With the rapid development of wearable and portable electronic devices, it is increasingly important to develop conductive paper-like films (CPFs) with the characteristics of light, thin and self-supporting. In this paper, nanofibrillated cellulose (NFC) was used as reinforcing phase of film-forming to combine with graphene oxide (GO). Then graphene-based CPFs were prepared by directly reducing the GO/NFC composite film without any additional adhesives, which effectively avoided the difficulties of dispersion and combination with other materials caused by direct using of high content graphene. Meanwhile, three representative reduction methods for direct reduction of GO/NFC composite films were also compared. The results show that 450 °C thermal reduction and hydroiodic acid reduction were more effective than ascorbic acid reduction. On this basis, hydroiodic acid reduction and thermal reduction were used to discuss the effect of NFC addition to the conductivity of the film. This occured when increasing the content of NFC from 10% to 50%, the electrical conductivity of the composite film by hydroiodic acid reduction decreased from 153.8 S/m to 22.2 S/m. While the conductivity of composite film increased first and then decreased after thermal reduction both at 450 °C and 550 °C. What's more, when NFC content was about 16.6% the electrical conductivity reached a high level which was 86.21 S/m and 168.9 S/m, respectively. This study provides a groundwork for the further development of graphene-based CPFs with low square resistance and high conductivity in large-scale preparation. In recent years, electronic technology has developed rapidly in the direction of intelligence, green, microminiaturization and integration. Accordingly, three-dimensional conductive papers (CPs) or conductive paper-like films (CPFs) with light, thin, self-supporting and excellent durability features exhibit attracting prospect for applications in wearable device 1,2 and the flexible electronic device 3-6. Graphene is a two-dimensional carbon nanomaterial with carbon atoms formed by sp 2 hybridization, which has attracted ever-increasing attention by researchers for its excellent electrical, thermal and mechanical properties 7. And it also has been widely researched in the preparation of conductive materials by virtue of its high electron mobility and high conductivity 8. El-Kady 9 et al. used LightScribe DVD optical drive to do the direct laser reduction of graphite oxide (GO) films to graphene with high electrical conductivity (1738 S/m), but the method requires high equipment and the laser-scribed process is difficult to control in actual production. Zhang 10 et al. prepared highly conductive graphene nanomesh films (27800-35400 S/m) by an in-situ carbothermal reduction strategy and well performed in supercapacitors. However, the preparation process is relatively complicated and the efficiency needs to be improved in large-scale preparation. Among various approaches to prepare graphene composite CPs or CPFs, the development of simple, low-...
The study aimed at developing a new spectrophotometric method for determining the pectin content. Take commercial pectin as an example, and the method is based on the reaction of copper ions with pectin to produce copper pectate. The spectrophotometer was used to measure the remaining content of copper ions so as to calculate the pectin content. This method eliminated the weight step and avoided the error associated with it. Effects of reaction time, temperature, and pH on absorbance were also studied. Additionally, the accuracy of this method was verified. It indicated excellent repeatability and accuracy with the relative standard deviation of 2.09%. In addition, three different plant types were used to demonstrate the reliability of the method. To summarize, this method can be widely used for the determination of pectin content in many materials.
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