Thermal Transition Temperature Research Articles

One‐step polymerization of polyvinyl alcohol/cashew gum/polypyrrole/copper oxide nanocomposites for high‐performance flexible films in optoelectronics

AbstractA ternary blend nanocomposite composed of polyvinyl alcohol/cashew gum/polypyrrole (PVA/CG/PPy) with varying contents of copper oxide (CuO) nanoparticles was synthesized via an in situ polymerization method, using water as an eco‐friendly solvent. Fourier‐transform infrared spectroscopy (FTIR), UV–visible spectroscopy, field emission scanning electron microscopy (FE‐SEM), x‐ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) were used to characterize the ternary blend nanocomposites. FTIR and UV–visible spectra demonstrated strong intermolecular interactions between the functional groups of the PVA/CG/PPy blend and the CuO nanoparticles. XRD patterns revealed that the CuO nanofillers were arranged in a structured manner within the ternary blend matrix. FE‐SEM confirmed the uniform dispersion and structured arrangement of CuO nanofillers at a concentration of 3 wt% within the blend matrix. TGA and DSC results showed that the addition of CuO nanoparticles to the PVA/CG/PPy blend improved both the thermal stability and glass transition temperature of the blend matrix. Electrical properties improved with CuO content up to 3 wt%, resulting in enhanced conductivity, an increased dielectric constant, and reduced activation energy. The highest tensile strength, 13.76 MPa, was also observed at this concentration. However, properties declined beyond 3 wt% due to agglomeration, making 3 wt% the ideal concentration for maximum performance. This study highlights the potential of PVA/CG/PPy/CuO nanocomposites for applications requiring improved electrical properties and thermal stability, particularly in flexible electronics and energy storage devices.Highlights Eco‐friendly synthesis of PVA/CG/PPy/CuO biopolymer nanocomposite films Improvement in morphological, and optical properties of PVA/CG/PPy/CuO films. CuO nanofillers magnify the thermal properties of the pristine PVA/CG/PPy Conductivity and dielectric characteristics: frequency and temperature dependence explored. PVA/CG/PPy/CuO nanocomposite films: pliable contenders unveiling industrial potentials.

Phase transformation and metallurgical characterization of heat-treated nickel–titanium rotary instruments using differential scanning calorimetry, X-ray diffraction, and energy dispersive spectrometry

Objective: The present study aimed to evaluate the phase transformation behavior and elemental analysis of thermomechanical-treated nickel–titanium (NiTi) rotary instruments, TruNatomy (Dentsply Sirona), HyFlex CM (coltene, Whaledent), and Neoendo Flex (Orikam healthcare India), using differential scanning calorimetry (DSC), X-ray diffraction (XRD), and energy dispersive X-ray spectrometry. Materials and Methods: A total of 18 NiTi rotary instruments, TruNatomy, Hyflex CM, Neoendo Flex, taper. 04, size 25 (except TruNatomy, size 26) were selected and were divided into three groups (n = 6). Three NiTi files from each group were investigated for the DSC test (n = 3). The two segments of each sample were cut carefully by slow-speed water-cooling carborundum disc at 3 mm from the tip and then 4 mm from the previous section. The mass of the samples was measured on the electronic balance and samples that weighed 10–15 mg were loaded into a 40 µL aluminum crucible. The samples are then subjected first to a heating cycle from 0°C to 100°C and subsequently a cooling cycle from 100°C to 0°C in the differential scanning calorimeter (Mettler-Toledo, NIT Srinagar) at a rate of 10°C min−1. XRD (Make. Rigaku Japan, smart lab 3kW, NIT Srinagar.) was performed to verify the DSC results. The remaining two samples from each group (n = 2) were subjected to XRD analysis. The sample preparation for XRD analyses was done precisely with slow speed water cooled carborundum disc and samples were sectioned into three segments. Each segment was 5 mm long and grounded to obtain a uniform smooth plane. The data obtained from DSC and XRD were subjected to origin 8.5 software and graphs were obtained that depict the transformation temperature and phase composition, respectively. Alloy distribution and trace elements of the NiTi rotary instruments were done using energy dispersive spectrometry microanalysis. Results: The DSC results showed that the TruNatomy, Hyflex CM, and Neo Endo instruments had an Austenite finish (Af) temperature exceeding 37°C. The XRD graphs show the different intensity peaks that correspond to the various phases of NiTi rotary instruments. The TruNatomy is predominantly Austenite, Hyflex CM exists mainly in R-phase with a variable amount of austenite and martensite, while Neoendo flex endo mostly contains austenite phase. The elemental analysis revealed that all three file systems show Nickel and Titanium within their bulk structure in an equiatomic ratio. Conclusion: This study concluded that TruNatomy is predominantly martensite with a variable amount of austenite phase. There are differences in thermal transition temperature between the files.

Thermosensitive polymer/nanosilica hybrid as a multifunctional additive in water-based drilling fluid: Rheologicalproperties and lubrication performance as well as filtration loss reduction capacity

In previous studies, for obtaining a flat rheological drilling fluid, binary and ternary thermosensitive silica (SiO2) nanohybrids as rheological modifiers were synthesized using N-isopropylacrylamide with a thermal association temperatureof 32–33 °C as the thermosensitive monomer [J. Petrol. Sci. Eng. 219 (2022), 111096; Geoenergy Science and Engineering 228 (2023), 211934]. However, the as-synthesized SiO2 nanohybrids exhibited limited performance and low thermal transition temperature. Thus surface initiated atom transfer radical polymerization was utilized to graft hydrophilic poly(ethylene glycol) methyl ether methacrylate (PEGMA) onto SiO2 surface to obtain PEGMA/SiO2 nanohybrids with an elevated thermal association temperature of 75 °C. The morphology and structure of the as-synthesized PEGMA/SiO2nanohybrid were characterized by infrared spectroscopy and transmission electron microscopy; and its effects as a thermosensitive multifunctional additive on the rheological properties and lubrication performance as well as filtration loss reduction capacity of a water-based drilling fluid were investigated. Results indicate that the drilling fluids with 1.0% PEGMA/SiO2 nanohybrids exhibited obvious thermal thickening behavior in the temperature range of 70–80 °C; at low temperatures, however, they had a significant viscosity reduction effect therein. At room temperature, the apparent viscosity and plastic viscosity were reduced by 68% and 50%, respectively. Besides, due to the tightly packed plugging layer formed by PEGMA/SiO2 nanohybrids and bentonite, the filtration loss of the drilling fluids containing 1.0% PEGMA/SiO2 nanohybrid was reduced by 37% as compared with that of the base slurry; and the lubrication coefficient was decreased by up to 50%. Moreover, the high-temperature aging process promoted the intermolecular interactions of the nanohybrids and their interaction with bentonite flakes, thereby further improving the rheological behavior, filtration reduction ability, and lubricity of the drilling fluids. The as-synthesized thermosensitive PEGMA/SiO2 nanohybrids with excellent multifunctionality could find promising application in water-based drilling fluids.

Fabrication of gallic acid containing poly(vinyl alcohol)/chitosan electrospun nanofibers with antioxidant and drug delivery properties

Chitosan-based nanofibers with excellent properties are attractive materials for specific industrial applications of contemporary interest. This work aims to fabricate functional nanofibers based on poly(vinyl alcohol)/chitosan (CS) with an antioxidant and model drug molecule, gallic acid (GA), by electrospinning, followed by cross-linking through glutaraldehyde (PVA-CS-GAs). PVA-CS-GAs were electrospun at two different concentrations by the adjustment of the CS feeding ratio. The detailed characteristics of the as-prepared electrospun nanofibers were elucidated by Fourier Transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), water contact angle (WCA) measurements, thermogravimetric and differential scanning calorimetry (TGA and DSC) analyses. SEM images indicated that the average fiber diameter distribution was in the range of 90–110 nm. The results show that morphology, mean diameter, wettability, and thermal characteristics of the composite nanofibers were affected by the CS feeding ratio. Although the increase in the amount of polar -OH groups with the addition of GA caused an improvement in the hydrophilicity and thermal stability of the electrospun nanofibers, it also caused a decrease in the thermal transition temperatures. Furthermore, antioxidant tests based on DPPH radical scavenging ability and in vitro release studies demonstrated that the cross-linked PVA-CS-GA composite nanofibers have good antioxidant activity and a pH-dependent drug release rate, indicating their potential for implementation in wound healing and drug delivery applications.

Ionic liquid/polybenzimidazole/SiO2 composite membranes for medium temperature operating

Fuel cells (FC) with proton exchange membranes (PEMs) are seen as an alternative energy source due to their efficiency, power density, low emissions, and reliable energy supply. Proton exchange membranes based on polybenzimidazole have shown potential for operating at high and medium temperatures to enhance FCs performance. New composite membranes made from m-PBI and diethylammonium mesylate [DEAH/MsO] ionic liquid were prepared trough a solution casting method. Silica nanopowder (SiO2) was used as an inorganic filler at varying concentrations (0.5–20 wt%). The ionic liquid content in the membranes ranged from 1 to 2.5 mol per mole of PBI monomer units. Our study is focused on the thermal properties, such as thermal stability and phase transition temperatures, morphology, conductivity, and electrochemical stability of the membranes. The influence of the inorganic filler on these properties was also discussed.

Thermal and textural properties of extruded rice affect its cooking performances and the texture of the steamed extruded rice

Extruded rice has increasingly gained popularity in the market due to its convenience and acceptable texture. The objective of this study was to understand how the physicochemical, thermal, and textural properties of the extruded rice affected its cooking properties and texture of the cooked one. It was found that air trapped in the grains during extrusion reduced the transparency of extruded rice. More air trapped in the grains reduced the true density of the extruded rice, which in turn decreased the hardness of extruded rice. A looser internal structure of extruded rice grain, as indicated by the lower true density, resulted in a faster hydration and shorter optimum cooking time. Extruded rices showed two thermal-transition peaks, with peak 1 from 93.3 °C to 112.8 °C and peak 2 from 107.5 °C to 132.5 °C. The increased hardness of extruded rice led to increases in its thermal-transition temperatures, longer optimum steaming time, and decreases in its water absorption and cooking loss, which resulted in an increase in the hardness and a reduction in the adhesiveness of the steamed one. This study provides insights into the key factors determining the eating quality of extruded rice, which is beneficial for food scientists in developing premium extruded rice.

Cryogenic mechanical performance and gas-barrier property of epoxy resins modified with multi-walled carbon nanotubes

Type V linerless hydrogen storage vessels made of all-composite face the challenges of cryogenic mechanical failure and hydrogen leakage of composites. The cryogenic mechanical performance and gas-barrier property of the carbon fiber reinforced polymer for Type V vessels are largely determined by the epoxy matrix. Carbon nanotubes are widely used as polymer reinforcement material to enhance the cryogenic mechanical performance and gas-barrier property of epoxy resins. In this work, multi-walled carbon nanotubes (MWCNTs) were dispersed into epoxy resins to prepare MWCNTs-modified epoxy resins. The cryogenic mechanical performance, gas-barrier and thermal properties of the modified resin were then investigated. The experimental findings revealed a 34.34% reduction in the gas permeability coefficient for the nanocomposites containing 0.9 wt% MWCNTs compared with the epoxy matrix. The tensile strength and failure strain at cryogenic temperature (77 K) experienced enhancements of 26.99% and 41.53%, respectively. In addition, the thermal stability and glass transition temperature of the modified resin were improved. As a result, the MWCNTs-modified epoxy resin exhibits improved gas-barrier property in addition to excellent cryogenic mechanical performance, making it ideal for manufacturing Type V linerless hydrogen storage vessels.

A Study on the Application of Lining Adhesives to Canvas Reinforcement Treatment(Patching)

Canvas patching utilizes various adhesives for localized reinforcement treatment, yet evaluations of their properties remain insufficient. This study presents surface changes and physical properties observed when seven types of lining adhesives, selected from prior research, were applied. Evaluations included contact angles, color changes, surface alterations, and tensile strength. Results indicated that glue paste was highly susceptible to moisture and exhibited decreased flexibility with environmental changes, while Beva film showed the most significant reduction in adhesion. Both glue paste and Beva film were sensitive to color changes, primarily displaying yellowing and browning. Plextol B500 demonstrated the greatest increase in adhesion and flexibility under environmental stress. Welding powder exhibited high adhesion but lower strain rates, causing notable deformations across the canvas. Within the same adhesive composition, higher hydrophilicity correlated with reduced yield stress and maximum strain, suggesting that hydrophilicity affects adhesion and flexibility. Adhesives with lower thermal decomposition and glass transition temperatures experienced greater changes in adhesion and flexibility. Rapid changes in adhesion following localized reinforcement treatment can lead to issues like peeling of reinforcing fabric or deformation of the canvas.

Investigation of the Interaction between Poly(trimethylene carbonate) and Various Hydroxyl Groups

The interaction of poly(trimethylene carbonate) (PTMC) with hydroxyl group compounds was investigated as a model for polymer blending with polysaccharides. While 1-butanol, 2-butanol, ethylene glycol, and 1,2-cyclohexanediol showed almost no detectable interaction with PTMC in both solution states with the 1H NMR and solid states with the FT-IR, glucose and cellobiose suggested a slight change in the spectral pattern in FT-IR analysis. The thermal properties of the blended samples of PTMC and these hydroxyl groups were also investigated. Although the blends of PTMC with 1-butanol and 2-butanol did not influence thermal degradation behaviors due to their low boiling points, the PTMC blend with a higher number of hydroxyl groups, especially glucose and cellobiose, tended to increase thermal resistance and glass transition temperature, hence showing the existence of an interaction through hydrogen bonding.

Probabilistic thermal analysis and phase transition temperature optimization for low-rise residential buildings with temperature-adaptive radiative cooling roofs

This paper conducts an optimization study on the energy performance of applying temperature-adaptive radiative cooling (TARC) coatings as building roofs. To provide guidance for the application of TARC roofs, a method for determining the optimal phase transition temperature of TARC coatings for application in buildings is proposed. Then, the thermal performance of the TARC roofs is analyzed for buildings located in five different climatic zones in China based on the probability density function and cumulative distribution function. Finally, the energy efficiency of the TARC roof and the effect of the phase transition temperature on the energy savings potential of the TARC roof are discussed in detail. The results showed that the TARC roof can address the issue of increased heating loads caused by passive daytime cooling (PDRC) roofs during the heating season. Furthermore, the annual total energy savings potential of the TARC roof is 6.3–23.5 MJ/m2 for buildings located in five different climatic zones in China. In addition, the annual energy savings of buildings with TARC roofs can be further improved by 3–7% once the optimal phase transition temperature is adopted.

Effect of potassium salt type on physicochemical properties of carrageenan films and rehydrated hydrogels

This study focused on the effect of potassium salt type on the physicochemical properties of carrageenan (Car) films and rehydrated hydrogels, with the aim of developing a new method for the preparation of Car hydrogels. The addition of potassium salt decreased the tensile strength (TS) of Car films, especially those containing KI. After rehydration, the weight and thickness change ratios of the Car films decreased with salt addition, and the sequence was as follows: K2CO3 < KH2PO4 < CH3COOK < KCl < K2SO4 < KSCN < KI < C6H5K3O7. The effect of potassium salt type on the TS and thermal transition temperature of rehydrated hydrogels was opposite that on weight and thickness change ratios. The hydrogels with K2CO3, KH2PO4, CH3COOK, KCl, and K2SO4 exhibited lower transverse relaxation time (T2) and smaller pore size compared with the other hydrogels. On the other hand, the effect of potassium salt type on hydrogels prepared using Car films soaked in potassium salt solution (S-Car) was similar to that observed on hydrogels prepared using Car films with potassium salt soaked in ultrapure water (U-Car). Compared with U-Car hydrogels, the S-Car hydrogels had higher TS and thermal transition temperature and lower elongation at break, T2, pore size, and hydrogen bond intensity. In conclusion, the potassium salt type and soaking method can be used to regulate the properties of Car hydrogels and provide a theoretical basis for the design of Car hydrogels.

Optical, thermal, and electrical characteristics of cashew gum/Polypyrrole/zinc oxide nanocomposites for next‐gen optoelectronics

AbstractIn this electronic era, there is a demand to switch from conventional polymers to conducting biopolymers. We developed conducting biopolymer nanocomposites of cashew gum (CG) and polypyrrole (PPy) with zinc oxide (ZnO) nanofillers [CG/PPy/ZnO] via in‐situ oxidative polymerization using a sustainable solvent. These nanocomposites were characterized using Fourier‐transform infrared spectroscopy (FTIR), UV–visible spectroscopy, field emission scanning electron microscope (FE‐SEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The FTIR signal at 855 cm−1 confirms the successful inclusion of ZnO nanofillers into the biopolymer. UV–vis absorption of the blend nanocomposite increases with the nanoparticle doses. Among the various blend nanocomposites, the least bandgap energy was observed for 7 wt% ZnO loading. FE‐SEM revealed homogeneous dispersion of ZnO nanofillers in the CG/PPy blend at 7 wt% ZnO. TGA and DSC demonstrated that the CG/PPy/ZnO nanocomposites have better thermal stability and glass transition temperature than the pure polymer blend, indicating enhanced thermal properties. The CG/PPy/7 wt% ZnO showed the highest conductivity, 4.62 times greater than the pristine blend at 100 Hz. Dielectric constant, activation energy, AC conductivity and dielectric loss measurements demonstrated that the nanocomposites outperformed the pure polymer blend. Complex impedance analysis revealed increased impedance with rising temperature. Overall, CG/PPy/ZnO nanocomposites exhibit superior optical, morphological, thermal, electrical, and dielectric properties, making them promising for energy storage and optoelectronic applications.Highlights Ecofriendly synthesis of CG/PPy/ZnO nanocomposites Enhancement in optical, structural, and thermal properties of CG/PPy/ZnO Dielectric properties and temperature‐dependent AC conductivity are summarized. Blend nanocomposite shows higher AC conductivity and dielectric constant CG/PPy/ZnO nanocomposites are suitable for energy storage applications

Preparation and properties of poly (ethylene-co-vinyl acetate)/boron nitride nanocomposite for energy storage devices

A simple open-mill mixing approach was employed to develop thermally and mechanically stable nanocomposites consisting of poly (ethylene- co-vinyl acetate) (EVA) as the matrix and boron nitride (BN) as a reinforcing nanofiller. The development of nanocomposites was examined by FT-IR, UV spectroscopy, XRD, TEM, TGA and DSC. The attachment of BN to EVA was confirmed by the characteristic BN band at 602 cm−1 in the FT-IR spectra. The UV measurements revealed a red shift in the nanocomposites due to nanoparticle interactions with polymer chains and the bandgap energy decreased with the nanofiller concentration. The XRD TEM analysis indicated the presence of a crystalline BN phase in EVA. Enhanced thermal stability and glass transition temperature of the polymer with the addition of BN nanoparticles were revealed from TGA and DSC, respectively. The EVA with 5% BN nanocomposite was discovered to have higher mechanical properties, electrical conductivity and lower optical bandgap energy. The tensile strength, tear resistance, impact strength and hardness of EVA increased with the inclusion of BN, whereas elongation at break was reduced. The findings of the experiments showed that the EVA/BN nanocomposites would provide excellent options for mechanically and thermally stable materials for energy storage applications.

Biobased polyesteramides derived from bisfuranic diamine and aliphatic diesters of varied chain lengths: synthesis and chemical stability

This study presents the development of a series of biobased polyesteramides, labeled as PEAF1–3, via a greener approach, from bisfuranic diamine and commercially available aliphatic diesters of varied chain lengths. The resulting polymers showed reasonable molar masses, in accordance with inherent viscosities ranging between 0.19 and 0.35 dL/g. Evaluation of their thermal properties by thermogravimetric analysis and differential scanning calorimetry showcased excellent thermal stability (Td ,max ≥ 335 °C), amorphous character and low glass transition temperature (Tg ) decreased with the increasing chain length. Moreover, notable finding was the exceptional stability of these polyesteramides against both hydrolytic and oxidative degradation processes. This resistance underscores their potential as highly stable materials, making them promising for various applications where durability and resistance to degradation are crucial.

Photo-triggered Phase Transition of Crystals and Photoactuation.

Photo-triggered phase transition is a new type of phase transition in which a photochromic crystal with a thermal phase transition transforms into an identical high-temperature phase in a temperature region lower than the thermal phase transition temperature upon light irradiation. Here, we report a second crystal that exhibits a photo-triggered phase transition, thereby demonstrating that the photo-triggered phase transition is a general phenomenon that occurs in crystals. When the chiral salicylidenephenylethylamine crystal was irradiated with ultraviolet (UV) light, the photo-triggered phase transition occurred in the temperature range -30 to -10 °C. The photo-triggered phase transition is induced by local stress due to trans-keto molecules produced by photoisomerization near the irradiated surface. Crystal cantilevers exhibited stepwise bending by the combination of the photo-triggered phase transition and photoisomerization. Alternate irradiation with UV and visible light achieved locomotion of single crystals driven by repeated stepwise bending. Finally, a detailed comparison of photo-triggered and non-photo-triggered phase transition crystals revealed that a sufficient molecular conformation change in affordable crystal voids, smooth photoisomerization, and most likely a chiral molecular arrangement are required for inducing the photo-triggered phase transition.

Spherical polystyrene/zinc oxide nanocomposite powder fabricated by continuous process chain of melt mixing and indirect heating

Polymer powders are limited by particle size, shape, and properties in various applications. Preserving the chemical properties of the material throughout the process is a critical part of developing consistently shaped nanocomposite powders across diverse polymer types. The goal of this study is to demonstrate continuous methods to produce spherical Polystyrene (PS) and zinc oxide (ZnO) nanocomposites. A single-screw extruder is used to melt mix PS pellets with ZnO nanoparticles, followed by pelletization, dry grinding, and spheroidization in a Downer Tower to form spherical polymers. To minimize agglomeration, the process incorporates an ethanol treatment and a final sieving step. The resulting nanocomposite powder exhibits exceptional flowability and well-defined spherical morphology. Additionally, incorporating ZnO nanoparticles enhanced the thermal stability and glass transition temperature of the nanocomposite while reducing particle size distribution. Thermogravimetric analysis and X-ray diffraction confirm the preservation of the chemical structure of the spherical nanocomposite specimens throughout processing.

Effect of solid lubricant reinforcing on drilling performance of castamide and thermal analysis

AbstractThis study addresses the pressing need for enhancing the machining performance and hole quality of castamide by investigating the effects of solid lubricant addition and drilling parameters. Castamide, a highly crystalline polyamide synthesized via anionic ring‐opening polymerization, offers superior mechanical, physical, and chemical properties compared to conventional polyamide 6. However, its machining process, particularly drilling, remains a critical challenge due to its viscoelastic nature and sensitivity to heat generation. Using experimental investigations, thrust forces, drilling temperatures, hole geometry, and quality parameters are systematically analyzed and discussed. Notably, the study introduces Kestlub, a modified version of castamide with solid lubricant, and evaluates its drilling performance, a previously unexplored area in the literature. The research employs response surface methodology to model experimental data, considering both linear and quadratic effects of drilling parameters. Additionally, the significance of each parameter is assessed using ANOVA tables and Pareto charts, offering valuable insights into optimizing the drilling process for enhanced hole quality in castamide. It found that optimal drilling conditions occur at low rotational speeds and high feed rates, but thermal damage, influenced by factors like thermal conductivity and transition temperature, affects hole geometry and burr formation.Highlights Drilling performances of solid lubricant reinforced castamides were investigated. Drilling temperatures were recorded with a thermal camera and differential scanning calorimeter and thermal gravimetric analyses were performed. Drilling properties were analyzed statistically according to the response surface method. It found that optimal drilling conditions occur at low rotational speeds and high feed rates.

Reactive organophosphorus retardant-enhanced sorbitol epoxy resins with highly thermal and flame-retardant performance

As a low-cost sugar-based chemical, sorbitol has been less reported in recent years in the field of epoxy resins. In view of the low viscosity characteristics of its epoxy monomer, it is of great significance to prepare the advanced resin system via a solvent-free green curing process. As known, most of the existing flame-retardant networks contain organophosphorus flame retardants. To achieve excellent flame- retardant effect, a large amount of phosphorus was added to the resin matrices. As a result, apart from exacerbating the migration of organophosphorus, their thermal stability and phase transition temperature are further reduced, thus weakening the thermal properties of the material to a certain extent. In order to overcome those problems, we introduced ultra-low amounts of phosphorus to achieve efficient flame retardant into the sorbitol -based epoxy resin. It was found that the introduction of EP-DOPO in 0.55 P wt% amount could achieve a UL94-V0 grade flame retardant effect. Different from other phosphorus-containing flame retardants, reactive EP-DOPO favored an improvement in both thermal stability and phase transition temperature, meanwhile, it effectively avoids the phosphorus migration as well.

Preparation and characterization of a novel allyl ether naphthalene phenolic modified bismaleimide resin and its composites

AbstractAllyl ether naphthol resin (ANPF) was synthesized by introducing 1,5‐dihydroxynaphthalene and 2,7‐dihydroxynaphthalene into phenolic resin and was copolymerized with 4,4′‐bismaleimidodiphenylmethane resin (BDM) to obtain allyl ether naphthol‐modified bismaleimide resins (15‐ANPF‐BDM and 27‐ANPF‐BDM). The resulting thermal stability and glass transition temperature (Tg) were explored by thermogravimetric and dynamic mechanical analyses. The char yield of 15‐ANPF‐BDM at a temperature of 800°C was 46.0%. Additionally, the Tg of 15‐ANPF‐BDM was measured as 311°C, which is an increase of 44°C compared to that of c. The mechanical properties of the ANPF‐BDM/quartz fiber (Qf) composites were also investigated. The results reveal that ANPF‐BDM/Qf composites exhibit similar mechanical strength to APF‐BDM/Qf composites at room temperature. In addition, the mechanical properties of the ANPF‐BDM/ Qf composites demonstrated significant improvement in mechanical properties retained significantly improved at 200°C, with a 68% flexural strength retention and a 96% interlaminar shear retention of 15‐ANPF‐BDM/Qf composites. Thus, ANPF‐BDM/Qf composites exhibit outstanding mechanical properties at 200°C.

High heat resistance and neutron shielding performance epoxy with carborane hybridized crosslinked network

Epoxy resin has gained significant attention in aviation equipment, coatings and electronic packaging materials due to its exceptional processability, adhesion and mechanical properties. However, its thermal resistance property and glass transition temperature (Tg) were relatively lower than cyanate resin (CE), polyimides (PI) and phenolic resins (PF), which largely restricts its application range. In this work, we had developed a new structural heat-and-shielding integrated epoxy resin via the design of carboranes-epoxy network. Benefiting from the structure of carborane, the thermal residual weight of the obtained epoxy reached 64.57 %, with a carbon atom protection rate of 45.47 % in air atmosphere at 800 °C, showing better thermal resistance property than most CE, PI and PF. And the Tg of the new epoxy was not observed within the tested temperature range (50–250 °C). Additionally, the introduction of carborane structures enhances the neutron shielding performance of the material (38.46 % enhanced). The reinforcement mechanisms of these above properties are systematically investigated. It's excepted that our work could provide some ideas to prepare structural -functional integrated epoxy and promote the development of carborane related materials.