Despite the great potential of graphene as a nanofiller, its inhomogeneous dispersion in polymers remains a key challenge for the effective reinforcement of polymer. Herein, we exfoliated worm graphite into graphene by in situ liquidphase exfoliation, and the graphene was coated on the surface of polypropylene (PP) pellets by stirring. Further, we examined several treatment conditions and graphene contents. When graphene was centrifuged at 1000 rpm and the extrusion temperature of the composite was 230 C, the composite achieved optimal overall performance with the addition of only 0.2 wt% graphene. Compared to those of pure PP, the yield strength, bending modulus, and impact strength of the composites increased by 8.71%, 18.32%, and 45.75%, respectively. The thermal conductivity is increased by 29.5%. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) showed that the PP sample exhibited a significant heterogeneous nucleation effect due to graphene addition, improving the crystallization temperature and crystallinity of the composites. Contact angle measurement and scanning electron microscopy (SEM) revealed that the surface energy of graphene and PP are close to each other, and the graphene was well-dispersed in the PP matrix. Thus, this technique can optimize the processing properties and interface structure of graphenepolymer nanocomposites.
Large vertical metal tanks are the primary vessels for the storage and turnover of crude oil, and the accuracy of their capacity calibrations are of great significance. The optical reference line method (ORLM) is used for capacity calibration and is time-consuming, labor-intensive, and hazardous, because of the elevated work. This paper aims to present a robot to overcome the problems above. We propose a tracked wall-climbing robot (TWCR) with permanent magnetic adhesion tracks, a collapsible scale, and an optional shovel-like rust remover that enable the TWCR to move stably on tank surfaces and perform the ORLM. Two sets of field tests (internal ORLM and external ORLM) indicate that capacity calibration by the TWCR is time saving, convenient, and safe, in addition to being accurate and reliable.
Catalytic synthesis of value-added chemicals from sustainable biomass or biomass-derived platform chemicals is an essential strategy for reducing dependency on fossil fuels. As a precursor for the synthesis of important polymers such as polyesters, polyurethanes, and polyamides, FDCA is a monomer with high added value. Meanwhile, due to its widespread use in chemical industry, 2,5-furandicarboxylic acid (FDCA) has gained significant interest in recent years. In this review, we discuss the electrochemical oxidation of 5-hydroxymethylfurfural (HMF) and summarize the most recent advances in electrode materials from the past 5 years, including reaction mechanisms, catalyst structures, and coupling reactions. First, the effect of pH on the electrocatalytic oxidation of furfural is presented, followed by a systematic summary of the reaction mechanism (direct and indirect oxidation). Then, the advantages, disadvantages, and research progress of precious metal, non-precious metal, and non-metallic HMF electrooxidation catalysts are discussed. In addition, a coupled dual system that combines HMF electrooxidation with hydrogen reduction reaction, CO2 reduction, or N2 reduction for more effective energy utilization is discussed. This review can guide the electrochemical oxidation of furfural and the development of advanced electrocatalyst materials for the implementation and production of renewable resources.
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