Toughened epoxy resin matrix for a membrane shell by wet filament winding

A toughened epoxy resin matrix was obtained with a reactive toughening agent and methyl hexahydrophthalic anhydride as a curing agent. The mechanical properties of the modified epoxy resin and its glass‐fiber‐reinforced composites were investigated systematically. The modified epoxy resin matrix possessed many good properties, including a high flexural strength (138 MPa), high elongation at break (5.2%), low viscosity, long pot life at room temperature, and good water resistance. In addition, the glass‐fiber‐reinforced composites showed a high strength conversion ratio of the glass fiber (86.7%) and good fatigue resistance. The results demonstrated that the modified epoxy resin matrix is very suitable for applications in reverse osmosis membrane shell products fabricated with wet filament winding for water treatment. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

复合材料缠绕成型用电子束固化环氧树脂体系研究

为了研究适合于缠绕成型的低粘度可电子束固化复合材料的耐热环氧树脂基体,研究了不同组成的电子束固化树脂体系的粘度与温度的关系、耐热性与辐射剂量的关系及浇注体的力学性能。研究表明,树脂EB-4在60℃时粘度为389 mPa.s,树脂辐射固化的最佳剂量为150 kGy,而且在150 kGy辐射固化的EB-1、EB-4的玻璃化转变温度Tg分别为212.96℃、214.77℃,EB-4树脂浇注体的拉伸强度可以达到52.7 MPa,拉伸弹性模量2.79 GPa,断裂延伸率为2.18%,是1种适用于室温或低温下缠绕成型的耐热电子束固化环氧树脂基复合材料树脂体系。     

长丝卷绕头摩擦辊表面的修复

介绍了一种可行的摩擦辊表面修复方法,说明了修复的工艺过程和控制参数以及需要注意的问题。     

Fabrication of porous thick films using room-temperature aerosol deposition

A novel technique for the rapid room-temperature deposition of porous ceramic, glass, or metal thick films using the aerosol deposition (AD) method is presented. The process is based on the co-deposition of the desired film material and a second water-soluble constituent, resulting in a ceramic-ceramic composite. Following the subsequent removal of water-soluble end member, a network of pores is retained. To demonstrate the process, porous BaTiO₃ thick films were fabricated through co-deposition with NaCl. Microstructural images show the clear development of a porous structure, which was found to enhance the dielectric properties over dense thick films, possibly related to the lower extent of internal residual stress. This simple but highly effective porous structure fabrication can be applied to any film and substrate material stable in water and is promising for the application of AD-processed films in gas sensors, solid oxide fuel cells, and humidity sensors.     

Injection of a microtextured polymer part surface: Influence of experimental parameters on the replication rate

Injection manufacturing makes it possible to functionalize the surfaces of microtextured plastic parts without resorting to expensive post-treatments. An instrumented mold was developed and microtextures were etched in the cavity with a femtosecond laser. A setting methodology only following in situ parameters, especially cavity pressurizing velocity was used to complete process control. The quality of the replication was quantified by the ratio, R, of microtexture part height replication over etched texture depth in the cavity. Different setting parameters such as injection velocity, V_f, mold temperature, T_Mo, and holding pressure, P_HMax, were investigated on two different injection molding machine. A statistical analysis enabled a validation of the protocol while showing that the influence of the injection molding machine is nonsignificant. Furthermore, injection velocity appeared as a key parameter, it acts at the same time on the thermal aspect of the flow front, frozen-layer fraction creation, but more importantly on the polymer's viscosity. An injection velocity threshold where above, mold temperature and holding pressure become secondary for better quality replication. This allowed as well to establish an empiric expression which makes it possible to calculate a pattern quality replication ratio, R, according to different parameters (V_f, T_Mo, P_HMax).     

Development of AMZ composites via mutual attraction of particles in wet processing

In this paper, three approaches were investigated for preparing alumina-mullite-zirconia (AMZ) composites. The weight ratio of alumina to zircon was selected to be 85/15. In the first approach, common well-known reaction sintering or solid-state mixing of alumina and zircon were used. In the second approach, suspensions of the raw materials were prepared to examine the effect of wet processing method. The third approach was based on the use of aluminum alkoxide coated zircon and alumina. The sintering of samples was carried out at the temperature of 1630°C for 3 hours. Phase composition and Rietveld refinement method, microstructural observation, EDS analysis, as well as physical and mechanical properties were used and determined to characterize the sintered samples. The results showed that aluminum alkoxide coating can develop the mentioned reaction sintering and mullite formation. However, the desired mechanical properties were not obtained. Wet processing approach resulted in more interesting data about the formation of mullite and could improve the microstructure homogeneity of final composites. Higher amount of tetragonal zirconia, good densification, high hardness, and fine microstructure were obtained by the wet approach. These interesting results were attributed to the fine discrete particles provided by mutual attraction in the wet preparation method.     

Measurement and numerical simulation of three‐dimensional fiber orientation states in injection‐molded short‐fiber‐reinforced plastics

To determine three‐dimensional fiber orientation states in injection‐molded short‐fiber composites, a confocal laser scanning microscope (CLSM) is used. Since the CLSM optically sections the specimen, more than two images of the cross sections on and below the surface of the composite can be obtained. Three‐dimensional fiber orientation states can be determined by using geometric parameters of fiber images obtained from two parallel cross sections. For experiments, carbon‐fiber‐reinforced polystyrene is examined by the CLSM and geometric parameters of fibers on each cross‐sectional plane are measured by an image analysis. In order to describe fiber orientation states compactly, orientation tensors are determined at different positions of the prepared specimen. Three‐dimensional orientation states are obtained without any difficulty by determining the out‐of‐plane angles utilizing fiber images on two parallel planes acquired by the CLSM. Orientation states are different at different positions and show the shell–core structure along the thickness of the specimen. Fiber orientation tensors are predicted by a numerical analysis and the numerically predicted orientation states show good agreement with measured ones. However, some differences are found at the end of cavity. They may result from the fountain flow effects, which are not considered in the numerical analysis. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 500–509, 2003     

A highly flexible,electrically conductive,and mechanically robust graphene/epoxy composite film for its self-damage detection

Advanced functional composites have attracted a great attention for fabricating flexible devices. In this article, the GnP/epoxy composite film was prepared by mixing graphene platelets (GnPs) with epoxy through sonication process. The morphology, mechanical properties, and electrical conductivity of the prepared composites were investigated. As the GnP contents increased from 2.5 to 7.5 vol%, the composites showed an increase in strain sensitivity with the rapid decrease in the strain gauge to 4.4. Additionally, when dynamic movement of the flexible film was performed, at bending and twist angle of 135° and 180°, respectively, steady increase in both resistance changes were detected and compared. The electrical resistance of the flexible was measured over a temperature range of 20–95°C, an increase in temperature lead to a linearly equivalent increase in resistance. The composites can also detect slight pressure changes at 2 kPa compression force with rapid decrease of resistance. Additionally, fatigue test was performed with stable, sensitive, and no distinguishable reading under 2,000 stretching cycles. The composite film exhibits an excellent self-sensing responds when fracture occurred. Thus, the obtained highly flexible, conductive, and mechanical robust composite sensor can be applied as advanced composites sensors for health monitoring.     

BaTiO3 incorporation effect on the dielectric properties of polymer from aqueous emulsion: An enhanced dispersion technique

An economic and environment friendly process was adapted to synthesize new dielectric composite materials. Using ethylene vinyl acetate (EVA)/vinyl ester of versatic acid (VeoVa) terpolymer as an aqueous emulsion provides a homogenous dispersion of BaTiO₃ (BT) particles, due to the high viscosity and polarity of the vinyl resin (VR). Composites films were obtained from these dispersions by water evaporation. The evolution of the dielectric properties as a function of the BaTiO₃ content, was correctly fitted by a Maxwell‐Garnett model. This fitting of the experimental curve shows a good dispersion of filler in the vinyl resin and the particles separation by a layer of resin as expected for the preparation method used in this study. The VR/BT composites show good synergy between the dielectric properties of the different phases of the composites due to the formation of macrodipoles and to the strong interactions between polar EVA/VeoVa groups and the BaTiO₃ particles surface. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44333.     

Comparison between wet deposition and plasma deposition of silane coatings on aluminium

Silane coatings are applied to metal surfaces for various purposes, e.g., to form a protective layer against corrosion or to act as a primer for subsequent coating. In this work bis-1,2-(triethoxysilyl) ethane (BTSE) was used as a precursor to deposit coatings on Al 99.99% substrates with three different techniques: dipcoating (water based solution), vacuum plasma and atmospheric plasma. Infrared reflection absorption spectroscopy (IRRAS), X-ray photoelectron spectroscopy (XPS) and field emission gun-scanning electron microscope (FE-SEM) were used to characterise the structure, composition and surface morphology of the silane coatings. The aim of this investigation is to compare the surface and bulk characteristics of the films prepared with the three different methods, in order to get information on how the BTSE molecule is modified by the deposition technique.     

Electrical resistance response of poly(ethylene oxide)‐based conductive composites to organic vapors: Effect of filler content,vapor species,and temperature

In this work conductive composites consisting of carbon black (CB) and poly(ethylene oxide) were prepared by solution mixing. The composites' resistance drastically changes in organic vapors so that the composites can be used as candidates for gas‐sensing materials. Owing to the different conduction mechanisms and solvent/composites interactions, the electrical response behaviors of the composites exhibit specific dependences on CB content and environmental temperature, which were only reported previously in a few instances. In addition, the rate of response was also correlated with solvent polarity, solubility, etc. The findings would help to understand the micromechanism of response of the composites and to improve the sensing performance as well. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1517–1523, 2005     

Influence of fused filament fabrication parameters on tensile properties of polylactide/layered silicate nanocomposite using response surface methodology

This study aimed at assessing and optimizing the influence of printing speed and extrusion temperature in a fused filament fabrication (FFF) process on the tensile properties of a polylactide/layered silicate nanocomposite. Mathematical models using Doehlert designs were formulated to examine factor and interaction effects. The models were corroborated by measurements using capillary rheology, tomographic images, and crystallinity analyses to find physical explanations for the differences in tensile properties. The tensile properties were a non-monotonic function of printing speed, which may be due to various deposition defects that influence the porosity of composite tensile specimens. This study provides new insights into FFF process optimization regarding rheological behavior and mesostructure of nanocomposite by highlighting new modes of deposition defects that originate from process parameter settings and materials. The results contribute to the properties mastery of FFF-processed materials.     

玻璃钢缠绕成型工艺的计算机辅助分析、设计和控制

本文综合分析了计算机辅助分析、辅助设计和控制在纤维缠绕成型工艺中的广泛应用，分析了系统的组成、结构、功能以及设计方法，并开了计算机软件和控制系统     

Examining the use of TiO2 to enhance the NH3 sensitivity of polypyrrole films

Polypyrrole/Titanium dioxide (PPy/TiO₂) composite thin films were prepared by polymerizing the monomer pyrrole in aqueous solution containing a certain amount of TiO₂ particles at room temperature, and their response to ammonia (NH₃) gas was examined systematically. Compared with the pristine PPy film, which reached the saturation at the concentration of NH₃ beyond 200 ppm, the composite films showed more stable response and higher sensitivity. Furthermore, the PPy/TiO₂ composite thin films exhibited a low detection limit of 2 ppm. The film thickness, which had a strong influence on the film sensitivity to NH₃, could be controlled by varying the polymerization time. The sensitivity to NH₃ gas of the samples with different content of TiO₂ and different molar ratio of PPy/TiO₂/oxidant was studied. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Investigations on the internal curing process and mechanical properties of winding composite considering the structure of plant fiber

In this study, the equivalent heat conduction model and internal curing process optimization model of the composite material based on the cavity and twisting structure of the plant fiber were established. Also, the effects of temperature, the volume fraction of the plant fiber cavity and twist on the temperature field, curing degree, and curing deformation during the internal curing process of the jute fiber winding composite pipe were analyzed. The accuracy of process simulation was verified by the internal curing experiment based on electromagnetic heating and was combined with using the microstructure test and tensile strength test of the NOL ring. However, in the case of twisted fiber, an extreme effect on the mechanical properties of the composite was noted.     

Manufacture and thermomechanical characterization of wet filament wound C/C-SiC composites

The paper presents manufacture of C/C-SiC composite materials by wet filament winding of C fibers with a water-based phenolic resin with subsequent curing via autoclave as well as pyrolysis and liquid silicon infiltration (LSI). Almost dense C/C-SiC composite materials with different winding angles ranging from ±15° to ±75° could be obtained with porosities lower than 3% and densities in the range of 2 g/cm³. Thermomechanical characterization via tensile testing at room temperature and at 1300°C revealed higher tensile strength at elevated temperature than at room temperature. Thus, C/C-SiC material obtained by wet filament winding and LSI-processing has excellent high-temperature strength for high-temperature applications. Crack patterns during pyrolysis, microstructure after siliconization, and tensile strength strongly depend on the fiber/matrix interface strength and winding angle. Moreover, calculation tools for composites, such as classical laminate and inverse laminate theory, can be applied for structural evaluation and prediction of mechanical performance of C/C-SiC structures.     

复合材料光纤应变传感器发展概况

本文简要介绍了国内外复合材料嵌入式光纤应变传感器的发展情况，重点介绍了二涉型、模式型、偏振型和光强型四种尖型光纤应变传感器的研制状况。     

Online Detection of Ellipsoidal Bubbles by an Innovative Optical Approach

Bubble and droplet size distribution influence chemical processes markedly. In order to enable an in‐line analysis of these distributions, a new single‐sided endoscopic version of the Optical Multimode Online Probe (OMOP) was developed. The acquired images are analyzed to gain bubble size distributions (BSDs) and main diagonals. A specific workflow was developed to detect and analyze overlapping bubbles based on standard image processing techniques. It can handle overlapping bubbles of both circular and elliptical shapes. Results confirmed that the combination of OMOP and the image processing workflow leads to robust detection of bubbles from two‐dimensional images. The new single‐sided OMOP proved to be a suitable tool for the acquisition of a BSD at industrial scale within a reasonable computing time.     

Effect of dry/wet spinning on the photooxidative degradation of acrylic fibers

The photooxidative degradation of acrylic fibers was investigated with two different fiber‐spinning processes, that is, dry spinning and wet spinning. Several analytical methods were used in this study: viscometry, X‐ray diffraction, Fourier transform infrared spectroscopy, optical measurements, and mechanical testing. Viscometry was used to determine the molecular weight as a monitoring factor for degradation. X‐ray diagrams showed lower changes in the crystallinity of wet‐spun fibers during a weathering process by irradiation. The results from mechanical testing indicated that the tenacity of dry‐spun fibers had less deterioration than that of wet‐spun fibers. Degraded wet‐spun and dry‐spun fibers showed similar trends in optical and spectroscopy analysis. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effect of fused deposition modeling process parameters on the mechanical properties of recycled polyethylene terephthalate parts

Fused deposition modeling (FDM) filaments made of recycled materials are desirable for environmentally friendly and sustainable manufacturing of prototypes and load-bearing components in many applications. We investigate the effect of FDM process parameters on the mechanical properties of 3D-printed parts made of recycled polyethylene terephthalate (rPET) filaments. Increasing the nozzle temperature from 230°C to 260°C improves the strength of the specimens by 100%. Using a raster orientation parallel to the loading direction improves the ductility by more an order of magnitude. Specimen orientation and infill ratio also influence the mechanical properties. The temperature and the orientation effects are related to the quality of fusion between the printed lines. A modified Gibson-Ashby model correctly predicts the strength as a function of the infill ratio. Through the optimization of process parameters, the mechanical strength of 3D-printed rPET structures can reach that of injection-molded PET, making FDM a suitable manufacturing technique for load-bearing applications.