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The application of polymer metallization in lightweight and high-strength materials for the sporting goods, automotive, aerospace and construction sectors has attracted considerable attention. The present study aims to deposit a thin, uniform copper (Cu) layer on an epoxy‑carbon fiber (epoxy-C f) composite material for lightweight, high-frequency radio reflector applications (Ka-Band and higher frequencies) required in space missions. In this work, a surface-activated electroplating technique in which the surface of the substrate is activated with a Sn/Ag system, followed by conventional electroplating is studied. Surface activation deposits layers of conducting metal ions on the surface of the epoxy-C f composite, which significantly improves the electrical conductivity of the composite surface. The subsequent electrodeposition takes place from a CuSO 4 solution with a pH value of 4 at three different current density values of 0.05 A/dm2, 0.5 A/dm2 and 1 A/dm2. The presence and abundance of metallic Cu over epoxy-C f composite were confirmed by X-ray diffraction and X-ray photoelectron spectroscopy. The morphology and elemental composition of the coating were characterized by scanning electron microscopy equipped with energy dispersive spectroscopy. With current density and coating thickness, morphology of the deposit changed from cauliflower-like to spherical along with grain refinement. Microhardness test shows a hardness of 330 HV and the pull-off adhesion test gave a bond strength of 1.69 MPa for 27.56 μm thick copper deposit. A major challenge encountered during the deposition of Cu is the oxidation of the metal followed by immediate tarnishing. This issue has been effectively addressed by employing benzotriazole solution as a protective agent. • Electrolytic Cu metallization of surface activated CFRP • Surface activated CFRP shows two-fold increase in surface electrical conductivity. • The thickness, morphology and grain size of Cu can be tuned with current density. • Adhesion strength and microhardness of Cu improved with current density. • Benzotriazole treatment imparts oxidation resistance to the deposited copper. [ABSTRACT FROM AUTHOR]

Primers are an appealing approach for enhancing adhesion to low-energy surfaces owing to their cost-effectiveness in manufacturing and operation, high efficiency, and scalability. Commercial adhesion coatings typically contain 3–20 % chlorinated polyolefins, which are environmentally unstable and contribute to the overall cost. This study proposes primers based on polypropylene grafted with maleic anhydride (PP-g-MAH) as a novel alternative. The research investigates the strength of adhesive joints formed using a PP-g-MAH-based primer. Polypropylene substrates coated with the primer were bonded to polyethylene foam coated with acrylic adhesive. The study examines various factors, including concentration of P P-g-MAH in the primer solution, the degree of grafting of polypropylene with maleic anhydride, the solvent type, the temperature of primer application, and pressure duration and magnitude. Peel strength analysis demonstrates that PP-g-MAH primers significantly enhance the adhesion of polypropylene substrates to the acrylic adhesive on the adhesive tape, requiring only a 1 % solution to achieve maximum joint strength (averaging 35.53 N and 37.29 N at 0.5 % and 1 % concentrations, respectively). Moreover, peel strength decreases with increasing polypropylene modification with maleic anhydride (41.1 N for 0.66 % grafting, 31.1 N for 1.0 %, and 29.7 N for 1.43 %). High-temperature application is necessary, with peak strength observed at 100 °C (54.4 % increase compared to 25 °C) and 120 °C (57.9 %). However, solvent selection can influence primer application temperature, with decalin and toluene yielding the highest strength (averaging 45.2 N and 42.8 N) compared to tetrachloroethane and xylene (37.3 N and 35.5 N). Pressure application is crucial for bonding polymers with foam adhesive tape, significantly enhancing strength (e.g., 71 % increase at 20 bar) with short-duration pressure (42.9 N for 10 s, 33.5 N for 60 s). [Display omitted] • Polypropylene grafted maleic anhydride can be used as polyolefins primer comparable effectiveness to chlorinated primers. • Primers based on PP-g-MAH work effectively at a low concentration of 0.5-1% compared to 3-20% of chlorinated polyolefins. • The most important parameters are the temperature of primer application and the concentration of the active substance. • PP-g-MAH primers work according to the diffusion theory of adhesion depends on solvent used and applied temperature. [ABSTRACT FROM AUTHOR]

Poly(lactic acid) (PLA) and poly(vinyl alcohol) (PVA) present complementary barrier properties, and their combination in multilayer assemblies (laminates) could provide materials with more effective barrier capacity for food packaging purposes. However, their low chemical affinity compromises adequate polymer adhesion. Surface free energy modification of thermo-processed PLA films through treatment with 1,6-hexanediamine was used to enhance adhesion with polar PVA aqueous solutions. Treatments of 1 and 3 min increased the polar component of the solid surface tension, while treatments above 10 min provoked a corrosive effect in the films' structure. Extensibility analyses of PVA solutions loaded with carvacrol (15 wt.%) and different Tween 85 ratios on PLA-activated surfaces allowed the selection of the 1-min aminolysed surface for obtaining PLA-PVA bilayers, by casting PVA solutions on the PLA films. This study revealed that despite aminolisation enhancing the PLA surface affinity for aqueous PVA solutions, casting-obtained bilayers presented limited oxygen barrier effectiveness due to heterogeneous thickness of PVA layer in the laminates. [ABSTRACT FROM AUTHOR]

Copper (Cu) film bonded with polymer substrates offers better dimensional stability than that of deposited Cu especially in humid environment. However, poor adhesion is an issue in both cases. In this paper, we demonstrate a two-step, low temperature direct bonding technique for liquid crystal polymer (LCP) and copper (Cu) using oxygen plasma. The bonded interface showed high peel strength. This strong adhesion is due to the interdiffusion of Cu and carbon atoms into LCP and Cu film respectively. These phenomena resulted in three-dimensional metal clusters of Cu atoms and islands at the LCP/Cu interface, which gradually diffuse into the LCP. Interfacial elemental analysis reveals an intermediate oxide layer formation due to Cu 2 O and C O. [ABSTRACT FROM AUTHOR]

Today, Ti6Al4V alloy is the most used and manufactured metallic implantable biomaterial in biomedical industry. However, in recent years it has demonstrated that Ti6Al4V based biomaterials could induce harmful diseases to human health in long-term implantations. Thus, biomedical community makes great efforts in order to improve the biocompatibility of Ti6Al4V implants and to afford additional antibacterial properties. For this, one promising strategy is the activation of Ti6Al4V surface through simple and industrially scalable physicochemical techniques that involve the increase of the thickness of the surface oxidation (TiO 2) and the creation of active hydroxyl groups (Ti-OH). In this work, Ti6Al4V biomaterials were activated with chemical wet (CWT), electrochemical (ET), and physical oxygen plasma (POPT) treatments. Their surface activation effectiveness was evaluated in terms of surface damage, changes in surface roughness, wettability, and oxidation and hydroxylation capability (Ti-OH/TiO 2 ratio). So, results show that acidic HCl:H 2 O 2 piranha CWT of Ti6Al4V surfaces is the most effective surface activation procedure with improved surface reactivity (highest Ti-OH/TiO 2 ratio), cytocompatibility, cell proliferation, and hemocompatibility. Antibiofilm activity of pristine Ti6Al4V was also enhanced by acidic HCl:H 2 O 2 piranha treatment, leading to a decrease in bacterial adhesion of 30 % against S. aureus and E. coli. • Ti6Al4V surface was activated using chemical wet (CWT), electrochemical (ET), and physical oxygen plasma (POPT) treatments. • CWTs activated more effectively Ti6Al4V surface displaying a roughness close to nano-scale plus an increased wettability. • CWTs significantly improved cytocompatibility, cell proliferation and hemocompatibility of pristine Ti6Al4V. • Ti6Al4V activated with CWT repelled S. aureus and E. coli bacteria strains endowing antibiofilm properties in 30 %. [ABSTRACT FROM AUTHOR]

This study focuses on cold-gas-sprayed deposition of metallic coatings onto ceramic substrates for application in power electronics. In order to achieve the required surface activation for bonding, the substrate is heated during spraying. The effects of substrate temperature on bond strength and coating properties are investigated for cold-gas-sprayed coatings of copper and aluminum on AlO. It is found that the adhesion strengths of the cold-gas-sprayed coatings and that of the single-impacting particles increase with the increasing temperature and roughness of the substrate. Coatings sprayed on heated substrates show relatively low compressive stresses and low hardness, while their electrical conductivity reaches high values of over 90% IACS. Overall, a higher substrate temperature is found to improve the coating properties significantly. [ABSTRACT FROM AUTHOR]

Abstract: The improved interfacial adhesion of PBO fiber-reinforced bismaleimide composite by oxygen plasma processing was investigated in this paper. After treatment, the maximum value of interlaminar shear strength was 57.5MPa, with an increase of 28.9%. The oxygen concentration of the fiber surface increased, as did the surface roughness, resulting in improvement of the surface wettability. The cleavage and rearrangement of surface bonds created new functional groups Oh name="sbnd" />O, Nh name="dbnd" />O and Ny activating the fiber surface. And long-time treatment increased the reaction degree of surface groups while destroyed the newly-created physical structures. The enhancement of adhesion relied primarily on the strengthening of chemical bonding and mechanical interlocking between the fiber and the matrix. The composite rupture planes indicated that the fracture failure shifted from the interface to the matrix or the fiber. [Copyright &y& Elsevier]

Abstract: A special surface pre-treatment protocol consisting of four steps is proposed to provide high adhesion levels for CVD diamond by hot-filament technique. In step 1, the silicon nitride ceramic substrates are surface ground with 15µm diamond slurry and mirror-like polished with colloidal silica (0.05µm). In step 2, plasma etching with CF4 (PE), mechanical anchoring is promoted due to the surface roughness increment. Surface activation (SA) is the following step, where the substrates are subjected to CVD diamond growth conditions for a short time (30min), leading to the deposition of an amorphous carbon layer responsible for enhancing the nucleation density and the further growth of diamond during early stages of deposition. The final step 4 is 0.5–1µm diamond powder seeding in an ultrasonic bath. The results show that the Si3N4 ceramic surface modified by the surface pre-treatment protocol allowed a high nucleation density promoting a continuous and homogeneous film of equally sized diamond grains, at a growth rate of ap. 1.5µmh−1. Brale tip indentation tests confirmed that highly adherent films are thus produced (no delamination under 900N). [Copyright &y& Elsevier]

Oxyfluorination was evaluated on a series of wood-fiber reinforced thermoplastic composite (WPCs) formulations as a means to improve the adhesion of a water-based acrylic coating. The oxyfluorination increased the acrylic coating peel load to WPCs by 179%, yielding adhesion levels higher than those obtained on control maple. For oxyfluorinated surfaces, the WPC formulation had a significant impact on the acrylic coating paint. Formulations without maleic anhydride polypropylene coupling agent developed better adhesion than formulations with the coupling agent. Formulations with polypropylene also performed better than formulations with high density polyethylene and so did formulations with pine compared with those with maple. Interestingly, the adhesion improvement imparted by oxyfluorination was higher for those formulations that were least amenable to bonding with the acrylic coating, i.e., those containing the coupling agent and high density polyethylene. Contact angle measurements and ATR-FTIR spectroscopy indicated that oxyfluorination improved wettability with polar liquids by generating new oxygenated groups on the surface. A moderate positive linear relationship (r2 = 0.5) was established between the carbonyl/C-H stretch band intensity ratio I1650cm-1/I2915cm-1 in the infrared spectra of oxyfluorinated WPCs and the coating peel strength. It is, therefore, proposed that oxyfluorination improves the adhesion properties of WPCs by oxidizing the surface, and by increasing wettability with polar liquids, thus allowing the development of stronger interfacial forces. [ABSTRACT FROM AUTHOR]

Four surface activation methods were evaluated on a series of wood-fiber reinforced thermoplastic composites (WPCs) as a means to improve the adhesion of a water-based acrylic coating. Treatments with chromic acid and oxygen plasma performed best, increasing the acrylic coating peel load to WPCs by 170 and 122%, respectively, and yielding adhesion levels equivalent to or higher than those obtained on wood. The benzophenone/ultraviolet and flame treatments also improved the coating adhesion by 100 and 64%, respectively, but did not reach the adhesion levels achieved on wood. For both the chromic acid and oxygen plasma treatments, the WPC formulation impacted the treatment efficacy. Profilometry and scanning electron microscopy (SEM) showed that the chromic acid treatment acted mainly by roughening WPC surfaces. While surface oxidation was not evident from attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), the improved wettability of WPCs with water suggested that the oxygen plasma treatment oxidized WPCs. [ABSTRACT FROM AUTHOR]

Abstract: Self-assembled organic monolayers (SAMs) of silanes with –SH, –NH2 and –C5H4N functional groups have been shown recently to act as ultra-thin, robust diffusion barriers at the Cu/SiO2 and Cu/ultra low-k dielectric interfaces. More generally, SAMs with their tunable surface chemistry are essential elements of future all-wet ULSI metallization with Cu deposited by electroless (ELD) over SAM-functionalized dielectrics. Far too small is known however on the electrical properties of thin metal films formed onto SAM/dielectric substrates. In this paper, we give first a brief literature survey of what is known about Cu films deposited by electroless over dielectrics modified by SAMs. Second, we present our observations of electrical resistivity ρ of sub-100nm ELD Cu films deposited over the surface of amino-silane SAM/SiO2 activated by Au monodispersed nano-particles and show that this techniques helps to obtain considerably smaller ρ compared to the previously reported data. [Copyright &y& Elsevier]

The mechanical product behaviour of cohesive ultrafine powders is characterized by insufficient flowability and large compressibility. Consequently, a comparatively large energy input is necessary to promote the non-rapid frictional shear flow in powder handling practice. The paper continues the new micromechanical philosophy demonstrated in the last publication [Tomas, J., 2007a. Adhesion of ultrafine particles—a micromechanical approach. Chemical Engineering Science 62, 1997–2010, doi: 10.1016/j.ces.2006.12.055]. When two adhesive particles are coming in contact, the constitutive models of four stressing modes, namely by compression and detachment (tension), sliding, rolling and torsion have to be derived. The consequences of elastic-dissipative, elastic-plastic, frictional unloading and reloading paths of normal and tangential forces, rolling and torsional moments are discussed with respect to energy absorption. The total energy absorption comprises contributions by elastic-dissipative hysteresis due to microslip within the contact plane and by fully developed friction work when the friction limits of displacements are exceeded during contact sliding, particle rolling or rotation. With increasing contact flattening by normal load these friction limits, hysteresis and friction work increase. The particle mass related, averaged energy densities of these various stressing modes are found to be 0.4–6mJ/g. But the enormous, mass of contact zone related energy density amounts to 0.2–20kJ/g. Besides this, the powder mass related energy consumption characterises the global intensity of energy absorption of macroscopic process within an apparatus, e.g. the specific preshear work of about 1–5mJ/g. Thus, it is very essential to understand the micromechanics of particle contact behaviour with respect to product quality assessment and process performance in particle technology. [Copyright &y& Elsevier]