Durable electromagnetic interference (EMI) shielding is highly desired, as electromagnetic pollution is a great concern for electronics’ stable performance and human health. Although a superhydrophobic surface can extend the service lifespan of EMI shielding materials, degradation of its protection capability and insufficient self-healing are troublesome issues due to unavoidable physical/chemical damages under long-term application conditions. Here, we report, for the first time, an instantaneously self-healing approach via microwave heating to achieve durable shielding performance. First, a hydrophobic 1H,1H,2H,2H-perfluorooctyltriethoxysilane (POTS) layer was coated on a polypyrrole (PPy)-modified fabric (PPy@POTS), enabling protection against the invasion of water, salt solution, and corrosive acidic and basic solutions. Moreover, after being damaged, the POTS layer can, for the first time, be instantaneously self-healed via microwave heating for a very short time, i.e., 4 s, benefiting from the intense thermal energy generated by PPy under electromagnetic wave radiation. This self-healing ability is also repeatable even after intentionally severe plasma etching, which highlights the great potential to achieve robust and durable EMI shielding applications. Significantly, this approach can be extended to other EMI shielding materials where heat is a triggering stimulus for healing thin protection layers. We envision that this work could provide insights into fabricating EMI shielding materials with durable performance for portable and wearable devices, as well as for human health care."Image missing"

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In this study, a novel compound lamination technique was applied to improve the mechanical properties of hemp fibrereinforced polylactic acid composites. Polylactic acid fibres were blended with hemp fibres in a specific weight ratio in order to produce needled mats. Then, sections of the needled mat were stacked with several polylactic acid resin layers on either side, then formed hemp/polylactic acid composites through hot-pressing. The tensile and flexural properties of hemp/polylactic acid composites were tested according to ASTM standards. A multi-factor orthogonal analytical approach was adopted to discuss the effect of factors such as the hybrid ratio, forming temperature and pressure on mechanical properties of the developed green composites. The adhesion between the fibres and the matrix in the fracture surfaces and the thermal stability of the produced composites were observed via scanning electron microscopy and thermogravimetric analysis. The component analysis of composites was conducted by infrared spectra for confirming the contribution of polylactic acid. The results showed that adhesion between fibres and matrix was enhanced, as well as mechanical properties also improved, especially the tensile strength and flexural properties were obviously improved by utilizing this novel compounding technique.

Fiber-reinforced plastic (FRP) is composed of reinforced fibers and matrix resin, and has high specific strength and low-density materials. Because of the orientation of the fibers within them, FRPs are prone to buckling damage when under compression along the axial direction of the fiber, especially flexible organic ones. The compressive performance of FRP is largely dependent on fiber properties. the buckling load of FRP will increase with the increasing of fiber's. In this study, we developed a way to improve the compressive and bending strength of ultra-high molecular weight polyethylene (UHMWPE) fibers. Carbon nanotubes (CNTs) and vapor-grown carbon fibers (VGCFs) were coated on the surface of UHMWPE fibers by pyrrole vapor deposition. The transverse compressive strength and bending strength of single UHMWPE fibers were determined by microcompression and single fiber bending measurements, respectively. The experiment result showed that coating UHMWPE fibers with CNTs and VGCFs increased both their transverse compressive strength and bending strength. It is excepted that the improved fiber would applied in FRP for better compressive performance.

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