Enhancement Of Interfacial Adhesion Research Articles

Enhancing Interface Performance Through Self-Assembly Mechanisms of APTES on Surface-Modified Tuff Aggregates

To enhance the adhesion between tuff and asphalt, this study investigates the efficacy of alkalinization treatment technology using a molecular self-assembly layer derived from the silane-coupling agent γ-aminopropyltriethoxysilane (APTES). APTES hydrolysis solutions at varying concentrations were prepared to assess their impact on the adhesive strength of the aggregate–asphalt interface and water damage resistance. Using surface energy theory, the interface adhesion work of tuff was analyzed, while SEM and EDS were employed to examine changes in surface morphology and composition after treatment. The results demonstrate that an APTES:water:ethanol mass ratio of 5:45:50, along with a curing temperature of 200 °C, significantly improves the bonding strength between tuff and asphalt. The silanol groups on APTES react with hydroxyl groups on the tuff surface to form siloxane bonds (Si-O-Si), anchoring APTES to the tuff. This study elucidates the self-assembly mechanisms of APTES on tuff aggregates and demonstrates the consequent enhancement of interfacial adhesion, providing valuable insights for the application of tuff as tunnel spoil in road engineering.

Preparation and Characterization of Tensile Properties of PMMA/SiC Nanowhiskers Nanocomposite Films: Effect of Filler Loading and Silane Treatment

The preparation of nanocomposites through melt mixing was challenging as the nanofillers tend to form agglomeration. The silicon carbide nanowhiskers (SiCNWs) filled poly (methyl methacrylate) (PMMA) thin film in this study was prepared by means of solution casting. Acetone with low toxicity was used as solvent to dissolve the PMMA pellets. A coupling agent, silane was used to enhance the properties of composite films. Besides, the untreated and treated SiCNWs were filled into PMMA matrix, respectively with the filler loading varied from 0.2 to 0.8 wt%. The universal testing machine was used to investigate the tensile properties of composites. It was found out that the tensile strength of the PMMA was reduced in the presence of SiCNWs. However, the tensile strength had increased with the rise of filler loading. At 0.8 wt% of SiCNWs, the composites’ tensile strength was comparable to virgin PMMA. Meanwhile, the SiCNWs had reduced the elongation at break but increased the elastic modulus of PMMA/SiCNWs nanocomposite films. In addition, silane surface treatment on SiCNWs had improved the tensile strength and ductility but lowered the elastic modulus of the nanocomposites. The improvement was due to the enhancement of interfacial adhesion between SiCNWs and PMMA.

DLC: Flexible bridge across heterogeneous interface between alumina filler and epoxy resin matrix

The heterogeneous interface between filler and matrix within composites often acts as a bottleneck for material performance. Carbon materials, particularly Diamond-Like Carbon (DLC), are representing a novel trend in interface design. This study investigates the nanoscale mechanical and electrical properties of the heterogeneous interface between DLC-coated alumina fillers and an epoxy resin matrix. The results demonstrate that the DLC layer is instrumental in creating a harmonious modulus transition between materials that exhibit significant variance in their elastic moduli, characterized by an exponential relationship, and approximately 50% enhancement in interfacial adhesion. Additionally, the DLC layer exhibits elevated sensitivity in dielectric response, attributed to a small RC time constant. This interface transition technology offers new tools for composite material design.

Enhancing GFRP fatigue durability for chassis component applications through glass fiber coupling variation

As the landscape of mobility trends continues to evolve, concerted efforts have been made to incorporate Carbon Fiber Reinforced Plastic (CFRP) into automotive components. However, the substantial increase in cost relative to the achieved weight reduction has limited its widespread adoption. Consequently, research endeavors have focused on exploring alternative composite materials, adapting fibers such as glass fibers, natural fibers, and recycled fibers, to reduce the cost of composite components. Of particular interest in the automotive industry is the utilization of Glass Fiber Reinforced Plastic (GFRP) in chassis components like leaf springs. Nevertheless, the development of GFRP leaf springs encounters a significant challenge related to the adhesive strength at the interface between epoxy resin and glass fibers, which is crucial for enhancing fatigue durability. While glass fibers were traditionally paired with unsaturated polyester or vinyl ester matrices, the pursuit of improved durability has led to the adoption of epoxy matrices. Regrettably, this transition has not consistently yielded the expected gains in interfacial adhesion.In light of these challenges, this study systematically compares the interfacial adhesion strength and fatigue endurance performance. For comparison, two coupling agents widely used commercially, amino silane and epoxy silane, were selected. Glass fibers treated with each coupling agent were purchased commercially, and glass fiber-reinforced plastic (GFRP) specimens were fabricated using the HP-RTM (High-Pressure Resin Transfer Molding) method. Static property evaluations and fatigue durability assessments were conducted using the fabricated specimens. The results showed that when epoxy silane was used as the coupling agent, the interlaminar shear strength (ILSS) increased by approximately 7 %. Furthermore, SEM(Scanning Electron Microscopes) analysis confirmed a significant enhancement in interfacial adhesion, providing support for the ILSS evaluation results. Consequently, the fatigue durability performance improved by approximately six-fold. This confirms that the improvement in interfacial adhesion due to the change in coupling agents led to enhanced fatigue durability performance.

Silane-modified high-yield lignocellulosic fibers as reinforcement of polylactic acid: Enhancement of interfacial adhesion for high-performance biocomposites

This study investigates the enhancement of PLA-based biocomposites using high-yield mechanical stone groundwood (SGW) pulp, with a focus on reinforcing fiber-matrix interactions through silane-coupling fiber modification. Different fractions of SGW (20 and 30 wt%) and (3-glycidyloxypropyl)trimethoxysilane (GPS) as a coupling agent (3, 5, 7, and 10 wt%) were incorporated into the PLA matrix. Thermo-mechanical properties including melt flow index, melt rheology, tensile strength, and Young’s modulus were evaluated, along with thermal degradation behavior via TGA and DSC. Non-modified and partially modified SGW fractions (20 and 30 wt%) improved PLA-SGW interface, resulting in increased tensile strength (14 % and 27 % respectively). Biocomposites with 30 wt% SGW modified with 5 and 7 wt% GPS exhibited the highest tensile strength improvement, along with the rest of the properties, attributed to GPS influence on melt flow index and processability. The obtained biocomposites showcased properties comparable to commodity polypropylene composites.

Revealing the mechanism of interfacial adhesion enhancement between the SiO2 film and the GaAs substrate via plasma pre-treatments

The formation mechanism of a highly adherent silicon dioxide (SiO2) film on gallium arsenide (GaAs) substrate by plasma enhanced chemical vapor deposition (PECVD) is proposed. Ar, N2, and NH3 were used as pre-treatment gas to improve the interfacial adhesion. The interfacial adhesion was measured by the cross-cut tape test. By the measurement of spectroscopic ellipsometry and x-ray photoelectron spectroscopy (XPS), it is revealed that nitrogen plasma pre-treatment had formed a very thin GaN transition layer on the surface, which was responsible for the improvement of interfacial adhesion. XPS depth-profiling further confirmed various pre-treatment gases generate plasma mixtures and form thin film layers with different compositions on the GaAs surface. These layers have a significant impact on the adhesion of the subsequently prepared SiO2 film. The primary mechanism for improving interfacial adhesion is the renovation of the substrate composition via plasma pre-treatment by PECVD, which forms a transition layer of nitrides that eliminates the negative effects of oxides on adhesion. This study reveals the mechanism of interfacial adhesion enhancement between SiO2 film and GaAs substrate, which is of significant importance in fabricating high-performance and reliable semiconductor devices.

Synergistic enhancement of interfacial adhesion for CF/PEEK composites through carbene chemistry and water‐based self‐catalyzed cross‐linkable PENK‐NH2 sizing agent

AbstractTo address the issue of inadequate interfacial adhesion in carbon fiber/poly ether ether ketone (CF/PEEK) composites, an innovative approach that combines carbene chemistry and sizing treatment was meticulously designed to achieve remarkable synergistic enhancement. Specifically, cyano groups were chemical‐grafted on CF surface via carbene reaction. Meanwhile, a water‐based self‐catalyzed cross‐linkable PENK‐NH2 sizing agent with good storage stability was prepared. Noteworthy, the presence of amino groups as blocking agents of sizing agent significantly accelerated the rate of cyano‐crosslinking, thus effectively avoiding the adverse effects of excessively prolonged cross‐linking period during composites preparation. As a result, robust interaction between cyano‐modified CF and PEEK was established by cross‐linking reaction, along with chemical bonds generated between amino groups of sizing agent and ketone groups in PEEK. The maximum interlaminar shear strength (ILSS) of CF‐CN‐1.5/PEEK composites was 22.0% and 57.0% higher than CF‐1.5/PEEK and CF/PEEK composites. Furthermore, the presence of cyano‐cross‐linked structure endowed interphase with outstanding solvent‐resistance, the mechanical properties of CF composites after solvent treatment were well‐preserved. The strong synergistic interfacial interactions facilitated by chemical bonds in different components provide an effective and fascinating methodology for producing high‐performance CF/composites.Highlights Water‐based self‐catalyzed cross‐linkable PENK‐NH2 sizing agents for CF/PEEK were prepared. NH2 was introduced to avoid the adverse effects of prolonged cyano‐crosslinking. Designed carbenoid motif with cyano group was grafted on CF via carbene chemistry. The interaction between sizing agent and CF was boosted by the cyano‐crosslinking. Mechanical properties of sized composites corroded by solvent were well‐preserved.

Enhancement of interfacial adhesion to carbon fibers via electrostatic interaction using polyvinyl chloride as a model matrix

The purpose of this study is to provide a framework for spectroscopic investigation of an enhancement mechanism of the interfacial adhesion using a polyvinyl chloride (PVC) matrix as a model. PVC dissolved in a tetrahydrofuran solution was dropped onto carbon fiber (CF) or glass fiber (GF), and the interfacial shear strength was measured after annealing at various temperatures. The interfacial shear strength of PVC/CF increased significantly with the annealing temperature compared with that of PVC/GF. As characterized by Raman spectroscopy, the polyene content (an indicator of PVC degradation) in bulk PVC was positively correlated with the interfacial shear strength. PVC radicals were not detected at the annealing temperature in the electro spin resonance spectroscopy. It was demonstrated that the interaction between the ions (C+Cl−) formed during the decomposition of PVC (formation of polyene) and the π electrons in the benzene of CF; the cation–π interaction is attributable to the enhancement of the interfacial shear strength.

Design of amphiphilic-function-aiding biopolymer adhesives for strong and durable underwater adhesion via a simple solvent-exchange approach

Achieving strong and durable underwater adhesion in an easy way is highly demanded for practical applications. Despite extensive progresses, developing high-performance underwater adhesives by leveraging low-cost and sustainable biopolymer materials remains a hard task. Here, we report a simple one-pot strategy to construct a superior underwater adhesive through designing an amphiphilic function (established by thioctic acid and epoxy connector) in commercial biopolymer system. This amphiphilic-function-aiding biopolymer adhesive (AFBA), prepared in ethanol solution, can harness solvent exchange to trigger hydrophobic aggregation and phase transition in water, thereby yielding hydrophobic repulsion for effective dehydration, high structural stability for bulk cohesion strengthening, and versatile molecular interactions for interfacial adhesion enhancement. As such, AFBA exhibits a strong yet durable underwater adhesion (constantly increasing from 560 to 729 KPa to wood substrate after storing 30 days) and remarkable tolerance to various harsh environments (seawater, acidic, and alkaline solutions), allowing for underwater applying as a sealant to repair damage. Moreover, this simple strategy is generic that can derive a family of AFBAs with excellent underwater adhesion. This work may provide a promising pathway for engineering high-performance adhesives, and also open up a new direction to overcome the limitations of hydrophilic biopolymers in underwater application.

A molecular dynamics assisted insight on the enhancement of interfacial adhesion of carbon fiber with polypropylene matrix via a combination of surface functionalization and defect laden carbon nanotube coating

The low compatibility of traditional carbon fibers with thermoplastics results in an inferior interfacial interaction. Therefore, it prohibits full exploitation of low-cost thermoplastics like polypropylene in developing high-strength carbon fiber reinforced composites. In the present study, atomistic and mesoscopic molecular dynamics simulations are carried out to postulate enhancement in interfacial shear strength among amine terminated carbon fiber and polypropylene. Pristine and amine functionalized carbon nanotubes are coated to the amine terminated carbon fiber separately. The influence of Stone-Wales and Di-vacancy defects of carbon nanotubes, with their varying defect concentration, is investigated. Besides, maleic anhydride-grafted-styrene ethylene butylene styrene is used as a compatibilizer. Interaction energy among maleic anhydride-grafted-styrene ethylene butylene styrene and amine terminated carbon nanotubes increases with amine weight percentage over carbon nanotube. The highest optimal interaction energy is shown by carbon nanotube functionalized with 6 wt percent amine groups and having 3 Stone-Wales defects, which is ∼41% higher than that with pristine carbon nanotubes. The pull-out coarse-grain simulations of the amine terminated carbon fiber coated with such optimal carbon nanotubes displayed the highest interfacial shear strength of 31.11 MPa, and it was ∼106% higher than the composite reinforced with neat carbon fiber.

Mussel-inspired ferric ion-polydopamine complex as a facile, green and efficient platform to functionalize carbon fiber for improving interfacial adhesion of composites

A mussel inspired co-deposition of ferric ion-polydopamine (PDA) is explored and constructed on carbon fiber via facile dip-coating strategy for the first time to realize the enhancement in interfacial adhesion of epoxy composites. Varied contents of ferric ion are designed to allow comparison how the contents of formed complexes affect the surface characteristics of fiber and interfacial adhesion of composites. Compared with pure PDA modified fiber, the size and number of PDA nanospheres attached on fiber first declines distinctly and then increases as the addition level of ferric ions raises, but the coordination product of both bis-and tris-Fe3+-catechol complexes exist, only the yield of complexes varies with the addition amount of FeCl3. This indicates that the level of Fe3+ ions obviously impact DA oxidation, not the complex product. Increments in interfacial shear strength across all ferric ion-PDA complex modified fibers are noticed, associating with the stronger Fe3+…O coordination bonds that could enhance the interfacial crosslinking density. However, the optimal IFSS is attainable when appropriate amount of Fe3+ ions were added, which endows the fiber with good resin wettability. The ferric ion-PDA complex assisted surface modification demonstrated to be an effective and feasible avenue in interphase tuning of fiber reinforced composites, which could be also anticipated to extend to other metallic ion-PDA complexes.

A Hofmeister effect induced hydrogel electrolyte–electrode interfacial adhesion enhancement strategy for energy-efficient and mechanically robust redoxcapacitors

Relying on Hofmeister effect, the interface adhesion of the hydrogel electrolyte on both the anode and cathode is tremendously enhanced, thus intensified energy efficiency and mechanical toughness of the fabricated flexible Zn-ion redoxcapacitor.

Contribution of fiber–matrix interface enhancement on flexural properties of Ultra–high–performance concrete

Herein, the effect of steel fiber–matrix interface reinforcement on the macromechanical properties of ultra–high–performance concrete (UHPC) is studied. Two types of nano–SiO2–coated steel fibers are prepared using the sol–gel method. Single–fiber pull–out tests are conducted, and flexural and compression tests of UHPC with fiber contents of 1 vol%, 2 vol%, and 3 vol% are performed. The results reveal that the enhancement of interfacial adhesion significantly influences the macromechanical properties of UHPC. However, the granular nano–SiO2 on the surface of the modified steel fibers increases the roughness of the steel fiber and reduces the fluidity of fresh UHPC mixture. Analysis of the images of crack section reveals that appropriate vibration can reduce the influence of the steel fiber surface roughness on the distribution of fibers in UHPC. A flexural load–deflection response model for UHPC that considers steel fiber–matrix interface bond strength and fiber orientation is established.

Restructuring the Interface of Silk-Polycaprolactone Biocomposites Using Rigid-Flexible Agents.

Natural fiber-reinforced biocomposites with excellent mechanical and biological properties have attractive prospects for internal medical devices. However, poor interfacial adhesion between natural silk fiber and the polymer matrix has been a disturbing issue for such applications. Herein, rigid-flexible agents, such as polydopamine (PDA) and epoxy soybean oil (ESO), were introduced to enhance the interfacial adhesion between Antheraea pernyi (Ap) silk and a common medical polymer, polycaprolactone (PCL). We compared two strategies of depositing PDA first (Ap-PDA-ESO) and grafting ESO first (Ap-ESO-PDA). The rigid-flexible interfacial agents introduced multiple molecular interactions at the silk-PCL interface. The "Ap-PDA-ESO" strategy exhibited a greater enhancement in interfacial adhesion, and interfacial toughening mechanisms were proposed. This work sheds light on engineering strong and tough silk fiber-based biocomposites for biomedical applications.

Design of an alternating distributed large and small amounts of CNT/polyether amine coating on carbon fiber to derive enhancement in interfacial adhesion

In this paper, an innovative concept of alternating distributed large and small amounts of CNT/polyether amine coating is proposed to be wrapped around the carbon fiber via vacuum filtration. This coating feature is similar to “concave-convex” interval structure, which significantly distinguishes it from widely reported CNT coating with uniform encapsulation. The modified fiber reinforced epoxy composite presents a tremendous enhancement in interfacial bond strength reaching up to 81.8% relative to de-sized fiber composite. This increase comes from the synergistic effects of alternating distribution of strong-weak interactions that effectively dissipating energy, improved wettability, increased mechanical interlocking, as well as pinning and crack suppression effects of CNTs. The concept of interval distribution of large and small levels of coating has more possibilities for optimization. Thus, this unique coating structure, simple and flexible approach provides an attracting candidate for enhancing interphase performance of composites, also with the potential of practical and scalable.

High-density grafting of carbon nanotube/carbon nanofiber hybrid on carbon fiber surface by vacuum filtration for effective interfacial reinforcement of its epoxy composites

Attempts to incorporate nanofillers onto the circumferential surface of traditional high-performance fibers via vacuum filtration toward gaining improved interfacial adhesion of corresponding composites are still in its infancy. Herein, we first achieve high-density grafting of carbon nanotube/carbon nanofiber (CNT/CNF) successfully on carbon fiber surface. The treated fibers with depositing positive and negative 5 ml CNT/CNF nanohybrid suspension shows 40.7% (85.4 MPa) gain in interfacial shear strength over that of untreated fiber (60.7 MPa). The reinforcement effect is mainly ascribed to the markedly improved wettability, which provides sufficient hydrogen bonding and pinning effect at interphase zone. Moreover, appropriate amount of CNT/CNF hybrid endows the interphase with gradual modulus transition, minimizing the stress concentration. Our research offers a promising, efficient and green approach for fully utilization of diverse nanofillers and rich interfacial interactions to realize substantial enhancement in interfacial adhesion in the future.

Mechanical and morphological properties of poly(vinyl chloride) and linear low‐density polyethylene polymer blends

AbstractIn this article, nonpolar polyethylene with polar poly(vinyl chloride) is considered as a polymer–polymer mixture. Direct mixing of poly(vinyl chloride) and polyolefins leads to the formation of incompatible mixtures that have weak complex properties. To form this mixture, chlorinated polyethylene and a copolymer of polyvinyl chloride with polyethylene were used as compatibilizers. An extreme relationship of the elastic modulus on the composition of the blend at a PE content (5–20 wt.%) was revealed. The use of EBM model representations made it possible to identify the reasons for this relationship, namely, the cumulative contribution of structural changes in PVC and the enhancement of interfacial adhesion due to the presence of a compatibilizer at the phase boundary.

Enhancement and Evaluation of Interfacial Adhesion between Active Screen Plasma Surface-Functionalised Carbon Fibres and the Epoxy Substrate.

This paper investigated the modification of the advanced active screen plasma (ASP) technology on PAN-derived carbon fibres (CFs) with gas mixtures of N2-H2 and N2-H2-Ar, separately. A more-than-30% improvement was found in the interfacial shear strength (IFSS) between the modified CFs and the epoxy substrate in the resulting composites, as disclosed by single fibre push-out tests. Based on the study of surface morphology, surface chemistry and water-sorption behaviour, the interfacial adhesion enhancement mechanisms were attributed to (1) the increased chemical bonding between the introduced functional groups on the fibre surface and the matrix; (2) the improved surface hydrophilicity of CFs; and (3) the enhanced van der Waals bonding due to the removal of surface contaminations.

Effect of MAPP on Interfacial Shear Strength of PP/Rice Straw Fiber Composites

Polypropylene (PP) composites filled with rice straw fiber were prepared and characterized to contribute to the realization of a low-carbon society. Generally, the mechanical properties of composites composed of cellulose fiber such as rice straw fiber and nonpolar polymer such as PP decrease due to poor interfacial adhesion. This paper reports the compatibilizer effects of maleic anhydride modified polypropylene (MAPP) on the mechanical properties of PP/rice straw fiber composites. As a result, interfacial shear strength (IFSS) between resin and fiber measured by a short beam test changes with the MAPP content, reaching a maximum value at 1 phr as a similar trend as changes in their tensile strength. Therefore, the improvement of tensile strength indicates the enhancement of interfacial adhesion between PP and rice straw fiber.

Effect of polyetherimide sizing on surface properties of carbon fiber and interfacial strength of carbon fiber/polyetheretherketone composites

AbstractThe sizing process is almost invariably performed after the manufacture of carbon fiber (CF) and the sizing agent takes the effect of protecting CF surface. However, the traditional sizing agent is not suitable for processing continuous CF reinforced thermoplastic composites (CFRTPs) with high processing temperature. In this work, polyetherimide (PEI) is chosen as the sizing agent for CF reinforced polyetheretherketone (CF/PEEK) composites, and the sizing content as well as the type of sizing agent (including solvent‐based and emulsion type) were systematically researched. After a series of characterization of CF surface properties and interfacial strength of CF/PEEK, the improvement of interfacial shear strength (IFSS) and mechanical performances of sized CF/PEEK proves the enhancement of interfacial adhesion after sizing. CF/PEEK composites which contain CF handled by emulsion type sizing agent have good mechanical properties, indicating that it has the potential to replace solvent‐based sizing agent. Besides, the miscible feature of PEEK with PEI, the raise of CF surface roughness and surface energy might cause the reinforcement of interfacial mechanical properties. This research may create a potential way for CF production field, aiming at improving the interfacial performance of CFRTPs.