Thermoplastic resins have contributed more and more to the field of fiber reinforced composites . The ability to fabricate fiber reinforced thermoplastic resin composites with excellent and functional interface performances has so far been elusive. Herein, we use a polyamide-imide (PAI)/Ti 3 C 2 T x MXene sizing to enhance the interfacial performance of CF reinforced polyetheretherketone (PEEK) composites. The composite sizing makes the composite with high interfacial adhesion and electromagnetic interference (EMI) shielding performances. Our results indicate that traditional composite materials can improve performance and increase functionality through interface treatment.
In this study, a novel environmentally friendly water-based sizing agent (HPPAEN-COOH) was designed and prepared This sizing agent exhibited good thermal stability and stability in aqueous solutions, significantly improving the interfacial and tribological properties of CF/PPEK composites. Compared to UCF/PPEK composites, the wear coefficients under dry friction and oil lubrication conditions were reduced by 52.3 % and 46.3 %, respectively. Furthermore, the interfacial strengthening mechanism of the sizing agent was investigated from a microscopic perspective using molecular dynamics (MD) simulations. Both experimental and simulation results demonstrated that the use of the sizing agent effectively enhanced the interfacial interaction between the resin and the fiber. This study offers novel insights for the development of high-performance thermoplastic resin-based composites and for understanding the microscopic mechanisms of their interfacial modification.
Countercurrent imbibition of the fracturing fluid is of much significance for enhancing oil production in tight oil reservoirs during the shut-in period after hydraulic fracturing. The addition of enhanced imbibition agents such as surfactants and nanoparticles into the polymer-based fracturing fluid is conducive to oil production. How different types of imbibition agents affect oil recovery and the applicable conditions for different imbibition agents, however, still need to be clarified. In this article, we used low-field nuclear magnetic resonance (NMR) to measure the one-dimensional (1D) oil signal profiles along the imbibition direction during the countercurrent imbibition process and determine the imbibition distance and water saturation of different imbibition agents including polymer, surfactant, nano-silica (NS) and NS-surfactant complexes. Moreover, by measuring oil–water interfacial tension (IFT), and the adhesion forces between alkanes and the hydrophobic surfaces before/after the imbibition agent treatments by atomic force microscope (AFM), the IFT reduction and wettability alteration abilities of these agents were evaluated. After the NS-surfactant complexes treatment, the adhesion force which represents the force required to pull off oil from the rock surface became the lowest (15.81 pN), merely a quarter of that of NS (73.48 pN) and surfactant (70.01 pN), indicating a superior capability of NS-surfactant to improve wettability. The imbibition efficiency of the four systems in terms of imbibition distance and oil recovery was: NS-surfactant complexes: 38.43 mm 13.2 % > nonionic surfactant: 32.15 mm 9.0 % > NS: 25.88 mm 7.6 % > polymer: 17.64 mm 4.9 %. NS-surfactant nanofluid displayed the longest imbibition distance and highest water saturation, thus possessing the highest imbibition oil recovery. Nonionic surfactant with an IFT of 4.19 mN/m could greatly reduce the IFT compared with NS (35.98 mN/m), but the recovery enhancement induced by IFT reduction was not significant. In contrast, the increase in oil recovery by wettability alteration was distinctly higher than that by IFT reduction, as indicated by the recovery difference between NS-surfactant complexes and surfactant. Accordingly, wettability alteration is the primary mechanism to enhance imbibition oil recovery when ultralow IFT cannot be achieved. This research provides guidance on which type of imbibition agent should be selected to improve imbibition efficiency.
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