The bonding state between the carbon fiber and the polymer directly affects the properties of carbon fiber reinforced polymer composites (CFRP), which is influenced by the surface structural characteristics of carbon fiber (CF). The surface of CF is composed of tightly packed graphite crystallites lacking active carbon atoms, which results in low surface energy of CF and weak interfacial performance of CFRP. The interfacial properties can be evaluated indirectly through macro-mechanical properties, and can also be characterized by micromechanical testing methods. In order to improve the interfacial combination between the carbon fiber and the polymer, it is usually to modify the interface of CFRP, which mainly includes carbon fiber surface functionalization, carbon fiber surface coating and introduction of micro-nano enhancement phase. In this paper, researches on the interfacial properties of CFRP were reviewed, and the existing problems and the future research focus were also discussed.
Microelectrodes are used in microfluidic devices for a variety of purposes such as heating, applying electric fields, and electrochemical sensing. However, they are still manufactured by expensive deposition techniques such as sputtering or evaporation and patterned using photolithography methods. More recently, alternate methods including nanoparticle sintering and use of liquid metal flowing through microchannels have been used to fabricate microelectrodes. These methods are limited in the material choices or require post processing to be integrated into microchannels. Here we developed a low-cost and versatile method to integrate high-quality metal microwires into polydimethylsiloxane (PDMS) using xurography. The microwire integration process includes cutting slit pattern on PDMS substrate and subsequent writing metal microwires into the slit pattern using a specialized tip. Then the microwire-integrated PDMS was sealed/bonded using uncured PDMS prepolymer. This method enables integration of metal microwires of diameter as small as 15 μm into PDMS devices. Integration of multiple microwires with minimum spacing of 150 μm has also been demonstrated. The versatility of this method is demonstrated by the fabrication of metal microwire suspended in the middle of the microchannel, which is difficult to achieve using conventional electrode fabrication methods. This low-cost method avoids expensive clean room fabrication yet producing high-quality electrodes and can be used in a variety of microfluidic and MEMS applications.
To improve the stress state of traditional antislide pile and utilize the stable soil on both sides of a landslide and slope foot, a spatial arc antislide pile supporting structure was proposed. Based on numerical calculation, a parametric study was conducted to assess the influence of the rise-span ratio on the stress state of the supporting structure, the displacement of the pile top, and the earth pressure in the front of the pile. The optimal rise-span ratio was 3-16 according to the numerical simulation results. An indoor model test at the optimal rise-span ratio was carried out, recording the pile strain and the earth pressure in front of the pile. The results showed that some indices increased with the increase in rise-span ratio, such as the load transferred to the pile at the arch foot, the bending moment of the piles, the displacement of the pile top, and the earth pressure; within a certain depth near the pile top, the soil in front of the pile is loose during the loading processes, and the earth pressure at the range was zero. The overall safety factors of the four supporting models were 2.42, 2.66, 2.78, and 2.84, respectively, which can satisfy the requirements for practical engineering. The test results verify the feasibility and rationality of the spatial arc antislide pile supporting structure, which can provide a new idea for landslide treatment.
A method for calculating thermal conductivity of graphene/carbon fiber reinforced resin composites (GnP-CFRP) was established basing on the Mori-Tanaka program in the DIGIMAT software. The influence of grapheme nanoplatelets (GnP) on the thermal conductivity of composites has been simulated and experimentally verified. The results show that the thermal conductivity of GnP-CFRP increased with the increase of GnP content, and when the GnP content is too high, the increasing rate of thermal conductivity decreases gradually. In addition, the maximum prediction error of the simulation calculation method in this paper is within 7.27%, which is in good agreement with the actual situation.
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