Porous nanocomposites consisting of cellulose nanocrystals (CNXLs) and polypyrrole (PPY) were fabricated using electrochemical co-deposition. The CNXLs were extracted from cotton using sulfuric acid hydrolysis and were subjected to 2,2,6,6-tetramethylpiperidine-1-oxyl-mediated oxidation, in which primary hydroxyls were oxidized to carboxylate moieties. The PPY/CNXL composites were electrodeposited from a solution of the carboxylated CNXLs and pyrrole (PY) monomers, and the negatively charged CNXLs were incorporated as the counteranion during electrodeposition. The resulting PPY/CNXL nanocomposites were characterized using scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). Cyclic voltammetry and EIS analysis of the PPY/CNXL nanocomposites showed that the stability and specific capacitance of the nanocomposite material were higher than that of PPY containing Cl− anions. The electrochemical performance of the PPY/CNXL nanocomposites was also compared to that of a PPY/carbon nanotube (CNT) composite deposited under the same conditions, which revealed that the PPY/CNXL nanocomposites had a capacitance similar to that of the PPY/CNT nanocomposite and was at least equally as stable as the PPY/CNT nanocomposite.

For practical applications, new supercapacitor electrode materials need to exhibit a high mass-specific capacitance (C M /F g 21 ), a high total-electrode capacitance (C E /F cm 22 ), and high stability during charge-discharge cycling. Very often, newly developed materials display high C M values for thin films (nm or mm thickness) but these rapidly drop off in the thicker electrode structures needed for commercial devices. In this work, we describe the fabrication of thick nanocomposites of polypyrrole (PPY) and cellulose nanocrystals (CNXLs) with consistently high capacitance (C M = 240 F g 21 ) and performance. C E of the PPY-CNXL nanocomposite increased linearly with increasing film thickness up to a value of 1.24 F cm 22 and this increased to a maximum of 1.54 F cm 22 for even thicker films where non-linear C E increases were due to electrolyte diffusion limitations. Testing of a symmetric supercapacitor with these high C E electrodes showed that it retained half of its initial capacity after 50 000 charge-discharge cycles, demonstrating the excellent stability of PPY-CNXL supercapacitor electrode materials.

CNXLs into the electrodepositing polymer film led to the formation of a porous polymer/CNXL nanocomposite structure. The films were characterised using scanning electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge analysis. The specific capacitances of the nanocomposite materials were higher than those of the CNXL-free counterparts (488 F g -1 for PANI/CNXL; 358 F g -1 for PANI; 69 F g -1 for PEDOT/CNXL; 58 F g -1 for PEDOT). The durability of the PANI/CNXL film under potential cycling was slightly better than that of the CNXL-free PANI, while the PEDOT film was slightly more durable than the PEDOT/CNX film. Using electrodeposition, it was possible to form thick PANI/CNXL films, with total electrode capacitances of 2.07 F cm -2 (and corresponding specific capacitances of 440 F g -1 ),demonstrating that this particular nanocomposite may be promising for the construction of high performance supercapacitors.

Cellulosic-crystals as a fumed-silica substitute in vacuum insulated panel technology used in building construction and retrofit applications, Energy and Buildingshttp://dx.doi.org/10. 1016/j.enbuild.2017.08.058 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractThis article investigates impact of substituting fumed silica with a cellulosic-crystal innovation in a commercial Vacuum Insulated Panel (VIP) core. High building performance demands have attracted VIP technology investment to increase production capacity and reduce cost. In building retrofit VIPs resolve practical problems on space saving that conventional insulations are unsuitable for. Three challenges exists in fumed silica: cost, low sustainability properties, and manufacture technical maturity. Cellulosic nano-crystal (CNC) technology is in its infancy and was identified as a possible alternative due to a similar physical nano-structure, and biodegradability. The study aim was to determine a performance starting point and establish how this compares with the current benchmarks. Laboratory cellulosic-crystal samples were produced and supplied for incorporation into commercial VIP manufacture. A selection of cellulosic-panels with core densities ranging 127 -170 kg/m 3 were produced. Thermal conductivities were tested at a pressure of 1 Pa (0.01 mBar), with the results compared against a selection of fumed silica-VIPs with core densities ranging 144 -180 kg/m 3 . Conductivity tests were then done on a cellulosic-VIP with 140 kg/m 3 density, under variable pressures ranging 1 -100,000 Pa (0.01 -1000 mBar). This investigated panel lifespan performance, with comparisons made to a fumed silica-VIP of similar core density. Manufactured cellulosic-samples were found unsuitable as a commercial substitute, with performance below current standards. Areas for cellulosic nano-material technology development were identified that show large scope for improvement. Pursuit could create a new generation of insulation materials that resolve problems associated with current commercial versions. This is most applicable in building retrofit where large ranges of domestic and commercial cases are marginalised from their construction markets due to impracticalities and high upgrade costs. This being a problem in multiple economies globally. Figure 3 with typical layer thicknesses [1,13].VIP thermal conductivities are five to ten times lower than commercial insulations, with the centreof-panel reaching 4 mW/m.K [3,4,14,16]. Albeit excellent performance, the technology is expensive with panel prices multiples of five to ten that of standard insulations [...

No abstract

In this paper, the separation of sulphuric acid from a suspension of cellulose nanocrystal by manual shaking is described. Cellulose nanocrystals are prepared from acid hydrolysis of cotton using 64 wt% sulphuric acid at ca. 45 °C for 45 minutes. After the hydrolysis was complete, water was added to dilute the mixture to a resulting concentration of 30 wt% of the acid. This mixture was shaken rigorously in a closed container and after 48 hours, separation occurs such that cellulose nanocrystals float, with the bubbles introduced by the shaking, to give clear acid solution at the bottom. This shaking-floating process is repeatable for several cycles after the acid was removed from the bottom and more water was added. Using this simple process, the total acid recovery of > 90% has been achieved, and the concentration of all the acid recovered combined was 17.5 wt%. This work demonstrates a method that allows energy efficient and up-scalable separation of cellulose nanocrystals from the acidic suspension from which it was extracted.

No abstract

No abstract