Flexible
strain sensors have recently attracted great attention
due to their promising applications in human motion detection, healthcare
monitoring, human–machine interfaces, and so forth. However,
traditional uniaxial strain sensors can only detect strain in a single
direction. Herein, an anisotropic flexible strain sensor is fabricated
based on conductive and highly aligned cellulose composite nanofibers,
via facile electrospinning cellulose acetate, deacetylation, and in
situ polymerization of pyrrole, to detect complex multidimensional
strains. Benefiting from the unique well-ordered structure of conductive
composite nanofibers, the obtained strain sensor shows extraordinary
anisotropic sensing performance with a sensitivity of 0.73 and 0.01
for the tensile applied perpendicular and parallel to the nanofiber
alignment, respectively. The sensor also exhibits outstanding durability
(2000 cycles) due to the strong hydrogen bonding between cellulose
nanofibers and polypyrrole. Moreover, the flexible strain sensors
exhibit promising potentials for application in motion detection,
as demonstrated by the detection of various joint movements in the
human body.
The aim of this study is to realize the controlled construction and modulation of micro-/nanostructures of conductive composite materials (CCMs) in a facile way. Herein, interdigital electrodes are prepared by direct-ink-write printing co-blended inks made of ethyl cellulose and carbon nanotubes on cellulose paper. The cellulose nanofibers (CFs) are prepared by electrospinning cellulose acetate on to an aluminum foil, followed by deacetylation in NaOH/ethanol. All co-blended inks exhibit a typical non-Newtonian shear thinning behavior, enabling smooth extrusion and printing. The above electrodes and the conductive CF films with excellent thermal stability are assembled into a pressure sensor, which has a high sensitivity (0.0584 KPa−1) to detect the change in external loading pressure. The obtained porous CFs film is further endowed with conductivity by in situ polymerization of polypyrrole (PPy), which are uniformly distributed on the CFs surface as particles; a triboelectric nanogenerator is constructed by using the CF@PPy film as a tribo-positive friction layer to achieve efficient energy harvesting (output voltage = 29.78 V, output current = 2.12 μA). Therefore, the construction of CCMs with micro-/nanostructures based on cellulose derivatives have essential application prospects in emerging high-tech fields, such as green electronics for sensing and energy harvesting.
Comprehensive optimization of distillation column operating parameters is very important in chemical production. Response surface methodology (RSM) was used in combination with process simulation for complex optimization of operating parameters on the butanol distillation column in solvent fermentation process. The singleparameter effect of theoretical number of plates, feed positions, flow rate, and reflux rate on the content of water and butanol in the overhead distillate were investigated using the chemical process simulation software PRO/II. Then, according to the results of single-parameter simulation, comprehensive optimization was done using the response surface optimization method -central composite design (CCD), with the minimization of water content in the overhead distillate as the objective. The best optimized mathematical model was established and the result was verified by industrial production process. It was that satisfactory results can be obtained when RSM is combined with process simulation. This can produce more optimal conditions than those obtained by single-factor optimization in multivariate optimization problems. The optimal operating conditions are as follows: number of theoretical plates = 47, feed positions at the 7th and 12th theoretical plates (from top to bottom), overhead distillate flow rate = 441 kg/h, and reflux rate = 1860 kg/h. The water and butanol contents in the overhead distillate under these conditions are 0.5093 and 0.001%, respectively. This process was a reference point for the optimization of operating parameters of a distillation system.
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