Barrier Performance Research Articles

Exploring g-C3N4 as a green additive for biodegradable poly(butylene adipate-co-terephthalate) film with enhanced UV shielding and mechanical properties.

Typical small organic dyes exhibit excellent UV absorption capabilities and are commonly used as additives to shield plastic films from photoaging. However, their tendency to decompose easily and migrate rapidly within a polymer matrix limits their service life. Herein we prepared g-C3N4 nanosheets and fabricated g-C3N4/PBAT films to investigate the effects of g-C3N4 on UV shielding and plasticizing of a biodegradable PBAT film. Photophysical characterizations revealed that an improved UV light barrier performance was achieved on g-C3N4/PBAT films compared to pure PBAT. Furthermore, the photoaging results show that g-C3N4 can stably exist in the PBAT matrix, enabling the aged g-C3N4/PBAT films to maintain their effective UV shielding ability, whereas the aged benzophenone (UV-0)/PBAT film shows a substantial decrease in UV light absorption due to the photodecomposition of UV-0. Additionally, g-C3N4 acted as a reinforcing material for PBAT, as evidenced by the approximately 1.5-fold increase in longitudinal tear strength and 1.6-fold increase in tensile strength of g-C3N4/PBAT films compared to pure PBAT. Remarkably, even after 100 hours of photoaging, the aged g-C3N4/PBAT films retained their favorable mechanical properties. This study highlights the potential of g-C3N4 as a new type of UV shield additive for future practical applications in protecting biodegradable plastic from photoaging.

Preparation, physicochemical properties, antioxidant, and antibacterial activities of quaternized hawthorn pectin films incorporated with thyme essential oil

To investigate the impacts of thyme essential oil (TEO) on the structural, physical, antioxidative, and antibacterial properties of quaternized pectin film (QHP), the 0.5%, 1.0%, and 1.5% TEO were incorporated to prepare quaternized pectin and TEO composites films. Scanning electron microscopy (SEM) pictures of the apparent morphology revealed that TEO had good compatibility with quaternized pectin. With TEO combined, the thickness and opacity of films increased, while the water content and swelling degree decreased. TEO has a plasticizing effect on films and improve the elongation at the break of films. However, hydrophobic TEO did not improve the hydrophobicity and water vapor barrier performance of films. The complex of TEO had slight influence upon the thermal stability of films. The composite films exhibited higher UV shielding, antioxidative, and antibacterial performance. Thus, the complex films have potential application value in active food packaging materials.

High ion barrier hydrogel with excellent toughness achieved by directional structures.

Owing to their nontoxicity, environmental friendliness, and high biocompatibility, physically cross-linked hydrogels have become popular research materials; however, their high water content and high free volume, along with the weak bonding interactions inherent to ordinary physically cross-linked hydrogels, limit their application in fields such as flexible devices, packaging materials, and substance transport regulation. Here, a structural barrier approach based on directional freezing-assisted salting out was proposed, and the directional structure significantly enhanced the barrier performance of the hydrogel. When the direction of substance diffusion was perpendicular to the pore channel structure of the directional freezing-PVA hydrogel (DFPVA), the Cl- transmission rate was 57.2% for the uniform freezing-PVA hydrogel (UFPVA). By adjusting the concentration of the salting-out solution and the salting-out time, the crystallinity and crystal domain size of the hydrogel could be further changed, optimizing and regulating the barrier performance of the hydrogel, with the best Cl- unit permeability being 36.02 mg mm per cm2 per day. Additionally, DFPVA had excellent mechanical properties (stress of 6.47 ± 1.04 MPa, strain of 625.85 ± 61.58%, toughness of 25.77 ± 3.72 MPa). Due to the barrier and mechanical properties of the direct structure, DFPVA is suitable as a drug carrier for slow drug release in vitro.

Unlocking sustainable solutions: Nanocellulose innovations for enhancing the shelf life of fruits and vegetables – A comprehensive review

Regarding food security and waste reduction, preserving fruits and vegetables is a vital problem. This comprehensive study examines the innovative potential of coatings and packaging made of nanocellulose to extend the shelf life of perishable foods. The distinctive merits of nanocellulose, which is prepared from renewable sources, include exceptional gas barrier performance, moisture retention, and antibacterial activity. As a result of these merits, it is a good option for reducing food spoilage factors such as oxidation, desiccation, and microbiological contamination. Nanocellulose not only enhances food preservation but also complies with industry-wide environmental objectives. This review explores the many facets of nanocellulose technology, from its essential characteristics to its use in the preservation of fruits and vegetables. Furthermore, it deals with vital issues including scalability, cost-effectiveness, and regulatory constraints. While the use of nanocellulose in food preservation offers fascinating potential, it also wants to be cautiously careful to assure affordability, effectiveness, and safety. To fully use the potential of nanocellulose and advance the sustainability plan in the food business, collaboration between scientists, regulatory bodies, and industry stakeholders is important as we stand on the cusp of a revolutionary era in food preservation.

Polymer Matrix Nanocomposites for Sustainable Packaging: A Green Approach

This research examines the characteristics and ecological viability of polymer matrix nanocomposites used in sustainable packaging. Nanocomposites were produced by combining varied proportions of polymer and nanofiller material. Through mechanical testing, it was determined that nanocomposite formulation 3 had the maximum tensile strength of 55 MPa, as well as a Young’s modulus of 3.5 GPa, showing greater stiffness in comparison to the other formulations. The evaluation of barrier qualities revealed that nanocomposite formulation 2 exhibited the most minimal oxygen permeability at a rate of 8 cc/m²/day and the lowest water vapor transmission rate at 4.5 g/m²/day, showing very efficient performance in preventing the passage of gases and moisture. The environmental impact study showed that nanocomposite formulation 3 had the most efficient energy consumption during manufacture, with a rate of 1.8 kWh/kg. It also had the lowest waste creation, with just 0.08 kg/kg, and the lowest CO2 emissions, with only 0.4 kg/kg. Nanocomposite formulation 3 demonstrated substantial improvements in mechanical characteristics, barrier properties, and environmental impact indicators when compared to the reference formulations, as shown by the percentage change analysis. In summary, this study showcases the capabilities of polymer matrix nanocomposites, specifically formulation 3, as environmentally friendly packaging materials that offer improved mechanical properties, effective barrier performance, and reduced ecological footprint. These findings contribute to the development of sustainable packaging solutions across different industries.

Superior toughness Anticorrosion-Bioactive integrated multilayer coating with excellent adhesion for biodegradable Magnesium-Based stents

Biodegradable magnesium-based stents overcome the limitations of non-degradable stents and exhibit superior mechanical properties compared to biodegradable polymer counterparts, representing an inevitable trend in cardiovascular stent evolution. However, the excessively rapid degradation rate remains a pivotal factor that constrains their clinical application. In this work, an anticorrosion-bioactive integrated multilayer coating is developed for magnesium-based stents. By optimizing the molecular structure of poly(L-lactide-co-ω-caprolactone) (PLCL), a biodegradable coating material with excellent mechanical properties and effective barrier performance is obtained. To enhance the wettability and adhesion strength between the highly surface-energy magnesium and the low-polarity PLCL, a silane-based transition layer and an intermediate connecting layer of covalently bonded PLCL chains are sequentially constructed on the magnesium substrate. Furthermore, bioactive polymer brush consists of poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) and Arg-Glu-Asp-Val (REDV) peptide is fabricated on the PLCL anticorrosion coating. The combined in vitro and in vivo experiments confirm that the multilayer coating exhibits commendable anti-corrosion performance, and is beneficial to anticoagulation and endothelialization, thereby making the degradation process of magnesium-based stents more compatible with the vascular remodeling process. The anticorrosion-bioactive multilayer composite coating developed in this study has the potential to overcome the corrosion resistance limitations of magnesium-based implants, thus promoting their clinical application.

One-step fast fabrication of multi-layer quantum dot diffusion plate for stable display and ultra-long life, a novel quantum dot packaging strategy

Quantum dots (QDs), renowned for their distinctive optical and physical attributes, are extensively employed in diverse fields such as lighting, displays, electronics, sensors, and solar cells. Nonetheless, the susceptibility to light, oxygen, and moisture is a major obstacle to the development of QDs. Achieving simple, efficient, and universal modification or encapsulation for enhanced stability remains a challenge. Herein, a one-step fast fabrication of multi-layer quantum dot diffusion plate (QD-DP) with excellent barrier and optical properties was proposed, which is alternately stacked by MS-EVOH and MS-QDs layers. The barrier phase morphology undergoes a fiber-flake transition induced by the bidirectional tensile force field during multiplication, and layer-by-layer encapsulation synergistically enhances the barrier performance, photo-oxygen stability, thermal-oxygen stability, and fluorescence lifetime of QD-DP in backlight applications. Under high-power UV irradiation, the fluorescence intensity ofMS/MS-QD 128L dropped to 90 % (T90) in only about 10 minutes, while the T90 of MS-E/MS-QD 128L was close to 216 hours, improved more than 1200 times. Concurrently, the quantum dot diffusion plate (QD-DP), characterized by an alternating multi-layer structure, demonstrated an elevated backlight color gamut value of ∼ 120 % NTSC, outperforming conventional quantum dot light emitting diodes (QLED). Compared with existing QDs backlight modules, a simpler structure, more efficient preparation process, and longer fluorescence lifetime of QD-DP were achieved.Moreover, unlike prevalent modification or packaging technologies that only target specific QD types, our alternating multilayer coextrusion packaging technology is applicable to all kinds of QDs and is simple, efficient, and universal.It was believed that this work could provide new opportunities for all kinds of QDs encapsulation and application in many fields and will be the dawn of large-scale commercialization of QDs.

Dual-Shell Microcapsules for High-Response Efficiency Self-Healing of Multi-Scale Damage in Waterborne Polymer-Cement Coatings.

Waterborne polymer-cement coatings have been widely applied in building materials due to their organic solvent-free nature, low cost, and eco-friendliness. However, these coatings can easily crack during the drying process as a result of construction environment factors, compromising the barrier performance of the coating and limiting its large-scale application. In this study, a dual-shell self-healing microcapsule was developed, which can effectively heal damage on a macro scale in waterborne polymer-cement coatings. Specifically, this dual-shell self-healing microcapsule was designed with a silica gel shell and a tannic acid-cuprum (TA-Cu) double-shell structure embedded with an epoxy resin (EP) healing agent, which was successfully fabricated via a two-step in situ polymerization. This silica gel shell self-healing microcapsules can effectively load into waterborne polymer-cement coatings. As the coating dries and solidifies, the silica gel shell of the microcapsule also becomes loose and brittle due to dehydration. This improves the mechanical initiation efficiency of the microcapsules in the coating. This study provides a novel approach for the application of self-healing microcapsules in waterborne coating systems, which can significantly reduce cracking during the drying process of waterborne polymer-cement coatings and improve the service life of the coating under complex conditions.

Experimental study and numerical analysis for vibration isolation performance on open trench and wave impeding block combined vibration isolation barrier

This paper presents a series of laboratory tests to investigate the vibration isolation performance of open trench and wave impeding block (WIB) combined vibration isolation barrier. To study the vibration isolation performance of open trench-WIB, design the 15 pairs of trials, including comparison with other vibration isolation methods, and the variation of vibration isolation performance with the depth, width, and thickness of open trench-WIB. The experiment is validated by FEM results with vibration isolation performance. The experimental results show that the vibration isolation effect of open trench-WIB combined vibration isolation barrier is better than that of the open trench at various excitation frequencies, and it is most obvious in the low frequency band. In addition, the effects of trench depth, wave barrier depth, barrier thickness, and barrier length on the vibration isolation performance of the open trench-WIB combined vibration isolation barrier are discussed. The research results are of great significance to guide the design of engineering vibration isolation.

Enhancing cathodic protection and barrier properties of zinc-rich epoxy coatings with mesoporous Ti4O7 additive

Searching for an optimal material additive that can enhance both the cathodic protection and barrier properties of zinc-rich epoxy coatings (ZRE) simultaneously remains a significant challenge nowadays. In this study, mesoporous Ti4O7 particles with high conductivity and chemical inertness were synthesised via the thermal reduction method and added to ZRE coating. The impact of different Ti4O7 filler contents on the corrosion resistance of ZRE coating containing 70 wt% zinc was assessed by electrochemical analysis, water uptake measurements, salt spray test and material characterisation techniques. The results demonstrated that the incorporation of mesoporous Ti4O7 significantly enhances the initial cathodic protection and long-term barrier properties of ZRE. The primary mechanism involves the conductive Ti4O7 ameliorating the Zn isolation caused by non-conductive Zn corrosion products and fostering a more efficient network for conductive penetration between zinc particles to improve cathodic protection efficacy. Moreover, mesoporous Ti4O7 promotes the uniform deposition and growth of ZnO/Zn(OH)2 by adsorption and anchoring of Zn(OH)42− and changes the shape of the corrosion product (columnar), thus improving the barrier performance of ZRE coating.

Enhanced corrosion resistance of epoxy resin coating via addition of CeO2 and benzotriazole

The use of fillers to enhance the corrosion protection of epoxy resins has been widely applied. In this work, CeO2 and Benzotriazole (BTA) were introduced into an epoxy resin to enhance the corrosion resistance of Q235 carbon steel. SEM results indicated that the CeO2 grains were rod-like and ellipsoidal in shape, and the distribution pattern of BTA was analyzed by EDS. The dynamic potential polarization curve proved the excellent corrosion resistance of the composite epoxy resin with CeO2 and BTA co-addition; and electrochemical impedance spectroscopy test (EIS) analysis indicated the significantly enhanced long-term corrosion protection performance of the composite coating. And the optimal protective performance was provided by the coating containing 0.3 wt.% CeO2 and 20 wt.% BTA, which attributed to the barrier performance of CeO2 particles and chemical barrier effect of BTA. The formation of corrosion products was analyzed using XRD. In addition, the corrosion resistance mechanism of the coating was also discussed in detail.

A method to improve the barrier performance of flexible riser internal pressure sheath—Heat transfer experiment and simulation

AbstractA considerable amount of acidic gas penetrates into the annulus between the internal pressure sheath and the outer protective sheath during the service of flexible risers, which will inevitably lead to corrosion of the metal functional layer. Many researchers have modified nanocomposites from the mass transfer perspective to reduce the materials' permeability coefficient. While permeation is an integrated process of heat and mass transfer process, heat distribution directly impacts gas permeation. Herein, the thermal conductivity of flexible riser liner materials is predicted for the first time by a combination of molecular dynamics and experiments, and then the radial temperature distribution under different seawater temperatures and internal fluid temperatures is investigated by finite element analysis. Finally, the effect of temperature distribution on the permeation coefficient was analyzed. The results demonstrate that the thermal conductivity can be predicted by molecular dynamics simulation, and the thermal conductivity of (polyvinylidene difluoride) PVDF/TiO2 decreases, while the thermal conductivity of PVDF/carbon nanotube (CNT) increases compared with pure PVDF. The temperature distribution of the internal pressure sheath material decreases when condensate water is present. As the fluid temperature rises from 30 to 110°C, the maximum increase ratio in the permeability of PVDF/CNT over PVDF increased from 3.6% to 14.8%, and the maximum decrease ratio of PVDF/TiO2 permeability coefficient compared with PVDF is from 1.2% to 4.6%. The results present a new idea to improve the barrier properties of materials by decreasing thermal conductivity.

Fabrication and film-forming mechanism of PCTFE films with exceptional water-vapor barrier and mechanical properties via solvent-assisted method

Polychlorotrifluoroethylene (PCTFE) has the outstanding water-vapor barrier performances among thermoplastics, and is with excellent transparency, high cryogenic toughness, and ultralow dielectric constant/loss. It plays an important role in high-performance packaging, electric circuit constructions, anti-corrosion coatings, cryogenic sealing, and so forth. Nevertheless, due to its borderline thermal stability and sensitivity to shearing effect, the melt-processing of PCTFE is rather difficult. Herein, a solvent-assisted method, which contained fabrication, coating, drying, and sintering of PCTFE suspension, was proposed for the fabrication of PCTFE films. The influence of processing parameters, including particle shape, drying temperature, and sintering time on the film-forming process was investigated. The as-prepared PCTFE films exhibited exceptional mechanical properties, with a tensile strength and failure strain of ∼42 MPa and ∼108 %, respectively. The water vapor transmission rate, light transmittance, and haze reached ∼0.02 g/(m2·24 h), ∼91 %, and ∼3 %, respectively. Finally, the potential film-forming mechanism was explained by the densification of PCTFE particles via capillary force, neck formation and particles coalescence driven by surface tension and viscous flow, and co-crystallization across the initial particle interfaces. In summary, the solvent-assisted method opened a new pathway for the processing of PCTFE films and is conducive to broadening their application fields.

Investigation of water vapor barrier performances of diamond-like carbon coatings on flexible PET fabricated at room temperature

Polyethylene terephthalate (PET) emerges as the predominant packaging material for food and electronics. To prevent water vapor from penetrating the polymer, an effective method is to deposit a coating on it that does not damage it. Diamond-like carbon (DLC), which can be deposited at low temperatures, offers a promising protective coating. In this research, DLC coatings were chemical vapor deposited (CVD) on PET substrates using an anode layer linear ion source method. The findings indicate that the water vapor transmission rate (WVTR) of PET substrates coated with DLC coating was significantly reduced to as low as 0.12 g/(m2·24 h), which represents a 30 times reduction compared to the uncoated PET substrates. To further understand the mechanism of water vapor barrier capabilities, molecular dynamics (MD) simulation and first-principles density functional theory (DFT) calculation were carried out to verify the capability and active site of the adsorption and dispersion of water molecules on carbon coating and PET. In addition, the DLC coated PET exhibited exceptional flexibility, and even after subjecting it to 2160 bending cycles, it showed no signs of cracking, indicating its mechanical robustness and durability. This research serves as a strong reference for utilizing DLC to address water vapor permeation challenges.

Fabrication of biodegradable and cold-water-soluble starch/polyvinyl alcohol films as inner packaging materials of pesticides: Enhanced emulsification, dispersibility, and efficacy

Developing environmentally friendly film materials for packaging pesticides is significant yet challenging. The use of native starch for preparing inner packaging materials of pesticides is limited by its physicochemical properties. In this study, a novel strategy of synergetic mechanical activation (MA)-enhanced solid-phase esterification of starch and cooperative combination of starch and polyvinyl alcohol (PVA) was proposed to fabricate biodegradable and cold-water-soluble starch (St)/PVA films. The appropriate esterification of starch and favorable compatibility between starch and PVA contributed to the production of St/PVA films by the extrusion-blowing method. The as-prepared film with St/PVA ratio of 4:6 exhibited outstanding mechanical properties (tensile strengths of 21.0 MPa; elongation at break of 213.9 %), cold-water solubility (dissolution time of 90 s), and oxygen barrier performance (oxygen transmission rate of 1.41 cm3/(m2·day·bar)). The dissolved St/PVA films with amphiphilic groups were conducive to the emulsification of butachlor (a fat-soluble liquid pesticide) and the dispersibility of oxyfluorfen (a fat-soluble solid pesticide). Furthermore, a mechanism of the interaction between pesticides and the surface of weed leaves was proposed to reveal the enhanced efficacy of St/PVA films-packaged pesticides. The strategy based on MA-enhanced esterification and PVA blending is efficient to produce starch-based films suitable for inner packaging materials of pesticides.

Enhanced kinetics and stability for aqueous Zn battery enabled by low-cost additive chemistry

Rechargeable aqueous zinc(Zn) batteries are a sustainable alternative to lithium-based energy storage devices due to their high safety, low cost, and scalability. Unfortunately, the Zn/Zn2+ redox chemistry is significantly plagued by undesirable interface caused by the instability of water, which directly dictates the low Zn reversibility and dendrite growth behavior. Here, we report an aqueous electrolyte in which low-cost ammonium dihydrogen phosphate is utilized as an electrolyte additive to enable the in-situ construction of phosphate-based interphase on the Zn-metal surface. Importantly, such interphase not only effectively eliminates water-related parasitic reactions and enables a highly reversible Zn deposition/dissolution, as demonstrated by its high Coulombic efficiency of 99.3 %, but also contributes a dendrite-free Zn morphology. Apart from the improved stability of the Zn anode, the addition of NH4H2PO4 also grants the enhanced reaction kinetics of Zn2+, bringing a lower Zn2+ de-solvation energy barrier and much-improved rate performance. Benefiting from the synergistic factors, excellent cycling performances of the Zn0.25V2O5·nH2O (ZVO)/Zn batteries are guaranteed. Additionally, a 31.2 mAh ZVO/Zn pouch cell also demonstrates a stable long life of 400 cycles, and capacity retention of 67.8 % is also retained. The low-cost and efficient electrolyte strategy points out a promising direction for practical Zn batteries.

Performance of amorphization AlCrTiZrMo high entropy alloy barrier for copper metallization

A reliable ultra-thin diffusion barrier is required for Cu interconnection. High entropy alloy (HEA) films have received attention in the development of diffusion barrier materials due to their remarkable properties. Here, the dense and smooth 17 nm AlCrTiZrMo high entropy alloy amorphous film (HEAAF) is obtained by the cofilter cathode vacuum arc deposition. After annealing at 700 °C for 1 h, no Cu-silicide compounds are formed and the sheet resistance is 0.27 Ω/□, which indicated that AlCrTiZrMo HEAAF has excellent diffusion barrier performance. Such barrier temperature is comparable to some ceramic barriers. The excellent diffusion barrier performance of AlCrTiZrMo HEAAF is due to its good stability of amorphous structure and chemical stability at high temperature.

Bio-inspired self-healing and anti-corrosion waterborne polyurethane coatings based on highly oriented graphene oxide

In the face of ubiquitous corrosion threats, the development of high-performance elastomer protective materials with active self-healing functions is extremely challenging and significant. We propose an approach by combining WPU elastomer with GO to create the multifunctional pearl layer structured polymers with interface hydrogen bonds. By crosslinking the polycaprolactone diol (PCL) chain with a hydrogen bond array, the elastomer with high mechanical strength, extensibility, elasticity, excellent damage resistance, and healing properties was successfully synthesized. The elastomer exhibits remarkable mechanical properties, including a tensile strength of 39.89 MPa, toughness value of 300.3 MJ m−3, and fracture energy of 146.57 kJ m−2. The enhanced damage resistance of the elastomer can be attributed to the decomposable hydrogen bond array as well as the strain-induced crystallization of PCL fragments, which effectively dissipate energy. Importantly, due to the reversibility of the hydrogen bonding array, the fractured WPU can easily heal and restore its original mechanical properties when subjected to heating at 50 °C. Moreover, the photothermal properties of GO enable the biomimetic polymer coating to achieve damage recovery after being irradiated with NIR for 30 s. The obtained biomimetic coating exhibits a highly oriented lamellar structure, thereby greatly enhancing physical barrier performance and anti-corrosion performance. Electrochemical impedance spectroscopy (EIS) shows that the impedance modulus is one order of magnitude higher than that of the blank coating. Additionally, scanning vibrating electrode (SVET) confirmed that the self-healing performance and protection effect of the biomimetic coating in 3.5 wt% NaCl solution were also reliable. This highly reliable biomimetic coating presents a revolutionary solution for creating multi-functional, high-performance smart material in harsh environments.

Effect of the Mid-Layer on the Diversion Length and Drainage Performance of a Three-Layer Cover with Capillary Barrier

The capillary barrier is a type of soil cover system commonly used in various geotechnical applications, such as limiting infiltration for slopes or landfills or providing cover for solid waste. It serves to prevent the movement of water through the soil layers by utilizing contrasting particle sizes. This paper focuses on investigating the effect of the granular layer on the performance of a three-layer cover with a capillary barrier, integrating the granular layer within clayey sand. The investigation involved one-dimensional infiltration tests utilizing four uniform granular soils with varying grain sizes. These tests were instrumental in calibrating soil water characteristic curves and hydraulic conductivity curves via back analysis. Subsequently, numerical analyses were conducted using a 15 m long model for each of the four distinct cover types. The results indicated that the fine gravel significantly improved the barrier performance beyond one-dimensional tests, owing to its high permeability and the influence of the slope. After the capillary barrier failure, the intermediate layers transitioned into efficient drainage layers, particularly in the gravel layer with the highest lateral drainage capacity. Clayey sand at the bottom delayed percolation, thereby supporting the conversion of the intermediate layer into an effective drainage component. Overall, the multi-layer system showed superior percolation performance compared to the clayey sand cover lacking a granular layer.

Shale barrier performance in petroleum systems: implications for CO 2 storage and nuclear waste disposal

Shale is often required to act as a natural barrier to fluid flow around nuclear waste repositories and above CO 2 storage sites. The small pore size of the shale matrix makes it an effective barrier to fluid flow. However, leakage could occur along faults or fractures. Experiments provide insight into fault/fracture-related leakage on short timescales (i.e. 1–10 years) compared to that needed for safe disposal (up to 1 Ma). Data collected by the petroleum industry provides strong evidence on how faults and fractures in shale impact fluid flow on such timescales. Faulted shales act as seals to petroleum reservoirs and abnormal pressures on geological timescales (>10 Ma). This observation suggests that faults in shale can either form without acting as flow conduits or act as temporary conduits but then reseal. Index properties such as clay content and elastic moduli are useful for identifying shales in which faults/fractures are likely to self-seal. However, fault and fracture-related fluid flow can occur through weak shales if high overpressures are maintained. Nuclear waste repositories can be sited away from where overpressures could develop. Leakage from CO 2 storage sites is more risky because the CO 2 provides drive to maintain high pressures, which could suppress self-sealing. Thematic collection: This article is part of the Fault and top seals 2022 collection available at: https://www.lyellcollection.org/topic/collections/fault-and-top-seals-2022