To increase the toughness of epoxy resin, an allyl-terminated furanylbenzoxazine (AFB) derived from eugenol was copolymerized with epoxy resin (E51). Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC) analyses were used to examine the curing behavior of the blended resins. With increasing AFB content, the crosslinking density of the EP-AFB resins decreases, while the residual carbon yield (Y c) of the epoxy resins after high-temperature combustion in a nitrogen atmosphere increases. The Y c of EP-4AFB increased from the initial 14.92% to 20.21%. In addition, appropriate concentration of AFB could be conducive to improving the mechanical properties. The flexural and impact strengths of EP-1AFB resins were 3.5% and 81.3% higher than EP resins, respectively. The elongation at break and tensile strength of EP-3AFB resins were 91.2% and 68.4% higher than EP resins, respectively. Furthermore, the addition of AFB significantly modified both adhesive (lap shear strength and peel strength) and dielectric properties of the epoxy resins.

This study reports the synthesis of a eugenol-derived benzoxazine resin (AEM) from 3-ethynylaniline and bio-based eugenol, and its structural characterization using Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance ( 1 HNMR). Subsequently, the AEM resin was copolymerized with bisphenol-type epoxy resin (E51) in varying proportions to form an EP-AEM modified resin system, whose processability, dynamic thermomechanical properties, thermal stability, dielectric properties, mechanical properties, and adhesion performance were investigated. The flexural strength, tensile strength, and elongation at break of EP-2AEM resins were 7.6%, 53.7%, and 41.2% higher than EP resins, respectively. In particular, AEM markedly increases the residual carbon yield ( Y c ) after high-temperature combustion in a nitrogen atmosphere, and this improvement becomes more pronounced as the AEM concentration increases. Compared with neat EP resin (14.92%), EP-4AEM resin exhibits a significantly higher value (21.59%). The high-temperature adhesion strength of EP-2AEM increases by 51.5%. Moreover, EP-4AEM shows the lowest dielectric constant (2.49) and dielectric loss tangent (0.022).

Epoxy resins are widely used but often limited by brittleness and poor thermal stability. In this work, a novel octopus-like toughener (FGO-E51) was developed via a two-step covalent grafting strategy. Bis-isocyanate-terminated HTBN was first grafted onto graphene oxide (GO) to form FGO, and its remaining isocyanate group was then reacted with hydroxyl groups of E51 epoxy resin, yielding FGO-E51, a hybrid architecture designed to bridge GO and the epoxy matrix through covalent bonding. FTIR confirmed the sequential formation of urethane linkages, validating the molecular bridge structure. FGO-E51 exhibited excellent dispersion and significantly enhanced thermal and mechanical properties. Compared to neat epoxy, the composite with 0.5 phr GO (EP-4) showed a 23.6 degrees C increase in glass transition temperature. Tensile strength, impact strength, and elongation at break increased by 25.1%, 144.4%, and 139.0%, respectively. Microstructural analysis revealed crack deflection and energy dissipation, indicating efficient toughening. This work demonstrates a rational design of reactive hybrid tougheners for high-performance epoxy composites.

Molybdenum disulfide (MoS2) with a sandwich-like layered structure is regarded as a highly promising nano-additive for enhancing the mechanical properties of polymer materials. However, the surface of MoS2 is inert and lacks any active functional groups, resulting in poor compatibility with the epoxy resin (EP). In this study, MoS2 was exfoliated by the liquid-phase exfoliation method, and its surface was functionalized with polythiol. The approach aimed to embed organic molecules into the sulfur vacancy sites on the MoS2 nanosheet surfaces, thereby modulating the interface between MoS2 and epoxy resin and enhancing their interfacial interaction. The modified product was characterized in terms of structure, thickness, and morphology. The functionalized MoS2 (SH-MoS2) was then incorporated into an epoxy resin to form an adhesive, and the bonding performance of the adhesive was investigated at different adhesive layer thicknesses. Compared with the epoxy adhesive without SH-MoS2, the mechanical and bonding properties of the SH-MoS2/epoxy nanocomposite adhesive were significantly improved. This method yielded an SH-MoS2 (0.50 wt.%)/epoxy nanocomposite adhesive that exhibited superior tensile shear performance across 0.1-1 mm bondline thicknesses, with all measured values surpassing 20.7 MPa. The findings offer practical design principles for developing polymer nanocomposite adhesives applicable to wide-gap structural bonding manufacturing.

Over the past few decades, the optimization of polymer properties through the design of functionalized MoS2 has attracted increasing attention owing to the excellent properties of two-dimensional fillers at the nanoscale. These fillers offer inherent advantages in terms of stiffness, strength, and toughness. This study investigates a facile process to synthesize amino-functionalized MoS2 for enhancing the mechanical properties of epoxy resins (EPs). We used 4,4 '-diaminodiphenyl sulfone (DDS) as a modifier to synthesize DDS-MoS2 nanosheets via high-frequency liquid-phase ultrasonication, obtaining nanosheets with an average longitudinal size of 1-2 nm. Raman spectroscopy confirmed that the DDS-functionalized nanosheets had greater structural disorder and improved dispersion within the matrix. The amino groups on the nanosheet surface formed bonds with the epoxy groups, preventing MoS2 accumulation. Compared with pure EP and MoS2/EP composites, the DDS-MoS2/EP demonstrated substantially improved thermal stability and mechanical properties and exhibited 11.1% and 42.4% higher tensile modulus and strength, respectively. Moreover, its impact strength was increased by 208.5%. Dynamic mechanical analysis revealed an increase of 31.6 degrees C in the glass-transition temperature (Tg) and an improvement in the storage modulus. These enhancements are attributed to the improved dispersion and compatibility between the nanosheets and resin matrix, facilitated by the DDS-based modification.

A bio-based allyl-terminated benzoxazine (AMP) was copolymerized with epoxy resins (E51) to enhance the toughness of epoxy resins. The curing behavior of the blended resins was investigated using differential scanning calorimetry (DSC) analysis and Fourier transform infrared (FTIR) spectroscopy. The crosslinking density and gel content of EP-AMP resins were decreased with the increasing AMP content. AMP significantly improved the residual carbon yield (Yc) of epoxy resins following high-temperature combustion in N2 atmosphere, with enhancements correlating positively with AMP concentration. Compared with the value of EP resins (14.92%), the value of EP-4AMP resins (19.41%) was well increased. The mechanical properties (including flexural, impact, and tensile tests) were evaluated, revealing substantial improvements. The flexural strength, tensile strength, and elongation at break of EP-3AMP resins were 11.7%, 104.8%, and 67.6% higher than EP resins, respectively. The impact strength of EP-2AMP resins was 66.9% higher than EP resins. Furthermore, the incorporation of AMP markedly modified both adhesive (lap shear strength and peel strength) and dielectric properties of the epoxy resins.

Phthalonitrile (PN) resins are highly valued in high-performance applications due to their exceptional thermal stability and mechanical properties. However, traditional PN monomers suffer from high melting points and slow curing rates, often requiring external curing accelerators that can compromise thermal performance. This study focuses on the synthesis and characterization of novel low-melting maleimide-containing PN monomers designed to enhance curing efficiency and thermal properties. Maleimide groups were introduced to improve self-catalytic properties, facilitating a more efficient curing process. The polymerization behavior, thermal stability, adhesive, and mechanical properties of these compounds were thoroughly investigated. Differential Scanning Calorimetry (DSC) and rheological tests showed that incorporating alkyl groups significantly improved flow properties, facilitating easier processing. The difference in the three-dimensional network structures of the cured PN resins was confirmed by Fourier Transform Infrared (FT-IR) spectroscopy. Thermogravimetric Analysis (TGA) demonstrated outstanding thermal stability, with 5 % weight loss temperatures ranging from 387 degrees C to 418 degrees C under air and from 420 degrees C to 471 degrees C under nitrogen. Dynamic Mechanical Analysis (DMA) confirmed high glass transition temperatures (Tg) exceeding 400 degrees C, indicating superior thermal performance and making these resins suitable for advanced applications in harsh environments. These findings suggest that low-melting maleimidecontaining PN systems are promising candidates for high-performance materials in aerospace, electronics, and other demanding fields.

Wet mixing and solvent evaporation were used to prepare in situ exfoliation and surface functionalization of graphene oxide (GO). The structure and composition of diglycidyl 7-oxabicyclo[4.1.0]heptane-3,4-dicarboxylate (TDE85) functionalized GO (TDE85-GO) were characterized. A thorough investigation was done into how surface functionalization affected the shape and dispersion of GO as well as the mechanical and thermal performance of the TDE85-GO/epoxy composites. TDE85-GO was evenly distributed throughout the matrix as a result of the special preparation method and excellent interfacial interaction between the functionalized GO and epoxy. By incorporating 0.5 wt% of TDE85-GO, the molecular weight between crosslinks decreased from 435.1 to 182.0 g/mol, and the glass transition temperature significantly increased by 45.7 degrees C from 148.8 to 194.5 degrees C. The tensile strength, Young's modulus, and elongation at break increased by 18.3%, 3.7%, and 29.9%, respectively. Moreover, thermomechanical and water resistance properties have also been improved. This approach is a workable one to produce high-performance structural composites. This approach represents a practical strategy for developing high-performance structural composites.

Bismaleimide (BMI) resins is widely used in the aerospace field because of its excellent properties, but its poor toughness limits the possibility of its application in a wider range of fields. Therefore, a novel bio-compound, 4-(allyloxy)-3-methoxy-N-(3-(triethoxysilyl)propyl)benzamide (AMTPM), was designed and synthesized from renewable vanillin, which has Schiff-base structure, silico-oxygen bond structure, and allyl structure. The chemical structure of AMTPM has been characterized and validated by Fourier transform infrared (FTIR) and hydrogen nuclear magnetic resonance (1H NMR). It was found that the addition of AMTPM can effectively promote the curing behavior of BD resins (BMI and diallyl bisphenol A (DBA) was mixed and cured at the ratio of 1:0.87, named BD resins). AMTPM can affect the thermal stability and improve the mechanical properties of BD-AMTPM resins (BD resins modified by AMTPM in different addition), and the detailed discussion was conducted. With the increase of AMTPM content, the thermal stability of BD-AMTPM resins was deteriorated while the residual weight percentage at 800 degrees C (Yc) was increased. When the content of AMTPM reached 12 wt%, the results showed that Yc achieved the values at a magnitude of 37.57%. Meanwhile, the glass transition temperature (Tg) achieved 320 degrees C. Among the BD-AMTPM resins system, the BD-6 wt% AMTPM has the best toughness and mechanical properties. The impact strength was increased by 29.2%, the tensile strength was increased by 22.1% and the elongation at break was increased by 44%. The fracture morphology of BD-AMTPM resins was also studied by scanning electron microscopy (SEM) to support the mechanical experimental conclusions. This study provides a more environmentally friendly and convenient modifier, which is of great significance for expanding the application of bismaleimide resin.Highlights A bio-based modifying agent (AMTPM) was designed and successfully synthesized. AMTPM has both Si-O and Schiff-base structures. AMTPM can effectively improve the toughness of BD-AMTPM resins through impact and tensile tests. The effect of the vanillin-derived Si-containing compound on the curing behavior, thermal and mechanical properties of bismaleimide resins. image

An aliphatic silicon-containing maleimide monomer 1,1 '-((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane3,1-diyl))bis(1H-pyrrole-2,5-dione) (TBB) with low melting point (56 degrees C) was successfully synthesized based on maleic anhydride (MA) and 3,3 '-(1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propan-1-amine) (BAT). The structure of TBB monomer was determined by FTIR, 1H NMR and 13C NMR. Meanwhile, the 3,3 '-(1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propan-1-amine) (BAT) and 4,4'-Bismaleimidodiphenylmethane (BDM) monomers were respectively prepared from diallyl bisphenol A (DBA), following a 1:0.87 molar ratio, and named TD resins and BD resins. The curing kinetics, thermal stability and processability of TD resins and BD resins were discussed and compared. The activation energy (E) value of TD resins was 26.2 % higher than BD resins, resulting in exothermic peak temperature (TP) of TD resins was higher than BD resins at different heating rates. Compared with BD resins, the crosslinking density (ve) of TD resins was reduced by 93.5%, which effectively destroyed the thermal stability of TD resins. However, TD resins exhibited outstanding processing window of 195.6 degrees C. The processing window of TD resins was 110.1 % wider than that of the BD resins, indicating that the former had excellent processability. Overall, this study has enriched the discussion on the curing kinetics of aliphatic bismaleimide resins and has a positive influence on the design of resins monomer with low melting point.

In this work, this study aimed to overcome the inherent disadvantage of low thermal stability and brittleness of epoxy resins. A novel modifiers containing alkynyl- and allyla- groups, (E)-1-(4-(allyloxy)-3-methoxyphenyl)-N-(3-ethynylphenyl)methanimine (MNEM) was prepared and confirmed by Fourier transform infrared spectroscopy (FTIR) and 1H-nuclear magnetic resonance (1H NMR), and selected to improve the thermal stability and toughness of bisphenol A-type epoxy resin (E51). The blend resins were produced by blending with different contents of MNEM into E51 resin, named E-MNEM resins. Meanwhile, the thermal stability, mechanical properties, and micromorphology of E-MNEM blends were analyzed in details. It was found that the thermal stability of E-MNEM resins was improved by increasing the proportion of MNEM. Compared with E-0MNEM resin, when the MNEM concentration reached 40 wt%, the char yield (Yc) increased from 14.95 to 29.62%, reflecting a 98.1% improvement. In addition, an appropriate concentration of MNEM could be conductive to improving the mechanical properties. An improvement of 25.5 and 7.1% in elongation and tensile strength along with the maximum value of 17.6 kJ/m2 for the impact strength was achieved by the cured E-MNEM resins containing 20 wt% of MNEM. Finally, the fracture surface morphology of the E-MNEM resins was analyzed by the scanning electron microscope (SEM).

In this work, phenylethynyl-terminated imide oligomers incorporating benzimidazole structures were synthesized and their structures were characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and proton nuclear magnetic resonance (1H NMR). The solubility, curing behavior, thermal stability, thermomechanical properties, and adhesive performance were systematically evaluated. Different dianhydride structures and isomer ratios were utilized to optimize the performance of the oligomers. Thermogravimetric analysis (TGA) revealed 5% weight loss temperatures (T5%) exceeding 520 degrees C under both nitrogen and air atmospheres, demonstrating excellent thermal stability. Lap shear strength (LSS) testing showed that oligomers based on 4,4 '-oxydiphthalic anhydride (ODPA) exhibited superior adhesive performance, particularly at elevated temperatures. The glass transition temperature (Tg) was significantly influenced by the ratio of 3,3 ',4,4 '-biphenyltetracarboxylic dianhydride (s-BPDA) to 2,3,3 ',4 '-biphenyltetracarboxylic dianhydride (a-BPDA), with a maximum Tg of 482 degrees C. These results underscore the potential of these oligomers for high-performance adhesive applications in industries such as aerospace and electronics.

In this study, a novel biobased allyl compound with Schiff-based structure (MPAM) was developed to improve the toughness and thermal properties of 4,4 '-bismaleimidodiphenylmethane (BDM). The chemical structure of MPAM was characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (H-1 NMR). A series of BDM/DBA-MPAM blend resins (BD-MPAM resins) were prepared by adjusting the mass ratio of BDM + DBA (BD) to MPAM. The effects of MPAM content on the curing behavior, thermal and mechanical properties of BD-MPAM resins were discussed in details. Compared with BD resin, the thermal stability of modified resins was improved by increasing the content of MPAM. Meanwhile, an increase of 37.1% in flexural strength, and 228 MPa in flexural modulus were obtained for the cured BD-MPAM resin having 10 wt% MPAM loading compared to the BD resin. The impact strength of BD-10 wt% MPAM is of the maximum value (6.6 kJ/m(2)). Finally, the fracture surface morphology of the BD-MPAM resins was studied by the scanning electron microscope (SEM).

Cyanate ester (CE) resins possess excellent thermal and mechanical characteristics, yet their brittleness and high cross‐link density limit their practical application. To overcome this limitation, the modification of CE with thermoplastic resins has been employed as an effective strategy to enhance their toughness and mechanical properties. In this study, a novel fluorinated poly(aryl ether nitrile) (PFPEN) with excellent solubility and thermal properties was synthesized through a nucleophilic substitution reaction. The effect of the addition of PFPEN on a blend composed of bisphenol A cyanate ester (ACE) and a mixed catalyst was investigated. Differential scanning calorimetry results showed that the addition of PFPEN facilitated the curing reaction of ACE, resulting in a lower exothermic peak temperature. Compared to the pure ACE, the addition of PFPEN at 20 phr significantly improved the tensile and impact strengths of the resin, as well as enhanced the lap shear strength at room temperature by 36% and the peel strength by 320%, respectively. The scanning electron microscope results showed a ductile fracture mechanism. However, it should be noted that the decrease in crosslinking density resulting from the addition of PFPEN may affect the lap shear strength at 300°C and the glass transition temperature ( T g ) of the material.

通过改变含氟单体双酚AF(BPAF)与酚酞(PP)的物质的量之比,在碱催化条件下与2,6-二氯苯甲腈缩聚,合成了一系列不同氟含量的共聚型聚芳醚腈(FPEN).对FPEN共聚物的分子结构、分子量及其分布、热性能、力学性能和介电性能进行了表征.研究结果表明:FPEN共聚物具有良好的溶解性,能溶解于二甲基乙酰胺(DMAc)、N,N-二甲基甲酰胺(DMF)等多种有机溶剂;FPEN的热学性能随氟含量出现规律性变化,其T8均高于200℃,T5％也都超过了470℃;当含氟单体加入量为30％,即n(PP)∶n(BPAF)=7 ∶3时,FPEN薄膜的拉伸强度和断裂伸长率分别为82.8 MPa和3.47％,同时具有良好的介电性能.本研究制备的FPEN是一类综合性能优异的新型特种高分子材料,在树脂基复合材料和胶粘剂改性方面有较大的应用前景.

The increasing attention to environmental protection has driven the rapid development of bio-derived materials, as they are expected to break the dependence of conventional polymer on fossil resources. Herein, the aim of the present work focuses on a newly developed vanillin-derived diene compound (TFBAM) incorporated with epoxy resin (E51) for the enhancement of the thermal, dielectric and mechanical properties. The chemical structure of TFBAM was confirmed by Fourier transform infrared (FTIR) and Nuclear magnetic resonance (1HNMR) spec-troscopies. The modified resins (E-TFBAM) were successfully prepared through the introduction of TFBAM into E51, and the consequences of TFBAM dosages on the curing behavior, thermal, mechanical and dielectric properties of E-TFBAM resins were dissected in details. The results revealed that an appropriate concentration of TFBAM could be conductive to improving the thermal stability and dielectric properties of E-TFBAM thermosets without damaging the mechanical properties. The dielectric permittivity and loss of 2.82-2.71 and 0.024-0.015 were obtained when the addition of TFBAM was 30 wt%, with 10-10.2% and 36.8-44.4% of reduction. Addi-tionally, the impact strengths and elongation at break of E-30 TFBAM resin increase to 18.0 kJ/m2 and 4.7%, respectively. Overall, this research can be seen as essential for expanding the application of the epoxy resins in high-end fields.

胶层厚度是影响粘接强度的重要因素之一.详细考察了胶层厚度变化对J-421胶粘剂粘接不同材质试片拉剪强度的影响,以及湿热老化前粘接性能的变化.对比数据表明,J-421对铝合金、复材F0和F45试片均具有较好的粘接性能,拉剪强度大部分呈现随胶层厚度增大而降低的趋势.因此,固定胶层厚度为0.1mm时,J-421粘接铝合金试片的室温拉剪强度高达47.04MPa,综合粘接性能及耐湿热老化稳定性优异.

A better understanding of the photosynthesis and soil water storage regulation of soybean production will be helpful to develop a water conservation strategy under a rain-fed farming system. Reducing the leakage of CO2 bundle sheath cells and improving the photosynthesis capacity and gas exchange characteristics of soybean leaves will contribute to increase yield under the dryland agricultural system and provide a scientific basis. Therefore, during 2019 and 2020, soybean exposed to different cultivation modes to analyze the response curves of photosynthesis and CO2 under different deficit irrigation strategies. In this study, we used two cultivation models: RB: ridge covered with biodegradable film and furrow area not covered; CF: conventional flat land planting under four deficit irrigation modes (R: rainwater irrigation; IB: branch stage irrigation (220 mm); IP: Irrigation during podding (220 mm); IBP: branch stage irrigation (110 mm), podding stage irrigation (110 mm). Compared with CF-IBP treatment, RB-IBP had significant effects on rainwater collection, SWS, and soybean yield. Photo-response curve analysis showed that RB-IBP treatment a significant increase in Pn, Gs, Ci, Tr, leaf WUE, and chlorophyll ab content. Under different irrigation strategies, maximum net photosynthetic rate (Pnmax), light saturation point (LSP), and apparent quantum efficiency under RB-IBP treatment (α), Pn under respiration rate and CO2 response curve were significantly higher than that under CF cultivation mode. Compared with RB culture mode under different irrigation strategies, CF cultivation mode significantly increases Δ13C and CO2 sheath cell leakage (Փ); it also led to a significant decline in the ratio of Ci/Ca concentration. This study shows that RB-IBP treatment is the best water-saving strategy because it means reducing the leakage of CO2 from the bundle sheath, thus significantly increasing soil water storage, photosynthetic capacity, and soybean yield.

J-421是一种高性能中温固化环氧胶粘剂,对复材试片具有优异的粘接性能.详细考察了处理方式对复材表面状态的影响,以及J-421粘接不同程度表面处理复材试片的拉剪强度.研究结果表明,打磨程度不同,复材表面微观状态、元素分布及浸润性均发生明显变化.复材表面粗糙度的增加有利于获得更高的胶接强度及胶接稳定性.