Adhesive Properties Research Articles

On-site extraction of benzophenones from swimming pool water using hybrid tapes based on the integration of hydrophilic-lipophilic balance microparticles and an outer magnetic nanometric domain

An on-site extraction device is presented consisting of scotch tape modified with concentric domains of micrometric hydrophilic-lipophilic balance (HLB) particles surrounded by a ring of nanometric magnetic ones. On the one hand, HLB microparticles are readily available at the surface of the tape, exposed to interact with the target analytes, being responsible for the extraction capacity of the sorptive phase. On the other hand, the presence of magnetic nanoparticles enables the attachment of the modified tape onto a metallic screw via a magnet, which is then coupled to a wireless drill, enabling the stirring of the microextraction device. Both are simply fixed to the cost-effective, flexible, and versatile support, i.e., scotch tape, owing to their adhesive properties. The microextraction device has been applied to the determination of six benzophenones in swimming pool water samples. The variables that may affect the extraction process have been evaluated. Under the optimum conditions and using liquid chromatography-tandem mass spectrometry as the instrumental technique, the method provided a limit of detection of 0.03 µg L−1. The intra-day precision, evaluated at three different concentration levels and expressed as relative standard deviation, was lower than 10%, which also comprises the variability within single-use sorptive tapes. The accuracy, calculated with spiked samples and expressed as relative recovery, ranged from 71 to 138%. The method was applied to the analysis of swimming pool water, revealing the presence of such compounds.Graphical

A study on thermal behaviour of thermal barrier coating: investigation of particle size, YSZ/polysilazane, time and temperature curing effect.

Thermal conductivity and adhesion strength effects were studied for thermal barrier coatings (TBCs) with different particle sizes, YSZ content, time, and temperature curing. The study involves three stages. The first step focuses on the characteristics of YSZ/polysilazane as the TBC, which is characterized using Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR), X-Ray Diffraction (XRD), and Thermal Gravimetric Analysis (TGA). The second and third steps assess thermal conductivity and adhesion strength based on variables such as particle size, YSZ/polysilazane, time, and curing temperature. Results show that there was a synergistic effect between particle size-YSZ content and time-temperature curing to obtain specimens with good thermal properties. SB270/70 showed the lowest temperature compared to other specimens, up to 160 °C. Furthermore, YSZ/polysilazane thermal conductivity and adhesion properties could be enhanced by a prolonged curing time and higher temperature. This study emphasizes that the modification of particle size, YSZ content, time, and temperature curing is a promising strategy to improve the thermal properties of TBCs.

Non‐Conductive and Conductive Washable Amylopectin‐Mastic Gum Adhesives for On‐Skin Applications

AbstractThe investigation of a skin adhesive based on amylopectin and mastic gum for attaching skin sensors are reported. The material provides reliable adhesion and is, at the same time, readily washable from the skin due to the hydrophilic character of the amylopectin compound. The effect of water and glycerol content on the adhesion properties in combination with polyimide‐based substrates is assessed and optimize the material for homogeneous and washable on‐skin applications. This results show that the adhesive material can withstand a shear stress of 88.7 ± 5.30 kPa in a lap shear test. The adhesive material can also be easily rendered conductive by adding sodium chloride. Impedance spectroscopy is performed on the conductive adhesive material to assess the impedance behavior during drying conditions over 24 h in comparison to commercial electrolyte gel. While the conductive adhesion material's initial impedance is slightly higher than the commercial gel, the long‐term assessment demonstrates a significantly improved stability over time. In conclusion, this study develops a skin adhesive combining amylopectin and mastic gum, demonstrating promising adhesion strength and conductivity properties, thus potentially addressing current stability challenges in skin‐sensor applications.

Environment-responsive dopamine nanoplatform for tumor synergistic therapy

Nanoparticle-based photothermal therapy (PTT) has emerged as a promising approach in tumor treatment due to its high selectivity and low invasiveness. However, the penetration of near-infrared light (NIR) is limited, leading it fails to induce damage to the deep-seated tumor cells within the tumor tissue. Additionally, inefficient uptake of photothermal nanoparticles by tumor cells results in suboptimal outcomes for PTT. In this study, we utilized the adhesive properties of photothermal material, polydopamine (PDA), which can successfully load the photosensitizer indocyanine green (ICG) and chemotherapeutic drug doxorubicin (DOX) to achieve photothermal and chemotherapy synergy treatment (PDA/DOX&ICG), aiming to compensate the defects of single tumor treatment. To extending the blood circulation time of PDA/DOX&ICG nanoparticles, evading clearance by the body immune system and achieving targeted delivery to tumor tissues, a protective envelopment was created using erythrocyte membranes modified with folate acid (FA-EM). After reaching the tumor tissue, the obtained FA-EM@PDA/DOX&ICG nanoparticles can specific bind with folate acid receptors on the surface of tumor cells, which can improve the uptake behavior of FA-EM@PDA/DOX&ICG nanoparticles by tumor cells, and leading to the release of loaded DOX and ICG in response to the unique tumor microenvironment. ICG, as a typical photosensitizer, significantly enhances the photothermal conversion performance of FA-EM@PDA/DOX&ICG nanoparticles, thus inducing tumor cells damage. In vitro and in vivo experimental results demonstrated that the coordinated NIR treatment with FA-EM@PDA/DOX&ICG not only effectively inhibits tumor growth, but also exhibits superior biocompatibility, effectively mitigating DOX-induced tissue damage.

Dyeing adhesives as binders in wood/bamboo biocomposites for improve the measurement accuracy of wood failure percentage by machine vision technology

Wood failure percentage (WFP) is an important evaluation index for assessing the bonding performance of biocomposites, but it is challenging to measure WFP accurately using machine vision technologies (MVTs). The purpose of this paper is to enhance measurement accuracy by modifying the hue properties of adhesives. Additionally, the physical and chemical changes induced in the adhesives by these dyes were investigated. The results indicated that the strategy significantly improved the accuracy of the three MVTs in measuring WFP, with the order of deep learning (DL) > machine learning (ML) > pixel statistics (PS) and a maximum of relative error decrease of 96.6 %. Furthermore, the strategy notably increased the pixel value of adhesives in the glulam failure surface image, reaching up to 170. Importantly, the strategy had no significant effect on bonding strength and failure mode, as the adhesive range was only 0.13 when compared to the shear state and specimen type. However, the strategy increased the content of Ca and Mg in the adhesives to 12.22 % and 6.32 %, respectively. Overall, this strategy provides a technical means to enhance gluing quality detection for glulam.

Achieving ultrastrong adhesion of soft materials by discretized stress dispersion

The adhesion of soft materials often fails due to stress concentration at the interface. Structural design offers an effective approach to disperse stress at the interface and enhance adhesion properties. Herein, we introduce the concept of discretized stress dispersion to achieve ultrastrong adhesion of soft materials. This involves incorporating discrete structures at the adhesion interface, with each unit structure designed to efficiently disperse stress. We implement this concept by introducing periodic strategic cuts into the adhesive, enabling it to deform into discrete mushroom-shaped structures under peel forces. Utilizing fracture mechanics theory, we demonstrate that such structural design can significantly improve adhesion strength compared to adhesives without structural design. Through 3D printing, we fabricate adhesive samples with strategic cuts, achieving a peak peel force of 3479 N/m, over 100-fold higher than adhesives without cuts (25 N/m). We analyzed stress dispersion of each unit structure through experiments of with different geometric parameters and analyze collaborative effects of multiple structures with theoretical model. Finite element analysis of the peel process highlights the critical role of cohesive zone influenced by geometric parameters, which determines the peak peel force. This concept of discretized stress dispersion advances the development of soft materials with ultrastrong adhesion.

Branched Oligomer-Based Reversible Adhesives Enabled by Controllable Self-Aggregation.

Supramolecular adhesion material systems based on small molecules have shown great potential to unite the great contradiction between strong adhesion and reversibility. However, these material systems suffer from low adhesion strength/narrow adhesion span, limited designability, and single interaction due to fewer covalent bond content and action sites in small molecules. Herein, an ultrahigh-strength and large-span reversible adhesive enabled by a branched oligomer controllable self-aggregation strategy is developed. The dense covalent bonds present in the branched oligomers greatly enhance adhesion strength without compromising reversibility. The resulting adhesive exhibits a large-span reversible adhesion of ≈140 times, switching between ultra-strong and tough adhesion strength (5.58MPa and 5093.92Nm-1) and ultralow adhesion (0.04MPa and 87.656Nm-1) with alternating temperature. Moreover, reversible dynamic double cross-linking endows the adhesive with stable reversible adhesion transitions even after 100 cycles. This reversible adhesion property can also be remotely controlled via a voltage of 8V, with a loading voltage duration of 45s. This work paves the way for the design of reversible adhesives with long-span outstanding properties using covalent polymers and offers a pathway for the rational design of high-performance adhesives featuring both robust toughness and exceptional reversibility.

Robust and customizable spheroid culture system for regenerative medicine

Three-dimensional cell spheroids show promise for the reconstruction of native tissues. Herein, we report a sophisticated, uniform, and highly reproducible spheroid culture system for tissue reconstruction. A mesh-integrated culture system was designed to precisely control the uniformity and reproducibility of spheroid formation. Furthermore, we synthesized hexanoyl glycol chitosan, a material with ultralow cell adhesion properties, to further improve spheroid formation efficiency and biological function. Our results demonstrate improved biological function in various types of cells and ability to generate spheroids with complex structures composed of multiple cell types. In conclusion, our spheroid culture system offers a highly effective and widely applicable approach to generating customized spheroids with desired structural and biological features for a variety of biomedical applications.

Evaluation of adhesive properties and enzymatic activity at the hybrid layer of a simplified adhesive loaded with 0.2% Cu and 5% ZnO nanoparticles: a Randomized Clinical Trial and ex vivo analysis.

ObjectiveThe aim of this study was to evaluate the effect of an adhesive loaded with 0.2% cooper (Cu) and 5% zinc oxide (ZnO) nanoparticles (Nps) on its adhesive properties and enzymatic activity at the hybrid layer ex vivo in a randomized clinical model. MethodsFifteen patients participated in this study, and a total of 30 third molars were used. Occlusal cavities (4 × 4 × 2 mm) were made in each tooth, and randomly divided into 2 groups: (i) Experimental group: commercial adhesive loaded with 0.2wt% CuNps and 5wt% ZnONps; and (ii) Control Group: non-loaded commercial adhesive. Teeth were restored with resin composite. Thirty days later, extractions were performed. Extracted teeth were longitudinally sectioned. Nps in powder were characterized by field emission scanning electron microscope (FE-SEM) and energy dispersive X-ray (EDX) analysis. Microtensile bond strength (μTBS), degree of conversion (DC), and nanoleakeage (NL) tests were executed. In situ zymography (Zym) was performed to evaluate the gelatinolytic activity at the hybrid layer. Student's t-test (α = 0.05) was applied for all tests. ResultsμTBS and DC did not show significant differences (p > 0.05) between both groups. However, NL and gelatinolytic activity at the hybrid layer showed significant values (p < 0.05) for experimental group in comparison with control group. ConclusionThe addition of 0.2% CuNps and 5% ZnONps to a universal adhesive decreases NL and gelatinolytic activity at the hybrid layer, without jeopardizing its adhesive properties. SignificanceThis randomized clinical trial with ex vivo analysis demonstrate that a commercial adhesive modified with 0.2wt% Cu and 5wt% ZnO Nps that does not affect its adhesive properties, reducing gelatinolytic activity and nanoleakage at the hybrid layer, which should contribute to an improvement of long term bonding-dentine clinical performance.

Ferulic acid-g-tamarind gum/guar gum based in situ gel-forming powders as wound dressings

The current research endeavour aimed to synthesize ferulic acid grafted tamarind gum/guar gum (FA-g-TG/GG) based powders as wound dressings, which could form in situ gels upon contact with wound exudates. In this context, variable amounts of FA were initially grafted with TG via the Steglich esterification reaction protocol and the resulting conjugates were subsequently amalgamated with GG and lyophilized to produce dry powders (F-1–F-3) with average particle size within 5.10–5.54 μm and average angle of repose ~30°. These powders were structurally characterized with 1H NMR, FTIR, DSC, TGA, XRD and SEM analyses. Pristine TG, FA-g-TG and FA-g-TG/GG powders (F-2) revealed their distinct morphological structures and variable negative zeta potential values (−11.06 mV–25.50 mV). Among various formulation (F-1–F-3), F-2 demonstrated an acceptable powder-to-gel conversion time (within 20 min), suitable water vapour transmission rates (WVTR, 2564.94 ± 32.47 g/m2/day) and excellent water retention abilities and swelling profiles (4559.00 ± 41.57 %) in wound fluid. The powders were cytocompatible and conferred antioxidant activities. The powders also displayed fibroblast cell proliferation, migration and adhesion properties, implying their wound-healing potentials. Thus, the developed in situ gel-forming powders could be employed as promising dressings for wound management.

Preparation and Evaluation of the In situ Gel-forming Chitosan Hydrogels for Nasal Delivery of Morphine in a Single Unit dose in Rats to Enhance the Analgesic Responses.

In this study, an in situ gel-forming chitosan hydrogel was prepared with the use of glutamate salt of chitosan (Ch-Ga), β-glycerophosphate (Gp), and morphine (Mor). The paper is focused on in vitro physicochemical properties and in-vivo analgesic effects of the prepared chitosan hydrogel. The thermosensitive properties of prepared chitosan hydrogel were evaluated during the different temperatures and times. The physicochemical properties of chitosan hydrogel were investigated by infrared (IR) spectroscopy and X-ray diffraction analysis (XRD). Also, its cell cytotoxicity effects were evaluated in murine NIH/3T3 normal cells. Subsequently, the distribution of chitosan hydrogel in the nasal cavity of rats and its analgesic responses were evaluated. The prepared chitosan hydrogel showed that it could be gelled at the temperature of 34 °C before leaving the nose in the shortest possible time of 30 s. The analgesic responses of the intranasal (IN) injection of chitosan hydrogel (IN-chitosan hydrogel, 10 mg Mor/kg) in a single unit dose in rat relative to the placebo and intranasal or intraperitoneal (IP) injection of free morphine solution (IN-Free Mor or IP-Free Mor, 10 mg Mor/kg) via the hot plate test, reveal that the IN-chitosan hydrogel could induce fast analgesic effects of morphine with maximum possible effect (MPE) of 93% after 5 min compare to the IN-Free Mor and IP-Free Mor with MPE of 80% after 15 min and 66% after 30 min, respectively. Also, prolonged analgesic effects with MPE of 78 % after 6 h of injection were only seen in the IN-chitosan hydrogel injected group. The obtained fluorescent images of rat's brain injected with IN-chitosan hydrogel containing doxorubicine (Dox) as a fluorescent agent showed that the mucosal adhesive and absorption enhancer properties of IN-chitosan hydrogel resulting in longer presence of them in the nasal cavity of rats followed by more absorption of Dox from the blood vessels of olfactory bulbs with a 74% color intensity compared to the IN-Free Mor and IN-Free Dox with 15%. These data reveal that the IN-chitosan hydrogel could induce fast and prolonged analgesic effects of morphine compare to the IN/IP-Free Mor, which could be considered as an in situ gel-forming thermosensitive chitosan hydrogel for nasal delivery of wide ranges of therapeutic agents.

A multifunctional hydrogel with mild photothermal antibacterial and antioxidant properties based on quercetin and dopamine-coated zinc oxide nanoparticles for healing bacteria-infected wound

Bacterial infection and inflammation hinder the natural healing process of skin wounds and may also cause wound complications. In light of the aforementioned considerations, this study developed an antibacterial and antioxidant QT/PDA@ZnO /QCS/(PAM-PAMPS) hydrogel (QPQH). The hydrogel dressing employs a dual network structure and incorporates quercetin (QT), quaternary ammonium salt chitosan (QCS), and polydopamine-coated zinc oxide nanoparticles (PDA@ZnO NPs) into a Polyacrylamide–Poly(2-acrylamido-2-methyl-1-propanesulfonic acid)（PAM-co-AMPS）hydrogel. This design enables QPQH to exhibit good mechanical properties, remarkable adhesion properties, and the capacity to adhere closely to the wound. The mild photothermal properties (˃50 °C) and Zn2+ release ability of PDA@ZnO NPs can cooperate with the destruction ability of QCS to bacterial cell membranes, thereby achieving efficient sterilization. This process has been demonstrated to be effective against Staphylococcus aureus and Escherichia coli, with approximately 98.5 % and 99.8 % efficiency, respectively. The incorporation of QT into hydrogel confers excellent antioxidant properties, which serve to reduce oxidative stress in wounds and prevent inflammation. Furthermore, hydrogel displays favorable blood compatibility and cell compatibility, facilitating the repair of bacteria-Infected wounds and promoting angiogenesis and collagen deposition in skin wounds. In conclusion, the antibacterial and antioxidant QPQH dressing has considerable potential for clinical use in the treatment of bacteria-Infected wounds.

Extracellular matrix regulation of cell spheroid invasion in a 3D bioprinted solid tumor-on-a-chip

Tumor organoids and tumors-on-chips can be built by placing patient-derived cells within an extracellular matrix (ECM) for personalized medicine. The ECM influences the tumor response, and understanding the ECM-tumor relationship is important before translating tumor-on-chips into clinics. In this work, we tuned the physical and structural characteristics of ECM in a bioprinted soft-tissue sarcoma microtissue. We formed 3D spheroids at a controlled size and encapsulated them into our gelatin methacryloyl (GelMA)-based bioink to make perfusable hydrogel-based microfluidic chips. We then demonstrated the scalability and customization flexibility of our hydrogel-based chip via engineering tools. A multiscale physical and structural data analysis suggested a relationship between cell invasion response and bioink characteristics. Tumor cell invasive behavior and focal adhesion properties were observed in response to varying polymer network densities of the GelMA-based bioink. Immunostaining assays and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) helped assess the bioactivity of the microtissue and measure the cell invasion. The RT-qPCR results showed higher expressions of HIF-1α, CD44, and MMP2 genes in a lower polymer density, highlighting the correlation between bioink structural porosity, ECM stiffness, and tumor spheroid response. In conclusion, this work is the first step in modeling STS tumor invasiveness in hydrogel-based microfluidic chips, and our tunable bioink may help reduce the variability of current tumor-on-chips. Statement of SignificanceWe optimized an engineering protocol for making tumor spheroids at a controlled size, embedding spheroids into a gelatin-based matrix, and constructing a perfusable microfluidic device. A higher tumor invasion was observed in a low-stiffness matrix than a high-stiffness matrix. The physical characterizations revealed how the stiffness is controlled by the density of polymer chain networks and porosity. The biological assays revealed how the structural properties of the gelatin matrix and hypoxia in tumor progression impact cell invasion. The cell spheroids' responses underscore the importance of replicating physical and structural properties to mimic tumor response. This work can contribute to personalized medicine by making more effective, tailored cancer models.

Physical, mechanical and antibacterial properties of the orthodontic adhesive doped with S-TiO2

Orthodontic adhesive doped with sulfur-modified TiO2 promotes antibacterial effect. The objective of the study was to characterize the physical, mechanical and antibacterial properties of the orthodontic bracket adhesive, doped with modified titanium dioxide nanoparticles. Sulfur-doped TiO2 was synthetized and morphological topography was analyzed with TEM and SEM imaging. The catalytic performance during the degradation of rhodamine B was assessed. Nanomaterial was added at four concentration (1, 3, 6, and 10 wt%) to a commercial orthodontic adhesive. The shear bond strength and microhardness of a resin-based orthodontic adhesive containing S-TiO2 were evaluated. The inhibitory effect of the pure and doped adhesives against Escherichia coli and Streptococcus mutans was examined. As the results, the highest antimicrobial activity and good adhesive properties were noticed for light-cured orthodontic adhesive doped with 3% of S-TiO2. In this case, orthodontic adhesives with strong and long-lasting bactericidal properties can be created through the incorporation of modified TiO2 without negatively influencing microhardnesses, and bonding ability. White spot lesion and demineralization, which occurs very often in patients during orthodontic treatment, can be therefore minimized.

Tunicate cellulose nanocrystal reinforced multifunctional hydrogel with super flexible, fatigue resistant, antifouling and self-adhesive capability for effective wound healing

Hydrogels as skin wound dressings have been extensively studied owing to their good flexibility and biocompatibility. Nevertheless, the mechanical performance, adhesive capability, antifouling and antibacterial properties of conventional hydrogels are still unsatisfactory, which hinder the application of hydrogel for cutaneous healing. Here, we developed a novel biocompatible multifunctional hydrogel with super flexible, fatigue resistant, antifouling and self-adhesive capability for effective wound healing, where naturally rigid polymers including quaternized chitosan (QCS) and Tunicate cellulose nanocrystals (TCNCs) are used as bioactive cross-linkers and reinforcers to endow the hydrogel with excellent mechanical and antibacterial property, and the synergistic contributions from the poly(acrylic acid/methacrylate anhydride dopamine/sulfobetaine methacrylate) (poly(AA/DMA/SBMA)) chains and QCS endow the hydrogel with excellent adhesive property, antioxidant, antifouling and pH-responsive sustained drug release capabilities. The optimized hydrogel exhibited high tensile strength (77.69 KPa), large tensile strain (889.9 %), large toughness (307.51KJ.m−3), high adhesive strength (35.57 KPa) and ideal compressive property. The in vivo infected full-thickness skin model demonstrated that the hydrogel with vanvomycin sustained release ability efficiently improved the granulation tissue formation, facilitating collagen deposition and reducing inflammatory expression, thus effectively accelerating wound healing. This superiorly skin-adhesive antibacterial biocompatible hydrogel appears to be a promising candidate for wound therapy.

Evaluation on the Adhesion Property of Recycled Asphalt Based on the Multi-Scale Experiments

The adhesion property has consistently been a critical focus in the utilization of recycled asphalt (RA). This research aimed to elucidate the mechanisms influencing the adhesion property of RA at various scales. Specimens of base asphalt (BA), aged asphalt (AA), and RA were systematically prepared. The impacts of aging and rejuvenators on the nano adhesion property of asphalt were assessed using multi-scale testing methods. The findings revealed that aging adversely affected the adhesive interaction between BA and aggregate, whereas the application of rejuvenators substantially improved this effect. When compared to acidic aggregate of granite, the alkaline aggregate of limestone demonstrated superior adhesion properties with RA. Moreover, the correlation analysis affirmed that mechanical testing across various scales consistently evaluated the trends in the adhesion property of RA with aggregates.

Preparation and performance verification of polyvinyl alcohol hydrogel biomimetic coating on the surface of vascular intervention guidewires

During guidewire interventions in intricate blood vessels, friction and collisions between the guidewire and the vessel wall can lead to complications such as vascular damage. This study focuses on the preparation of a lubricating hydrogel as a biomimetic coating on the guidewire surface. Four types of composite hydrogel biomimetic coatings were prepared using polyvinyl alcohol (PVA), dimethyl sulfoxide (DMSO), silane coupling agent (SCA), and glycerol in different ratios. The fundamental properties of the composite hydrogels were initially investigated, including the swelling behavior, mechanical characteristics, friction property, as well as adhesive property. Subsequently, the practical application of the hydrogel biomimetic coatings on guidewires were analyzed through intervention frictional force analysis, friction resisting tests, and collision tests in intricate blood vessels. The experimental results indicate that the hydrogel biomimetic coating, comprising PVA, DMSO, and SCA, exhibited a maximum friction force at least 0.07 N lower than the minimum friction force observed with the uncoated guidewires. Additionally, it significantly shortens the time required for the guidewire to break through collision area in intricate blood vessels, reducing it from 1.8 s to 0.9 s, indicating its superior lubrication performance. This finding offers experimental evidence for enhancing the safety of clinical intervention surgeries.

Towards the optimal design of optically clear adhesives for flexible display

As device form factors evolve towards increased complexity and flexibility, the role of adhesives within the display module stack becomes increasingly crucial. These adhesives are essential for bonding functional layers with minimal thickness while mitigating stress during the dynamic behavior of flexible devices. This paper offers a comprehensive overview of the essential properties of adhesives - such as adhesion, viscoelasticity, optical characteristics, and environmental reliability - necessary for the stable operation of flexible display devices across diverse form factors and environments. In particular, it provides an in-depth look at ongoing research in simulation, material selection, polymer network control, and the integration of new functionalities to achieve optimal performance. Furthermore, this paper discusses extensive research outcomes addressing the growing demand for sustainable solutions. Building on this knowledge, we highlight the future direction of adhesives for flexible displays.

Reducing the moisture susceptibility of recycled hot‐mix asphalt mixture with composite modification technology

AbstractStyrene–butadiene–styrene block copolymer (SBS)‐modified asphalt is a key material for constructing recycled hot‐mix asphalt mixtures (RHMAs). However, these mixtures still risk insufficient moisture stability. To this end, this study investigates the feasibility of asphalt composite modification technology to enhance RHMA performance. SBS, high‐viscosity agent (HVA) and crumb‐rubber materials (CRM) were used to prepare SBS‐HVA‐ and SBS‐CRM‐modified asphalt, with SBS‐modified asphalt as the control group, and the adhesion properties of the asphalt were evaluated using surface free energy tests. RHMAs with 50% reclaimed asphalt pavement were then prepared with each type of modified asphalt. The moisture susceptibility of these mixtures was analyzed using moisture‐induced sensitivity, freeze–thaw splitting and immersion Marshall tests. It was found that HVA significantly enhanced the adhesion of SBS‐modified asphalt under dry conditions, while CRM had a minimal effect. Compared to RHMA with SBS‐modified asphalt, HVA and CRM additives are crucial for enhancing the moisture stability of RHMA in the immersion Marshall test. However, CRM does not improve the moisture stability of RHMA in the moisture‐induced sensitivity and freezing–thaw splitting tests. From the conducted study, it can be proposed that SBS and HVA composite‐modified asphalt can be utilized in RHMAs to achieve higher moisture stability. © 2024 Society of Chemical Industry.

Modeling and Laboratory Investigation of Tack Coats as Bituminous Pavement Interlayer

The adhesive properties of tack coats between asphalt pavement layers are crucial for the pavement’s structural behavior. This study first involved numerical analyses to compare stress patterns, deformations, and displacements in the pavement structure under various geometric and mechanical conditions. A rational calculation method based on the theory of elastic multilayer systems was used to quantify the impact of layer properties such as thickness, stiffness modulus, and Poisson’s ratio on interlayer bonding. Three bonding conditions—Full Friction, Partial Bonding, and Full Debonding—were analyzed to understand the tack coat’s effect between the top two layers. The second phase involved characterizing the mechanical behavior of the interface through shear strength tests (Leutner shear test) on both laboratory-prepared specimens and samples from a 10-year-old highway. Specimens were prepared using a Roller Compactor and tested under different interface conditions: hot-on-hot (H/H), residual bitumen 200 g/m2 (RB 200), and residual bitumen 400 g/m2 (RB 400). The tests examined the bonding effects in terms of tangential force and shear displacement at failure, as well as the impact of vehicular traffic on rutting and fatigue failure. Finally, this study investigated the long-term aging effects of the binder on interlayer bonding and sought to correlate the results of numerical calculations with those of the laboratory tests.