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Simulation Techniques for the Characterization of Structural and Transport Properties of Catalyst Pellets
Published in E. Robert Becker, Carmo J. Pereira, Computer-Aided Design of Catalysts, 2020
Sebastian C. Reyes, Enrique Iglesia
The percolation threshold gives the minimum fraction of bonds required for the network to have macroscopic transport (conductivity); below Φc, the bonds remain as isolated bonds and clusters of bonds. The percolation threshold is also a measure of the connectivity of the pore space; the smaller the threshold is, the more connected the pores in the network.
Manufacturing Methods of PLA Composites
Published in Jyotishkumar Parameswaranpillai, Suchart Siengchin, Nisa V. Salim, Jinu Jacob George, Aiswarya Poulose, Polylactic Acid-Based Nanocellulose and Cellulose Composites, 2022
Guang-Way Bill Jang, Cheng-Han Hsieh, Allen Lai, Sagle Chan
A tertiary system consisting of PLA, CNF, and epoxidized soybean oil (ESO) was developed to maintain tensile strength and to increase the ductility of the biocomposite [71]. The mixture of PLA, CNF, and ESO was melt blended with a Brabender at 160°C and 60 rpm rotor speed. It was followed by extrusion and compress molding at 220°C for sample preparation. For a two-component system, the tensile strength and modulus were improved in the PLA-CNF biocomposites with increasing CNF content, while the values decreased in the PLA-ESO cases with the increase of ESO content. By combining CNF and ESO to the PLA matrix, the biocomposite retained comparable tensile strength and 20% increased modulus values to that of PLA while the ductility and toughness reached at least three times of neat PLA. According to the study results, it was suggested that 10 wt.% CNF was responsible for maintaining the tensile strength and modulus and ESO contributed to the improvement of ductility of the biocomposite. Further increase of CNF to 20 and 30 wt.% did not lead to improvement in strength, modulus, or strain in the presence of ESO (5 wt.%) compared to the case of the PLA-CNF binary system. Superior properties at high volume fractions of CNFs were attributed to the formation of strong hydrogen bonds among NCs, which results in geometrical and mechanical percolation. Force transfer occurring between CNF and PLA matrix became the dominant factor at 20 wt.% CNF content. The percolation threshold range depended on the dispersion of the filler, aspect ratio, and filler/matrix interaction. In a binary system, at low filler content, both CNF (10 wt.%) and ESO (2 and 5 wt.%) enhanced the PLA crystallization rate. At higher content, the fillers may serve as impurities that interfere with nucleation or crystal growth. Irregular degrees of crystallization were observed for the tertiary system due to hydrogen bonding interaction between CNFs and ESO. Thus, it is critical to optimally control the amount of CNF and ESO to obtain a biocomposite with desired mechanical performance.
Strain-sensing characteristics of self-consolidating concrete with micro-carbon fibre
Published in Australian Journal of Civil Engineering, 2020
Arvind Kumar Cholker, Manzoor Ahmad Tantray
Prior to testing, initial resistance was measured with DMM and initial resistivity was obtained using Eq. (3). The initial resistivity of all the samples is shown in Figure 4. It is observed that the rate of decrease in resistivity is less for 0 to 1% of fibre content and sharply decreases when the fibre content increases from 1 to 1.5%. The decrease rate in resistivity is again low beyond fibre content of 1.5%. This shows that percolation threshold can be considered between 1 and 1.5% of fibre content and is attributed to the fact that fibres at these dosages form a continuous electric link, allowing free flow of current and therefore decrease in resistance. The percolation threshold is defined as the phase in which the material continues on an electric path due to the random distribution of the conductive electrical fibres (Javier Baeza et al. 2010). Similar trend was observed by (D’Alessandro et al. 2016b) when multi wall carbon nano-tubes (MWCNT’s) and CF’s were embedded in concrete that is shown in Figure 4. According to (D’Alessandro et al. 2016b)study, percolation threshold was 0.8–1 and 1.5% for MWCNT’s and CNF’s, respectively.