Facile preparation of poly(p-phenylene benzobisoxazole)/graphene composite films via one-pot in situ polymerization

Properties of Graphene-Thermoplastic Polyurethane Flexible Conductive Film

Flexible conductive films were prepared via a convenient blending method with thermoplastic polyurethane (TPU) as matrix and nanocrystalline cellulose (NCC) modified chemically reduced graphene oxide (RGO/NCC) as the conductive fillers. The relationships between the electrical and thermal properties as well as the tensile strength and electrothermal response performance of the composite film and the mass content of reduced graphene oxide (RGO) and the initial TPU concentration were systematically investigated. The experimental results show that the resistivity of the composite film with the mass content of RGO/NCC of 7 wt% and an initial TPU concentration of 20 wt% is the minimum of 8.1 Ω·mm. However, the thermal conductivity of composite film with mass content of RGO/NCC of 5 wt% and the initial TPU concentration of 30 wt% reaches a maximum of 0.3464 W·m−1·K−1, which is an increase of 56% compared with pure TPU. The tensile strength of the composite films with mass contents of RGO of 3 wt% prepared with the initial TPU concentrations of 20 wt% reaches the maximum of 43.2 MPa, which increases by a factor of 1.5 (the tensile strength of the pure TPU is 28.9 MPa). The composite conductive film has a fast electrothermal response. Furthermore, superhydrophobic composite conductive films were prepared by immersing the composite conductive film into fluorinated decyl polyhedral oligomeric silsesquioxane (F-POSS) ethanol solution. The water contact angle of the superhydrophobic composite conductive film reaches 158.19° and the resistivity of the superhydrophobic composite film slightly increases and still has good conductivity.

Enhancement of hydrophobicity and UV aging resistance of Poly (p-phenylene benzobisoxazole) fibers modified by fluorosilane and UV absorber

Poly (p-phenylene benzobisoxazole) (PBO) fibers were functionalized by 3-Glycidoxypropyltrimethoxysilane (KH-560) and then coated with 1 H, 1 H, 2 H, 2H-Perfluorodecyltrimethoxysilane (HFTES) and UV absorber (UV-328) to improve hydrophobicity and UV aging resistance. The chemical compositions of PBO fibers before and after modification were analyzed by XPS and surface morphologies were observed by SEM. The hydrophobicity of PBO fibers was evaluated by the measurement of contact angle for water and the UV aging resistance was evaluated by the tensile strength retention ratio of PBO fibers. The results showed that KH-560 was successfully introduced onto the PBO fiber surface. The contact angle for water was increased by 128% from 51.7° to 127°, suggesting a huge improvement of hydrophobicity. The UV aging resistance of PBO fibers was also greatly improved. After 400 h UV exposure, the tensile strength retention ratio was increased to 53%, which was much higher than that of 21.4% for pristine PBO fibers. And the results of variable coating times demonstrated that the optimal UV aging resistance was obtained by coating three times.

Improved Mechanical Properties of Copoly(Phthalazinone Ether Sulphone)s Composites Reinforced by Multiscale Carbon Fibre/Graphene Oxide Reinforcements: A Step Closer to Industrial Production

The properties of carbon fibre (CF) reinforced composites rely heavily on the fibre-matrix interface. To enhance the interfacial properties of CF/copoly(phthalazinone ether sulfone)s (PPBES) composites, a series of multiscale hybrid carbon fibre/graphene oxide (CF/GO) reinforcements were fabricated by a multistep deposition strategy. The optimal GO loading in hybrid fibres was investigated. Benefiting from the dilute GO aqueous solution and repeated deposition procedures, CF/GO (0.5%) shows a homogeneous distribution of GO on the hybrid fibre surface, which is confirmed by scanning electron microscopy, atomic force microscope, and X-ray photoelectron spectroscopy, thereby ensuring that its PPBES composite possesses the highest interlaminar shear strength (91.5 MPa) and flexural strength (1886 MPa) with 16.0% and 24.1% enhancements, respectively, compared to its non-reinforced counterpart. Moreover, the incorporation of GO into the interface is beneficial for the hydrothermal ageing resistance and thermo-mechanical properties of the hierarchical composite. This means that a mass production strategy for enhancing mechanical properties of CF/PPBES by regulating the fiber-matrix interface was developed.

Thermal Conductivity of Graphene-Polymer Composites: Mechanisms, Properties, and Applications

With the integration and miniaturization of electronic devices, thermal management has become a crucial issue that strongly affects their performance, reliability, and lifetime. One of the current interests in polymer-based composites is thermal conductive composites that dissipate the thermal energy produced by electronic, optoelectronic, and photonic devices and systems. Ultrahigh thermal conductivity makes graphene the most promising filler for thermal conductive composites. This article reviews the mechanisms of thermal conduction, the recent advances, and the influencing factors on graphene-polymer composites (GPC). In the end, we also discuss the applications of GPC in thermal engineering. This article summarizes the research on graphene-polymer thermal conductive composites in recent years and provides guidance on the preparation of composites with high thermal conductivity.

Defect/Edge-Selective Functionalization of Carbon Materials by "Direct" Friedel-Crafts Acylation Reaction

Popularly utilized oxidation media, via nitric acid/sulfuric acid mixtures, are too corrosive and oxidizing to preserve structural integrity of highly ordered graphitic materials (carbon nanotubes (CNTs) and graphene). Here, for the most commonly used oxidation method, the important advantages of defect/edge-selective functionalization of carbon materials (CNTs/graphene/graphite) in a polyphosphoric acid (PPA)/phosphorous pentoxide (P₂ O₅ ) medium are elucidated. The optimized PPA/P₂ O₅ medium is a mild acid that is not only less corrosive than popularly utilized oxidation media, but also has a strong capability to drive Friedel-Crafts acylation by covalently modifying carbon materials. With a broader spectrum of functional groups accessible, the PPA/P₂ O₅ -driven Friedel-Crafts acylation offers more options for tailoring the properties and processing of carbon materials.