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This work investigated the effects of moisture absorption treatment on composite−to−metal double−lap shear joints (DLSJs) bonded with epoxy adhesive film through experiments and simulations. The composite−to−metal DLSJ can be divided into five parts (the interface between the composite and adhesive, the interface between the adhesive and metal, the composite adherend, the metal adherend, and the adhesive layer). First, the wet−dependent properties of the adhesive and interfaces were obtained through adhesive tensile tests and GC tests, which showed that the properties of the adhesive and interfaces were significantly affected by the moist environment. Then, tensile tests of the composite−to−metal double−lap shear joints were carried out in dry and wet environments. Finally, based on the experimental investigations, a finite element (FE) model that considered cohesive damage was established for simulating damage evolution and predicting the failure loads and failure modes of the DLSJs. The results of both the experimental and numerical tests show that the DLSJ failure load decreases significantly after immersion in 95 °C water, and the major failure mode transfers from adhesive failure to interface failure. The research results provide a theoretical basis or basic data for the structural design of adhesively bonded composite−to−metal. [ABSTRACT FROM AUTHOR]

In this study, a one-pot aryl diazonium reaction was used as a simple and mild method to graft graphene onto the smooth and inert surface of T1100-grade carbon fiber (CF) through covalent bonding without any damage on CF, to refine the interface performance of CF/bismaleimide (BMI) composites. XPS, SEM, AFM, and dynamic contact angle testing (DCAT) were used to characterize chemical activity, morphologies, and wettability on untreated and grafted CF surfaces. Meanwhile, the impact of the graft method on the tensile strength of CF was also examined using the monofilament tensile test. IFSS between CF grafted with graphene and BMI resin achieved 104.2 MPa after modification, increasing from 85.5 MPa by 21.8%, while the tensile strength did not decrease compared to the pristine CF. The mechanism of this interface enhancement might be better chemical bonding and mechanical interlock between CF grafted with graphene and BMI resin, which is generated from the high surface chemical activity and rough structure of graphene. This study may propose a simple and mild method to functionalize the CF surface and enhance the interface performance of composites without compromising the tensile properties of T1100-grade CF. [ABSTRACT FROM AUTHOR]

Carbon fabric/polyphenylene sulfide (CF/PPS) composite has been used in the aircraft industry, which might suffer moisture and high temperature in service, leading to degradation and even failure. Therefore, knowledge of hydrothermal aging behavior and effects is needed to ensure service life. This work explores the water diffusion behavior, crystallization, and interfacial properties of CF/PPS composite under hydrothermal aging in continuous 3 months and periodical cycles. Diffusion coefficients were calculated through the Fickian model, crystallization behaviors were measured through differential scanning calorimetry and polarized optical microscope, and interfacial properties were characterized by interfacial shear strength, and interlaminar shear strength. The results demonstrate the crystal morphology transforms from transverse crystals to spherulites at the CF/PPS interface after recrystallization through hydrothermal aging, revealing water has a significant impact on the nucleation performance of T300 carbon fiber in the PPS matrix. Hydrothermal aging affects the crystallinity and crystal morphology of CF/PPS composite after recrystallization, and impacts the micro and macro interfacial properties. Highlights: Transverse crystals transform to spherulites at CF/PPS interface after water uptake.Water impacts on nucleation performance of T300 carbon fiber in PPS matrix.Hydrothermal aging effect can be accumulated and promotes water uptake.ILSS drop is related to water uptake content, crystallization and IFSS changes. [ABSTRACT FROM AUTHOR]

In this work, carbon fiber reinforced polyimide (CF/PI) composites via surface modification using metal mesh were obtained. The interfacial adhesion performance of metal mesh and composites, mechanical properties and electrical properties of composites were characterized. The results revealed that introducing metal mesh on CF/PI composites surface obviously decreased the resistivity of composites, which was of great significance for lightning protection. For the mechanical properties, the short‐beam shear strength and flexural properties of modified composites slightly declined, and the failure mode of samples did not change significantly. From microscopic failure morphology and finite element analysis, it can be illustrated that the crack generated from edge may lead to the mechanical properties changes of metal mesh modified sample. Based on practical application condition, the performance change rule of modified composite system after thermal treatment was also reported. This study enables a surface modification thought as a promising way for the application of high temperature resistant CF/PI composite system. [ABSTRACT FROM AUTHOR]

The preparation of continuous carbon fiber reinforced polyether ether ketone (PEEK) composites by the powder slurry method has many advantages, but the stability of PEEK suspension is required to be high. So far, there is a lack of in‐depth studies on the aqueous suspension of PEEK. In this study, two non‐ionic surfactants were selected for compounding. Then PEEK aqueous suspension and continuous carbon fiber reinforced PEEK composites were prepared. The stability mechanism of PEEK aqueous suspension with different surfactants was analyzed. Studies have shown that in the PEEK aqueous suspension, Triton X‐100 can help to infiltrate the PEEK powder. The steric hindrance of polyethylene glycol contributes to the stability of the suspension. The synergistic steric hindrance effect of the two surfactants can increase the stability time of PEEK suspension from 5 min to more than 50 min. The PEEK composites prepared by the powder slurry method has good quality stability, the fiber volume fraction is about 60%, the flexural strength of the composites can reach 1336 MPa, and the interlayer shear strength can reach 106 MPa. This study provides useful insights for the stability mechanism of PEEK aqueous suspension, and can guide the preparation process of thermoplastic composites by powder slurry method. [ABSTRACT FROM AUTHOR]

Background: The long non-coding RNA (lncRNA) LINC00969 is involved in human disease progression, and n6-methyladenosine (m6A) modification of lncRNAs in cancer has been proven to be a key regulatory mechanism. However, our understanding of its effects and mechanisms of action in papillary thyroid carcinoma (PTC) remains limited., Objectives: This study aimed to elucidate the role of methyltransferase-like 3 (METTL3)-induced m6A modification of LINC00969 in PTC tumorigenesis., Material and Methods: Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was performed to analyze LINC00969 and METTL3 mRNA levels in PTC. The regulation of LINC00969 by METTL3 was confirmed using cell function experiments, molecular biology assays and bioinformatics analysis. LINC00969 stabilization analysis was performed to verify the regulatory roles of METTL3 and LINC00969., Results: LINC00969 expression was downregulated in PTC tissues. Increased LINC00969 expression inhibited the invasion, growth and migration of PTC cells. METTL3 downregulation in PTC mediated the m6A modification of LINC00969, increasing its stability. Furthermore, METTL3 levels were downregulated in PTC, and its silencing partially reversed the inhibitory effect of LINC00969 overexpression on PTC cell malignancy., Conclusions: LINC00969 overexpression inhibits PTC cell malignancy via METTL3-mediated m6A modification. These findings suggest that METTL3-m6A-LINC00969 is a promising therapeutic target for PTC.

This work investigated the effects of moisture absorption treatment on composite-to-metal double-lap shear joints (DLSJs) bonded with epoxy adhesive film through experiments and simulations. The composite-to-metal DLSJ can be divided into five parts (the interface between the composite and adhesive, the interface between the adhesive and metal, the composite adherend, the metal adherend, and the adhesive layer). First, the wet-dependent properties of the adhesive and interfaces were obtained through adhesive tensile tests and GC tests, which showed that the properties of the adhesive and interfaces were significantly affected by the moist environment. Then, tensile tests of the composite-to-metal double-lap shear joints were carried out in dry and wet environments. Finally, based on the experimental investigations, a finite element (FE) model that considered cohesive damage was established for simulating damage evolution and predicting the failure loads and failure modes of the DLSJs. The results of both the experimental and numerical tests show that the DLSJ failure load decreases significantly after immersion in 95 °C water, and the major failure mode transfers from adhesive failure to interface failure. The research results provide a theoretical basis or basic data for the structural design of adhesively bonded composite-to-metal.