Effect of gamma irradiation on the physical and structural properties of basalt fiber

Digital holographic interferometry (DHI), X‐ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR) and scanning electron microscopy (SEM) were used to study the effects of gamma irradiation on the physical and structural properties of basalt fibers. For this purpose, set samples of basalt fibers were subjected to different doses of gamma irradiation (3, 10, 25, and 40 kGy). The Mach–Zehnder interferometer was used to capture holographic patterns which are used then to determine the unwrapped phase. From the unwrapped phase distributions, the optical path difference within the irradiated basalt samples was determined. Thus, refractive indices, and birefringence of irradiated basalt fibers were determined at different irradiation doses using DHI method. XRD technique was used to investigate the effect of irradiation doses on the crystalline behavior of fibers. FTIR was performed to each of the basalt samples to evaluate the changes in the surface chemical properties due to radiation exposure doses. The morphology of irradiated fibers was examined using SEM. The results indicate that basalt fiber has a resistance to gamma radiation. There are no significant effects on the physical, structural and chemical properties were demonstrated of basalt fibers in the doses range of irradiation.     

The impact of the thermal annealing conditions on the structural properties of polylactic acid fibers

Polylactic acid (PLA) is a prominent biomaterial for plentiful applications in medicine and industry. The main goal of using this new material is replacing polymers based on petrochemical. Different thermal and structural properties of PLA fibers were studied after the thermal treatment using two different conditions (taut and free ends). Different techniques were used to study the effect of the thermal treatment conditions on the crystallinity and molecular orientations for PLA fibers such as differential scanning calorimetry technique, X-ray diffraction technique, and polarized light microscopy. The impact of the thermal annealing treatment on both the crystallinity and crystalline orientation was calculated. In case of taut ends thermal annealing treatment method, the measured parameters were higher than the case of free ends thermal annealing condition. The oriented segment relaxation due to the thermal annealing results an increase in the crystallinity values, but it does not indicate that the molecular orientation will be high. Results showed that the orientation of crystal and crystallinity was improved after thermal treatment. The taut conditions of annealing show significant improvement of crystallinity than free conditions.     

The impact of processing conditions on the structural and optical properties of the as‐spun polyamides fibers

The development of crystallinity and orientation during the melt spinning of polyamides (nylon 66) was investigated. This study reports the question of the orientation and crystallinity determination of nylon 66 by means of differential scanning calorimetry, optical polarized microscope, and X‐ray diffraction techniques during the cold drawing process. The different structural properties such as crystallinity, crystal size, birefringence, and different orientation functions were measured as a function of the draw ratio. From the obtained thermogram, it is clear that the melting temperature of the drawn nylon 66 fibers did not show a significant change due to the cold drawing process. As the draw ratio increase, the crystallinity and crystal size increase. The drawing process improves the chain orientations along the fiber axis of nylon 66 fibers. The orientations of the chain segments enhanced due to the cold drawing process of nylon 66 fibers.     

电子束辐射聚四氟乙烯的耐磨性研究及其在阀门上的应用

以纯聚四氟乙烯(Pure PTFE)和14%玻璃纤维增强聚四氟乙烯(PTFE GF)为对象,研究了在0~300 kGy的辐射剂量范围内,PTFE的耐磨性随电子束辐射剂量的变化情况。分析认为由电子束辐射引起的聚四氟乙烯结晶度和密度的提高,使聚四氟乙烯的细晶强化和分子力增大,耐磨性提高。     

改性聚四氟乙烯材料的力学性能实验研究

为了研究改性低密度聚四氟乙烯材料的力学性能,利用万能试验机进行了准静态拉伸和压缩试验,通过霍普金森杆实验研究其在冲击载荷作用下的动态力学特性.对不同长径比改性与非改性试样在不同载荷加载下的力学特性以及不同冲击速度下的动态响应特性进行了分析.结果表明,通过在聚四氟乙烯材料中添加铜粉可以提高其抗拉强度,改善伸长率,增强抗压缩强度;随应变率的增大,改性聚四氟乙烯的屈服强度得到提高.     

Effect of rare earths on mechanical and tribological properties of carbon fibers reinforced PTFE composite

The effect of a rare earth (RE) surface treatment on the mechanical and tribological properties of carbon fiber (CF) reinforced polytetrafluoroethylene (PTFE) composites was experimentally investigated. The tensile properties of the CF reinforced PTFE (CF/PTFE) composites treated with air oxidation and RE modifier were superior to those of untreated CF/PTFE composites, while RE treatment was most effective in promoting the tensile strength and strain at break of the CF/PTFE composite. The bending strength of the RE treated CF/PTFE composite was improved by about 16% compared with that of untreated composites, while 2% improvement was achieved by air oxidation. Under oil-lubricated conditions, RE treatment was more effective than air oxidation to reduce the friction coefficient and wear of PTFE composite. RE treatment effectively improved the interfacial adhesion between CF and PTFE. The strong interfacial coupling of the composite made CF not easy to detach from the PTFE matrix, and prevented the rubbing-off of PTFE, accordingly improved the friction and wear properties of the composite.     

PTFE复合材料的摩擦磨损性能研究

用机械共混、冷压成型烧结的方法制备了纳米SiO2/石墨/玻璃纤维/PTFE复合材料试样。用MM-200型磨损试验机测试了在干摩擦条件下不同载荷时各试样的摩擦磨损性能;用扫描电镜对磨损后试件表面进行观察和分析。研究结果表明：纳米SiO2和玻璃纤维有效提高了PTFE的承载能力,石墨的加入起到了减小摩擦的作用;在本试验条件下,在摩擦过程中三元混合填充PTFE复合材料在偶件表面形成了转移膜,减少了复合材料与偶件的直接接触,因而表现出优异的抗磨性。     

Studying the properties and structure of polytetrafluoroethylene filled with Belum modified carbon fibers

The effect of Belum discrete carbon fibers on the service properties and structure of polytetrafluoroethylene has been studied. It has been shown that a filling of polytetrafluoroethylene with 1–5 wt % of carbon fibers does not worsen the stress–strain properties of composites. The introduction of carbon fibers improves the tribological characteristics of polytetrafluoroethylene. The thermodynamic and structural studied of polymer composites have been performed.     

The effect of short heat treatment on different properties of PET fiber using double beam interference microscopy

Pluta microscope used to throw light on the effect of heat treatment time on the different properties of poly (ethylene terephthalate) PET fibers. PET fibers were annealed at times ranged from 5 to 30 min at different temperatures (150, 170, 190, 210°C) using two different processes (fast cooling and slow cooling processes) in air. The refractive indices, the shrinkage, orientation factor and crystallinity of PET fibers were determined for different annealing temperature during the short time treatment. The shrinkage percentage and degree of crystallinity increased with increasing the temperature and time of annealing. Microinterferograms are given for illustration.     

短玻璃纤维和石墨填充PTFE的摩擦磨损特性研究

利用自主研制的往复式摩擦试验机对短玻璃纤维(SGF)及石墨填充聚四氟乙烯(PTFE)复合材料的摩擦磨损特性进行了研究,探讨了共混材料对PTFE摩擦学性能的影响。利用扫描电子显微镜对材料的磨损表面进行了观察和分析。研究结果表明,短玻璃纤维有效提高了PTFE的承载能力,石墨的加入起到了减小摩擦的作用,在较高载荷下,短玻璃纤维和石墨填充的PTFE复合材料表现出优异的抗磨性能。     

Toxicological effects of the chemical and green ZnO NPs on Cyprinus carpio L. observed under light and scanning electron microscopy

Nanoparticles in aquatic bodies cause serious harm to the aquatic organisms when accumulated in high amounts. However, green nanoparticles synthesized using plants can be less toxic as compared to chemical nanoparticles. Hence, we designed our study to investigate the toxicological effects of chemical and green zinc oxide nanoparticles (ZnO NPs) on the biological activity of juvenile Cyprinus carpio. The green ZnO NPs were synthesized from Solieria robusta, and chemical ZnO NPs were synthesized using zinc chloride solution and ammonium hydroxide. Characterization was done by using light microscopy, scanning electron microscope (SEM), Fourier transmission infrared radiation, and X-ray diffraction (XRD) techniques. The highest absorbance of nanoparticles was observed at 360 which confirmed the synthesis of ZnO. The SEM analysis showed that green nanoparticles were hexagonal while the chemical nanoparticles were spherical to cubic in shape. Definite peaks were observed in XRD of green and chemical NPs at 2θ angles 45.84° and 32.18°, respectively. Oxidative stress was determined by chemical analysis of catalase, glutathione S-transferase (GST), glutathione (GSH), and lipid peroxidation (LPO) activities. The toxicological effects of chemical ZnO NPs on the catalase, LPO, GST, and GSH activities were more than green ZnO NPs. The histopathological investigation proved that the effect of chemical nanoparticles was worse than green ZnO NPs. More tissue damage was found in chemical nanoparticles than green synthesized nanoparticles. It was concluded that chemical nanoparticles can be replaced by green nanoparticles, as green nanoparticles are eco-friendly with less toxicological effects. This replacement can limit the toxic effect of nanoparticles when they get accumulated in high amounts in water bodies.     

Hydrogen storage properties of MgH2‐diatomite composites obtained by high‐energy ball milling

To investigate the effects of specific porous microstructure of diatomite on the hydrogen storage properties of MgH₂, a two‐step preparation was carried out. The first step was decrepitation of MgH₂ particle size during 10 h of milling. The second step was additional 1 h of milling with diatomite. The microstructure and phase composition of materials was characterized by X‐ray diffraction, whereas the powder morphology and degree of additive dispersion were analyzed by scanning electron microscopy. The hydrogen desorption behaviour of nanocomposites was investigated by differential scanning calorimetry. The results show that addition of porous diatomite structure leads to decrease in desorption temperature, since there was no other effect that can have an influence on kinetics, such as formation of the metastable γ‐phase, reduction of oxides to the native metal and/or homogeneous dispersion of the catalyst. This indicates that the microstructure of added material plays the main role in the enhancement of desorption properties of composites.     

Measurements on room temperature gas sensing properties of CSA doped polyaniline-ZnO nanocomposites

In this paper, we report on the performance of an ammonia gas (NH₃) sensor based on camphor sulfonic acid doped polyaniline-zinc oxide nanocomposites fabricated by a simple spin coating technique. The nanocomposite showed the sensitivity to ammonia gas (NH₃) at room temperature (300 K). Maximum response up to 28.11% was achieved for 100 ppm NH₃. Depending on the concentration of NH₃, the response time was ranged between 22 and 66 s, whereas the recovery time was 256-418 s.     

Interferometric investigation of the opto‐mechanical and structural properties of iPP/TiO2 nanocomposite fibers

Fibers that missing specific features and functionalities could be innovated and functionalised via nano additives, in particular metal oxides. Titanium oxide (TiO₂) nanoparticles have been added to isotactic polypropylene (iPP) to form iPP/TiO₂ nanocomposite fibers. Three samples of iPP/TiO₂ fibers were extruded at three extrusion speeds 25, 50, and 78 m/min were considered in this study. Mach–Zehnder interferometer was used to assess the changes in the opto‐mechanical and geometrical parameters of iPP/TiO₂ nanocomposite fibers along the fiber axis. The mechanical drawing device along with Mach–Zehnder interferometer was utilized to stretch the filaments to different draw ratios. The effect of mechanical cold drawing and extrusion speed on the optical and physical characteristics of iPP/TiO₂ nanocomposite fibers were determined along the fiber axis. The optical and physical variation along the nanocomposite samples were characterized by measuring their refractive indices, birefringence, refractive index profile along the fiber axis. The diffraction of He–Ne laser beam was used to define the variation of the fiber diameter along the fiber axis through their cross‐sectional area and shape. A sample of uniform diameter from neat iPP fibers was used as reference material for studying the variation of the iPP/TiO₂ fiber diameter along the fiber axis. As result, the iPP/TiO₂ nanocomposite fibers exhibited nonuniform diameters. The dispersion of TiO₂ particles in nanocomposite fibers influences the properties' consistency along and across the fiber.     

热处理对AB5型储氢合金微观结构的影响

研究了热处理温度对AB5型储氢合金La Ni3.6 C0．7Mn0.4Al0.3相结构的影响。经过不同温度热处理的储氢合金，a轴变长，c轴缩短，晶胞体积增大。SEM结果表明，合金的微观组织形貌呈现由枝晶长大变为片状组织的变化规律。     

表面改性硅灰石纤维填充PTFE复合材料的摩擦学性能

用KH550硅烷偶联剂表面改性的硅灰石纤维(WF)填充PTFE,在MPX-2000型磨损试验机上研究复合材料的摩擦磨损性能,并与经典的炭纤维(CF)填充PTFE复合材料进行比较。采用SEM对磨损面和对偶面进行分析。结果表明:较高载荷(200和300 N)下复合材料摩擦因数随WF含量变化的幅度不大,较稳定地维持在较低值;细小尺寸WF填充PTFE复合材料的耐磨性能较好,在WF质量分数为10%时,复合材料的磨损量只有相同含量CF填充PT-FE复合材料的81%;细小尺寸WF填充PTFE复合材料的磨损面较为平整,存在轻微黏着磨损,其对偶面转移膜平整光滑、结构致密;而CF/PTFE复合材料磨损面存在许多裸露和碎断的CF,犁削和磨粒磨损是主要的磨损形式。     

FIB/SEM characterization of carbon-based fibers

The aim of this paper is to show how a focused ion beam combined with a scanning electron microscope (FIB/SEM machine) can be adopted to characterize composite fibers with different electrical behavior and to gain information about their production and modification. This comparative morphology investigation is carried out on polyacrylonitrile (PAN) carbon fibers and their chemical precursor (the oxidized PAN or oxypan) which has different electrical properties. Fibers are imaged by electron and ion beams and sectioned by the focused ion beam (FIB). A sample of oxypan fibers processed by a radio frequency (RF) plasma is also investigated and the role of the conductive carbon layer around their unmodified, insulating bulk is discussed. A suitable developed edge detection technique (EDT) on electron, ion images, and after the FIB sectioning, provides quantitative information about the thickness of the created layer.     

Brush-like fibers on the human chromosome periphery

A brush-like border apparently composed of fibers protruding from metaphase chromosomes of human lymphocytes was observed for the first time using transmission (TEM) and scanning electron microscopy (SEM). On the basis of size and sensitivity to colcemid, the fibers may be related to microtubules and spindle organization. The brush-like fibers were observed when chemically fixed metaphase chromosome spreads were placed on glass slides and maintained under "wet" conditions (not allowed to air dry after fixation for conventional cytogenetic protocols) until postfixation protocols for TEM and SEM were performed. The purpose of this study was to establish the occurrence of the brush-like fibers and to determine the effects of colcemid on these fibers.     

Evaluation on synergistic antioxidation of methylene dibutyldithiocarbamate with tolutriazole derivative

The antioxidation properties of methylene bis(di‐n‐butyldithiocarbamate) (V 7723)‐ and tolutriazole derivative (V 887)‐containing poly‐α‐olefin (PAO)‐derived lubricants were evaluated by differential scanning calorimetry (DSC) and modified penn state micro‐oxidation test (PMOT). The DSC test measured the onset temperature (OT) and induction time (IT) of the lubricant at high temperatures, and oxidation stability of oil by weight loss was measured by the PMOT. The DSC test showed that the OT and IT of V 7723‐containing PAO were improved significantly by the addition of V 887. The PMOT indicated that when combined with V 7723 antioxidants, V 887 could also effectively reduce the increase in the weight loss of PAO. These results suggested that the V 887 showed a good oxidative synergism with the V 7723 antioxidant. In addition, Fourier Transform Infrared (FTIR) results from the PMOT confirmed that the addition of V 887 could significantly enhance the oxidation IT of oils and inhibit the formation of oxidation products containing carbonyl bonds or hydroxyl group. Copyright © 2007 John Wiley and Sons, Ltd.