Significant Improvement In Adhesion Research Articles

Effect of Different Compatibilizers on the Properties of Green Low-Density Polyethylene Composites Reinforced with Bambusa Vulgaris Bamboo Fibers.

Low-density green polyethylene (LDGPE) composites reinforced with 5 wt% of bamboo fiber and 3 wt% of a compatibilizing agent (polyethylene grafted with maleic anhydride and tannin) were processed through extrusion and injection molding. Bamboo fiber, Bambusa Vulgaris, was characterized using Fourier-transform infrared spectroscopy (FTIR). The molded specimens were analyzed for their thermal, mechanical, and morphological properties. The estimated concentration was chosen to provide the best mechanical strength to the material studied. FTIR analysis of the fibers revealed the presence of groups characteristic of bamboo fiber and tannin. Differential scanning calorimetry revealed that both compatibilizing agents increased the matrix's degree of crystallinity. However, scanning electron microscopy (SEM) showed that, despite the presence of compatibilizing agents, there was no significant improvement in adhesion between the bamboo fibers and LDGPE.

Fabrication of GNPs sprayed carbon fiber and its effects on the interfacial and mechanical behavior of reinforced epoxy multiscale laminated composite

AbstractThe current research compares the effects of modifying carbon fiber [via spraying graphene nanoplates (GNPs)] and/or GNPs reinforcement on the mechanical and interfacial behavior of carbon fiber epoxy composites. Using a spraying method, the epoxy matrix was reinforced, and carbon fiber was modified with 0.2 and 1 wt% of GNPs, respectively. Tensile, interlaminar, and dynamic mechanical analyses (DMA) tests were conducted on the composite to assess the role of GNPs in enhancing mechanical, interfacial, and thermomechanical properties. The obtained results indicate that the spraying technique effectively enhanced the ultimate tensile strength (UTS) and interlaminar fracture toughness (ILFT) of the composite. The UTS improved by 31%, while the ILFT significantly improved by 38%. Additionally, assessing the modulus gradient through the interface shows improved interfacial interaction between modified carbon fiber and reinforced epoxy. Scanning electron microscopy examination of the fractured surfaces indicated that the existence of nanofillers with high surface area contributed to significant improvements in adhesion between the modified fiber and reinforced epoxy matrix, leading to enhanced interfacial, mechanical, and thermomechanical properties of CFRPs for structural applications.Highlights Incorporation of surface modified carbon fibers and GNPs reinforcement in the epoxy matrix to enhance the interfacial interaction. Evaluation of the effects of GNP nanofiller on interfacial and mechanical performance of the composite. Fracture surfaces in ILSS, tensile, and mode I test were analyzed using FESEM. Utilization of nanoscale modulus mapping for the fiber‐matrix interface assessment.

Synthesis and characterization of waterborne polyurethane-based ink binder modified via a silane coupling agent

The development of high-performance waterborne polyurethane ink binder presents challenges due to the lack of outstanding water resistance, adhesion, and heat resistance in traditional waterborne polyurethane. Herein, series of waterborne polyurethane emulsions were synthesized using the pre-polymerization chain expansion and self-emulsification method, with varying contents of 3-aminopropyl triethoxysilane as the modified post-chain extender. The effect of varying the concentration of 3-aminopropyl triethoxysilane on the characteristics of waterborne polyurethane dispersions and films was investigated. The results indicated that there was a significant improvement in adhesion, thermal stability, and water resistance with an increase in the concentration of 3-aminopropyl triethoxysilane. Specifically, When the introduction amount was 3 wt%, the resulting film exhibited the best overall properties, including a tensile strength of 48.4 MPa, water absorption of 4.3 wt%, shear strength and adhesion of 3.9 MPa and 3.86 MPa respectively, as well as a T-peel strength of 14.9 N/mm. This work provided meaningful guidance for developing a novel waterborne polyurethane-based ink binder with strong adhesion, high mechanical properties, and excellent water resistance.

Electrochemical Deposition of Polypyrrole in the Presence of Silanes as Adhesion Promoters.

Polypyrrole adhesion to indium-tin oxide electrodes was improved by adding pre-hydrolyzed alkoxysilanes to the electrodeposition media. The pyrrole oxidation and film growth rates were studied by potentiostatic polymerization in acidic media. The morphology and thickness of the films were studied by contact profilometry and surface-scanning electron microscopy. The bulk and surface semiquantitative chemical composition was studied by Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. Finally, the adhesion was studied by scotch-tape adhesion test, where both alkoxysilanes showed a significant improvement in adhesion. We proposed a hypothesis for the improvement in adhesion, that involves the formation of siloxane material as well as in situ surface modification of the transparent metal oxide electrode.

PBAT/PLA/cellulose nanocrystals biocomposites compatibilized with polyethylene grafted maleic anhydride (PE‐g‐MA)

AbstractThe use of biodegradable polymers has grown exponentially due to their lower environmental impact when compared to conventional polymers. In this sense, biocomposites are an alternative due to their promising properties, maintaining biodegradability. For this purpose, in the present study, a biodegradable biocomposite of PBAT (poly [butylene adipate co‐terephthalate]) and PLA (polylactide) blend containing cellulose nanocrystals (CNC) were obtained, using polyethylene grafted with maleic anhydride (PE‐g‐MA) as a coupling agent. Seven formulations were produced by extrusion and had their structure, morphology, thermal, and rheological properties analyzed. The results showed a significant improvement of adhesion among the components using PE‐g‐MA as a coupling agent. Moreover, CNC and PE‐g‐MA increased the PLA crystallinity degree and reduced the complex viscosity. These results are unprecedented in the literature using these compositions and extrusion processing conditions. Therefore, these new insights provide a vast horizon for the use of biodegradable mixtures using PBAT/PLA and CNC.

Enhancement of Adhesion Characteristics of Low-Density Polyethylene Using Atmospheric Plasma Initiated-Grafting of Polyethylene Glycol.

The low-density polyethylene/aluminum (LDPE/Al) joint in Tetra Pak provides stability and strength to food packaging, ensures protection against outside moisture, and maintains the nutritional values and flavors of food without the need for additives in the food products. However, a poor adhesion of LDPE to Al, due to its non-polar surface, is a limiting factor and extra polymeric interlayers or surface treatment is required. Plasma-assisted grafting of the LDPE surface with different molecular weight compounds of polyethylene glycol (PEG) was used to improve LDPE/Al adhesion. It was found that this surface modification contributed to significantly improve the wettability of the LDPE surface, as was confirmed by contact angle measurements. The chemical composition changes after plasma treatment and modification process were observed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). A surface morphology was analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Adhesion characteristics of LDPE/Al adhesive joints were analyzed by the peel tests. The most significant adhesion improvement of the PEG modified LDPE surface was achieved using 10.0 wt.% aqueous (6000 M) PEG solution, while the peel resistance increased by approximately 54 times in comparison with untreated LDPE.

Engineered chitosan for improved 3D tissue growth through Paxillin-FAK-ERK activation.

Scaffold engineering has attracted significant attention for three-dimensional (3D) growth, proliferation and differentiation of stem cells in vitro. Currently available scaffolds suffer from issues such as poor ability for cell adhesion, migration and proliferation. This paper addresses these issues with 3D porous chitosan scaffold, fabricated and functionalized with cysteine-terminated Arg-Gly-Asp (Cys-RGD) tri-peptide on their walls. The study reveals that the compressive moduli of the scaffold is independent to RGD functionalization but shows dependence on the applied freezing temperature (TM) during the fabrication process. The low freezing TM (−80°C) produces scaffold with high compressive moduli (14.64 ± 1.38 kPa) and high TM (−30°C) produces scaffold with low compressive moduli (5.6 ± 0.38 kPa). The Cys-RGD functionalized scaffolds lead to significant improvements in adhesion (150%) and proliferation (300%) of human mesenchymal stem cell (hMSC). The RGD-integrin coupling activates the focal adhesion signaling (Paxillin-FAK-ERK) pathways, as confirmed by the expression of p-Paxillin, p-FAK and p-ERK protein, and results in the observed improvement of cell adhesion and proliferation. The proliferation of hMSC on RGD functionalized surface was evaluated with scanning electron microscopy imaging and distribution though pore was confirmed by histochemistry of transversely sectioned scaffold. The hMSC adhesion and proliferation in scaffold with high compressive moduli showed a constant enhancement (with a slope value 9.97) of compressive strength throughout the experimental period of 28 days. The improved cell adhesion and proliferation with RGD functionalized chitosan scaffold, together with their mechanical stability, will enable new interesting avenues for 3D cell growth and differentiation in numerous applications including regenerative tissue implants.

Preparation and characterization of starch composites with cellulose nanofibers obtained by plasma treatment and ultrasonication

AbstractThe cellulose nanofibers (CNF) are novelly extracted via air plasma treatment combined with the ultrasonication procedure. This study prepares and characterizes the starch‐based biocomposites reinforced by CNF within the glycerol plasticized matrix. The application of starch‐based polymers is improved with fabricating a biocomposite of thermoplastic starch (TPS) as matrix and the CNF as reinforcement. After modifying the surface of the cellulose fibers (CF) by air plasma treatment, CNFs are extracted by using an ultrasonic bath. The CNF are studied using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy. The TPS/CNF composites are prepared using the high‐friction and hot‐compression procedure. Tensile test results and SEM images of the fracture surfaces show significant improvement of adhesion between CNF and TPS matrix compared to composites reinforced by neat CF. The thermogravimetric analysis shows a considerable decompositionat approximately 270–340°C.

Improvement of the adhesion of continuously manufactured multi-material joints by application of thermoplastic adhesive film

The development of tailored lightweight solutions is especially required for the support of the structural change from combustion to electric driven vehicles, due to the still challenging weight of the currently used lithium-ion batteries. The manufacturing of tailored multi-material structures consisting of steel and carbon fibre reinforced thermoplastics (CFR-TP) within a continuous roll forming process is a promising approach to combine innovative lightweight design and large-scale production capability.Nevertheless, fusion bonding as joining technology for steel and carbon fibre reinforced thermoplastics within a continuous process is still challenging because of not achieving sufficient joint strength. The application of adhesive films, which can be easily integrated in a roll forming line by coil-coating processes, seems to be promising to increase the adhesion between metal and CFR-TP. Therefore, a thermoplastic adhesive multilayer-film, consisting of functionalized polymers in different thermoplastic layers, is used within this study. The most important challenge consists in the even heating and consolidation of the multi-material structure within the limited joining time in a continuous fusion bonding process.To enable a variation in joining time, the existing test set-up is extended to a reversible, continuous process. The manufactured hybrid specimens as well as high pressure blasted references without adhesive film application are tested mechanically by climbing drum peel test to determine the production-related influence. In addition, micrographs of specimens are evaluated analytically by scanning electron microscopy.The examinations show the significant improvement of adhesion between steel and CFR-TP by application of thermoplastic adhesive multilayer-film. Lower steel temperatures in combination with reversing operation result in peel resistances almost comparable to sequential process.

Improvement in adhesion of cellulose fibers to the thermoplastic starch matrix by plasma treatment modification

This work deals with provision and characterization of the biopolymer-based composites achieved by incorporation of cellulose fibers as the reinforcement within the glycerol plasticized matrix formed by thermoplastic cornstarch biopolymer. The function of starch-based polymers is limited due to poor mechanical properties. However, it is improved with forming a biocomposite of thermoplastic starch (TPS) as matrix and the cellulose fibers (CF) as reinforcement. The surface of cellulose fibers is successfully modified using the air plasma treatment with the aim of improving the matrix/fiber adhesion. The modified fibers are studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The TPS/CF composites are prepared using high friction and hot compression procedure. Tensile test results and SEM images of the fracture surfaces show significant improvement of adhesion between treated cellulose fibers and TPS matrix. Thermogravimetric analysis shows a considerable decomposition at approximately 250–350 °C. XRD proved the significant increase in crystallinity percentage of composites compared to TPS.

Improvement in Adhesion between Ethylene–Propylene–Diene Terpolymer (EPDM)-based Elastomer and Polyurethane Coating Using Epoxy–Polysulfide Copolymer As Adhesion Promoter

Epoxy–polysulfide copolymer as an adhesion promoter was added to ethylene–propylene–diene terpolymer and the effect of maleation of terpolymer with maleic anhydride on its adhesion to polyurethane coating was studied. The results show that using epoxy-polysulfide copolymer as the adhesion promoter cause a significant improvement in adhesion of terpolymer to polyurethane coating. The contact angle of the water reduced from 88° for the unmodified terpolymer to 65° for the maleated terpolymer containing 10 phr of epoxy–polysulfide copolymer. Peel strength was also increased from 0.2 N/mm for the unmodified terpolymer to 1.12 N/mm for the above-mentioned modified elastomer. Effect of the composition of the polymer blends on the loss tangent and storage modulus was studied to evaluate phase separation and crosslink density. The improvement of adhesion to polyurethane occurred without phase separation, which was further confirmed by the results of the mechanical and morphological investigations.

Microstructure evolution, wear and corrosion resistance of Cr[sbnd]C nanocomposite coatings in seawater

CrC nanocomposite coatings were deposited by multi-arc ion plating with various argon/acetylene mixtures. The XRD, XPS and HRTEM characterization suggest that the coatings consist of a carbide phase and an amorphous carbon-rich phase. The carbide phase is shown to be CrC with a fcc NaCl (B1) structure. Experiment findings and theoretical calculations reveal phase segregation of sp2-carbon from carbides in which the excess amounts of carbon are incorporated. Nanoindentation, scratch test and Rockwell indentation were performed to investigate the toughness and adhesion ability. A significant improvement of adhesion and toughness is achieved by increasing C content at the expense of hardness. The wear resistance of CrC coatings is controlled by the friction rather than hardness. Compared to dry friction, lower friction coefficients but higher wear rates were obtained under seawater condition. The corrosion behavior of CrC nanocomposite coatings with different C % was determined by potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS). The coatings with higher Cr content display excellent anti-corrosion properties in seawater.

Enhancing the barrier properties of a fluorocarbon plasma-deposited coating by producing an Interface of amorphous oxide layer on 316L stainless steel for stent applications

An amorphous nano-thick oxide layer was produced by plasma oxidation on a AISI 316L stainless steel substrate to increase the adhesion and stability of a fluorocarbon plasma-deposited coating for biomedical applications. This oxide layer decreased the corrosion rate >10-fold compared with a previous plasma-etched interface. The high corrosion resistance of the oxide layer as a new interface for fluorocarbon plasma-deposited coatings showed significant adhesion improvement by decreasing blisters formation, which are formed due to substrate corrosion. After aging in an aqueous saline solution, defluorination of the coating was less which evidenced that the fluorocarbon coating was more stable on the new interface compared with the plasma-etched interface. The coating on the new interface decreased the corrosion rate >20-fold in deformed samples compared with uncoated deformed samples. Moreover, the fluorocarbon coatings withstood a 25% plastic deformation and also a two-week aging in an aqueous saline solution. The results revealed remarkable properties of the amorphous oxide layer as a new interface on the adhesion and stability enhancement of the fluorocarbon coating to the SS316L substrate in an aqueous saline solution.

Compositional and Tribo‐Mechanical Characterization of Ti‐Ta Coatings Prepared by Confocal Dual Magnetron Co‐Sputtering

Titanium‐Tantalum coatings are deposited by magnetron co‐sputtering technique, using independently driven titanium and tantalum targets. The effect of the Ta content on the structure, mechanical, and wear properties of Ti films is investigated. It is found that the percentage of the added Ta varies linearly from 3.7 to 31.3 at% by increasing the power applied to the Ta target from 10 to 100 W. The XRD results show that the coatings are crystalline, and there is no evidence of the formation of intermetallic phases, instead formation of metastable phases of α″ and β depending on Ta content are observed, though the samples are deposited at low temperature (150 °C). It is shown that the elastic strain to failure (H/Er; hardness to reduced elastic moduli ratio) can be increased by 40% through the formation of crystalline phases with a lower E, while the hardness remains constant. The tribological study shows that increasing the Ta content up to 14.9 at% causes a significant improvement in adhesion of the coating to a soft metallic substrate.

Property study of structured self-crosslinking acrylic latex binder: Effect of molar mass and particle design

Abstract In the present contribution, the optimization of coating properties of structured self-crosslinking latexes based on diacetone acrylamide and adipic acid dihydrazide crosslinking system by varying particle design and molar mass was investigated. Latexes were prepared by the semi-continuous non-seeded emulsion polymerization of methyl methacrylate, butyl acrylate, diacetone acrylamide and methacrylic acid as main monomers. Two series of latex particles of hard-core/soft-shell or soft-core/hard-shell design were synthesized with a predominant soft phase. In both series, molar mass of the soft phase was gradually reduced by isooctyl 3-mercaptopropionate included in the synthesis. The results show that desired coating properties can be tailored successfully by varying the molar mass and particle design. Better properties exhibited coatings drawdowned from latexes of soft-core/hard-shell particle design. A moderate reduction of molar mass of emulsion copolymers caused a significant improvement of adhesion and blocking resistance, obviously due to enhanced coalescence leading to favoured inter-particle diffusion of copolymer molecules of reduced molar mass.

Polyaniline-poly(2-acrylamido-2-methyl-1-propanesulfonic acid) electrodes coated on plasma-treated thiolene-based polymer substrates for high-efficiency electrochemical capacitors

In this article, we report a novel high-efficiency electrochemical capacitor using PANI-PAAMPSA films on thermally stable UV-curable thiolene-based substrates. For the first time, surface modification of the thiolene polymer-based substrates via O2 plasma prior coating was employed in combination with a conducting polymer, resulting in significant improvements in adhesion and uniformity of PANI-PAAMPSA films. Novel supercapacitors using PANI-PAAMPSA coated on plasma-treated thiolene-based polymer substrates exhibited a significant maximum specific capacitance of 42 Fg−1. This work could open up opportunities for water-soluble PANI-PAAMPSA and thiolene-based polymer substrates in various areas, such as solution-based energy-storage and light-weight functional devices in the very near future.

Scratch Behavior, Microstructure, Resistivity and Optical Properties of Indium Tin Oxide Film Grown at Low Deposition Temperature

Abstract Indium tin oxide (ITO) films prepared by RF magnetron sputtering were characterized by Hall measurement, optical transmission spectra, X-ray diffraction (XRD), atomic force microscopy (AFM) and scratch testing. Deposition was performed at low temperature in different Ar sputtering pressures. The adhesion between the film and the substrate was estimated quantitatively by a scratch testing, in which a special attention was paid to the different stages. It can be found that the significant adhesion improvement is obtained in the ITO films deposited on the polymethyl methacrylate (PMMA) substrate with decreasing of the Ar sputtering pressure. The surface morphology and the resistivity of the ITO films are also significantly dependent on the Ar sputtering pressure. The low temperature films consist of an amorphous phase, the resistivity (1.25×10 −3 ω·cm) and high transmittance (90%) in a visible range can be obtained in the Ar pressure 0.8 Pa. The typical resistivities are mainly governed by the carrier concentration in the ITO films at biggish Ar sputtering pressure, and the optical band gap is about 3.85 eV for all the ITO films.

Direct metallization of PMMA with aluminum films using HIPIMS

Abstract Ionized sputtering like high power impulse magnetron sputtering HIPIMS opens new horizons for cost effective, environmental friendly plastic metallization with excellent adhesion. First reports on HIPIMS deposited films on polymer foils, textiles, and different untreated plastics showed significant adhesion improvement of the metallic or oxide coatings applied. Plexiglas (PMMA) is a very attractive substrate material due to its properties for several commercial applications. Since PMMA is very sensitive to the UV radiation of technical plasmas, direct metallization of the surface by sputtering is conventionally not possible. Using ionized sputtering it is shown that the adhesion can be enhanced to excellent level, passing a combined cross cut and tape test without any failure. The study of the interface correlated to the different peak current densities of the HIPIMS processes shows some trends for the significant adhesion improvement. With increasing peak current in the HIPIMS discharge, i.e. increasing degree of ionized species forming the film, the adhesion is significantly improved. The failure mechanism changes from adhesive failure and poor adhesion to a cohesive failure and excellent adhesion. Furthermore, the surface of the polymer was modified as a result of the increasing ionization. The PMMA surface reorganizes and roughens due to ions forming the film and additionally electrons providing local thermal annealing by recombination.

Adhesion Improvement between Epoxy and Stainless Steel Using a Silane Coupling Agent in an Atmospheric Plasma Process

3-Aminopropyltriethoxysilane coatings have been deposited on stainless steel (SS) samples by means of an atmospheric pressure dielectric barrier discharge as an adhesive promotion layer in epoxy resin/SS composites. A multi-diagnostic analytical approach (FTIR, XPS) was used for the chemical characterization of the deposited coating with regard to improvement of adhesively bonded joint strength. The effect of a plasma post-treatment after the plasma coating deposition was compared to a thermal post-treatment. Both enhanced the siloxane networking resulting in a significant adhesion improvement. Fracture strength between SS and epoxy was increased with more than 20 MPa.

Toughening Thin‐Film Structures with Ceramic‐Like Amorphous Silicon Carbide Films

A significant improvement of adhesion in thin-film structures is demonstrated using embedded ceramic-like amorphous silicon carbide films (a-SiC:H films). a-SiC:H films exhibit plasticity at the nanoscale and outstanding chemical and thermal stability unlike most materials. The multi-functionality and the ease of processing of the films have potential to offer a new toughening strategy for reliability of nanoscale device structures.