Compliance switching for adhesion control

Climbing lizards display numerous advanced features in their locomotion, notably a method to quickly switch between a state of low and high adhesive force capacity. Inspired by the gecko's adhesive switching, a method of mechanically switching between low and high adhesive states is reported. In particular, the first switching of an adhesive system using only a change in system compliance is demonstrated. Mechanical clamping and a novel magnetic clamping system are used to switch an iron/PDMS composite adhesive between a soft and rigid state. The switch in compliance directly influences the maximum load of the adhesive as measured in lap‐shear. Notably, contact area and the contact chemistry remain unaltered despite significant changes in force capacity. The demonstration of a compliance‐only switching mechanism has broad implications for understanding natural adhesive systems—especially in organisms that can dynamically alter their rigidity (e.g. cells). © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 48–57     

Analysis of torque transmitting behavior and wheel slip prevention control during regenerative braking for high speed EMU trains

The wheel-rail adhesion control for regenerative braking systems of high speed electric multiple unit trains is crucial to maintaining the stability,improving the adhesion utilization,and achieving deep energy recovery.There remain technical challenges mainly because of the nonlinear,uncertain,and varying features of wheel-rail contact conditions.This research analyzes the torque transmitting behavior during regenerative braking,and proposes a novel methodology to detect the wheel-rail adhesion stability.Then,applications to the wheel slip prevention during braking are investigated,and the optimal slip ratio control scheme is proposed,which is based on a novel optimal reference generation of the slip ratio and a robust sliding mode control.The proposed methodology achieves the optimal braking performancewithoutthewheel-railcontactinformation.Numerical simulation results for uncertain slippery rails verify the effectiveness of the proposed methodology.     

Self‐adhesive epoxy modified silicone materials for light emitting diode encapsulation

In this paper, we prepared the light emitting diode (LED) encapsulant with self‐adhesion and high refractive index. In order to improve adhesion properties, we synthesized a series of multifunctional polysiloxanes with different contents of epoxy groups via the sol–gel condensation of methylvinyldimethoxysilane, diphenylsilanediol and 3‐glycidoxypropyldimethoxymethylsilane. The structures of epoxyphenylvinyl silicone (EPVS) resins were confirmed by proton nuclear magnetic resonance and Fourier‐transform infrared. The effect of epoxy group content on the adhesion property of EPVS resins was fully studied. The performances of the LED encapsulation materials based on EPVS resins were investigated in detail. These self‐adhesive encapsulating materials showed excellent thermal stability, a high refractive index of 1.55 and good adhesive property. These EPVSs can be used as an adhesion promoter for LED encapsulation materials. Copyright © 2017 John Wiley & Sons, Ltd.     

Functional Isoeugenol‐Modified Nanogel Coatings for the Design of Biointerfaces

A new route for the synthesis of functional aqueous nanogels decorated with a controlled amount of surface‐drafted isoeugenol molecules has been developed. Obtained nanogels exhibit two key functions: a) antibacterial activity against different oral pathogens and b) cell‐adhesive and ‐growth‐promoting properties. Functional nanogels can be potentially used as building blocks in the design of bioactive coatings on various implants preventing infections and accelerating tissue regeneration.     

The mechanical and tribological behaviors of PI composite filled with plasma treated UHMWPE fiber

The friction and wear behaviors of ultra‐high molecular weight polyethylene (UHMWPE)/PI composite were investigated in a ring‐on‐block wear tester. Ti6Al4V alloy ring were selected as the counterbody in this study. It was found that the detachment of particles, ripples, and ploughs were observed under higher load. Plasma treatment efficiently improves the interfacial adhesion of UHMWPE/PI composite. Both the friction coefficient and wear increased with load, and the plasma treated one shows lower friction coefficient and wear.     

Fracture resistance measurement of fused deposition modeling 3D printed polymers

A method is presented to characterize the fracture resistance and interlayer adhesion of fused deposition modeling (FDM) 3D printed materials. Double cantilever beam (DCB) specimens of acrylonitrile butadiene styrene (ABS) were designed and printed with a precrack at the layers' interface. The DCBs were loaded in an opening mode and the load-displacement curves were synchronized with the optical visualization of the crack tip to detect the critical load at the crack initiation. A finite element model, coupled with J-integral method and fracture surface analysis was then developed to obtain the apparent fracture resistance (J_cr,a) and the interlayer fracture resistance (J_cr,i), as a measure of the interlayer adhesion. The maximum J_cr,i was measured to be 4017 J/m², a value close to the fracture resistance of bulk ABS. Both J_cr,a and J_cr,i increased with the printing temperature. This method can find a great importance in the structural applications of printed materials.     

Enhanced adhesion of polypropylene to copper substrates

Varying concentrations of maleic anhydride (MAH) were grafted onto three types of polypropylene (PP) in the presence of dicumyl peroxide (DCP). Pull-off adhesive strength from a copper substrate, tensile Young's modulus, and tensile strain-at-break were determined and SEM observations made as a function of the MAH concentration for each PP. One of the PPs plus 3 wt% MAH provides a high value of the adhesive strength along with the Young modulus and the strain-at-break sufficient for the use as a coating for copper wires and cables.     

Plasma pretreatment of polycarbonate substrates for indium zinc oxide film deposition

The influence of plasma treatment of polycarbonate (PC) substrates on the morphological, electrical, and adhesion properties of deposited amorphous transparent indium zinc oxide (IZO) by direct current magnetron sputtering was investigated by analyzing atomic force microscopy, contact angles, Hall, and nano‐scratch measurements. The surfaces of PC substrates were performed by plasma treatment at various processing times in Ar/O₂ mix atmosphere. The atomic force microscopy images indicated that the microstructure of the substrates considerably influenced the surface morphology of deposited IZO films, and the least surface roughness of IZO was obtained after 5‐s plasma treatment. The IZO film deposited on PC with 5‐s plasma treatment presented an improved electrical conductivity and thermal stability after annealing at 120 °C in air, whereas the significant decrease in carrier concentration and increase in resistivity with extending plasma treatment time were observed, which was attributed to the elevated oxygen adsorption during annealing for a loosely packed structure. Moreover, the adhesion properties of IZO films with PC substrates decreased after 30‐s plasma treatment because of the significant difference on the surface polarity between the PC and thin films and the increased roughness caused by plasma etching. Copyright © 2016 John Wiley & Sons, Ltd.     

Aging behavior of dielectric barrier discharge‐modified Twaron fibers in different storage environments

The aging behavior of air dielectric barrier discharge plasma treatment was investigated by storing the treated fibers respectively in air and in the oxidizing environment. Based on several testing methods, this study led us to the conclusion that the aging effects in the oxidizing environment were less obvious than that in air. X‐ray photoelectron spectroscopy and Fourier transform infrared spectroscopy indicated that the decay of fiber surface polar groups was more remarkable for fibers aged in air. The atomic force microscopy photos showed that the further oxidation generated by the oxidizing chemicals such as ozone increased fiber surface roughness. Thus, there was no obvious reduction in the wettability of the modified fibers during the aging process in the oxidizing environment. These changes in surface properties could explain the variation in interlaminar shear strength of Twaron fiber reinforced composites. After the fibers were aged in air for 48 h, interlaminar shear strength of the composites declined by 18.4% while had a decrease of only 11.4% after aging for 48 h in the case of the oxidizing environment. The results were supported by the water absorption test, which also reflected the effects of different storage conditions on the composite interfacial adhesion, and showed the inhibitory effect of the oxidizing environment on plasma aging. Copyright © 2016 John Wiley & Sons, Ltd.     

伴有盆腔黏连的妇科腹腔镜手术临床分析

目的 分析伴有盆腔黏连的妇科腹腔镜手术临床应用价值。方法 选择2015年3月至2016年3月珠海市妇幼保健院收治的伴有盆腔黏连妇科疾病患者96例,随机分为两组,各48例。对照组采用传统开腹手术,观察组应用腹腔镜手术。比较两组手术疗效及手术情况。结果观察组手术总有效率为95.8%,明显高于对照组的83.2%,差异有统计学意义(P0.05);观察组手术时间、出血量及住院时间分别为(76.7±9.4)min、(45.6±4.7)m L、(4.6±1.3)d,均明显少于对照组[(89.3±10.2)min、(98.4±11.6)m L、(10.3±2.4)d],差异有统计学意义(P0.05)。结论 伴有盆腔黏连的妇科腹腔镜手术应用价值显著,是一种安全可靠的盆腔黏连治疗手段,值得推广。