In order to improve the interfacial adhesion between aramid fiber (AF) and rubber matrix, a simple and facile method of aramid nanofiber (ANF) coating is demonstrated in this article. Tannic acid (TA) and polyethyleneimine (PEI) are polymerized in an alkaline solution to form a thin TA/PEI (TP) layer that is deposited on the surface of AF to introduce functional groups such as hydroxyl and amino groups. Then, the ANF coating is utilized to construct nanostructures on the surface of AF to improve the interfacial adhesion between the fiber and the rubber. Through hydrogen bonding and/or π-π stacking between the TP layer and the ANF, the ANF coating is firmly attached to the surface of AF. Compared with the untreated fiber, the interfacial adhesion of AF coated with ANF after 1, 3, 5, 7, 9 deposition cycles is increased by 27.8%, 29.1%, 31.5%, 43.1%, and 30.3%, and the mechanical properties of the fibers remain almost unchanged. This method shows its advantages of simple, facile, and time-effective, which is of great significance for industrial applications. 相似文献
Poly(vinyl alcohol) (PVA)-based hybrids have demonstrated broad liquid separation applications but separation performances are constrained by the compatibility between fillers and polymer, and thus it is essential to study the interfacial properties of these hybrids. In this work, PVA hybrids with four different porous fillers have been fabricated and characterized with Fourier transform infrared, X-ray diffraction, Scanning electron microscope, swelling and contact angle tests. Swelling results show that PVA has a degree of swelling (DS) of 79% in water but the swelling is compressed after adding fillers and the DS for PVA hybrids has decreased by 19%, 17%, 15%, and 9% for 30 wt% loading of ZIF-8, UiO-66, Hβ and ZSM-5, respectively. For methanol and its 10 wt% aqueous solution, similar swelling results are obtained due to mutual interactions among the filler, polymer and test liquids. Based on water and glycerol contact angle results, the surface energy of PVA is estimated to be 40.56 Nm−1 and it drops to 27.39 Nm−1 after adding less hydrophilic ZIF-8 or rise to 48.56 Nm−1 after introducing more hydrophilic ZSM-5. The high-film hydrophilicity and then large surface energy have rendered methanol/water sorption selectivity of PVA hybrids decrease to some extent or vice versa. 相似文献
A simple approach was developed to fabricate high-performance MXene/cellulose (MC)-based electromagnetic interference (EMI) shielding papers. The oriented MXene sheets located on one side of cellulose filter paper construct a continuous conductive layer, endowing the MC paper with high electrical conductivity (240.1 S/m) and excellent EMI shielding effectiveness (29.3 dB for 0.192-mm thickness) at an MXene content of 0.72 vol%. Moreover, the EMI shielding effectiveness of four stacked MC papers reached 40.5 dB. This result means that 99.9911% of the microwave radiation is attenuated, and 0.0089% is transmitted, through the four-piece MXene/cellulose filter papers. Therefore, MC paper has promising properties for excellent EMI shielding materials in current electronic devices. 相似文献
In this paper, the use of the ball burnishing process to improve the final quality of form tools (moulds and dies) is studied. This process changes the roughness of the previously ball-end milled surfaces, achieving the finishing requirements for plastic injection moulds and stamping dies. Ball burnishing can be easily applied in the same machining centres as those used for milling. In this way, both lead times and production costs can be dramatically reduced.
Both the burnishing system and its main parameters are taken into account, considering their influence on finishing. Workpiece surface integrity is ensured due to the surface smoothing effect of process and the associated cold working. Examples of different materials, machined surfaces, and industrial applications are explained, with respect to the maximum and mean surface roughness achieved.
The main conclusion is that using a large radial depth of cut in the previous ball-end milling operation, together with a small radial depth during burnishing can produce acceptable final roughness. Savings of production times are high, as burnishing is applied using the maximum linear feed of the machine, while milling must be made at moderate feeds. Moreover, ball burnishing NC programming is less critical and needs less care in its definition than CAM for milling. 相似文献
FLUOROPOLYMERS(FPs)are thermoplasticmaterials which exhibit a number of unique chemicaland physical characteristics that no other man-madeplastic product gets together.For example,FPs showvery good resistance to almost all chemicals,excellentwater vapor barrier properties,high thermal stability,outstanding electrical insulation properties(lowdielectric constant and dissipation factors),extremelylow frictional coefficient giving them high auto-lubrication properties,high resistance to rad… 相似文献
The electrical discharge machining (EDM) process produces the recast layer with or without cracks on the surface that requires a remedial post-treatment in the manufacture of critical or highly stressed surfaces. One of the frequently used post-treatment processes is also the abrasive electrochemical grinding (AECG) and it has been widely used in the precision machining of difficult-to-cut materials due to an enhanced surface integrity and productivity. The aim of this study is to investigate improvability of surface integrity in terms of machining voltage, electrolyte flow rate and table feed rate parameters of AECG in EDMed Ti6Al4V alloy. Scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrograph (EDS) and surface roughness measurement were performed to study the surface characteristics of the machined samples. Experimental results indicate that the AECG process effectively improves the surface roughness and eliminates the EDM damages completely by setting suitable grinding parameters. 相似文献