低断面轿车子午线轮胎PDEP-S设计理论

ＰＤＥＰＳ设计理论是在ＰＤＥＰ设计理论的基础上发展、完善而成的。用ＰＤＥＰＳ设计理论可使轮胎设计进一步优化，从而改善轮胎的使用性能。ＰＤＥＰＳ与ＰＤＥＰ设计理论的区别是：它在轮廓设计中把轮胎的预应力和动平衡轮廓两者有机地结合起来，深入地研究了轮胎的带束层、胎体和胎圈的压力分担率，在使其各部件充分发挥其作用的条件下，优化设计出最佳轮廓并使其使用性能提高     

高性能纤维模量表征中的几个问题

采用万能材料试验机对超高相对分子质量聚乙烯纤维（SK75型）和芳纶（Twaron2000型）两种样品的单丝、复丝模量进行了表征。研究发现,单丝的模量测定时,启动时拉伸夹具的惯性是初始模量误差的主要来源。样品处于松弛状态,使预张力为零,可以准确地测量样品初始模量;选取加载预张力的方法,应变取值范围设定为0．5％～1．5％时可以克服启动力的影响,得到合理的结果。在复丝测定时启动力可以忽略。测试时需要加捻的复丝样品,不合理的应变取值范围是误差主要来源,应变取值范围设定为0．1％～1．0％时可以得到合理的结果。     

高厚径比PCB深镀能力影响因素的研究

高厚径比PCB的电镀加工中,深镀能力越来越成为一个重要的评价指标。对比了PCB电镀过程的几种循环方式以及增加振荡对孔内溶液交换的影响,并进行理论分析及实验验证。结果表明：采取底喷以及增加夹具振荡措施可以有效提升高厚径比PCB小孔镀铜的深镀能力。     

Impact of the Fiber Length Distribution on Porous Sponges Originating from Short Electrospun Fibers Made from Polymer Yarn

Ultralight highly porous sponges made of short electrospun polymer fibers have gained significant attention for a variety of applications. According to the established procedures, short electrospun fibers are obtained by cutting or homogenization of electrospun fibers in suspension, which yield fibers with inhomogeneous fiber length. The role of the fiber length distribution and the fiber length in the mechanical compressibility of the sponges is unknown. Therefore, as a model study, sponges made from suspensions of short electrospun poly(acrylonitrile) (PAN) fibers with controlled fiber length distribution are investigated, and the role of the fiber length distribution in the compressibility of the sponges is analyzed quantitatively. These sponges are also compared to the ones prepared by established procedure as a benchmark. It is found that the compression stress and modulus of ultralight sponges with monodisperse short fibers are respectively 32% and 45% higher than that made with polydisperse short fibers. The study also shows that sponges made from longer fibers have higher modulus in comparison to the sponges made from shorter fibers.     

Effect of Blend Ratio and Draw Ratio on the Mechanical Properties of PET/PP Blended Conjugate Fibers

This study analyzes the influence of blend ratio and draw ratio on the fiber properties of blend fibers composed of poly (ethylene terephthalate), or PET, and polypropylene, or PP, (hereafter referred to as PET/PP conjugate fibers). For a comparison, PET and poly (butylene terephthalate), or PBT blends, (hereafter referred to as PET/PBT conjugate fibers) are also investigated. Various blend ratios of fibers are melt spun and drawn in a multistep drawing method. The conjugate fibers are evaluated using tenacity, Young's modulus, wide-angle X-ray diffraction, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) tests. The results show that multistep drawing using a lower first-step draw ratio provides a higher tenacity and Young's modulus. Furthermore, when the blend ratio is 75/25 in a PET/PP conjugate fiber and 50/50 in a PET/PBT conjugate fiber, the polymer components undergo a phase inversion phenomenon. A PP sub-micron (10^?1 ～ 10⁰ micron) fiber of about 0.0001 ～ 0.00017 tex in fineness, or about 0.4 ～ 0.5 micron in diameter, can be obtained when PET/PP conjugate fiber is treated with a 25% NaOH aqueous solution by weight. However, A PBT sub-micron fiber cannot be achieved using a PET/PBT conjugate fiber.     

Geometrical and Optical Properties of Irregular Fibers as a Function of Draw Ratio

The Pluta polarizing interference microscope with a fiber rotator-mechanical device was used to detect the variation in the cross-sectional area, shapes and optical properties of irregular fibers during the cold drawing process. The rotation method was used to overcome the difficulty of measuring the transverse cross-sectional area of fibers with irregular shapes during their drawing process. Acrylic fibers of two denier were used during this investigation. Some optical parameters were measured, such as refractive indices and birefringence. The measurements of the refractive indices show that acrylic fibers have a negative birefringence. The polarizability-per-unit volume was used to clarify the negative birefringence of these fibers. Microinterferograms and the digitized images with their contour lines are given for illustration.     

大长径比卧螺离心机螺旋输送器的有限元分析

应用SolidWorks对大长径比卧螺离心机的转鼓-螺旋输送器系进行了三维建模,采用与SolidWorks无缝衔接的有限元分析插件Simulation对其进行了有限元仿真。通过SolidWorks Simulation对螺旋输送器在正常工况下的整体结构进行了静力分析和模态分析,得到了螺旋输送器前5阶固有频率、应力分布和...     

Optimizing the Aspect Ratio of Nanopatterned Mesoporous TiO2 Thin-Film Layer to Improve Energy Conversion Efficiency of Perovskite Solar Cells

The energy conversion efficiency (ECE) (η), current density (J_sc), open-circuit voltage (V_oc), and fill factor (ff) of perovskite solar cells were studied by using the transmittance of a nanopatterned mesoporous TiO₂ (mp-TiO₂) thin-film layer. To improve the ECE of perovskite solar cells, a mp-TiO₂ thin-film layer was prepared to be used as an electron transport layer (ETL) via the nanoimprinting method for nanopatterning, which was controlled by the aspect ratio. The nanopatterned mp-TiO₂ thin-film layer had a uniform and well-designed structure, and the diameter of nanopatterning was 280 nm. The aspect ratio was controlled at the depths of 75, 97, 127, and 167 nm, and the perovskite solar cell was fabricated with different depths. The ECE of the perovskite solar cells with the nanopatterned mp-TiO₂ thin-film layer was 14.50%, 15.30%, 15.83%, or 14.24%, which is higher than that of a non-nanopatterned mp-TiO₂ thin-film layer (14.07%). The enhancement of ECE was attributed to the transmittance of the nanopatterned mp-TiO₂ thin-film layer that is due to the improvement of the electron generation. As a result, better electron generation affected the electron density, and J_sc increased the V_oc, and ff of perovskite solar cells.     

高性能纤维的发展现状及特点与应用

介绍我国高性能纤维的发展现状以及聚对苯撑苯并二噁唑(PBO)纤维、聚苯硫醚(PPS)纤维、超高相对分子质量聚乙烯(UHMWPE)纤维三种常见的高性能纤维的应用,并采用了热性能分析(热重分析、热力学分析、动态力学分析)的测试方法介绍了PBO纤维、PPS纤维的特点。     

超分子自组装及其在高分子合成领域中的应用

超分子自组装是近年来倍受重视的国际前沿课题,它将会极大促进信息、能源、生命、环境和材料科学等学科领域的发展,介绍了基于氢键、π键、配位键、双亲分子4种自组装体系,重点综述了这4种自组装体系在高分子合成领域中的最新进展,最后对超分子自组装的发展趋势做了展望。     

Preparation of Hydroxyapatite Fibers by Electrospinning Technique

Hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂, HA) fibers were prepared by electrospinning a precursor mixture of Ca(NO₃)₂·4H₂O and (C₂H₅O)₃PO with a polymer additive, followed by a thermal treatment. The X-ray diffraction (XRD) analysis of the annealed composite fibers revealed that pure HA phase could be obtained by annealing at 600°C for 1 h. The scanning electron microscopy (SEM) analysis showed the surface of as-electrospun composite fibers with an average diameter of 50 μm was smooth due to the amorphous nature of the polymer. However, the surface of the calcined HA fibers was rough because of the complete removal of the polymer. The pure HA fibers obtained by electrospinning in this work were up to 10 mm in length and 10–30 μm in diameter and the hydroxyapatite grain size was ∼1 μm in the HA fibers.     

Tunable Supramolecular Chirogenesis in the Self-Assembling of Amphiphilic Porphyrin Triggered by Chiral Amines

Supramolecular chirality is one of the most important issues in different branches of science and technology, as stereoselective molecular recognition, catalysis, and sensors. In this paper, we report on the self-assembly of amphiphilic porphyrin derivatives possessing a chiral information on the periphery of the macrocycle (i.e., D- or L-proline moieties), in the presence of chiral amines as co-solute, such as chiral benzylamine derivatives. The aggregation process, steered by hydrophobic effect, has been studied in aqueous solvent mixtures by combined spectroscopic and topographic techniques. The results obtained pointed out a dramatic effect of these ligands on the morphology and on the supramolecular chirality of the final self-assembled structures. Scanning electron microscopy topography, as well as fluorescence microscopy studies revealed the formation of rod-like structures of micrometric size, different from the fractal structures formerly observed when the self-assembly process is carried out in the absence of chiral amine co-solutes. On the other hand, comparative experiments with an achiral porphyrin analogue strongly suggested that the presence of the prolinate moiety is mandatory for the achievement of the observed highly organized suprastructures. The results obtained would be of importance for unraveling the intimate mechanisms operating in the selection of the homochirality, and for the preparation of sensitive materials for the detection of chiral analytes, with tunable stereoselectivity and morphology.     

干喷湿纺中凝固牵伸对碳纤维前驱体PAN初生纤维的影响

为了研究PAN纤维干喷湿纺中凝固浴牵伸的作用机理。采用DMso水溶液作为凝固浴,利用纤维强伸度仪、分析天平、X射线衍射仪、电子探针等手段,研究了干喷湿纺中凝固牵伸对PAN初生纤维及最终原丝结构及性能的影响。结果表明,干喷瀑纺中,在凝固浴浓度（65％）、温度（20℃）、空气层厚度（2mm）等条件下,随凝固浴牵伸的增加,初生纤维及PAN原丝的孔隙率逐步降低,结晶度逐渐增大,初生纤维表现出较高的断裂强度,纵表面更加光洁,横截面更加致密;适当调整凝固浴牵伸,得到了纤度1．01dtex,强度7．52cN,dtcx的聚丙烯腈原丝。     

利用静电纺丝技术制备多孔聚苯乙烯纤维

利用静电纺丝技术制备聚苯乙烯（PS）聚乙烯吡咯烷酮（PVP）复合纤维,通过除去复合纤维中的PVP成分,成功地制备了PS多孔纤维,并对其进行了SEM谱图分析测试。结果表明,纺丝电压、PS与PVP配比直接影响着复合纤维的微观形态;PS／PVP复合纤维的浸泡时间、浸泡后的干燥方式、PS与PVP配比都会影响PS多孔纤维的表面形态以及纤维的内部结构。     

玄武岩纤维及聚丙烯纤维对水泥砂浆性能影响的对比分析

以聚丙烯纤维为对比,研究了不同掺量的玄武岩纤维对水泥砂浆抗压、抗折、抗弯性能的影响,并采用扫描电子显微镜观察纤维在砂浆中的分布状态.结果表明:在最佳掺量下,玄武岩纤维水泥砂浆的各种力学性能优于聚丙烯纤维水泥砂浆并与砂浆具有更好的结合形态,可以取代聚丙烯纤维作为水泥基材料增强体,玄武岩纤维对水泥浆体早期具有显著的增强作用,但降低了水泥砂浆的28d强度;玄武岩纤维对砂浆的抗弯破坏荷载改善不显著,但明显增大了相同荷载下试件的挠度.     

Composites of Plasticized Polyamide 66 and Chemically Modified Vegetal Fibers

This work aims to prepare composites of polyamide 66 with vegetal fibers from curauá, jute, and flax. Alkaline treatment was conducted followed by silanization, improving the thermal properties of treated natural fibers. To reduce the processing temperature of polyamide 66, a combination of LiCl and N-butylbenzenesulfonamide was added to pure polyamide 66. It is shown that plasticizing polyamide 66 is one way to prepare composites with natural fibers using this high temperature polymer. The increase in elastic modulus of polyamide 66 and the decrease in strain at break were observed.     

热拉伸倍数对芳砜纶结构和性能的影响

通过应力—应变和动态力学热分析研究了热拉伸倍数对芳砜纶力学性能和动态热力学性能的影响,同时利用广角X-射线衍射(WAXD)对不同热拉伸倍数的芳砜纶的结晶度和晶区取向度进行了分析。结果表明:随着热拉伸倍数的增加,纤维的断裂强度提高,在拉伸倍数为2.6倍时,断裂强度达到3.83 cN/dtex;纤维的玻璃化较变温度随拉伸倍数的增加变化不大,而结晶度和晶区取向度则显著增加。     

Fabrication of Regenerated Cellulose Fibers with Good Strength and Biocompatibility from Green Spinning Process of Ionic Liquid

In this study, 1-ethyl-3-methylimidazolium diethyl phosphate, having the advantages of regulating the performance of cellulose dissolution and degradation, simplicity in synthesis, is chosen as solvent to dissolve wood pulp cellulose for regenerated cellulose fibers (RCFs) manufacture using dry-jet wet spinning equipment. The effect of draw ratios on RCFs’ mechanical properties in three bathes, including coagulation bath, stretch bath, and washing bath is investigated and a series of RCFs with high strength are obtained. The morphology, crystallinity, thermal stability, and dyeing behavior of the prepared RCFs are analyzed and discussed. More importantly, the biocompatibility of the RCFs, which is first performed, demonstrated that the toxicity of RCFs is as low as the viscose fibers. These RCFs could be easily dyed by natural turmeric and antibacterial fibers are obtained finally. In conclusion, this work provides tools for achievement of RCFs with good strength and environmental friendliness by changing the draw ratios, and also further develops a new green process for fabricating RCFs based on ionic liquids.     

溶胶-凝胶法制备多晶氧化铝纤维的研究

本文探讨了溶胶-凝胶法制备多晶氧化铝过程中影响胶体性能的因素,成纤方法与工艺参数,热处理工艺制度及晶相转化关系等一系列问题.实验得到了以莫来石为主晶相长期使用温度超过1500℃的多晶氧化铝纤维.     

Preparation of Ultrafine Ethylene/Propylene/Diene Terpolymer Rubber Fibers by Coaxial Electrospinning

Elastomeric EPDM fibers with diameters of 200–400 nm are prepared by coaxial electrospinning of PVP/EPDM fibers, subsequent vulcanization of the polymers and finally removal of the outer PVP layer using ethanol. The initially applied PVP layer restricts the elastic recovery of the EPDM fibers. The crosslinking density of the EPDM fibers reaches 8.44 × 10^?5 mol · cm^?3. The original morphology of EPDM is preserved after removing the PVP layer. The ultrafine EPDM fibers are expected to be useful in many fields, such as brittle plastics toughening, as well as applications in extremely high or low temperatures.