Enhanced fatigue behavior of a glass fiber reinforced hybrid particles modified epoxy nanocomposite under WISPERX spectrum load sequence

Two types of glass fiber reinforced plastic (GFRP) composites were fabricated viz., GFRP with neat epoxy matrix (GFRP-neat) and GFRP with hybrid modified epoxy matrix (GFRP-hybrid) containing 9 wt.% of rubber microparticles and 10 wt.% of silica nanoparticles. Fatigue tests were conducted on both the composites under WISPERX load sequence. The fatigue life of the GFRP-hybrid composite was about 4–5 times higher than that of GFRP-neat composite. The underlying mechanisms for improved fatigue performance are discussed. A reasonably good correlation was observed between the experimental fatigue life and the fatigue life predicted under spectrum loads.     

国产碳纤维上浆剂的比较

探索了不同类型国产上浆剂对碳纤维接触角、表面能、耐磨性、表面微观形态等物理特性的影响。结果表明:使用YJ上浆剂的碳纤维的硬挺度、耐磨性比使用FD、HIT的好,使用HIT上浆剂的碳纤维的外观、丝束幅宽比YJ的好。     

分散染料易染海岛复合聚酯纤维的热应力分析

以易水解聚酯(EHDPET)和新型分散染料常压可染聚酯(NEDDP)分别作为海与岛组分,通过熔融纺丝方法,制备了不同复合比的海岛复合聚酯的预取向丝(POY)。采用动态热应力仪模拟纤维加弹工艺,对EHDPET-NEDDP POY进行了不同拉伸温度、拉伸速度、拉伸倍数下的热应力测试。结果表明:随着温度从140℃提高到180℃,POY的热应力呈减小趋势;而当拉伸速度从60 m/s提高至100 m/s,或拉伸倍数从1.4增大到1.8时,POY的热应力均呈增大的趋势。     

油剂特性与PAN基碳纤维及其原丝性能的关联性

研究了单一组分油剂中氨基、环氧基、聚醚等特征官能团的特性,摸索了单一组分油剂与复合油剂对碳纤维生产中原丝含油率及表面形态、预氧化过程径向一致性、碳纤维强度等的关联性变化规律。研究表明:碳纤维及原丝性能与油剂的组分有直接关联性。由氨基、环氧基、聚醚等复配后的油剂,具有稳定性好、耐热性高、保护性强等特点。     

Temperature and voltage sensings by mode‐mode interference in polarization‐maintaining optical fibers

Abstract

Two optic fiber sensing systems for temperature and voltage have been developed which utilize the mode‐mode interference of the two orthogonally polarized modes, HE^x _II and HE^y _II, in two commencal polarization‐maintaining fibers (bow‐tie and elliptical core fibers). A package of controlled programs in a Macintosh computer, which can record and process all related data automatically, is established for temperature sensing. The signal drifting problem in voltage sensings has been investigated, and the elimination of signal drifting is obtained by the phase tracking with direct current technology The agreement between the sensing results for temperature and dynamic voltage and those predicted by experimental principles is satisfactory, which confirms the validity of the developed sensing systems.     

Fiber reinforced mortar affected by alkali-silica reaction: A study by synchrotron microtomography

Alkali-Silica reaction (ASR) is a physicochemical process that can deteriorate concrete and is a recurring engineering problem. In this study three different cylindrical samples affected by ASR were prepared: a plain mortar and two composite mortars containing fibers (polypropylene and a polymer hybrid), which were analyzed at the microtomography (μCT) beamline 8.3.2 at the Advanced Light Source (ALS). In general, three different features were observed during the 136 day observation period: (1) aggregate dissolution, (2) crack propagation from inside the aggregate, through the cement matrix, and at the ITZ, and (3) the alkali-silica gel filling cracks and voids. In addition, accelerated mortar bar tests were utilized to observe ASR's expansive effect in the plain and composite mortars, and the fibers' ability to restrain expansion due to ASR.     

Effects of carbon fiber length on the tribological properties of paper-based friction materials

Four kinds of paper-based friction materials reinforced with carbon fibers of 100, 400, 600 and 800 μm were prepared by paper-making processes. Experimental results showed that the friction materials became porous with fiber length increasing. The friction torque curves were flat except the sample with 100 μm fibers. The wear rate of the sample with 100 μm fibers was only 1.40×10⁻⁵ mm³/J. Tiny debris and fine scratches formed in the worn surface were the reason for excellent wear resistance of friction pairs with 100 μm fibers. The friction pairs with 400, 600 and 800 μm fibers showed typically abrasive wear and fatigue wear.     

Effect of Fiber Length on Carbon Nanotube-Induced Fibrogenesis

Given their extremely small size and light weight, carbon nanotubes (CNTs) can be readily inhaled by human lungs resulting in increased rates of pulmonary disorders, particularly fibrosis. Although the fibrogenic potential of CNTs is well established, there is a lack of consensus regarding the contribution of physicochemical attributes of CNTs on the underlying fibrotic outcome. We designed an experimentally validated in vitro fibroblast culture model aimed at investigating the effect of fiber length on single-walled CNT (SWCNT)-induced pulmonary fibrosis. The fibrogenic response to short and long SWCNTs was assessed via oxidative stress generation, collagen expression and transforming growth factor-beta (TGF-β) production as potential fibrosis biomarkers. Long SWCNTs were significantly more potent than short SWCNTs in terms of reactive oxygen species (ROS) response, collagen production and TGF-β release. Furthermore, our finding on the length-dependent in vitro fibrogenic response was validated by the in vivo lung fibrosis outcome, thus supporting the predictive value of the in vitro model. Our results also demonstrated the key role of ROS in SWCNT-induced collagen expression and TGF-β activation, indicating the potential mechanisms of length-dependent SWCNT-induced fibrosis. Together, our study provides new evidence for the role of fiber length in SWCNT-induced lung fibrosis and offers a rapid cell-based assay for fibrogenicity testing of nanomaterials with the ability to predict pulmonary fibrogenic response in vivo.     

Controllable electrodeposition synthesis of Pd/TMxOy-rGO/CFP composite electrode for highly efficient methanol electro-oxidation

A novel and high-efficiency Pd/TM_xO_y-rGO/CFP (TM_xO_y = Co₃O₄, Mn₃O₄, Ni(OH)₂) electrocatalyst for directly integrated membrane electrode was synthesized by controllable cyclic voltammetry electrodeposition combined with hydrothermal process. The results showed excellent performance towards methanol oxidation reduction. The Pd/Co₃O₄-rGO/CFP as-prepared catalyst has the best electrocatalytic activity, and mass activity is 5181 mA·mg⁻¹_Pd, which is about 40 times and 4.3 times that of the commercial Pd/C and Pt/C catalyst (JM). It can be attributed that the small size of Pd nanoparticle, uniformity of distribution, and the synergistic interaction between transition metal oxide on the support surface and Pd nanoparticles. The prepared Pd/TM_xO_y-rGO/CFP composite electrode is a promising catalyst for integrated membrane electrode assembly of proton exchange membrane fuel cells in the future.     

Electrospinning preparation and dye adsorption capacity of TiO2@Carbon flexible fiber

TiO₂@carbon flexible fiber was prepared by combining electrostatic spinning technology and hydrothermal synthesis method. The XRD, SEM, TEM and Zeta potential techniques were used to characterize the phase, microstructure and surface charge properties of the samples. The growth mechanism of TiO₂ nanoarray on carbon flexible fiber with different morphologies was studied, and the dye adsorption capacity of the samples was evaluated by methylene blue (MB) degradation effect. The results showed that proper doping amounts of TiO₂ particles improved the flexibility and the hydrophilic property of carbon fiber significantly, which was conducive to the deposition and growth of TiO₂ on the carbon fiber. With the increase of hydrothermal time, the TiO₂ nanoarray grew denser gradually along the [110] crystal surface. The negative charge on the surface of carbon fiber increased, which was benefited to the removal of MB. The dye adsorption capacity of TiO₂@carbon fiber was resulted from the synergistic effect of physical adsorption (carbon fiber) and photocatalysis (TiO₂) process.