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The development of easy and direct real-time monitoring of welded joint quality instead of surface damage analysis is crucial to improve the quality of industrial products. This work presents the results of high-density polyethylene (HDPE)-based composites with various carbon black (CB) content (from 20 to 30 vol.%) for use as a heating element and strain sensor in electrofusion-welded polymer joints. The pyroresistive heating process was used to determine the effect of generated Joule heat during welding on the structure and sensor properties of polymer–carbon composites. It is shown that the generation of Joule heat depends on the nanocarbon content and affects the crystallinity of the polymer matrix. The partial disruption of the conductive path of carbon black particles was observed and, as a result, a decrease in electrical conductivity for composites with lower CB content after welding was found. For the highest CB amount, conductivity increased, which is caused by smaller particle-to-particle distance for filler paths. Therefore, the best balance between pyroresistive and sensor properties was found. [ABSTRACT FROM AUTHOR]

To create materials that interact effectively with electromagnetic (EM) radiation, new nanosized substituted ferrites (NiZn)1−xMnxFe2O4 (x = 0, 0.5, and 1) anchored on the surface of multi-walled carbon nanotubes (CNTs) have been synthesized. The concentration of CNTs in the (NiZn)1−xMnxFe2O4/CNT system was from 0.05 to 0.07 vol. fractions. The dielectric and magnetic characteristics of both pristine (NiZn)1−xMnxFe2O4 ferrites and (NiZn)1−xMnxFe2O4/CNT composite systems were studied. The introduction of (NiZn)1−xMnxFe2O4/CNT composites into the amorphous epoxy matrix allows to tailor absorbing properties at the high-frequency by effectively shifting the maximum peak values of the absorption and reflection coefficient to a region of lower frequencies (20–30 GHz). The microwave adsorption properties of (NiZn)1−xMnxFe2O4/0.07CNT–ER (x = 0.5) systems showed that the maximum absorption bandwidth with reflection loss below −10 dB is about 11 GHz. [ABSTRACT FROM AUTHOR]

Growing demand for electric energy in newly developed electronic systems causes increasing interest in research on piezoelectric nanogenerators (PENGs). Design and fabrication of such devices is challenging, considering cost of materials used in their construction. This is the main reason why intensive research has begun on 0‐3 composites with piezoelectric properties. One of the most promising constituent materials for composites fabrication are polymers, due to their low cost and easy processing. Herein, we present fabricated wearable PENG with good impact and vibration energy conversion properties. Correlation between matrix stiffness and piezoelectric properties of 0‐3 type composite is proposed. It was found that composite with 10 wt.% of BiFeO3 particles exhibits power output density for vibrations, finger tapping, and air stream pressure P = 11.12 nW cm−3, P = 4.83 μW cm−3, and P = 769.2 μW cm−3, respectively. Decrease in stiffness of epoxy matrix results at least in two‐times lower power output density for this same PENG. The obtained results demonstrate that the fabricated BFO/epoxy composites show the wide applicability and potential to be integrated with other functional devices, for example, as a part of wearable devices in smart shoes. [ABSTRACT FROM AUTHOR]

The use of graphene materials, i.e. graphene oxide, reduced graphene oxide, graphene nanoplatelets and their functionalized forms as fillers of epoxy composites, is reviewed. The purpose of the time- and reagent consuming functionalization methods of graphene materials is justified by the noticeable improvement of dispersity and adhesion of the graphene sheets to the epoxy matrix, which affects the final properties of graphene-epoxy composites. The state-of-the-art of multifunctional graphene-epoxy composites developed over the last years is critically reviewed. The influence of the graphene filler structure and dispersion preparing procedure on the morphology of epoxy-graphene composites and, consequently, their electrical and thermal conductivities, mechanical strength and flame retardant characteristics is considered. An evolution from epoxy-graphite microcomposites to epoxy-graphene nanocomposites is presented, showing the benefits of graphene materials for composites. Some recent works on the epoxy composites reinforced with hybrid graphene fillers and combinations of graphene materials with other fillers are described. [ABSTRACT FROM AUTHOR]

To create materials that interact effectively with electromagnetic (EM) radiation, new nanosized substituted ferrites (NiZn) 1-x Mn x Fe 2 O 4 (x = 0, 0.5, and 1) anchored on the surface of multi-walled carbon nanotubes (CNTs) have been synthesized. The concentration of CNTs in the (NiZn) 1-x Mn x Fe 2 O 4 /CNT system was from 0.05 to 0.07 vol. fractions. The dielectric and magnetic characteristics of both pristine (NiZn) 1-x Mn x Fe 2 O 4 ferrites and (NiZn) 1-x Mn x Fe 2 O 4 /CNT composite systems were studied. The introduction of (NiZn) 1-x Mn x Fe 2 O 4 /CNT composites into the amorphous epoxy matrix allows to tailor absorbing properties at the high-frequency by effectively shifting the maximum peak values of the absorption and reflection coefficient to a region of lower frequencies (20-30 GHz). The microwave adsorption properties of (NiZn) 1-x MnxFe 2 O 4 /0.07CNT-ER (x = 0.5) systems showed that the maximum absorption bandwidth with reflection loss below -10 dB is about 11 GHz.