Firstly, the bio-inspired polydopamine (PDA) was coated on the surface of carbon nitride (CN), then used it (CNP) as nano-dispersant to improve the dispersion of graphene (Gr) in water on the basis ...of π-π interaction. After that, the KH560 was further grafted on the CNPG surface to improve the compatibility between inorganic hybrids and epoxy resin. The results of large plate experiments showed that the backside temperature of composite IFR coating containing CNPG@Si hybrids was significantly lower than that of other samples. Meanwhile, its expansion height after furnace test reached the maximum value (17.8 mm), which was greatly improved compared with the pure epoxy coating. Further, the maximum thermal decomposition temperature and the amount of char residue for the CNPG@Si/EP sample were significantly enhanced through the TGA test result. Besides, CNPG@Si based sample showed the lowest smoke density rating (SDR) due to its excellent smoke suppression performance. From the analysis of the morphology and composition of the char layer for CNPG@Si based sample, it can be seen that the introduction of Gr and CN increased the compactness of the char layer, and silicon network structures remained in the char layer after combustion, which effectively increases its strength and heat insulation effect.
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•CN and Gr were successfully combined by using PDA as an intermediary.•The combination of CN and Gr enhances the thermal barrier effect of coating.•The introduction of PDA improves the antioxidant function of char layer.•Modification of KH560 increases the thermal insulation properties of char layer.
In this study, the flexibility of carbon nanotubes (CNTs) and the excellent flame barrier property and catalytic carbon formation effect of layered double hydroxide (LDH) were fully combined to ...obtain a high performance composite flame retardant coating. Specifically, polydopamine (PDA) with superior adhesion properties was encapsulated on the surface of CNTs to enhance their dispersion in water. More importantly, the introduction of PDA provided abundant active sites for the adsorption of precursor cations of LDH, which facilitates the uniform loading of LDH on the surface of CNTs to obtain well-structured CNTs@PDA@LDH (CPL) hybrids. The synergistic effect of CNTs and LDH on the flame retardant properties of epoxy resin matrix was investigated. The CPL2%/EP sample showed the lowest backside temperature (170.78 °C), maximum expansion height (21.60 mm) and expansion rate (17.70), proving its highest thermal insulation effect. In addition, the thermal weight loss test illustrated that CPL2%/EP exhibited a higher thermal degradation temperature and char residue under both air and nitrogen, confirming its excellent thermal stability. Through the morphological analysis and characterization of the residual char, a reasonable flame retardant mechanism for the CPL hybrid material was proposed.
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•The PDA is uased to improve the dispersion of CNTs in the epoxy resin.•LDH is grown in situ CNTs@PDA surface to reduce the self-clustering of hybrids in the coating.•The synergistic effect of CNTs and LDH further enhanced the thermal insulation performance of char.•Metal oxides can promote the formation of char layer and adsorb volatile substances.
Inspired by the multifunctional adhesion ability of poly dopamine (PDA), ZrO2 and aluminum magnesium hydroxide (LDH) were combined by PDA, which increased the function of this material in intumescent ...fire retardant (IFR) coatings. Briefly, PDA was coated on the surface of LDH to improve its dispersion stability in water. Then, the high thermal stability ZrO2 nanoparticles were immobilized in situ on the LDH/PDA surface to improve the strength and temperature resistance of the char layer by a hydrothermal strategy. The fire protection performance of LDH@PDA@ZrO2 (LPZ) modified intumescent fire retardant (IFR) coatings was performed by large plate method, thermogravimetric analysis (TGA) and furnace experiments. From the results, the IFR coating loaded with 2.5% LPZ exhibited the lowest backside temperature and the highest heat insulation, which reached 177.9 °C and 64.42, respectively. Besides, the coating exhibited the greatest expansion height (23.65 mm) and expansion rate (18.92), which is significantly higher than that of other coatings. Moreover, the maximum thermal degradation temperature (Tmax) and residual char of LPZ2.5%/EP were significantly higher than other samples. Further, the LPZ2.5%/EP based sample indicated the lowest smoke density rating (SDR) due to its excellent smoke suppression performance. The residual carbon analysis showed that ZrO2 nanoparticles and LDH nanosheets remained in the char layer during the combustion process, which is beneficial to increase the strength of the char layer and its barrier effect on heat and oxygen.
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•The free radical scavenging effect of PDA enhanced the oxidation resistance of coating.•PDA encapsulated LDH to improve the dispersion of the material in the epoxy resin.•ZrO2 was introduced to improve the strength and compactness of the char layer.•The synergistic effect of ZrO2 and PDA further enhanced the thermal insulation performance of char.
•Combined-effects of octenylsuccination and beeswax on pullulan films were studied.•FTIR spectra confirmed octenylsuccination and beeswax presence in pullulan films.•Octenyl succinylated pullulan ...formed a stable film-forming emulsion (FFE).•Octenyl succinylation eliminated the need to use synthetic emulsifiers to form FFE.•Incorporation of beeswax (BW) improved WVP and TS of modified pullulan films.
In this study, to improve the water resistance properties of pullulan (PU) edible-films, the combination of the modification with octenyl succinic anhydride (OSA) and beeswax (BW) incorporation was used. The FTIR spectra results confirmed the PU octenylsuccination and also the presence of the BW in the composite films. The scanning electron microscopy (SEM) micrographs showed that the PU modification with OSA powerfully retarded the coalescence of BW droplets in film casting process and led to their homogeneity in the dried films. Also, the findings indicated that the water-proof properties including water solubility, water vapor permeability and water contact angle in the PU films were improved by the PU modification and BW incorporation. In addition, the obtained data showed that the octenylsuccination of PU had a negative effect on the mechanical properties of the produced films, while BW incorporation into PU-OSA films led to resolve this drawback.
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The surface of poly (p-phenylene benzobisoxazole) (PBO) fibers with self-healing and ultraviolet (UV)-resistance performance play the key role in prolonging their service lifespan. ...Although great advances have been made in the single aspect of above two properties, integration of self-healing and anti-UV performance into the surface of PBO fiber is still a challenge. In this study, the coagulation strategy mediated by metal-organic framework (MOF) is proposed to construct the multifunctional surface of PBO fibers. The spindle-like iron (III)-based MOF (MIL-88B-NH2) nanocrystals are firstly immobilized onto the surface of PBO-COOH through hydrothermal reaction, then serving as the medium layer to further immobilize sufficient graphene oxide (GO) nanosheets. Benefitting from the favorable near-infrared (NIR, 808 nm) photothermal conversion performance of GO nanolayers, the monofilament composite-PBO@Fe-MIL-88B-NH2-GO-TPU (thermoplastic polyurethane) exhibited a stable and high self-healing efficiency (approximately 80%) within five cycle times. Meanwhile, the cooperative adsorption and shielding weaken effects of MOF-GO nanolayers enabled PBO fibers with excellent anti-UV properties that are superior to much reported literatures after 96 h aging time and eventually increased by 75% compared with untreated PBO fiber. In view of the varieties and multifunctionalities of MOFs and carbon nanomaterials, MOF-mediated coagulation strategy would provide guidance for preparing multifunctional composite materials.
Self‐healing is the way by which nature repairs damage and prolongs the life of bio entities. A variety of practical applications require self‐healing materials in general and self‐healing polymers ...in particular. Different (complex) methods provide the rebonding of broken bonds, suppressing crack, or local damage propagation. Here, a simple, versatile, and cost‐effective methodology is reported for initiating healing in bulk polymers and self‐healing and anticorrosion properties in polymer coatings: introduction of carbon dots (CDs), 5 nm sized carbon nanocrystallites, into the polymer matrix forming a composite. The CDs are blended into polymethacrylate, polyurethane, and other common polymers. The healing/self‐healing process is initiated by interfacial bonding (covalent, hydrogen, and van der Waals bonding) between the CDs and the polymer matrix and can be optimized by modifying the functional groups which terminate the CDs. The healing properties of the bulk polymer–CD composites are evaluated by comparing the tensile strength of pristine (bulk and coatings) composites to those of fractured composites that are healed and by following the self‐healing of scratches intentionally introduced to polymer–CD composite coatings. The composite coatings not only possess self‐healing properties but also have superior anticorrosion properties compared to those of the pure polymer coatings.
This work utilizes a novel, simple, and versatile approach to produce self‐healing polymers by introduction of surface functionalized carbon dots to the polymer. The concept is successfully validated for several common bulk polymers and standard polymer coatings. The introduction of carbon dots not only induces self‐healing but also significantly improves the anticorrosion resistance of the polymer coatings.
To address the phenomenon of rapid fire spread in high-rise steel buildings, this paper used the in situ growth method to crystallize sodium metaborate (SMB) on the surface of layered double ...hydroxide (LDH) and grafted Ti-O onto LDH@SMB hybrid material by hydroxyl action. The synthesized LDH@SMB@Ti (LST) hybrid material was then doped into epoxy resin (EP) to prepare a composite coating. The fire test showed that the LST/EP coating makes the steel plate reach a stable temperature in a shorter time, so that the plate temperature did not continue to rise, and the temperature on the back side of the plate was stabilized at 172.9 °C, which was 87.4 °C lower compared to pure EP. This proves that the LST material gives the coating stronger fire retardant properties upfront and strengthens the continuous insulation ability of the char layer. Cone calorimeter tests showed that the total heat release rate (THR) of LST/EP was reduced by 47.3% and the total smoke release rate (TSR) was reduced by 45.4%, proving the excellent fire and smoke suppression performance of LST/EP. In the expansion performance test, the expansion height and expansion rate of LST/EP reached 29.90 mm and 23.36 respectively, and the expansion of char layer was more uniform. This indicates that the addition of LST hybrid material can improve the mechanical strength of char layer and attenuate the heat transfer rate in the vertical direction. The residual char of LST/EP was 33.2% by thermogravimetric analysis, indicating that the addition of LST could reduce the volatilization of volatile components and improve the thermal stability of EP.
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The properties of potato flour film-forming dispersions obtained with high pressure homogenization (HPH) at a pressure ranging from 15 to 60 MPa with 1, 3, and 5 passes and their resultant films were ...investigated. The median particle size of the dispersions with HPH treatment decreased from 111.65 μm to 10.71 μm, and the result was confirmed by microscopic images. Although the apparent viscosity of homogenized dispersion was smaller than that of the unhomogenized sample, it was noted that the apparent viscosity of homogenized dispersions increased sequentially with pressure and pass. The resultant films with HPH treatment had smoother surfaces, better moisture barrier properties, higher hydrophobicity, lower moisture content, and better transparency. The HPH treatment favored the retrogradation of film, but glass transition temperature had no significant change. The use of HPH increased tensile strength from 6.58 MPa to 11.14 MPa, while elongation at break decreased first and then increased. Potato flour films with HPH treatment show good physicochemical properties and have potential application in food packaging.
•Decrease in particle size and aggregations of dispersion after homogenization.•Apparent viscosity increased with homogenization pressure and passes.•High pressure homogenization improved water resistance performance of films.•Homogenization increased retrogradation enthalpy and tensile strength of films.
The main objective of the present research is to determine the feasibility of using polypropylene (PP) waste to produce eco-friendly gypsum-based composites. Four different replacement levels of ...plastic waste were selected for analysis - 2.5%, 5%, 7.5% and 10% by weight of gypsum. The first stage of the experimental campaign consisted of analysing the resulting composites based on density, mechanical performance (flexural and compressive strength) and surface hardness (Shore C). In the second stage, samples were evaluated based on their water absorption by capillary action or exposing them to continuous moisture in a wet chamber, and water resistance by subjecting them to several wetting-drying cycles. After that, scanning electron microscopy (SEM) analyses were carried out to evaluate the quality of the cohesion at the interfacial transition zone (ITZ) between the PP waste particles and the gypsum matrix. The results showed equivalent compressive strength and even a slight improvement (up to ∼9% when using 2.5% of PP waste when compared to the control material) most likely due to the greater compactness from the improved particle size distribution. In addition, a considerable reduction in water absorption and retention capacity was observed, due to the increasing incorporation of recycled PP into the gypsum matrix. The new PP-containing composites subjected to water absorption by capillary action and continuous moisture tests presented lower water absorption and adsorption capacity, wherein specimens with 10% of PP waste showed a decline of up to ∼37% when compared to the reference material. It was generally observed that the waste material can be considered as a viable partial substitute to the current commercial gypsum for the production of gypsum plasterboards.
•Recycling PP waste in production of gypsum-based materials.•Sustainable application of recycled PP from beneficiated disposable coffee capsules.•Physico-mechanical properties of gypsum compounds with polypropylene (PP) waste.•Compressive strength and surface hardness increased for all PP waste composites.•PP waste composites exhibited lower water absorption and retention capacity.
