Initial Degradation Temperature Research Articles

Tuning thermal and structural properties of nano‐filled PDMS elastomer

AbstractIncreasing the thermal stability and thermal conductivity of polydimethylsiloxane (PDMS) is a crucial issue for thermal applications. This paper focuses on enhancing PDMS's thermal and structural properties by incorporating nanocomposite into the PDMS matrix. An investigation of the impact of rGO‐CaCO3 nanocomposite on the thermal and structural properties of PDMS was performed using Field Emission Scanning Electron Microscopy (FESEM), X‐ray diffraction (XRD), the thermogravimetric analysis and differential thermal analysis (TGA‐DTA), and thermal analyzer tests. It was observed that PDMS doped with rGO‐CaCO3 nanocomposite shows better thermal stability, thermal conductivity, and higher crystallinity. The thermal stability was enhanced significantly by adding a 5% rGO‐CaCO3 nanocomposite, and the initial and end degradation temperatures rose to 492°C and 605°C, respectively. The thermal conductivity of pure PDMS is approximately 0.17 W/mK, whereas a conductive elastomer filled with 5% rGO‐CaCO3 nanocomposite exhibits a thermal conductivity of 0.44 W/mK at a temperature of 20°C. In contrast, the thermal diffusivity is enhanced from 0.13 mm2/s to 0.366 mm2/s. Additionally, the Fourier Transform Infra‐Red (FTIR) spectrum at 1411 cm−1 becomes sharp and noisy, and an additional peak arises at 1398 cm−1, corresponding to the vibrational rocking of the CC bond and COC bond in CaCO3 and rGO.Highlights The manuscript focuses on the development of conductive elastomer by incorporating rGO‐CaCO3 doped and its effect on the morphology, structure, and thermal properties of PDMS. The variation in peak intensity observed in XRD attributed to disparities in the crystalline structure of PDMS due to the inclusion of nanocomposite. The thermal degradation range is observed to shift toward the upper end. The degradation temperature at the beginning and end of the process is observed to move to 492°C and 605°C, respectively, upon introducing a 5% rGO‐CaCO3 nanocomposite. The addition of 5% rGO‐CaCO3 filled conductive elastomers shows a significant improvement of approximately 2.6 times in heat conductivity than bare PDMS.

Effect of desalination of Sargassum algae on its potential use as a stabilizer in sustainable earth-based bricks

Since 2011, Caribbean beaches have been flooded by massive quantities of pelagic Sargassum, causing environmental, health and financial problems. The use of Sargassum ash as a stabilizer in the manufacture of bricks can help mitigate the economic impact of Sargassum grounding by adding value. This study assesses the effect of the Pelagic Sargassum algae desalination process on the properties of the biomass as well as the potential application of their ash as a stabilizer in soil-based bricks. Fresh Sargassum algae was subjected to two cycles of immersion in water, then calcined under different conditions (temperature and time) and characterized. The desalinated Sargassum ash (SA) was used to partially replace cement in the stabilization of earth bricks. Characterization of raw and desalted Sargassum shows a reduction in ash content from 28.44 to 17.25 % after desalination. Furthermore, the thermo gravimetric analysis show a slight reduction in the initial degradation temperature between 204 and 602 °C, which is associated with a reduction in the amount of residual char from 35 % to 27 %. The results of the XRF analysis of the SA showed a very low alumiosilica content (SiO3 + Al2O3 < 4 %), but a significant increase in CaO content after desalination from 21.96 to 50.17 %. The XRD results of the SA are consistent with the XRF analysis which reveals that the desalination process significantly increased the CaCO3 content from 19 to 67 %, while KCl decreased significantly from 26 to 8 %. Furthermore, the characterization of the composites reveal that partial substitution of 10 wt% cement by SA calcined at 700 °C for 2 h has no significant effect on water absorption, density, compressive strength and chemical composition of earth bricks. This material could help reduce pollution linked to the decomposition of sargassum on Caribbean coasts and beaches, as well as greenhouse gas emissions linked to cement production.

The rigid-flexible balanced molecular crosslinking network transition interface: An effective strategy for improving the performance of bamboo fibers/poly(butadiene succinate-co-butadiene adipate) biocomposites

The poor interfacial compatibility of natural fiber-reinforced polymer composites has become a major challenge in the development of industry-standard high-performance composites. To solve this problem, this study constructs a novel rigid-flexible balanced molecular crosslinked network transition interface in composites. The interface improves the interfacial compatibility of the composites by balancing the stiffness and strength of the fibers and the matrix， effectively improving the properties of the composites. The flexural strength and flexural modulus of the composites were enhanced by 38 % and 44 %, respectively. Water absorption decreased by 30 %. The initial and maximum thermal degradation temperatures increased by 20 °C and 16 °C, respectively. The maximum storage modulus increased by 316 %. Furthermore, the impact toughness was elevated by 41 %, attributed to the crosslinked network's efficacy in absorbing and dissipating externally applied energy. This innovative approach introduces a new theory of interfacial reinforcement compatibility, advancing the development of high-performance and sustainable biocomposites.

Influence of multi-walled carbon nanotubes on thermal behaviour and mechanical properties of pineapple leaf fibre-based natural rubber composites

Replacing synthetic fibres with natural fibres as reinforcement fillers in natural rubber (NR) tends to yield eco-friendly bio-composites. This study investigated the tensile and hardness properties, and the thermal behaviour of pineapple leaf fibre (PALF)-reinforced NR composites with and without the addition of multi-walled carbon nanotubes (MWCNT). The fibre content was varied at 0, 10, 20, and 30 parts per hundred rubber (phr) and the MWCNT content was fixed at 10 phr. The surface morphology of the tensile-fractured specimens was examined using scanning electron microscopy (SEM) to identify the rubber-matrix adhesion and tear mechanisms of the fibres in the NR matrix. The results revealed that including the PALF and MWCNT allowed the NR composites to exhibit excellent stretching stress at low elongations. Additionally, the composites displayed enhanced stiffness, further increasing the hardness of the composite, ranging from 46.8 to 62.8 Shore A. However, PALF reduces the thermal stability of the composite, where the initial degradation temperature increases. From the thermogravimetric analysis, the residues remaining in the NR composites ranged from 6 to 13% at various fibre loadings. Therefore, this study provides valuable insights into the tensile and hardness properties and the thermal behaviour of PALF-reinforced NR composites to improve end-use properties.

Optimization and prediction of thermodynamic parameters in co-pyrolysis of banana peel and waste plastics using AIC model and ANN modeling

The optimization and prediction of thermodynamic parameters including synergistic effects, and kinetic analysis in co-pyrolysis of banana peel (BP) and waste polystyrene (PS) plastic at different heating rates using ANN and AIC models has been performed. Thermogravimetric analysis was performed to determine the initial, maximum, and final degradation temperatures. The synergistic effect was studied using additive formula to determine the theoretical thermal behavior and compared with experimental TGA data. Kinetic parameters were determined by using the advanced isoconversional (AIC) model for estimation of activation energy (Eα), Criado master plot for reaction mechanism (f(α)), and compensation method for frequency factor (Aα). The analysis showed that the average activation energy values were 182.5, 140.6, and 161.8 kJ mol−1 for PS, BP, and PS+BP, respectively. It also clearly shows positive synergy in co-pyrolysis of PS and BP by reducing 11.3 % activation energy compared to that of PS alone. The frequency factor was found to be 1.0 × 1014, 1.0 × 1015, and 1.0 × 1023 s−1 for PS, BP, and PS+BP, respectively. The reaction mechanism was identified as R3, D4, and D4+R3 for PS, BP, and PS+BP, respectively. Further, the obtained kinetic parameters were used to determine the thermodynamic parameters such as enthalpy (ΔH), Gibbs energy (ΔG), and Entropy (ΔS). Finally, ANN was designed to address the co-pyrolysis behavior subjected to various heating rates. Subsequently, the trained ANN model (5 × 4×4 × 4) was employed to forecast thermal degradation behavior. Impressively, the model yielded highly accurate results with a correlation coefficient R2 > 0.998 in each case. The optimized model was further used to predict TGA data and activation energy for unknown mixtures of PS and BP. The suggested ANN model showed a great advantage in optimizing to avoid extensive experiments at various heating rates to achieve the goal.

Mussel-inspired synergistic anticorrosive coatings for steel substrate prepared basing on fully bio-based epoxy resin and biomass modified graphene nanoparticles

Traditional epoxy anticorrosive coatings face challenges such as reliance on non-renewable petroleum resources, environmental pollution, brittleness and poor long-term anticorrosion performance. In this work, the bio-based coatings are fabricated to address the above issues by using epoxidized soybean oil (ESO) as the resin matrix, tannic acid (TA) as curing agent and modified graphene (TH-rGO) nanoparticles as functional fillers. Inspired by mussels, the phenolic hydroxyl groups of TA are fully used, so that the coating has in-situ adhesion to the steel substrate. The TH-rGO nanoparticles, formed by grafting L-histidine onto GO and reducing them with TA, exhibit favourable dispersion stability in epoxy coating suspension. And the prepared coating films exhibit favourable tensile ductility with the strain of higher than 14%, thermostability with the initial degradation temperature above 300 ℃, as well as impervious performance and antimicrobial activity. Furthermore, the results of electrochemical impedance spectroscopy test demonstrate that after 8 weeks of immersion in simulated seawater, the low-frequency impedance modulus at 0.01 Hz of the nanocomposite coating with optimal nanoparticles content reaches 4.42×109 Ω cm2, resulting in favourable durability of anticorrosion performance. This study presents a facile fabrication approach of bio-based epoxy coatings with durable anticorrosion performance, demonstrating potential for industrial applications.

A strong hydrogen bond bridging interface based on tannic acid for improving the performance of high-filled bamboo fibers/poly (butylene succinate-co-butylene adipate) (PBSA)biocomposites

Natural plant fiber-reinforced bio-based polymer composites are widely attracting attention because of their economical, readily available, low carbon, and biodegradable, and showing promise in gradually replacing petroleum-based composites. Nevertheless, the fragile interfacial bonding between fiber and substrate hinders the progression of low-cost and abundant sustainable high-performance biocomposites. In this paper, a novel high-performance sustainable biocomposite was built by introducing a high density strong hydrogen-bonded bridging interface based on tannic acid (TA) between bamboo fibers (BFs) and PBSA. Through comprehensive analysis, this strategy endowed the biocomposites with better mechanical properties, thermal stability, dynamic thermo-mechanical properties and water resistance. The optimum performance of the composites was achieved when the TA concentration was 2 g/L. Tensile strength as well as modulus, flexural strength as well as modulus, and impact strength improved by 22 %, 10 %, 15 %, 35 %, and 25 % respectively. Additionally, the initial degradation temperature(Tonset) and maximum degradation temperature(Tmax) increased by 12.07 °C and 14.8 °C respectively. The maximum storage modulus(E'), room temperature E', and loss modulus(E")elevated by 199 %, 75 %, and 181 % respectively. Moreover, the water absorption rate decreased by 59 %. The strong hydrogen-bonded bridging interface serves as a novel model and theory for biocomposite interface engineering. At the same time, it offers a promising future for the development of high performance sustainable biocomposites with low cost and abundant biomass resources and contributes to their wide application in aerospace, automotive, biomedical and other field.

Preparation and characterization of halloysite nanotube‐silica/silicone rubber composites: Effect of HNTs on mechanical and thermal properties

AbstractA series of halloysite nanotube‐silica (HNTs‐SiO2) nanocomposite fillers were prepared by in‐situ assembly, and a reinforced SiO2/SR composite was obtained by filling them into silicone rubber (SR). The morphology and structural characterization of HNTs‐SiO2 and HNTs‐SiO2/SR and the properties of the HNTs‐SiO2/SR were studied. As a result, the small particle size SiO2 was firmly anchored onto the HNTs surface, and the obtained HNTs‐SiO2 nanofillers were uniformly dispersed in SR. At a 30 phr fixed filler loading, the weakest filler network and the best filler dispersion were obtained when HNTs content in HNTs‐SiO2 was 5%. This resulted in a maximum tensile strength obtained of 6.2 MPa, 1.55 times that of SiO2/SR with the same filler loading, and a maximum elongation at break of 418%, 1.67 times that of the SiO2/SR with the same filler loading, and at the same time the tearing strength and hardness are also improved. Furthermore, the silicone rubber also showed improved thermal stability, with an initial degradation temperature increase of 30°C under a nitrogen atmosphere.Highlights HNTs–SiO2 nanocomposites were successfully prepared by the self‐assembly method and used as fillers in SR as a new type of reinforcing material. The 1D HNTs act as a barrier to prevent SiO2 aggregation and improved fillers dispersion. The elongation at break and tensile strength of 5% HNTs‐SiO2/SR are 67% and 55% higher than those of SiO2/SR, respectively. The silicone rubber also showed improved thermal stability.

Ultra-high cross-linked active ester-cured epoxy resins: Side group cross-linking for performance enhancement

Active ester hardeners are a unique class of epoxy hardeners that undergo a curing reaction without generating secondary hydroxyl groups. This characteristic enables the production of low dielectric and low moisture absorption epoxy resins. In this study, two active ester hardeners, bisphenol A diisobutyrate (DIB) and bisphenol A dimethacrylate (DMA), were used to prepare epoxy resins by reacting with a resveratrol-based epoxy monomer (REP). By cross-linking the double bonds in the resin (using dicumyl peroxide, DCP), the properties of the resin can be dramatically changed. Among the resins prepared, REP/DMA/DCP exhibited the highest cross-linking density, approximately 48 times that of REP/DIB. Its storage modulus at 300 °C remained at 600 MPa, indicating an equivalent glass transition temperature (Tg) higher than 300 °C. Additionally, the cross-linking of the ester side groups increased the initial degradation temperature by 12–13 °C, reaching 395–396 °C. Regarding the coefficient of thermal expansion (CTE), the cross-linking of ester side groups had no significant effect on the CTE in the glassy state. However, it drastically reduced the CTE above the glass transition temperature. The average CTE (30–300 °C) of REP/DMA/DCP was only 106 ppm/°C. Furthermore, the cross-linking of the ester side groups appeared to reduce the dielectric constant but increased the dielectric loss and the water absorption rate. Nevertheless, REP/DMA/DCP's dielectric constant at 10 MHz of 3.07, dielectric loss of 0.01, and saturated water absorption of 0.77 wt% remain in the low range.

Effect of metals and brominated flame retardants on thermal degradation kinetics of waste printed circuit board

Waste printed circuit board (WPCB) is an indispensable component in any waste electrical and electronic equipment (WEEE). A promising method for recycling WPCB is pyrolysis. To understand the effect of metals and brominated flame retardants (BFR) on WPCB pyrolysis, four samples were prepared, namely (a) raw WPCB (RW), (b) non-metallic WPCB (NM), (c) bromine extracted WPCB (RWBFR_ext) and (d) bromine and metal extracted WPCB (NMBFR_ext). The degradation kinetics study using the isoconversional methods: Friedman, Ozawa-Flynn-Wall (OFW), Kissinger–Akahira–Sunose (KAS), and Starink showed that the extraction of metals exhibited an increase in final degradation temperature and activation energy (Eα), and altered the reaction mechanism (f(a)) whereas, the reduction of BFR reduced initial degradation temperature. The identified kinetic triplets were verified using the reconstruction profiles. The parameters can be used in designing applications and developing an energy-efficient pyrolysis process.

Extraction of lignin-containing nanocellulose fibrils from date palm waste using a green solvent

Lignin-containing nanocellulose (LNC) is a compelling alternative to traditional nanocellulose (NC), it offers enhanced yields and a reduction in the demand for toxic chemicals. This research involves the isolation of LNC from date palm waste using a green hydrolysis process and its subsequent characterization. The potential of using ionic liquids (ILs) as green solvents to isolate LNC has not yet been explored. Our findings suggest that 1-ethyl-3-methylimidazolium chloride ([Emim]Cl) can hydrolyze partially delignified and unbleached lignocellulose, achieving LNC synthesis. The obtained LNC showed a higher yield than its NC counterpart and exhibited rod-shaped fibers with nanoscale diameters and micrometer lengths, indicating a high aspect ratio. Dynamic Light Scattering (DLS) results indicate average particle sizes of 143.20 nm for NC and 282.30 nm for LNC, with a narrow particle size distribution conforming their monodisperse behavior. Thermogravimetric analysis and differential scanning calorimetry revealed high thermal stability (initial degradation temperature = 222.50 °C and glass transition temperature = 84.45°C) of LNC. Moreover, the obtained LNC fibers were crystalline (crystallinity index = 52.76 %). Their activation energy (124.95 kJ/mol) was determined using the Coats–Redfern method by employing eight solid-state diffusion models. Overall, this study motivates the use of ILs as green solvents to produce lignocellulose derivatives that are suitable for various applications.

Pu-erh tea-derived cellulose exhibits superior water/oil holding capacity compared to black and green tea celluloses: A comprehensive analysis

In this study, residues from black, green, and Pu-erh teas were used as raw materials to extract cellulose through alkali treatment and two-stage bleaching process. The structure and properties of the tea celluloses were compared. The yield and purity of the cellulose ranged from 6.3% to 10.1% and 75.5%–88.9%, respectively. The celluloses exhibited a typical bundle fiber morphology and an I-type crystal structure, with the Iβ structure being the predominant allomorph. Crystallinity was highest in Pu-erh tea cellulose (54.8%), followed by black tea cellulose (52.6%), and green tea cellulose (47.4%). Green tea cellulose displayed the highest initial thermal degradation temperature, while Pu-erh tea cellulose had the lowest. Pu-erh tea cellulose showed the highest moisture absorption rate (12.6%), water holding capacity (10.1 g/g), and oil holding capacity (5.7 g/g), whereas these values were lowest in black tea cellulose. The correlation coefficient between Iβ structure content and water holding capacity is −0.90, and −1.00 with oil holding capacity. This study not only opens new pathways for the recycling of tea residues and their application in food packaging but also highlights the potential of tea-derived cellulose as an innovative material for dietary fiber resources with excellent water/oil holding capacities.

Evaluation of the impact of natural weathering on the properties of high‐density polyethylene bottles by experimental approach

AbstractThis work presents an in‐depth experimental study aimed at assessing the impact of natural weathering on the behavior of high‐density polyethylene (HDPE) bottles. To this end, several analytical techniques were employed, including Fourier transform infrared spectroscopy (FTIR) to examine molecular changes, scanning electron microscopy (SEM) to study morphology, thermogravimetric analysis (TGA) to assess thermal properties, and tensile and compression tests to evaluate mechanical properties. The results obtained reveal significant changes in HDPE exposed to natural weathering. FTIR analysis enabled us to identify that the HDPE bottles had been subjected to an oxidation process initiated by the absorption of solar radiation during natural weathering treatments, while SEM analysis showed the presence of holes resulting from the detachment of material fragments after exposure, TGA analysis confirms the impact of natural exposure time on the decrease in the average molecular weight and chemical degradation of HDPE macromolecules, through a reduction in the initial degradation temperature and the maximum thermodegradation temperature. However, tensile and compressive tests showed a reduction in the mechanical strength of HDPE after exposure to natural conditions, with notable variations depending on environmental conditions, making the material damaged. These results enabled us to calculate the damage caused by three damage laws. These results offer important insights into the mechanisms of HDPE degradation under the influence of natural climatic factors, paving the way for the development of more resistant and durable packaging materials in the face of variable environmental conditions.Highlights The objective of this study is to analyze and describe the effects of natural weathering on high‐density polyethylene bottles. This involves evaluating the deterioration of physicochemical, mechanical, and morphological properties. Additionally, three damage laws are employed to assess the extent of damage inflicted by this material. Analytical techniques were used, including SEM, FTIR, and TGA, tensile and compressive test.

Synthesis and characterization of perfluorocyclopentene‐thioether polymers

AbstractDue to their unique properties and use in high performance materials, the ability to obtain fluorinated polymers utilizing straightforward synthetic methods remains of interest. In this study, we report the facile synthesis of new fluoropolymers via nucleophilic addition of a di‐thiol to perfluorocyclopentene. Initially, model studies were completed with perfluorocyclopentene, benzenethiol and tetramethylsilane‐protected benzenethiol to identify the optimal reaction conditions for the polymerization. These reaction conditions were then utilized to prepare perfluorocyclopentene‐thioether polymers from perfluorocyclopentene and 4,4′‐thiobisbenzenethiol. The isolated polymers had molecular weight distributions consistent with step‐growth polymers and 19F NMR spectroscopy revealed that the addition of the nucleophile to perfluorocyclopentene was controlled. Analysis by DSC showed that the polymers were amorphous with glass transition temperatures around 65 °C. TGA in both air and nitrogen showed an initial degradation temperature around 370 °C, while the air analysis produced an additional plateau with a degradation temperature near 592 °C. This is the first known report of utilizing perfluorocyclopentene for the preparation of perfluorinated‐thioether polymers. © 2024 Society of Industrial Chemistry. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Fabrication of boron nitride reinforced carboxymethyl modified lignin-based re-crosslinkable hydrogel with excellent heat dissipation ability

In this work, a series of re-crosslinkable hydrogels comprising carboxymethylated lignin, PVA and 3-aminophenylboronic acid (3-ABA) was successfully synthesized. Incorporation of polydopamine (PDA) coated boron nitride (PDA@BN) endowed the hydrogel with significantly improved heat dissipation ability, mechanical strength and swelling resistance. The hydrogel containing 20 % of PDA@BN, namely Gel-20 %BN displayed an initial degradation temperature of 131 ℃ and a high thermal conductivity of 3.74 W/m·K, surpassing a plethora of different biobased hydrogels. Gel-20 %BN maintained stable morphology even under continuous heating at 200 ℃ for 15 min and exhibited low surface temperatures without undergoing melting or decomposition, thus demonstrating remarkable heat dissipation capability. The re-crosslinked hydrogel, referred to as Re.Gel-20 %BN, retained similar performance to Gel-20 %BN, maintaining excellent heat dissipation characteristics and stability at 130 ℃ over an extended period. Further investigation is warranted to explore degradation or recovery methods of this hydrogel in reservoir conditions, aiming to minimize the environmental impact of petroleum extraction and contribute to a greener and more sustainable oil production process.

Sm2O3 micron plates/B4C/HDPE composites containing high specific surface area fillers for neutron and gamma-ray complex radiation shielding

In this study, a series of Sm2O3 micron plates/B4C/HDPE composites composed of synthesized Sm2O3 fillers (Sm2O3 micron plates) are prepared for shielding neutron and gamma radiation. The influence of micromorphology of Sm2O3 fillers on neutron and gamma radiation shielding properties of composites is investigated in detail. The XRD pattern reveals that the phase of synthetic Sm2O3 is cubic crystal systems, body-centered cubic lattices, and its space group is Ia 3‾ (206). SEM images and BET analyses reveal that the micromorphology of synthesized Sm2O3 is micron plates. The BET-specific surface area of the Sm2O3 fillers is increased with addition of urea content. The differential scanning calorimetry (DSC) curves reveal that Sm2O3 fillers increase the melting temperature of the composites, which is up to 138.6 °C. The thermogravimetric analysis (TGA) results reveal that the initial thermal degradation temperatures of the composites are all above 440 °C. The neutron and gamma radiation shielding tests show that Sm2O3 fillers with high BET-specific surface area (8.20 m2/g) and uniform size improve the neutron and gamma shielding rate of composites. A superior composite containing 10 wt% Sm2O3 (R = 1:25, R value represents the molar ratio of rare earth elements to urea)/20 wt% B4C/70 wt% HDPE has a neutron radiation shielding rate of 98.7% with a thickness of 15 cm under the 252Cf neutron source and a gamma radiation shielding rate of 72.1% with a thickness of 15 cm under 137Cs gamma source. And these lead-free and environment-friendly composites can be widely used in the neutron and gamma complex radiation fields.

Fabrication of thermally resistant and mechanically flexible polyimide foams with anisotropic pore structures for thermal insulation and irradiation tolerance applications

Flexible polyimide foams (PIFs) demonstrate a great potential for applications in the fields of thermal insulation, flame retardancy and irradiation tolerance. In this work, mechanically flexible PIFs with anisotropic pore structure were prepared by adopting the copolymerization strategy and microwave-assisted foaming process. The copolymerization reaction was conducted to synthesize polyester ammonium salt (PEAS) precursors using 3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride (BTDA) as dianhydride, 4,4′-diaminodiphenyl ether (ODA) and 4,4′-diaminodiphenyl sulfone (DDS) as the copolymerized diamines; afterwards, PEAS powders with particle sizes ranging from 100 to 300 μm were obtained by drying, crushing and sieving treatments, which were used as the feedstock for “bottom-up” microwave-assisted foaming and thermal imidization process, thereby leading to the formation of PIFs with regular three-dimensional near-spherical pores in vertical direction (parallel to the pore growth direction) and the aligned ellipsoidal strip-like pore structure in horizontal direction. The directional growth of foam pores resulted in anisotropic mechanical flexibility and thermal insulation performance. Moreover, PIFs possessed excellent thermal stability and flame retardancy with the initial thermal degradation temperature higher than 545 °C and limited oxygen index up to 58.8%. The PIFs exhibited exceptional thermal insulation performance with thermal conductivity values ranging from 0.0276 to 0.0517 W/(m·K) between 25 and 300 °C. Additionally, the PIFs demonstrated excellent irradiation tolerance, with the mechanical and thermal stability retention rate being above 96% after the irradiation experiment (radiation dosage: 1.15 × 105 Gy) using 60Co source. Thus, lightweight PIFs with superior high temperature thermal insulation performance, flame retardancy and irradiation tolerance were successfully prepared, which showed potential applications in aerospace, medical and nuclear power sectors.

Nanoarchitectured composite of polysulfone and carbon-based fillers bearing magnetically stimulable function for efficient CO2 capture

Mitigating the global warming caused by CO2 emissions from anthropogenic sources is a hot research topic in the current era. The high cost and difficulty in handling liquid solvent absorbents for CO2 capture are the main barriers to their industrial application. Earth-abundant solid sorbents are favorable candidates for CO2 separation, offering a low energy penalty for CO2 desorption. Here, Polysulfone (PSF) nanocomposites were prepared by simple solution blending. The carbon-based fillers, namely carbon nanotubes (CNT), and activated carbon (CA) in the range of 5–20 wt%, containing iron nanoparticles, were used as fillers. Their morphological, thermal, CO2 capture capacity and magnetic properties were comprehensively studied. Transmission electron microscopy (TEM) evidenced uniform filler distribution in the polymer matrix with sizes of 47–54 nm. Thermal analysis revealed an approximately 4 °C improvement in both the initial (Tonset) and maximum (Tmax) degradation temperatures by adding 5 wt% of nanoparticles compared to the pristine polymer. The glass transition temperature (Tg) of the pristine PSF and produced nanocomposites showed identical values as estimated by differential scanning calorimetry (DSC). The increase in filler amount gradually decreased the water contact angle values, indicating a hydrophilic classification of the PSF nanocomposites. The obtained PSF nanocomposites exhibited an efficient CO2 capture capacity of about 40–61 mgCO2/g at 45 °C, higher than pristine PSF. This remarkable achievement sets a new benchmark compared to previously developed systems. The introduction of the filler transforms the diamagnetic polymer matrix into a ferromagnet, presenting a coercivity of about 480 Oe, enhancing the material's potential for applications in microelectronics.

Biodegradable compatibilizer modified corn stover/poly(butylene adipate‐co‐terephthalate) composites

AbstractGreat environmental and economic benefits can be achieved by utilizing the agricultural residue corn stover (CS) to prepare the biodegradable poly(butylene adipate‐co‐terephthalate) (PBAT) composites. However, CS contains polarized hydroxyl groups from its main component cellulose, thus leading to its poor wetting by hydrophobic PBAT. It is of great significance to promote the compatibility between CS and PBAT for the improvement of interfacial interactions and composite performance, but the compatibilizer modified CS/PBAT biocomposites have been rarely mentioned until now. In this study, polyethylene glycol (PEG), glycidyl methacylate (GMA), and ethylene vinyl alcohol copolymer (EVOH) were chosen to investigate the compatibilizer effect on the morphology, microstructure, thermal properties, mechanical strength, and water absorption capacity of the biodegradable CS/PBAT composites. The results reveal that the incorporated compatibilizers obviously improve the interface adhesion between CS and PBAT by reducing the hydrophilicity of CS surface. The enhanced interfacial bonding interactions effectively promote the crystallinity and mechanical strength of the CS/PBAT composites, but the initial degradation temperature and hydrophilicity of compatibilizers themselves also remarkably influence the composites’ thermostability and water absorption.Highlights The agricultural residue corn stover (CS) was used to reinforce PBAT. Effects of three different compatibilizers on the composites were studied. Compatibilizer improves the interface adhesion between CS and PBAT. Compatibilizer promotes crystallinity and mechanical strength of composites. The stability and hydrophilicity of compatibilizer affect those of composite.

Eco-friendly flame-retardant coatings based on γ-ureidopropyltriethoxysilane for cotton fabrics with improved flame retardancy and mechanical properties

In this study, a bio-based coating was constructed by sol-gel technique deposition based on γ-ureidopropyltriethoxysilane (TESPR) and ammonia phytate (AP) to acquire fire-safety cotton fabrics. The flame retardancy, thermal stability, burning behavior, flame retardant mechanism, and mechanical properties of the coated cotton fabrics were evaluated. With about 9.91% weight gain of TESPR/AP coatings, the coated cotton fabrics self-extinguished in the vertical flame test, and the limiting oxygen index arrived at 31%. The thermogravimetric analysis revealed that although the initial thermal degradation temperature of Cotton/TESPR/AP was lower than that of uncoated cotton fabrics, the char residues in the high-temperature range increased. Meanwhile, the results of the cone calorimetry test revealed that both the heat and smoke production released of cotton/TESPR/AP was greatly reduced during burning. The flame-retardant mechanism of this system was eventually suggested depending on the assessment of gaseous products and char residues. Furthermore, TESPR/AP coatings did improve the breaking force of cotton fabrics compared with that of AP coatings, while retained better air permeability compared with that of uncoated cotton fabrics. These bio-based coatings not only ensure safety, but also provide a practical flame-retardant solution for inflammable natural fabrics.