Lignin-containing Microfibrillated Cellulose Prepared from Corncob Residue via Calcium Hydroxide Co-grinding and Its Application in Paper Reinforcement

In this study,lignin-containing microfibrillated cellulose(MFC)was prepared from corncob residue after xylose extraction via co-grinding with calcium hydroxide.The product was then compared with the MFC obtained by direct grinding and applied to strengthen paper.The chemical composition and morphological structure analysis results showed that the corncob residue can be used to prepare lignin-containing MFC and does not require further purification.Moreover,the co-grinding with calcium hydroxide is easier to fibrillate corncob residue.The MFC obtained by cogrinding with calcium hydroxide had a higher aspect ratio,and its surface was coated with calcium carbonate nanoparticles.MFCs obtained by both the methods mentioned above had an obvious strengthening effect on paper.Compared with the paper without MFC,the tensile index,elongation,burst index,and folding strength of the paper with MFC obtained by co-grinding with calcium hydroxide significantly increased by 17.5%,22.1%,19.5%,and 157.1%,respectively.This study provides a novel idea for the utilization of corncob residue,which may enhance the value and promote the comprehensive utilization of corn by-products.

Octadecylamine Graft-modified Cellulose Nanofiber and Its Reinforcement to Poly(butylene adipate-co-terephthalate) Composites

Biodegradable polymers such as poly(butylene adipate-coterephthalate)(PBAT)have attracted great interest as alternatives to traditional petroleum-based polymers.Nonetheless,it is necessary to improve some properties of PBAT,such as mechanical strength.Cellulose nanofiber(CNF)can improve PBAT mechanical strength,but its dispersion and compatibility in the PBAT matrix require further improvement.In this study,octadecylamine(ODA)was utilized to graft-modify CNF to change the fiberto-fiber interaction and improve its compatibility with the PBAT matrix.PBAT composites with 1 wt%CNF were prepared using a masterbatch premixing method to avoid CNF aggregation during extrusion.The effects of ODA graft modification on CNF properties were studied;varying degrees of CNF modification were investigated for their effect on PBAT properties.ODA-modified CNF(OCNF)/PBAT melt-extruded composites possessing 17.2%higher tensile strength than pure PBAT polymer were obtained without affecting the thermal stability of PBAT.As a result,surface modification of CNF with ODA is an effective strategy for improving CNF-PBAT compatibility.

Preparation and Characterization of Cellulose Nanofibril-Waterborne Polyurethane Composite Films

To improve the performance of polyurethane films,small amounts of cellulose nanofibrils(CNF)were physically blended with a waterborne polyurethane(WPU)emulsion,and then CNF/WPU composite films were prepared by cast-coating and drying.The particle size of the emulsions and the chemical structure,micromorphology,thermal stability,mechanical properties,and water resistance of the composite films were characterized using a Malvern laser particle size analyzer,Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),thermogravimetric analysis(TGA),an electronic strength machine,water contact angle analysis(WCA),and water absorption tests,respectively.The results showed that at a low CNF content of 0.3 wt%,the particle size of the WPU emulsion and chemical structure of the film did not change significantly.In addition,the tensile strength of the composite film increased by up to 108%compared to the neat WPU film,and the thermal stability and water resistance were slightly improved.The addition of CNF greatly enhanced the tensile strength while maintaining the other original properties of the WPU film,which may greatly improve the service life and tear resistance of commercial coatings in the future.

Comparison of Nanofibrillated Cellulose and Hydroxyethyl Cellulose in Improving the Storage Stability of Waterborne Coatings

Waterborne coatings often delaminate and settle during long-term storage,requiring the addition of thickeners.The effects of nanofibrillated cellulose(NFC)and the commonly used thickener,hydroxyethyl cellulose(HEC),on the storage stability of waterborne coatings were compared in this study.The morphology of NFC was characterized using infrared spectroscopy(FT-IR)and scanning electron microscopy(SEM).The rotational viscosity and rheological properties of the waterborne coatings with NFC and HEC were tested.Stationary settling experiments were also conducted at different temperatures to compare the difference of NFC and HEC on improving the storage stability of the waterborne coatings.The results showed that the waterborne coating with NFC exhibited pseudoplastic fluid characteristics;a small addition of NFC can achieve the same improvement effect on the storage stability of waterborne coatings as HEC.Further,the improvement effect of NFC was not affected by temperature.The waterborne coating with NFC still exhibited good storage stability at high temperatures,which was significantly superior to that of HEC.Therefore,NFC is a feasible agent for improving the prolonged storage stability and warming-induced delamination of waterborne coatings.

Preparation and Application of Microfibrillated Cellulose-modified Ground Calcium Carbonate

Microfibrillated cellulose(MFC) was first prepared by 2,2,6,6-tetramethylpiperidine-1-oxyl(TEMPO) oxidation pretreatment and mechanical grinding in the presence of a certain amount of ground calcium carbonate(GCC).The effects of GCC dosage and grinding concentration on the fibrillation were investigated.The obtained MFC was then added to the bulk GCC to form MFC-modified GCC fillers.The properties of MFCmodified GCC fillers were compared to those of the traditional GCC fillers.Results showed that the resulting fibrils became more uniform when the dosage of GCC was 10%~15% and the concentration of the suspension was 6.97%.Compared to traditional GCC,the average particle size of the MFCmodified GCC fillers was larger.Scanning electron microscopy images showed that GCC and MFC formed a bridge structure in the MFC-modified GCC fillers.In the process of papermaking,the MFC-modified GCC fillers decreased the drainage rate but increased the retention of fillers.The prepared papers filled with MFC-modified GCC fillers had higher tensile strength than those filled with traditional GCC fillers.

Preliminary Study on the Reinforcing Effect of Nanocellulose on Supercapacitor Membranes

In this study,six types of nanocellulose,as paper strengthening agents,were investigated for their reinforcing effects on a supercapacitor membrane by adding them to a slurry.The results indicated that adding 3%nanocellulose bacterial cellulose(BC)-B could effectively increase the tensile strength of the supercapacitor membrane by 36.5%without changing the pore structure of the membrane.Scanning electron microscopy images revealed that adding polyacrylamide to the supercapacitor membrane caused serious adhesion between fibers and affected the pore structure of the supercapacitor membrane,whereas adding BC-B did not produce similar effects.

Degradable Foam Tray Based on High-concentration Dispersed Cellulose Fibers Obtained by a Hot-press Baking Process

Degradable industrial packaging foam trays made from cellulose fibers were fabricated using a hot-press baking process.Bleached softwood pulp fibers with a concentration of 30%were dispersed at a high speed under the action of a dispersant.The effects of the dispersant dosage of the fibers on the porosity,foam density,and static compression characteristics were discussed.Furthermore,the effects of the reinforcing adhesive including polyvinyl alcohol(PVA),and cassava starch on the physical and mechanical properties of the foam trays were studied,as well as the relationship between these properties and the microstructure of the foam trays.The dispersant enhanced the rheological and blistering properties of the fiber dispersion.As the dispersant dosage increased from 2%to 4%,the foam density gradually increased and the compressive strain performance and residual compressive strain of the foam trays decreased.Under the condition of constant dosage of dispersant,increasing the fiber proportion from 67%to 77%improved the porosity and foam density and slightly reduced the static compression performance.In additioton,the static compression resistance of the foamed materials was improved by increasing the PVA dosage since PVA was beneficial for improving the strength of the foam trays.

Pore Structure Regulation of Carboxyethylated Microfibrillated Cellulose Films

Carboxyethylation is a recent chemical pretreatment for preparation of microfibrillated cellulose(MFC).The carboxyethylated MFC film prepared by coating method has compact structure and high mechanical properties.In order to expand its application,three approaches including using organic solvents,different drying methods and cationic additives,have been adopted in this paper to enrich and regulate the pore structure of MFC film.The results show that all the approaches can improve the pore structure but decrease the mechanical properties of MFC film.When organic solvents such as ethanol,isopropanol and n-butanol were used to replace the water in MFC suspension or pre-dried MFC film,the pore structure of films were increased.Additionally,the film obtained by freeze-drying or air-drying after freezing in liquid nitrogen or freezer has high porosity but poor strength.The best drying process is to rewet dry MFC film,freeze in liquid nitrogen and then freeze-dry.Moreover,the addition of cationic polyelectrolytes or alkene ketone dimer(AKD)in MFC suspension can also significantly increase the film's porosity.Through the above approaches,the porosity of carboxyethylated MFC film can be regulated between 20% and 90%.

Different Kinds of Microfibrillated Cellulose as Coating Layers Providing Fiber-based Barrier Properties

In this study,we investigated the barrier properties of different kinds of microfibrillated cellulose(MFC)coating layers.The air,oxygen,and water vapor permeability,as well as the water contact angles(WCA),were measured to quantify the barrier efficacy of the applied coatings.The WCA data showed that the surfaces of MFC-coated cardboards are more hydrophilic than those of uncoated cardboards.However,different MFC coatings realize different oxygen transmission rates(OTRs)and water vapor transmission rates(WVTRs).The MFC coating derived from bleached bamboo pulp subjected to carboxyethylation pretreatment(MFCCBP)gave the best oxygen and water vapor barrier performances.The OTR of the virgin cardboard(>16500 cm^(3)/(m^(2)·24 h))decreased to 4638 cm^(3)/(m^(2)·24 h)after coating with the MFCCBP.The WVTR similarly decreased from 1016.7 g/(m^(2)·24 h)to 603.2 g/(m^(2)·24 h).

Carboxyethylated Microfibrillated Cellulose Fibers Prepared from Different Raw Materials

Carboxyethylation pretreatment was used to prepare microfibrillated cellulose(MFC)in this study.In order to evaluate the adaptability of this pretreatment method,carboxyethylated MFC was prepared from six different cellulosic materials.The carboxyl content,degree of polymerization,water retention value,charge density,chemical structure,size distribution,and micromorphology of the materials before and after pretreatment and grinding were studied and compared.The viscosity,ultraviolet(UV)transmittance,and thermal stability of the MFC samples at a certain concentration were determined.The results showed that the carboxyl content,water retention value,charge density,degree of polymerization,size distribution,and micromorphology of the pretreated and ground samples varied with those of the raw materials.The initial viscosity varied based on the type of raw material used.The MFC suspension prepared from cotton linter pulp had the highest UV transmittance,while the MFC prepared from bleached softwood kraft pulp had the highest viscosity at a low shear rate.After thermal degradation,the amount of residual char from the MFC prepared with the thermo-mechanical pulp was slightly higher than that of the other MFCs.This study demonstrates that carboxyethylation is an effective pretreatment method for different cellulosic materials.

Parameters Influencing Power Generation in Eco-friendly Microbial Fuel Cells

Pulp and papermaking industries generate high volumes of carbohydrate-rich effluents. Microbial fuel cell(MFC) technology is based on organic materials' consumption and efficient power production. Using a classical two-chamber lab-scale MFC design with an external resistance of2000 W, we investigated the effects of anode chamber biofilm adaptation(ACBA) and cathode chamber redox solutions(CCRS) on the operation efficiency of MFC when treating wastewater. In ACBA studies, biofilm growth activation showed an increase in the power density to 20.48, 35.18, and36.98 mW/m^2 when the acetate feeding concentrations were 3, 6, and 12 g/L,respectively. Improvement by biofilm adhesion on granular activated carbon(GAC) was examined by scanning electron microscopy(SEM). The obtained power density increased to 25.47, 33.42, and 40.39 mW/m^2 when the GAC particles concentrations were 0, 50, and 100 g/L, respectively. The generated power densities were 51.26 and 40.39 mW/m^2 as well as the obtained voltages were 0.41 and 0.72 V when the electrode area increased from 16 to 64 cm^2,respectively. Using the MFC optimized parameters, CCRS studies carried out using five different cathodic redox solutions. The results revealed that the use of manganese dioxide dissolved in hydrochloric acid generated the maximum power density of 112.6 mW/m^2, current density of 0.094 A/m^2, and voltage of1.20 V with a successful organic removal efficiency of 86.0% after 264 h of operation.

A review on raw materials,commercial production and properties of lyocell fiber

As one of the regenerated cellulosic fibers,viscose fiber has the largest output.However,the wastes produced in the manufacturing process are difficult to eliminate,which restricts the de-velopment of viscose fiber.Lyocell fiber is claimed as“green and eco-friendly fiber”with a good application prospect in the 21st century.The preparation of lyocell fiber is based on the cellu-losic non-derivative solution system,i.e.,N-methylmorpholine-N-oxide system which is nontoxic and recyclable.In this review,firstly,the demands of dissolving pulp properties for regenerated-cellulosic fiber(RCF),especially for lyocell fiber,were introduced in detail.Next,the whole manu-facturing processes including pretreatment,preparation of spinning dope,spinning,posttreatment and efficient solvent recovery technologies were reviewed emphatically.Then,the properties and structural characteristics of lyocell fiber were illustrated.At last,some suggestions were proposed for lyocell fiber development in China.