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Characterizing photovoltaic backsheet adhesion degradation using the wedge and single cantilever beam tests, Part II: Accelerated tests
摘要： Photovoltaic (PV) backsheets provide critical moisture, mechanical, and electrical insulation to the backside of PV modules, but their continued functionality depends upon their ability to remain well adhered over years of harsh environmental exposure. A study of adhesive strength was conducted on several PV backsheet types exposed to indoor accelerated weathering. Two adhesion tests – the wedge test and single cantilever beam test – were used to measure adhesion energy in four backsheets: two with fluoropolymer-based outer (airside) layers – polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF) – and two with non-fluoropolymer-based outer layers–polyamide (PA) and polyethylene terephthalate (PET). The effects of changes in temperature, ultraviolet (UV) irradiance, relative humidity, and a periodic water spray were studied. The PET-, PVF- and PVDF-based backsheets all showed instances of debonding in an adhesive layer, which is commonly reported. For the PA-, PET-, and PVDF-based backsheets, adhesion energy dropped fairly rapidly with exposure, reaching very low levels by 4000 h. The PVF-based backsheet was relatively robust to weathering. Pull-off of an outer chalking layer in the PA- and PET-based backsheets suggested a sensitivity to UV. Adhesion in these two backsheets was also highly sensitive to changes in moisture level. Changes in UV irradiance and temperature did not show a statistically significant effect on adhesion loss for the exposure levels used. The present work is part of a two-part adhesion study on both field-weathered and indoor-exposed backsheets, and forms a basis for understanding adhesion degradation across a variety of backsheet types and degradation factors.
关键词： Backsheet,Delamination,Photovoltaic,Accelerated weathering,Degradation,Adhesion
更新于2025-09-19 17:13:59
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Influence of surface treatment with infrared nanosecond laser on adhesion performance of adhesion-bonded carbon fiber/epoxy composite
摘要： The surface treatment of carbon fiber/epoxy composites with a pulsed infrared (1064 nm wavelength) nanosecond (7 ns pulse duration) laser has been investigated. It is found that single 1064 nm laser pulse can remove the polymer matrix from composite surface to expose the carbon fibers by expansion of the pyrolysis gas resulting from laser-induced polymer degradation. The influences of laser power density and scan strategy on matrix removal process have been studied. The bonding strength of laser processed, adhesion-bonded CFRP (carbon fiber reinforced plastic) increase with lower matrix residues on the fibers and a linear relation is found. The adhesion-bonding strength of CFRP surfaces, tested by lap-joint shear test, exceeds the strength measured for untreated and abrasion treated (SiC paper) samples. The main origin of fiber damage of the laser-treated surface is mechanical fracture rather than thermal damage as found by laser scanning confocal microscope and scanning electron microscope. The characteristic morphologies and failure modes of shear-tested surfaces are analyzed. The obvious improvement of adhesive strength is achieved by the laser-treated surfaces attributed to matrix removal and carbon fibers protruding. A 1 D model is established to describe temperature and internal gas pressure of the irradiated surface. The new laser treatment method needs less laser energy and low pulse numbers and prove the way to an efficient, low-cost surface treatment for preparation of high quality adhesion bonded CFRP components.
关键词： matrix removal,adhesion strength,1064 nm laser,Carbon fiber/epoxy composite
更新于2025-09-19 17:13:59
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Surface passivation of zero-mode waveguide nanostructures: benchmarking protocols and fluorescent labels
摘要： Zero mode waveguide (ZMW) nanoapertures efficiently confine the light down to the nanometer scale and overcome the diffraction limit in single molecule fluorescence analysis. However, unwanted adhesion of the fluorescent molecules on the ZMW surface can severely hamper the experiments. therefore a proper surface passivation is required for ZMWs, but information is currently lacking on both the nature of the adhesion phenomenon and the optimization of the different passivation protocols. Here we monitor the influence of the fluorescent dye (Alexa Fluor 546 and 647, Atto 550 and 647N) on the non-specific adhesion of double stranded DNA molecule. We show that the nonspecific adhesion of DNA double strands onto the ZMW surface is directly mediated by the organic fluorescent dye being used, as Atto 550 and Atto 647N show a pronounced tendency to adhere to the ZMW while the Alexa Fluor 546 and 647 are remarkably free of this effect. Despite the small size of the fluorescent label, the surface charge and hydrophobicity of the dye appear to play a key role in promoting the DNA affinity for the ZMW surface. Next, different surface passivation methods (bovine serum albumin BSA, polyethylene glycol PEG, polyvinylphosphonic acid PVPA) are quantitatively benchmarked by fluorescence correlation spectroscopy to determine the most efficient approaches to prevent the adsorption of Atto 647N labeled DNA. Protocols using PVPA and PEG-silane of 1000 Da molar mass are found to drastically avoid the non-specific adsorption into ZMWs. Optimizing both the choice of the fluorescent dye and the surface passivation protocol are highly significant to expand the use of ZMWs for single molecule fluorescence applications.
关键词： fluorescent dyes,Zero mode waveguide,single molecule fluorescence,DNA adhesion,surface passivation
更新于2025-09-19 17:13:59
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[IEEE 2019 SBFoton International Optics and Photonics Conference (SBFoton IOPC) - Sao Paulo, Brazil (2019.10.7-2019.10.9)] 2019 SBFoton International Optics and Photonics Conference (SBFoton IOPC) - Evaluation of the Adhesive Strength in Dentin after Irradiation with Ti:Sapphire Ultrashort Laser Pulses
摘要： This study was done to evaluate whether the irradiation of dentine with ultrashort laser pulses prior to adhesive procedures contributes to increase the adhesive resistance to microtraction essays. Twenty-four human teeth (third molars) were used, divided into 4 groups (n=6): standard adhesive procedures with etch-rinse adhesive were used in the control group, and in the experimental groups, the dentin was irradiated by 25 fs pulses prior to the adhesive procedures, with varying fluences. One tooth from each group was used to evaluate its surface roughness. After 24h, the teeth were sectioned with perpendicular cuts, producing toothpicks that were submitted to the microtraction test. The results showed that the groups irradiated with fluences under 4 J/cm2 presented similar results among themselves, comparable to the control group, while the group irradiated with 8 J/cm2 showed lower adhesive strength. We propose that the adhesive strength and surface roughness reduction resulting from the fluence increase is probably related to the shielding arising from an electron plasma formation during the ablation, decreasing the material removal efficiency. Nevertheless, the lower energy densities did not affect the adhesiveness, maintaining values similar to the control.
关键词： dentin,femtoseconds laser pulses,microtensile bond strength,adhesion,Ti:Sapphire laser irradiation
更新于2025-09-19 17:13:59
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UV or blue light excited red persistent perovskite phosphor with millisecond lifetime for use in AC-LEDs
摘要： Problem: The function of CD49a on human decidual natural killer (dNK) cells is unknown. Method of study: The expression of CD49a on dNK cells from human patients with recurrent spontaneous abortions or age‐matched healthy controls was analyzed by flow cytometry. DNK cells were treated with CD49a neutralizing antibody and analyzed for function (cytokines production and cytotoxic activity). Long non‐coding RNA (lncRNA) microarray analysis was used to identify a potential regulator of CD49a. Results: DNK cells from human patients who underwent recurrent spontaneous abortions had lower levels of CD49a and increased perforin, granzyme B, and IFN‐r expression, when compared to dNK cells from age‐matched healthy controls. Perforin, granzyme B, and IFN‐r expression levels in dNK cells were upregulated, while the migration and adhesion of dNK cells were downregulated by CD49a‐neutralizing antibody. By the 51Cr release assay, the killing activity of dNK cells also increased with CD49a neutralizing antibody. Further, lnc‐49a, a newly identified lncRNA, was shown to be a positive regulator of CD49a in primary human NK cells. Conclusion: CD49a is involved in the regulation of dNK cells functions, including cytotoxic activity, migration, and adhesion. Further, lnc‐49a is a positive regulator of CD49a in human primary dNK cells.
关键词： long non‐coding RNAs,natural killer cells,CD49a,adhesion,migration
更新于2025-09-19 17:13:59
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Metal Polymer Connections: Laser-Induced Surface Enlargement Increases Joint Strength
摘要： The trend towards hybrid materials consisting of metals and polymers is strongly driven by requirements such as weight reduction and improved functionality. A crucial step towards new hybrid materials is the advancement of joining technology. While metals and polymers are currently often joined using adhesives, this technology has major drawbacks such as long process cycle time, low robustness with regard to changes of the material composition, and are almost impossible to recycle, a point which is becoming increasingly important. A promising joining method is thermal direct joining of metals and thermoplastic polymers due to its fast cycle time, its robustness of the process and the absence of duroplastic adhesives. Direct joining requires surface treatment of the metallic joining partner prior to the thermal joining process to achieve a sufficiently high contact strength. It is known that laser-induced topologies on the metal surface are beneficial with regard to contact strength of the joints. Designing a joint based on laser structured metals requires a fundamental understanding of the interface interactions. The present paper focuses on the influence of surface enlargement on the joint strength. Laser pretreatment was utilized to generate surface structures with specific surface enlargement on the metallic joining partner. The pretreated metallic parts were subsequently joined with a thermoplastic polymer by injection molding. The joint strength was investigated in single lap shear tests. The key finding is that the contact strength increases almost linearly with the surface area within the tested parameter range, while the structure geometry parameters have only a minor influence. This may help as a design guideline for future adhesive-free hybrid material joining technologies.
关键词： hybrid joining,laser material processing,metal polymer connection,micro structuring,metal polymer joints,lightweight,adhesion,in-mold assembly
更新于2025-09-16 10:30:52
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Effect of laser texturing on the performance of ultra-hard single-point cutting tools
摘要： This paper investigates the cutting performance and anti-adhesive properties of textured single-point polycrystalline diamond (PCD) cutting tools in machining Aluminium 6082 alloys. The micro/nano textures were first milled using a fibre laser (1064-nm wavelength) at different power intensities, feed speeds and pulse durations, and finally characterised using scanning electron microscopy, white light interferometry and energy dispersive X-ray spectroscopy. The effect of different textures on the cutting performance was investigated in turning tests under dry cutting conditions. The test was stopped at regular lengths of cut to allow analysis of height of adhesion through 3D white light interferometry. The data processing of the cutting forces and the microscopical characterisation of the tested cutting tools enabled the evaluation of the effects of texture design, friction coefficient and adhesive properties. The results indicated that feed force in tools with grooves perpendicular to the chip flow direction (CFD) was more stable (20–40 N) than the benchmark (6–41 N). Similarly, the thrust force for tools with grooves parallel to CFD and grooves perpendicular to CFD showed a homogeneous trend fluctuating between 60 and 75 N as compared with the benchmark (ranging between 73 and 90 N). For texture depth in the order of 260 nm and post process roughness in the order of tens of nanometers, a reduction of average friction coefficient (0.28 ± 0.14) was reported when using lasered inserts with grooves parallel to the chip flow direction compared with the benchmark tools (0.34 ± 0.26) corroborated by reduced stiction of workpiece material on the rake face. In machining via textured tools with grooves perpendicular to CFD, the cutting forces were reduced by 23%, and the surface quality of the machined workpiece was improved by 11.8%, making this geometry the preferred choice for finishing applications. Using grooves parallel to CFD reduced the cutting forces by 11.76%, adhesion by 59.36% and friction coefficient by 14.28%; however, it increased the surface roughness of the machined workpiece, making this geometry suitable for roughing operations. For the first time, laser manufacturing is proposed as a flexible technique to functionalise the geometrical and wear properties of PCD cutting tools to the specific applications (i.e. roughing, finishing) as opposed to the standard industrial approach to use microstructurally different PCDs (i.e. grain size and binder %) based on the type of operation.
关键词： Adhesion,Dry cutting,Nanosecond pulse,Laser milling,Polycrystalline diamond insert,Laser surface texturing,Cutting forces
更新于2025-09-16 10:30:52
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Reduced bacterial adhesion on zirconium-based bulk metallic glasses by femtosecond laser nanostructuring
摘要： As high-performing materials, bulk metallic glasses have attracted widespread attention for biomedical applications. Herein, the bacterial adhesion properties of femtosecond laser-nanostructured surfaces of four types of zirconium-based bulk metallic glasses are assessed. Laser-induced periodical surface structures and nanoparticle structures were fabricated by femtosecond laser irradiation under different energy intensities (0.23 and 2.3 J/mm2). Surface topography, roughness, wettability, and surface energy were investigated after femtosecond laser irradiation and the surface bacterial adhesion properties were explored using Escherichia coli and Staphylococcus aureus as respective representatives of Gram-negative and Gram-positive bacteria. 4#,6-Diamidino-2-phenylindole fluorescence staining was used to characterize and assess the bacterial surface coverage rate. The in vitro cytotoxicity of polished and laser-nanostructured surfaces was investigated using MC3T3-E cells. The obtained results demonstrate that femtosecond laser surface nanostructuring retained the amorphous structure of zirconium-based bulk metallic glasses and led to an obvious decrease in bacterial adhesion compared with polished surfaces. The inhibition of bacterial adhesion on laser-induced periodical surface structures was greater than on nanostructured surfaces after 24 h of bacterial incubation. In addition, femtosecond laser nanostructuring did not have an apparent effect on the cytotoxicity of zirconium-based bulk metallic glasses.
关键词： femtosecond laser,Bacterial adhesion,nanostructure,bulk metallic glass
更新于2025-09-16 10:30:52
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All-Waste Hybrid Composites with Waste Silicon Photovoltaic Module
摘要： Nowadays, global warming, energy issues and environmental concern have forced energy production stakeholders to find new low carbon solutions. Photovoltaic technologies as renewable energy resources represent a competitive way for the transition from conventional fossil fuels towards a renewable energy economy. The highest renewable energy systems (RES) market share is based on silicon photovoltaic (Si-PV). The installed RES have rapidly increased over the last two decades, but, after the end of their service life, they will be disposed of. Therefore, the constant increase of the installed RES has attracted the global concern due to their impact on the environment and, most of all, due to the content of their valuable resources. However, the rational management of RES waste has not been addressed so far. The paper represents an extension of a previous work focused on Si-PV recycling by developing all waste hybrid composites. The extension research conducted in this paper is related to the influence of Si-PV characteristics on the mechanical performances and water stability of the hybrid composites. All waste hybrid composites developed by embedding different Si-PV grain sizes were tested before and after water immersion in terms of mechanical strength, interfacial adhesion, crystallinity and morphology by scanning electron microscopy (SEM) analyses. The results revealed the better performance of such Si-PV composites compared to that of sieved composites even after long term water immersion. Therefore, high-content Si-PV hybrid composites could be developed without Si-PV powder sieving. Further on, all waste hybrid composites could be used as paving slabs, protective barriers for outdoor applications.
关键词： silicon photovoltaic module,water stability,all waste hybrid composite materials,interfacial adhesion,recycling,mechanical properties
更新于2025-09-16 10:30:52
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Adhesion‐Engineering‐Enabled “Sketch and Peel” Lithography for Aluminum Plasmonic Nanogaps
摘要： Aluminum is one of the most significant plasmonic materials for its advantage of low cost, natural abundance, as well as the ultraviolet optical response. However, it is still very challengeable for the fabrication of aluminum plasmonic nanogaps, which greatly limits the applications of aluminum plasmonics considering the essential role of nanogaps for electric field enhancement. Here, the reliable patterning of aluminum plasmonic nanogaps employing a modified “Sketch and Peel” lithography strategy is demonstrated. By introducing a self-assembled monolayer to engineer the surface energy of the substrate, the adhesiveness of the aluminum film outside outline template is significantly decreased to implement the selective peeling process. Besides, the near-infrared Fano resonance in the periodic aluminum heptamers has been first revealed by enabling the strong electric field and plasmon coupling in the aluminum nanostructures with 10 nm scale nanogaps. In addition, surface-enhanced Raman spectroscopy and infrared spectroscopy are also illustrated in the rationally designed aluminum dimers. The present work provides a robust method to obtain aluminum plasmonic nanogaps, which may play an important role on the practical applications of aluminum plasmonics, such as surface-enhanced vibration spectroscopy and nonlinear optics.
关键词： surface-enhanced spectroscopy,aluminum plasmonics,Sketch and Peel lithography,adhesion engineering,plasmonic nanogaps
更新于2025-09-12 10:27:22