer is expected to be similar because of their virtually identical chemical composition. It is proposed that this difference in peel strength (between the SBS and SBR) is a consequence of the much higher dissipative capacity of the former elastomer. Another manifestation of this is the higher cohesive tear strength of the SBS compared to the SBR. Extents of energy dissipation within each elastomer during detachment of the Mylar adherend are consistent with the hypothesis that the average maximum stress experience before detachment is some similar fraction of each elastomer's tensile strength. 相似文献
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责任是人应主动承担的角色义务和对其因过失所造成后果应承担的责罚.有两层涵义:一是义务;二是后果.责任心是个体自觉做好分内事务和履行道德义务的心理倾向,是个性心理品质成分中自我特征维度上的重要内容.责任心具有两个方面的涵义:一是角色分内职责;二是角色道德义务.责任心是一种通过责任认知、责任个性和责任适应的动态形式表现出来的静态品质,责任心是责任心过程结构与责任心关系结构相互制约、相互影响的统一体. 相似文献
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The variation of the Au 4f binding energy of Au clusters with the cluster size has been established by measuring the binding energies of clusters whose size distributions were independently determined by HREM and STM. The binding energy increases significantly when the cluster size is less than 2 nm. Au-Cu bimetallic clusters of the composition Cu3Au have been deposited for the first time on carbon substrates. The shifts in the core level binding energies of the bimetallic clusters show the effect of alloying in the case of large clusters, but show effects of both alloying and cluster size in the case of the small clusters. The interaction of CO with Cu3Au clusters is stronger than with a bulk Cu metal. The interaction of CO with small Cu clusters also seems to be stronger than with bulk Cu or with large Cu clusters. 相似文献
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《国际聚合物材料杂志》2012,61(1-4):113-122
Abstract Kinetics and mechanisms of oxidation of 6 acetals by molecular oxygen and ozone in liquid phase have been studied. Reaction with molecular oxygen (70°C, 15–16 hr) leads to the formation monoethers of the corresponding glycols with 68–90% selectivity. Salts of metals and complexes with crown-ethers have increased the reaction rate significally. Ozone have reacted with acetals with formation similar products. The mechanisms of intermediate stages have been proposed. 相似文献