Moisture Mechanical Properties Research Articles

Waterborne cellulose acetate pickering emulsion generation mediated by cellulose nanocrystals for paper coating applications

There is a continually increasing demand for alternatives to single-use, non-degradable, and synthetic plastic packaging. Environmentally friendly paper products offer a potential solution, but typically do not meet stringent demands for barrier and other physical property performance unless coated with polymeric films, usually polyolefins. Replacing conventional plastic film coatings with bio-based polymer alternatives, such as cellulose acetate, can provide competitive barrier property performance while also providing sustainability benefits. Furthermore, water can be used as a coating medium for added environmental and coatability advantages. In this study, 10 wt% Pickering emulsions of cellulose acetate dispersed in water and stabilized via cellulose nanocrystals (CNC) were generated. Rheological behavior, particle size, stability, and particle morphology were analyzed, as was the effect of modifying the CNCs using (2-Dodecen-1-yl)succinic anhydride over several weeks. Unbleached kraft paper was coated and compared to polyolefin coated and uncoated paper. Water vapor permeability, grease resistance, water absorption, and wet mechanical properties were all investigated, displaying promising properties for barrier paper coating. The grease kit test yielded a result of 10/12 for the coated paper versus 0/12 for uncoated, and water Cobb value showed a 60 % improvement. Lastly, the performance of the coated paper as a food takeout container coating was explored, with convincing results demonstrating a strong avenue of applicability. Overall, the waterborne cellulose acetate Pickering emulsion formation and its paper coating application yielded promising results for sustainable packaging development.

Implantable Patch of Oxidized Nanofibrillated Cellulose and Lysozyme Amyloid Nanofibrils for the Regeneration of Infarcted Myocardium Tissue and Local Delivery of RNA-Loaded Nanoparticles.

Biopolymeric implantable patches are popular scaffolds for myocardial regeneration applications. Besides being biocompatible, they can be tailored to have required properties and functionalities for this application. Recently, fibrillar biobased nanostructures prove to be valuable in the development of functional biomaterials for tissue regeneration applications. Here, periodate-oxidized nanofibrillated cellulose (OxNFC) is blended with lysozyme amyloid nanofibrils (LNFs) to prepare a self-crosslinkable patch for myocardial implantation. The OxNFC:LNFs patch shows superior wet mechanical properties (60MPa for Young's modulus and 1.5MPa for tensile stress at tensile strength), antioxidant activity (70% scavenging activity under 24h), and bioresorbability ratio (80% under 91 days), when compared to the patches composed solely of NFC or OxNFC. These improvements are achieved while preserving the morphology, required thermal stability for sterilization, and biocompatibility toward rat cardiomyoblast cells. Additionally, both OxNFC and OxNFC:LNFs patches reveal the ability to act as efficient vehicles to deliver spermine modified acetalated dextran nanoparticles, loaded with small interfering RNA, with 80% of delivery after 5 days. This study highlights the value of simply blending OxNFC and LNFs, synergistically combining their key properties and functionalities, resulting in a biopolymeric patch that comprises valuable characteristics for myocardial regeneration applications.

Green and facile fabrication of robust calcium alginate sponges via thermally bonded nonwoven induced freeze-drying for dressing applications

Alginate sponges have been widely studied in areas of wound healing, drug release, tissue engineering, and wastewater treatment due to their potential biological activity, biocompatibility, high porosity, and large surface area. However, their poor mechanical properties greatly limit the practical applications of alginate sponge. In this study, a structurally controllable and high-performance sponge material preparation strategy was proposed by optimizing the structure of the freeze-dried calcium alginate (CA) sponge using fluffy and porous thermally bonded nonwovens (NWs). The performance of composite sponges (CA@NWs) prepared at different pre-freezing temperatures and concentrations were tested. The results showed that the NWs skeleton could improve the formation structure and size stability of the freeze-dried CA sponge, making it have good fluid absorption, moisture permeability, moisture retention, and wet state mechanical properties. The RF-1.0-CA@NWs sponge had the highest fluid absorption rate of 1415 %. The wet state RF-1.5-CA@NWs sponge had tensile strengths of 1.913 MPa and 0.465 MPa in the MD and CD directions, respectively, which was about 95 times higher than that of the wet state pure CA sponge.

Gelatin Enhances the Wet Mechanical Properties of Poly(D,L-Lactic Acid) Membranes.

Biodegradable (BP) poly(D,L-lactic acid) (PDLLA) membranes are widely used in tissue engineering. Here, we investigate the effects of varying concentrations of PDLLA/gelatin membranes electrospun in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP; C3H2F6O) solvent on their mechanical and physical properties as well as their biocompatibility. Regardless of the environmental conditions, increasing the gelatin content resulted in elevated stress and reduced strain at membrane failure. There was a remarkable difference in strain-to-failure between dry and wet PDLLA/gelatin membranes, with wet strains consistently higher than those of the dry membranes because of the hydrophilic nature of gelatin. A similar wet strain (εw = 2.7-3.0) was observed in PDLLA/gelatin membranes with a gelatin content between 10 and 40%. Both dry and wet stresses increased with increasing gelatin content. The dry stress on PDLLA/gelatin membranes (σd = 6.7-9.7 MPa) consistently exceeded the wet stress (σw = 4.5-8.6 MPa). The water uptake capacity (WUC) improved, increasing from 57% to 624% with the addition of 40% gelatin to PDLLA. PDLLA/gelatin hybrid membranes containing 10 to 20 wt% gelatin exhibited favorable wet mechanical properties (σw = 5.4-6.3 MPa; εw = 2.9-3.0); WUC (337-571%), degradability (11.4-20.2%), and excellent biocompatibility.

Effect of Gelatin Content on Degradation Behavior of PLLA/Gelatin Hybrid Membranes.

Poly(L-lactic acid) (PLLA) is a biodegradable polymer (BP) that replaces conventional petroleum-based polymers. The hydrophobicity of biodegradable PLLA periodontal barrier membrane in wet state can be solved by alloying it with natural polymers. Alloying PLLA with gelatin imparts wet mechanical properties, hydrophilicity, shrinkage, degradability and biocompatibility to the polymeric matrix. To investigate membrane performance in the wet state, PLLA/gelatin membranes were synthesized by varying the gelatin concentration from 0 to 80wt%. The membrane was prepared by electrospinning. At the macroscopic scale, PLLAcontaining gelatin can tune the wetmechanical properties, hydrophilicity, water uptake capacity (WUC), degradability and biocompatibility of PLLA/gelatin membranes. As the gelatin content increased from 0 to 80wt%, the drytensile strength of the membranes increased from 6.4 to 38.9MPa and the drystrain at break decreased from 1.7 to 0.19. PLLA/gelatin membranes with a gelatin content exceeding 40% showed excellent biocompatibility and hydrophilicity. However, dimensional change (37.5% after 7days of soaking), poor tensile stress in wet state (3.48 MPa)and rapid degradation rate (73.7%) were observed. The highest WUC, hydrophilicity, porosity, suitable mechanical properties and biocompatibility were observed for the PLLA/40% gelatin membrane. PLLA/gelatin membranes with gelatin content less than 40% are suitable as barrier membranes for absorbable periodontal tissue regeneration due to their tunable wetmechanical properties, degradability, biocompatibility and lack of dimensional changes.

Natural Underwater Bioadhesive Offering Cohesion Modulation via Hydrogen Bond Disruptor: A Highly Injectable and in Vivo Stable Remedy for Gastric Ulcer Resolution.

Injectable bioadhesives are attractive for managing gastric ulcers through minimally invasive procedures. However, the formidable challenge is to develop bioadhesives that exhibit high injectability, rapidly adhere to lesion tissues with fast gelation, provide reliable protection in the harsh gastric environment, and simultaneously ensure stringent standards of biocompatibility. Here, a natural bioadhesive with tunable cohesion is developed based on the facile and controllable gelation between silk fibroin and tannic acid. By incorporating a hydrogen bond disruptor (urea or guanidine hydrochloride), the inherent network within the bioadhesive is disturbed, inducing a transition to a fluidic state for smooth injection (injection force <5N). Upon injection, the fluidic bioadhesive thoroughly wets tissues, while the rapid diffusion of the disruptor triggers instantaneous in situ gelation. This orchestrated process fosters the formed bioadhesive with durable wet tissue affinity and mechanical properties that harmonize with gastric tissues, thereby bestowing long-lasting protection for ulcer healing, as evidenced through in vitro and in vivo verification. Moreover, it can be conveniently stored (≥3m) postdehydration. This work presents a promising strategy for designing highly injectable bioadhesives utilizing natural feedstocks, avoiding any safety risks associated with synthetic materials or nonphysiological gelation conditions, and offering the potential for minimally invasive application.

Bioinspired polysaccharide-based nanocomposite membranes with robust wet mechanical properties for guided bone regeneration

ABSTRACT Polysaccharide-based membranes with excellent mechanical properties are highly desired. However, severe mechanical deterioration under wet conditions limits their biomedical applications. Here, inspired by the structural heterogeneity of strong yet hydrated biological materials, we propose a strategy based on heterogeneous crosslink-and-hydration (HCH) of a molecule/nano dual-scale network to fabricate polysaccharide-based nanocomposites with robust wet mechanical properties. The heterogeneity lies in that the crosslink-and-hydration occurs in the molecule-network while the stress-bearing nanofiber-network remains unaffected. As one demonstration, a membrane assembled by bacterial cellulose nanofiber-network and Ca2+-crosslinked and hydrated sodium alginate molecule-network is designed. Studies show that the crosslinked-and-hydrated molecule-network restricts water invasion and boosts stress transfer of the nanofiber-network by serving as interfibrous bridge. Overall, the molecule-network makes the membrane hydrated and flexible; the nanofiber-network as stress-bearing component provides strength and toughness. The HCH dual-scale network featuring a cooperative effect stimulates the design of advanced biomaterials applied under wet conditions such as guided bone regeneration membranes.

Sodium carboxymethyl cellulose as a stabilizer for fabricating mineralized collagen films with improved wet mechanical properties

Collagen casings, as a type of collagen film, have weak mechanical properties when wet. Therefore, in this research, sodium carboxymethyl cellulose was used to make sodium carboxymethyl cellulose (CMC)-amorphous calcium phosphate (ACP) composite (CMC-ACP) to enhance the collagen film wet mechanical properties. Collagen films were immersed in different CMC-ACP suspensions containing different CMC ratios for 30 min. The wet mechanical properties of collagen films were tested after soaking in deionized water for 2 min. The optimal CMC concentration was determined to be 0.2%, with the Young's modulus (YM) of the collagen film increasing from 0.043 MPa to 0.054 MPa, elongation at break (EAB) increasing from 41.42% to 56.98%, tensile strength (TS) increasing from 1.51 MPa to 2.5 MPa, and toughness (TH) increasing from 316 kJ/m3 to 797.63 kJ/m3. The effects of CMC concentration on the effectiveness of CMC-ACP and the mechanism of action on collagen films were studied by using scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), Fourier transform infrared (FTIR) spectroscopy, and differential scanning calorimetry (DSC). In conclusion, CMC-ACP can mineralize collagen films and improve their wet mechanical properties when using appropriate concentrations.

Stable aqueous dispersions of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) polymer for barrier paper coating

The demand for alternatives to single-use, synthetic, and non-degradable plastic packaging is continuously increasing. Paper products offer an environmentally friendly solution, however, typically do not meet strict barrier and other physical property performance demands unless coated with polymeric films, typically conventional polyolefins. Replacement of the conventional plastic film coating with bio-based and biodegradable polymers, such as poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) could provide competitive packaging properties while meeting sustainability objectives. In this study, PHBV is dispersed and stabilized in water for further environmental and coatability benefits. Four 10 wt% solids waterborne dispersions of PHBV with sodium dodecyl sulfate surfactant and guar gum rheological modifier were prepared and remained stable for several weeks at room temperature when evaluated using rheological study and particle size analysis. Manila paper substrate was coated, evaluated, and compared to uncoated paper. A smooth, transparent film, with great substrate adhesion and flexibility was obtained. Wet mechanical properties, water vapor permeability, oil resistance, and water absorption all displayed excellent results for barrier packaging applications, with substantial improvement over uncoated paper. Overall, the waterborne PHBV dispersion and paper coating exhibited promising results as a sustainable packaging option.

Supramolecular cross-linking affords chitin nanofibril nanocomposites with high strength and water resistance

Polysaccharide nanofibrils of chitins or celluloses are emerging biobased building blocks for sustainable, high-performance bioinspired nanocomposites fusing high stiffness, strength, and other functionalities. Owing to their hygroscopicity, a crucial challenge towards real-life applications of these nanocomposites is to maintain their mechanical performances in the humid or even fully swollen conditions. Here, we report water resistant nanocomposites composed of sustainable chitin nanofibrils (ChNFs) and polyvinyl alcohol (PVA) that are physically cross-linked by tannic acid (TA) to enhance and stabilize wet mechanical properties. We demonstrate that the formation of polymer-coated core/shell nanofibrils at the intermediate stage is crucial for the well-defined nanopaper structures after casting. By infiltrating TA, the formation of hydrogen bonding in the PVA matrix and at the ChNF/PVA interface renders the nanocomposites with extremely high strength and stiffness, even under high humidity and swelling conditions. With the increase in the amount of conjugated TA, the Young's modulus and tensile strength of the swollen nanocomposites reach up to 3.0 GPa and 70 MPa, respectively, which are superior to the existing water-borne nanofibils/polymer nanocomposites. Moreover, the nanocomposite films show excellent gas barrier properties at high relative humidity (90%), as well as UV shielding, antibacterial properties and biodegradability, complementing the multifunctional property profile and allowing a transfer into applications as advanced packaging materials.

Preparation of biodegradable recycled fiber composite film using lignin-based polyurethane emulsion as strength agent

Poor wet mechanical and barrier properties restrict cellulose-based materials from replacing petroleum-based plastics. Herein, an environmentally benign blocked lignin-based water-borne polyurethane emulsion which could be stored stably was prepared for the development of a hydrophobic, translucent, and biodegradable recycled fiber composite film through a blocked terminal isocyanate group. The tensile strength, Young's modulus, and toughness of the film were determined to be 48.15 MPa, 4.66 GPa, and 755.93 kJ m−3, respectively, which were 2.7, 3.9, and 4.3 times higher than of control. Besides, the composite film showed excellent water stability with improved water contact angle (114°) and wet strength (30.60 MPa) compared to the control. Furthermore, the composite film manifested excellent UV- blocking properties and it had good thermal stability. The developed functionally integrated composite film with exceptional physiochemical properties is expected to be applied as a green packaging and construction material.

Collagen films with improved wet state mechanical properties by mineralization

Collagen films have weak wet mechanical properties due to poor water resistance. Herein, two mineralization processes were designed to improve the mechanical properties of collagen fibers under wet conditions for use as packaging materials. One scheme (S1) involved preparing carboxymethyl chitosan amorphous calcium orthophosphate (CMCS-ACP) nanoparticles, dispersing them in an aqueous solution and then immersing the collagen film in the dispersion to introduce the inorganic phase. Another scheme (S2) introduced the inorganic phase by alternately soaking in a CaCl2 and a Na2HPO4 solution. S1 introduced an amorphous inorganic phase and enhanced the wet tensile strength of collagen films from 2.71 MPa (Control) to 4.08 MPa (1.0%C-A). S2 introduced a large number of inorganic phases, which did not significantly enhance the wet tensile strength of the film, but reduced its swelling ratio from 176.15% to 112.87%. The amorphous inorganic phase from S1 did not destroy the triple helix structure of the collagen film, whereas the direct calcium phosphate deposition from S2 greatly damaged the original structure of the collagen film, resulting in poorer mechanical properties from 2.71 MPa (Control) to 1.55 MPa (N3).

Phosphoric acid-doped Gemini quaternary ammonium-grafted SPEEK membranes with superhigh proton conductivity and mechanical strength for direct methanol fuel cells

Proton exchange membranes (PEMs) with excellent proton conductivity, high mechanical strength, and low methanol permeability are essential for their application in direct methanol fuel cells (DMFCs). Herein, flexible alkyl side chains containing Gemini quaternary ammonium (QA) ions were grafted onto sulfonated poly(ether ether ketone) (SPEEK) to obtain novel amphiphilic polymers (S-DMEAx-BPT), and then doped with phosphoric acid (PA) to prepare S-DMEAx-BPT/PA membranes. PA immobilized on flexible side chains can possess more mobility and higher proton conduction ability when compared with PA bound to rigid main chains, thus contributing to the extremely high proton conductivity of S-DMEAx-BPT/PA (295.4 mS cm-1, 80 °C, 100% R.H) even at low PA doping levels. Moreover, with the help of abundant ionic crosslinking, the membranes had excellent dry and wet mechanical properties. Benefiting from the negligible PA leaching, these membranes could be used as the electrolyte in DMFCs and output the peak power density of 110.7 mW cm-2, which was 2.1 times that of Nafion 212 (52.8 mW cm-2). Moreover, the open-circuit voltages (OCV) retention remained at 82.4% after 140 h. Therefore, the strategy combining Gemini QA cations grafting, flexible side chains, and low-level PA doping provides a new methodology for fabricating high-performance PEMs for DMFCs.

Reutilization of gangue wastes in phosphogypsum-based excess-sulphate cementitious materials: Effects of wet co-milling on the rheology, hydration and strength development

This paper presents an experimental study on the effects of calcined gangue and wet co-milling on the properties of phosphogypsum-based excess-sulphate cementitious materials (PESCMs), including setting time, rheology, heavy metal solidification and strength development. For PESCMs containing 0%-50% calcined gangue, with and without wet co-milling, we examined hydration and microstructural evolution. Results indicate that the addition of calcined gangue shortens the initial and final setting time of fresh PESCM pastes, and impairs stability, fluidity and strength development. After wet co-milling, the rheological and mechanical properties of PESCM pastes are improved, where the binders with 10–20% calcined gangue show a 40% increase in 28-d compressive strength. Hydration of calcined gangue is rapid and weakens the retarding effect of impurities, providing more active aluminates and silicates for further hydration. Wet co-milling promotes physical dispersion, chemical dissolution and thus hydration, which helps refine microstructure for a better development of strength and heavy metal solidification capability.

Effect of nano-MgO on basic properties and microstructures of cement-based materials

Nano-magnesium oxide (MgO) can be used as an expansion agent for cement-based materials, but little is known about the influence of nano-magnesium oxide on the mechanics, microstructure and expansion stability of cement materials. The influence of nano-magnesium oxide on the consistency, fluidity, porosity, dry and wet densities, mechanical properties and microstructures of cement-based materials was researched in this study. The results show that the compressive strength and flexural strength of the cement mortar test block containing nano-magnesium oxide particles increase and are higher than those of the control cement mortar test block at any time. The addition of nano-magnesium oxide increases the mechanical strength of the cement mortar block, and the strengthening effects are most obvious in the early stage of maintenance. When the curing age is 28 days and the nano-magnesium oxide content is 1.5%, the compressive strength and flexural strength of the modified cement mortar test block are the best. Fourier transform infrared spectroscopy and scanning electron microscopy show that the expansion effect of nano-magnesium oxide makes the microstructure of cement-based materials denser and more uniform. This paper also discusses the influence mechanism of nano-magnesium oxide on cement-based materials, which provides a reference for the application of nano-magnesium oxide in cement-based materials.

Water-resistant hybrid cellulose nanofibril films prepared by charge reversal on gibbsite nanoclays

A novel method is reported for the preparation of a hybrid gibbsite-cellulose nanofibril (CNF) nanocomposite film with improved wet and dry mechanical properties and barrier properties. A gibbsite and cationic CNF dispersion was dewatered at pH 7 to prepare well-ordered films. Thereafter, the charge on gibbsite was reversed by dipping the film in pH 12 water to induce an ionic interaction between CNFs and gibbsite, enhancing the film properties; modulus improved from 9 GPa to 12 GPa, with a maintained strain-at-break of 6 % and tensile strength of 190 MPa. Additionally, the charge-reversed film swelled a factor of 24 less than a film without any gibbsite. At 23 °C and 80 % RH, the oxygen barrier properties were improved by a factor of 28, to a value of 18 ml·μm·m−2·kPa−1·24 h−1 and the water vapour barrier properties were improved by a factor of 12, to a value of 105 g·μm·m−2·kPa−1·24 h−1.

Investigation of steel fiber reinforced high-performance concrete with full aeolian sand: Mix design, characteristics and microstructure

High-performance concrete with full aeolian sand (FA-HPC) has the characteristics of low water binder ratio, large cementitious materials content and no restriction of coarse aggregates, resulting in a high risk of shrinkage cracking. Aiming at reducing the shrinkage of FA-HPC and improving its cracking resistance, mechanical properties and durability, steel fibers with different lengths are employed to reinforce FA-HPC and develop a new type of cement-based composites (FA-HPFRC). For this purpose, the modified Andreasen & Andersen (MAA) model was adopted to determine the volume fractions of aeolian sand (AS), cement, fly ash (FA) and silica fume (SF). Then, the water binder ratio (W/C), superplasticizer (SP) and steel fiber content of FA-HPFRC were optimized through wet packing compactness, flowability, mechanical properties and shrinkage tests. Furthermore, the cracking resistance and microstructure of the developed FA-HPFRC were tested and analyzed from macro-micro perspectives. The results show that the volume fractions of AS, cement, FA and SF are determined as 0.482:0.316: 0.109:0.093 when the powder materials in FA-HPFRC are stacked to the most compact state. The wet packing compactness decreases with a higher W/C ratio while it increases first and then decreases with the increase of SP content. Considering the influences on mechanical properties, the W/C and SP content shall be 19% and 1% of the cementitious material separately. The introduction of steel fibers in FA-HPC reduces the concrete's flowability, destroys its dense packing system and lowers its wet packing compactness. However, the characteristics such as high toughness, and large elastic modulus of steel fibers endow FA-HPFRC with excellent mechanical properties, chloride resistance and shrinkage resistance. Especially steel fibers with 12 mm length perform well in improving the comprehensive performance of FA-HPFRC and increasing the cracking resistance 15.03% higher than that of 6 mm steel fibers. This research further improves FA-HPC's mechanical properties and durability, especially the shrinkage cracking resistance, and provides technical and theoretical support for the application of FA-HPFRC.

Recyclable grease-proof cellulose nanocomposites with enhanced water resistance for food serving applications

Recyclable cellulose nanofibril (CNF) and lignin-containing cellulose nanofibril (LCNF) coated wood flour composites were fabricated using a vacuum-filtration process for food serving applications. The coated cellulose nanofibril composites had excellent mechanical, and oil, and grease barrier properties compared to a commercial container. However, the composites with both LCNF and CNF coating layers had poor performance in wet conditions compared to the commercial container. The addition of 1 wt.% aluminum sulfate (alum) to the CNF and LCNF coating layer significantly improved the water-resistance of the composites. CNF + 1% alum coated composites had inferior water resistance and lower mechanical strength in wet conditions compared to the commercial container. However, the LCNF + 1% alum coated composites had comparable water resistance and higher wet mechanical properties than the commercial container. The recyclability of the composites was assessed through the disintegration of the samples in water and subsequent reformation, and it was found that the composites were fully recyclable. The composites could fully retain their mechanical and excellent oil and grease barrier properties after each recycling level. These recyclable fully bio-based nanocomposites can be an eco-friendly alternative for currently used food container systems that use harmful chemicals.Graphical abstract

Dual composite bioadhesives for wound closure applications: An in vitro and in vivo study

AbstractOver the years, new biomaterials have been introduced as an alternative to conventional wound closure methods. Compared with traditional methods including sutures and staples, bioadhesives are more convenient to use and less time‐consuming. Nevertheless, the application of topical skin adhesives such as Cyanoacrylates (CA) is limited, due to cytotoxicity. Hence, developing skin adhesives with strong adhesion to soft tissue in wet environment, controlled physical and mechanical properties, and excellent biocompatibility has been a significant challenge. In the current study, we developed a new bioadhesive based on the highly biocompatible natural polymers gelatin and alginate. In order to enhance the mechanical‐ physical properties and functionality, two types of fillers were loaded: hemostatic agent (kaolin or montmorillonite) and cellulose fibers. Our in‐vitro results show that the addition of the functional fillers increased the tensile strength and modulus of the bulk material, leading to higher sealing ability and higher bonding strength. In addition, the gelation time and swelling degree were significantly decreased and the viscosity increased with the incorporation of the filler, which enables better functioning. The in‐vivo model focused on using a porcine skin incision, demonstrated superior efficacy of these new bioadhesives compared to the control group. I.e., they resulted in rapid healing, less inflammation, and a higher degree of wound closure. In conclusion, our dual‐composite bioadhesives demonstrated promising potential for use in wound closure applications and may serve as a suitable alternative for conventional sutures. Their unique properties make them beneficial, especially for first medical care applications such as rescuing casualties.

Enhancing mechanical performance and wet‐skid resistance of emulsion styrene butadiene rubber/natural rubber latex composites via in‐situ hybridization of silanized graphene oxide and silica

AbstractThe wet skid resistance and thermal conductivity of “green tire” are the focus of research. In this work, through the use of different types of silane coupling agents, the surface of SiO2 and graphene oxide (GO) were grafted with amino and epoxy groups, respectively. The in‐situ generated SiO2 was grafted to the surface of GO by ring‐opening reaction of amino and epoxy groups. The emulsion styrene butadiene rubber/natural rubber latex (ESBR/NRL) composites were prepared by gas assisted spray flocculation process to improve the dispersion performance of hybrid filler. Because the surface of the hybrid filler contains amino and epoxy groups, it can be added as a reactive compatibilizer into the ESBR/NRL composites to improve the interface compatibility and synergistic reinforcement effect. Compared with the composites filled with SiO2, the composites filled with hybrid filler have excellent wet skid resistance and mechanical properties. When the mass ratio of GO to SiO2 is 3:10, the mechanical properties and wet skid resistance of rubber composites increase by 96.7% and 20.6%, respectively. Our preparation method of hybrid filler and flocculation process of rubber composites have broad application prospects in “green tire.”