Mineral fillers are important for conserving raw fiber materials and reducing production costs in the paper industry.However,the increase in filler content will inevitably result in strength reduction,which limits the...Mineral fillers are important for conserving raw fiber materials and reducing production costs in the paper industry.However,the increase in filler content will inevitably result in strength reduction,which limits the adding amount of filler in paper production.In this study,we designed a cellulose fiber/filler co-refining approach to improve the strength and optical properties of paper;moreover,the synergistic interaction between fibers and precipitated calcium carbonate(PCC)fillers in the co-refining process was investigated.Results of fiber separation and PCC particle size analysis showed that,compared with conventional refining,the content of fines increased,whereas the PCC particle size decreased.More importantly,composites were formed between the PCC and fines,which promoted strength improvement of paper.Physical tests show that the tensile index of paper with 15%PCC content increased by 22%compared with that of the paper filled by conventional method,whereas the brightness and opacity of paper improved by fiber/filler co-refining for a specified filler content.These findings provide a basis for the further development of co-refining filling technology.展开更多
The textile industry is considered a major industry worldwide, and some countries use available domestic raw materials for textile manufacturing, being one of many other economic resources. Meanwhile, the Kingdom of S...The textile industry is considered a major industry worldwide, and some countries use available domestic raw materials for textile manufacturing, being one of many other economic resources. Meanwhile, the Kingdom of Saudi Arabia is at the forefront of States paying great attention to the cultivation of palm trees due to their great importance, which are an indispensable traditional food for a large portion of the population. However, huge quantities of palm’s by-products, especially palm fibers, are constantly wasted, although they can be effectively used to produce textiles of particular end uses such as ropes. This study, therefore, sought to explore the potential of extracting cellulose from palm fibers for use in the textile industry. The study has utilized the experimental approach by applying alkaline to palm fibers so as to extract inherent cellulose. It has also applied mechanical processing to turn cellulose into fibers. Fibers’ physical properties (color, diameter, length), chemical properties (ratios of cellulose, hemicellulose, and lignin), and mechanical properties (tensile strength and elongation of fibers before and after treatment) were all studied. The study has proved that the physical, chemical and mechanical properties of regenerated cellulose fibers extracted from palm fibers are similar to those of other natural fibers such as bamboo and linen, and thus can be used in the textile industry. The study also compared different types of palm trees to determine the one that contains the largest concentration of cellulose. However, it was found that sugar palm fibers contain the highest cellulose concentration of 44% and therefore, it was selected for the application of the study’s theory. The study recommends making use of palm fiber in manufacturing textiles for particular end uses such as ropes, fillings and filters, as well as applying the theory of the study to other plants that have not yet been manipulated.展开更多
This study was conducted to evaluate the effectiveness of enzymes in purifying and reducing the degree of polymerization of cellulose for the production of dissolving pulp.Our goal was to determine the contributions o...This study was conducted to evaluate the effectiveness of enzymes in purifying and reducing the degree of polymerization of cellulose for the production of dissolving pulp.Our goal was to determine the contributions of xylanase(X)and endoglucanase(EG)in the treatment of pulp,specifically by quantifying the formation of soluble and insoluble reducing sugars using the dinitrosalycilic acid(DNS)test.Predominantly,the release of soluble reducing sugars(RSSol)was enhanced after xylanase treatment,while endoglucanase(EG)treatment led to changes in insoluble reducing sugars(RSIns).The maximum synergism was observed for RSIns when a high ratio of endoglucanase to xylanase(320EG:5X/g pulp)was used.The relative contribution of endoglucanase to RSins was determined to be 15.6%of the total reducing sugar.The viscosity of pulps treated with xylanase decreased only by 7%,whereas endoglucanase treatment significantly reduced viscosity by 45%.Modifications in the particle size were observed after pulp treatment with the combination of endoglucanase and xylanase.In summary,the DNS test is a rapid and effective method for evaluating the efficiency of enzyme treatments on pulps.The measurement of RSIns correlates with changes in pulp viscosity to different extents,providing valuable insights into the effectiveness of enzyme treatments.展开更多
We have investigated the effect of zinc oxide as a photocatalyst and durable flame-retardant on cellulosic fibers. Zinc oxide nanocrystals were successfully synthesized and deposited onto cellulosic fibers using sol-g...We have investigated the effect of zinc oxide as a photocatalyst and durable flame-retardant on cellulosic fibers. Zinc oxide nanocrystals were successfully synthesized and deposited onto cellulosic fibers using sol-gel process at low temperature. The samples were characterized by means of several techniques such as scanning electron microscopy, transmission electron microscopy, diffuse reflectance spectroscopy, X-ray diffraction and thermogra- vimetric analysis. The photocatalytic activity was tested by measuring the photodegradation of methylene blue under UV-Vis illumination. Moreover, flame-retardancy was tested by vertical flame spread test. The optimum add-on value for donating flame-retardancy onto cellulosic fabric was obtained to be in the range of 15.24 to 23.20 g of the ZnO per 100 g of fabric. Thermogravimetric analysis of pure and flame-retarded samples were accomplished and discussed. The results obtained are in agreement with Wall effect theory and Coating theory. The originality of this work on introducing photoactive flame-retarded fibers is highly valuable for industrial implementation.展开更多
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 ...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.展开更多
It is very difficult to directly spin the lignocellulose without pretreatment.Ionic liquids(ILs)are promising solvent to dissolve lignocellulose to prepare cellulose fiber.However,the degree of cellulose polymerizatio...It is very difficult to directly spin the lignocellulose without pretreatment.Ionic liquids(ILs)are promising solvent to dissolve lignocellulose to prepare cellulose fiber.However,the degree of cellulose polymerization(DP)is reduced when lignocellulose is dissolved in ILs,and the lignin removal rate is low.The elongation at break and tensile strength of the fibers obtained by spinning the lignocellulose dissolved in ILs are poor.In this paper,preparing cellulose fiber directly from lignocellulose based on dissolving corn stalk via[C4mim]Cl-L-arginine binary system is achieved.It shows that the removal rate of lignin can reach 92.35%and the purity of cellulose can reach 85.32%after corn stalk was dissolved at 150℃C for 11.5 h when the mass fraction of arginine is 2.5%.The elongation at break of fiber reached 10.12%and the tensile strength reached 420 MPa.It is mainly due to the fact that L-arginine not only inhibits the degradation of cellulose but also promotes the delignination.Without any pulping or pretreatment,preparing cellulose fibers via direct dissolution and extrusion may provide a simple and effective way to prepare many novel cellulose materials.展开更多
Polypyrrole(PPy)@cellulose fiber-based composites have been widely investigated as electrode materials for use in flexible supercapacitors.However,they cannot readily provide high specific capacitance and cyclic stabi...Polypyrrole(PPy)@cellulose fiber-based composites have been widely investigated as electrode materials for use in flexible supercapacitors.However,they cannot readily provide high specific capacitance and cyclic stability owing to their inherent drawbacks,such as high resistance,Weber impedance,and volume expansion or collapse during charging/discharging.In this study,iron oxyhydroxide(FeOOH)is incorporated in the abovementioned composite to decrease the equivalent series resistance,charge transfer resistance,and Weber impedance,thereby enhancing electron transfer and ion diffusion,which results in superior electrochemical performance.The PPy-wrapped FeOOH@cellulose fiber-based composite electrode with the molar ratio of FeSO_(4) to NaBH4 of 1∶1 exhibits a high specific capacitance of 513.8 F/g at a current density of 0.2 A/g,as well as an excellent capacitance retention of 89.4% after 1000 cycles.展开更多
In this study, bio-yogurts, which contain L. acidophilus and Bifidobacterium animalis subsp. lactis, were produced with cellulose fiber (CF) addition at a various level (0%, 0.5%, 1% and 2%) and stored at 4°C ...In this study, bio-yogurts, which contain L. acidophilus and Bifidobacterium animalis subsp. lactis, were produced with cellulose fiber (CF) addition at a various level (0%, 0.5%, 1% and 2%) and stored at 4°C ± 1°C for 20 days. Bio-yogurts were analysed 1, 10 and 20 days after production. The storage period significantly influenced overall properties of the samples. Addition of CF has positively affected the physical and textural properties of yoghurt, such as serum separation, water holding capacity, viscosity, firmness, adhesiveness, cohesiveness, springiness, gumminess and chewiness (p < 0.05). It also slightly stimulated the development of probiotic bacteria (p < 0.05). Bio-yogurt, which contains 0.5% CF in sensory aspect, is the most appreciated.展开更多
In this work,bioinspired anisotropic polymeric heart valves were fabricated using composite materials from polyurethane(PU)and natural cellulose fiber bundles.Cellulose fibers with good alignment were obtained from ba...In this work,bioinspired anisotropic polymeric heart valves were fabricated using composite materials from polyurethane(PU)and natural cellulose fiber bundles.Cellulose fibers with good alignment were obtained from balsa wood by a top-down process,which were then distributed in polyurethane to pre-pare cellulose fiber bundles reinforced polyurethane(CPU)by hot pressing.The storage modulus of the CPU along the direction parallel to the fiber alignment was 16.70±0.80 MPa,whereas that along the direction perpendicular to the fiber alignment was 8.41±0.94 MPa by dynamic mechanical analysis(DMA)tests at 1 Hz,comparable to aortic valve leaflets.Moreover,2-methacryloyloxyethyl phosphoryl-choline(MPC)was grafted onto the CPU surface(CPU-MPC)to improve hemocompatibility.With MPC modification,the water contact angle decreased significantly from 54.58°±2.98°to 26.42°±3.50°,and the platelet adhesion was reduced by 92%,compared to the original CPU.In vitro cell culture proved that both CPU and CPU-MPC samples did not show any cytotoxicity.Furthermore,the CPU composites were used to fabricate polymeric heart valves,which showed excellent hydrodynamic performance with a large orifice area(1.70 cm 2)and low regurgitation fraction(0.7%),meeting the requirements of ISO 5840-2 standard.展开更多
Electrochemical determination of paracetamol(PCT)was successfully performed using carbon paste electrodes(CPEs)modified with treated coffee husks(CHt)or cellulose powder(Ce).Scanning electron microscopy was used to ch...Electrochemical determination of paracetamol(PCT)was successfully performed using carbon paste electrodes(CPEs)modified with treated coffee husks(CHt)or cellulose powder(Ce).Scanning electron microscopy was used to characterize unmodified or modified CPEs prior to their use.The electrochemical oxidation of PCT was investigated using square wave voltammetry(SWV)and cyclic voltammetry(CV).The oxidation current density of PCT was two-fold higher with the CPE-CHt sensor and 30%higher with CPE-Ce in comparison with the unmodified CPE,and this correlated with the higher hydrophilicity of the modified electrodes.Using SWV for the electrochemical analysis of PCT,carbon paste electrode modified with raw coffee husks(CPE-CHr)showed the presence of impurities at+0.27 V/SCE,showing the interest in using pure cellulose for the present analytical application.Furthermore,CPE-Ce presented a higher real area compared to CPE-CHr,which explains the increase in the limit of saturation from 400 mg/L to 950 mg/L.The better saturation limit exhibited by CPE-Ce justifies its choice for electroanalysis of PCT in commercialized tablets.The proposed method was successfully applied in the determination of PCT in commercialized tablets(DolipraneR 500)with a recovery rate close to 100%,and no interference with the excipients contained in the tablets analyzed was observed.This novel sensor opens the way for sustainable development of electroanalytical control of drugs sold individually in developing countries.展开更多
As the global population grows,the demand for textiles is increasing rapidly.However,this puts immense pressure on manufacturers to produce more fiber.While synthetic fibers can be pro-duced cheaply,they have a negati...As the global population grows,the demand for textiles is increasing rapidly.However,this puts immense pressure on manufacturers to produce more fiber.While synthetic fibers can be pro-duced cheaply,they have a negative impact on the environment.On the other hand,fibers from wool,sisal,fique,wood pulp(viscose),and man-made cellulose fibers(MMCFs)from cotton can-not alone meet the growing fiber demand without major stresses on land,water,and existing markets using these materials.With a greater emphasis on transparency and circular economy practices,there is a need to consider natural non-wood alternative sources for MMCFs to supple-ment other fiber types.However,introducing new feedstocks with different compositions may require different biomass conversion methods.Therefore,based on existing work,this review ad-dresses the technical feasibility of various alternative feedstocks for conversion to textile-grade fibers.First,alternative feedstocks are introduced,and then conventional(dissolving pulp)and emerging(fibrillated cellulose and recycled material)conversion technologies are evaluated to help select the most suitable and promising processes for these emerging alternative sources of cellulose.It is important to note that for alternative feedstocks to be adopted on a meaningful scale,high biomass availability and proximity of conversion facilities are critical factors.In North America,soybean,wheat,rice,sorghum,and sugarcane residues are widely available and most suitable for conventional conversion through various dissolving pulp production methods(pre-hydrolysis kraft,acid sulfite,soda,SO2-ethanol-water,and potassium hydroxide)or by emerging cellulose fibrillation methods.While dissolving pulp conversion is well-established,fibrillated cel-lulose methods could be beneficial from cost,efficiency,and environmental perspectives.Thus,the authors strongly encourage more work in this growing research area.However,conducting thorough cost and sustainability assessments is important to determine the best feedstock and technology combinations.展开更多
Uncontrollable hemorrhage leads to high mortality and thus effective bleeding control becomes increasingly important in the military field and civilian trauma arena.However,current hemostats not only present limitatio...Uncontrollable hemorrhage leads to high mortality and thus effective bleeding control becomes increasingly important in the military field and civilian trauma arena.However,current hemostats not only present limitation when treating major bleeding,but also have various side effects.Here we report a self-expanding porous composites(CMCP)based on novel carboxymethyl cellulose(CMC)fibers and acetalized polyvinyl alcohol(PVA)for lethal hemorrhage control.The CMC fibers with uniform fibrous structure,high liquid absorption and procoagulant ability,are evenly interspersed inside the composite matrix.The obtained composites possess unique fiber-porous network,excellent absorption capacity,fast liquid-triggered self-expanding ability and robust fatigue resistance,and their physicochemical performance can be fine-tuned through varying the CMC content.In vitro tests show that the porous composite exhibits strong blood clotting ability,high adhesion to blood cells and protein,and the ability to activate platelet and the coagulation system.In vivo hemostatic evaluation further confirms that the CMCP presents high hemostatic efficacy and multiple hemostatic effects in swine femoral artery major hemorrhage model.Additionally,the CMCP will not fall off from the injury site,and is also easy to surgically remove from the wound cavity after the hemostasis.Importantly,results of CT tomography and 3D reconstruction indicate that CMCP can achieve shape adaptation to the surrounding tissues and the wound cavities with different depths and shapes,to accelerate hemostasis while protecting wound tissue and preventing infection.展开更多
Centrifugal cleaners are commonly used in the pulp and paper industry to separate contaminates from pulp fibers.To reveal the separation mechanism of cellulose fibers and impurities in a centrifugal cleaner,three-dime...Centrifugal cleaners are commonly used in the pulp and paper industry to separate contaminates from pulp fibers.To reveal the separation mechanism of cellulose fibers and impurities in a centrifugal cleaner,three-dimensional computational fluid dynamics(CFD)models were established based on experimental analyses with the inlet flow rate and outlet diameter as the variables.The incompressible three-dimensional Navier-Stokes equations were applied to describe the fluid motion.Numerical simulation results showed that an increased inlet flow rate could improve the efficiency by enhance of the centrifugal force on particles.Secondary swirling patterns were predominant for centrifugal cleaners with smaller lower outlets.The crowding effect played an important role in the separation of heavy contaminants,and the separating efficiency was proportional to the inlet flow rate and inverse proportional to the lower outlet diameter.展开更多
Recent research efforts in the field of electromagnetic interference shielding(EMI)materials have focused on biomass as a green and sustainable resource.More specifically,wood and cellulose nano fiber(CNF)have many ad...Recent research efforts in the field of electromagnetic interference shielding(EMI)materials have focused on biomass as a green and sustainable resource.More specifically,wood and cellulose nano fiber(CNF)have many advantages,some of which include lightweight,porosity,widespread availability,low cost,and easy processing.These favorable properties have led researchers to consider these types of biomass as an EMI shielding material with great potential.At present,while many excellent published works in EMI shielding materials have investigated wood and CNF,this research area is still new,compared with non-biomass EMI shielding materials.More specifically,there is still a lack of in-depth research and summary on the preparation process,pore structure regulation,component optimization,and other factors affecting the EMI shielding of wood and CNF based EMI shielding materials.Thus,this review paper presents a comprehensive summary of recent research on wood and CNF based EMI shielding materials in recent three years in terms of the preparation methods,material structure design,component synergy,and EMI mechanism,and a forward future perspective for existing problems,challenges,and development trend.The ultimate goal is to provide a comprehensive and informative reference for the further development and exploration of biomass EMI shielding materials.展开更多
Transparent paper with good hydrophobicity and flexibility was expected to act as an alternative substrate in fabrication of flexible electronics.However,conventional paper made of cellulose fibers was opaque and hydr...Transparent paper with good hydrophobicity and flexibility was expected to act as an alternative substrate in fabrication of flexible electronics.However,conventional paper made of cellulose fibers was opaque and hydrophilic without undergoing special processing.Herein,cellulose fiber paper was treated by impregnating with hydrolyzed tetraethyl orthosilicate(TEOS)followed by coating with hydrophobic polydimethylsiloxane(PDMS)to prepare hydrophobic transparent pa-per.The results showed that silica nanoparticles produced by the TEOS hydrolysis improved the paper transparency to some extent,increased the paper thermal stability,but still remained the hydrophilicity of paper.After the paper was further coated with the PDMS and the PDMS was consolidated,the paper became clearly transparent and hydrophobic.The processed paper had a transmittance of more than 90%at 550 nm.The water contact angle of the paper reached about 110°.This work provided a new approach for the fabrication of hydrophobic transparent paper with conventional cellulose fiber paper.展开更多
The use of magnesium hydroxide(Mg(OH)_(2))was proposed as a filler to replace part of the calcium carbonate(CaCO_(3))in cigarette paper and reduce the toxicity of the smoke from cigarettes.Physical property changes an...The use of magnesium hydroxide(Mg(OH)_(2))was proposed as a filler to replace part of the calcium carbonate(CaCO_(3))in cigarette paper and reduce the toxicity of the smoke from cigarettes.Physical property changes and smoke reducing ability of this possible substitution were effectively studied.The results showed that adding 10%Mg(OH)_(2) could meet the requirements of the physical property of the cigarette paper.Moreover,with the addition of Mg(OH)2 as a filler in the cigarette paper,the pyrolysis temperature of the cigarette paper decreased,while the porosity and specific surface area increased.As a result,the main-stream smoke had a lower smoke total particle matter(STMP),tar,nicotine and carbon monoxide content,and the side-stream smoke also had a lower STMP.展开更多
Ammonium polyphosphate-diatomite composite filler(APP-diatomite composite filler)was modified with silane coupling agent KH550 to improve the flame retardancy of filled paper.Cone calorimeter was used to analyze the h...Ammonium polyphosphate-diatomite composite filler(APP-diatomite composite filler)was modified with silane coupling agent KH550 to improve the flame retardancy of filled paper.Cone calorimeter was used to analyze the heat and smoke releasing rates,as well as smoke toxicity of the filled paper.The distribution of the composite filler particles in paper and the morphology of the charred residues after combustion were investigated by scanning electron microscope(SEM),and the chemical structure of the charred residues was studied with fourier transform infrared spectroscopy(FTIR).Results show that the peak heat releasing rate(PHRR),total heat release(THR)and peak mass loss rate(PMLR)of the filled paper with the modified APP-diatomite decreased markedly,compared with those for the control paper,while the charred residue after combustion increased.In addition,the filled paper had an increased peak rate of smoke release(RSR)and increased total smoke release(TSR)and peak CO production rates,but a decreased peak CO_(2) production rate.It was also found that part of the carbon element in the charred residue of the paper loaded with the modified APP-diatomite was in the forms of C=C=C,C≡C and C≡N,and the charred residue had a relatively more intact structure without apparent fiber breakage and longitudinal cracks.展开更多
基金This work was financially supported by Innovation Capability Support Program of Shaanxi(2020KJXX082)the Foundation(202005)of Tianjin Key Laboratory of Pulp&Paper(Tianjin University of Science&Technology).
文摘Mineral fillers are important for conserving raw fiber materials and reducing production costs in the paper industry.However,the increase in filler content will inevitably result in strength reduction,which limits the adding amount of filler in paper production.In this study,we designed a cellulose fiber/filler co-refining approach to improve the strength and optical properties of paper;moreover,the synergistic interaction between fibers and precipitated calcium carbonate(PCC)fillers in the co-refining process was investigated.Results of fiber separation and PCC particle size analysis showed that,compared with conventional refining,the content of fines increased,whereas the PCC particle size decreased.More importantly,composites were formed between the PCC and fines,which promoted strength improvement of paper.Physical tests show that the tensile index of paper with 15%PCC content increased by 22%compared with that of the paper filled by conventional method,whereas the brightness and opacity of paper improved by fiber/filler co-refining for a specified filler content.These findings provide a basis for the further development of co-refining filling technology.
文摘The textile industry is considered a major industry worldwide, and some countries use available domestic raw materials for textile manufacturing, being one of many other economic resources. Meanwhile, the Kingdom of Saudi Arabia is at the forefront of States paying great attention to the cultivation of palm trees due to their great importance, which are an indispensable traditional food for a large portion of the population. However, huge quantities of palm’s by-products, especially palm fibers, are constantly wasted, although they can be effectively used to produce textiles of particular end uses such as ropes. This study, therefore, sought to explore the potential of extracting cellulose from palm fibers for use in the textile industry. The study has utilized the experimental approach by applying alkaline to palm fibers so as to extract inherent cellulose. It has also applied mechanical processing to turn cellulose into fibers. Fibers’ physical properties (color, diameter, length), chemical properties (ratios of cellulose, hemicellulose, and lignin), and mechanical properties (tensile strength and elongation of fibers before and after treatment) were all studied. The study has proved that the physical, chemical and mechanical properties of regenerated cellulose fibers extracted from palm fibers are similar to those of other natural fibers such as bamboo and linen, and thus can be used in the textile industry. The study also compared different types of palm trees to determine the one that contains the largest concentration of cellulose. However, it was found that sugar palm fibers contain the highest cellulose concentration of 44% and therefore, it was selected for the application of the study’s theory. The study recommends making use of palm fiber in manufacturing textiles for particular end uses such as ropes, fillings and filters, as well as applying the theory of the study to other plants that have not yet been manipulated.
基金supported by CNPq(303416/2018-1)and FAPESP(2019/25867-3).
文摘This study was conducted to evaluate the effectiveness of enzymes in purifying and reducing the degree of polymerization of cellulose for the production of dissolving pulp.Our goal was to determine the contributions of xylanase(X)and endoglucanase(EG)in the treatment of pulp,specifically by quantifying the formation of soluble and insoluble reducing sugars using the dinitrosalycilic acid(DNS)test.Predominantly,the release of soluble reducing sugars(RSSol)was enhanced after xylanase treatment,while endoglucanase(EG)treatment led to changes in insoluble reducing sugars(RSIns).The maximum synergism was observed for RSIns when a high ratio of endoglucanase to xylanase(320EG:5X/g pulp)was used.The relative contribution of endoglucanase to RSins was determined to be 15.6%of the total reducing sugar.The viscosity of pulps treated with xylanase decreased only by 7%,whereas endoglucanase treatment significantly reduced viscosity by 45%.Modifications in the particle size were observed after pulp treatment with the combination of endoglucanase and xylanase.In summary,the DNS test is a rapid and effective method for evaluating the efficiency of enzyme treatments on pulps.The measurement of RSIns correlates with changes in pulp viscosity to different extents,providing valuable insights into the effectiveness of enzyme treatments.
文摘We have investigated the effect of zinc oxide as a photocatalyst and durable flame-retardant on cellulosic fibers. Zinc oxide nanocrystals were successfully synthesized and deposited onto cellulosic fibers using sol-gel process at low temperature. The samples were characterized by means of several techniques such as scanning electron microscopy, transmission electron microscopy, diffuse reflectance spectroscopy, X-ray diffraction and thermogra- vimetric analysis. The photocatalytic activity was tested by measuring the photodegradation of methylene blue under UV-Vis illumination. Moreover, flame-retardancy was tested by vertical flame spread test. The optimum add-on value for donating flame-retardancy onto cellulosic fabric was obtained to be in the range of 15.24 to 23.20 g of the ZnO per 100 g of fabric. Thermogravimetric analysis of pure and flame-retarded samples were accomplished and discussed. The results obtained are in agreement with Wall effect theory and Coating theory. The originality of this work on introducing photoactive flame-retarded fibers is highly valuable for industrial implementation.
文摘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.
基金This research was financially supported by the National Natural Science Foundation of China(No.21878292,No.21606240,No.21878314)K.C.Wong Education Foundation(No.GJTD-2018-04)the Strategic Priority Research Program of Chinese Academy of Science(No.XDA21060300).
文摘It is very difficult to directly spin the lignocellulose without pretreatment.Ionic liquids(ILs)are promising solvent to dissolve lignocellulose to prepare cellulose fiber.However,the degree of cellulose polymerization(DP)is reduced when lignocellulose is dissolved in ILs,and the lignin removal rate is low.The elongation at break and tensile strength of the fibers obtained by spinning the lignocellulose dissolved in ILs are poor.In this paper,preparing cellulose fiber directly from lignocellulose based on dissolving corn stalk via[C4mim]Cl-L-arginine binary system is achieved.It shows that the removal rate of lignin can reach 92.35%and the purity of cellulose can reach 85.32%after corn stalk was dissolved at 150℃C for 11.5 h when the mass fraction of arginine is 2.5%.The elongation at break of fiber reached 10.12%and the tensile strength reached 420 MPa.It is mainly due to the fact that L-arginine not only inhibits the degradation of cellulose but also promotes the delignination.Without any pulping or pretreatment,preparing cellulose fibers via direct dissolution and extrusion may provide a simple and effective way to prepare many novel cellulose materials.
基金This study was supported by the National Natural Science Foundation of China(grant no.31770620).
文摘Polypyrrole(PPy)@cellulose fiber-based composites have been widely investigated as electrode materials for use in flexible supercapacitors.However,they cannot readily provide high specific capacitance and cyclic stability owing to their inherent drawbacks,such as high resistance,Weber impedance,and volume expansion or collapse during charging/discharging.In this study,iron oxyhydroxide(FeOOH)is incorporated in the abovementioned composite to decrease the equivalent series resistance,charge transfer resistance,and Weber impedance,thereby enhancing electron transfer and ion diffusion,which results in superior electrochemical performance.The PPy-wrapped FeOOH@cellulose fiber-based composite electrode with the molar ratio of FeSO_(4) to NaBH4 of 1∶1 exhibits a high specific capacitance of 513.8 F/g at a current density of 0.2 A/g,as well as an excellent capacitance retention of 89.4% after 1000 cycles.
文摘In this study, bio-yogurts, which contain L. acidophilus and Bifidobacterium animalis subsp. lactis, were produced with cellulose fiber (CF) addition at a various level (0%, 0.5%, 1% and 2%) and stored at 4°C ± 1°C for 20 days. Bio-yogurts were analysed 1, 10 and 20 days after production. The storage period significantly influenced overall properties of the samples. Addition of CF has positively affected the physical and textural properties of yoghurt, such as serum separation, water holding capacity, viscosity, firmness, adhesiveness, cohesiveness, springiness, gumminess and chewiness (p < 0.05). It also slightly stimulated the development of probiotic bacteria (p < 0.05). Bio-yogurt, which contains 0.5% CF in sensory aspect, is the most appreciated.
基金supported by the National Key Research and Development Program (No.2018YFC1105503)the National Natural Science Foundation of China (No.31670981).
文摘In this work,bioinspired anisotropic polymeric heart valves were fabricated using composite materials from polyurethane(PU)and natural cellulose fiber bundles.Cellulose fibers with good alignment were obtained from balsa wood by a top-down process,which were then distributed in polyurethane to pre-pare cellulose fiber bundles reinforced polyurethane(CPU)by hot pressing.The storage modulus of the CPU along the direction parallel to the fiber alignment was 16.70±0.80 MPa,whereas that along the direction perpendicular to the fiber alignment was 8.41±0.94 MPa by dynamic mechanical analysis(DMA)tests at 1 Hz,comparable to aortic valve leaflets.Moreover,2-methacryloyloxyethyl phosphoryl-choline(MPC)was grafted onto the CPU surface(CPU-MPC)to improve hemocompatibility.With MPC modification,the water contact angle decreased significantly from 54.58°±2.98°to 26.42°±3.50°,and the platelet adhesion was reduced by 92%,compared to the original CPU.In vitro cell culture proved that both CPU and CPU-MPC samples did not show any cytotoxicity.Furthermore,the CPU composites were used to fabricate polymeric heart valves,which showed excellent hydrodynamic performance with a large orifice area(1.70 cm 2)and low regurgitation fraction(0.7%),meeting the requirements of ISO 5840-2 standard.
文摘Electrochemical determination of paracetamol(PCT)was successfully performed using carbon paste electrodes(CPEs)modified with treated coffee husks(CHt)or cellulose powder(Ce).Scanning electron microscopy was used to characterize unmodified or modified CPEs prior to their use.The electrochemical oxidation of PCT was investigated using square wave voltammetry(SWV)and cyclic voltammetry(CV).The oxidation current density of PCT was two-fold higher with the CPE-CHt sensor and 30%higher with CPE-Ce in comparison with the unmodified CPE,and this correlated with the higher hydrophilicity of the modified electrodes.Using SWV for the electrochemical analysis of PCT,carbon paste electrode modified with raw coffee husks(CPE-CHr)showed the presence of impurities at+0.27 V/SCE,showing the interest in using pure cellulose for the present analytical application.Furthermore,CPE-Ce presented a higher real area compared to CPE-CHr,which explains the increase in the limit of saturation from 400 mg/L to 950 mg/L.The better saturation limit exhibited by CPE-Ce justifies its choice for electroanalysis of PCT in commercialized tablets.The proposed method was successfully applied in the determination of PCT in commercialized tablets(DolipraneR 500)with a recovery rate close to 100%,and no interference with the excipients contained in the tablets analyzed was observed.This novel sensor opens the way for sustainable development of electroanalytical control of drugs sold individually in developing countries.
文摘As the global population grows,the demand for textiles is increasing rapidly.However,this puts immense pressure on manufacturers to produce more fiber.While synthetic fibers can be pro-duced cheaply,they have a negative impact on the environment.On the other hand,fibers from wool,sisal,fique,wood pulp(viscose),and man-made cellulose fibers(MMCFs)from cotton can-not alone meet the growing fiber demand without major stresses on land,water,and existing markets using these materials.With a greater emphasis on transparency and circular economy practices,there is a need to consider natural non-wood alternative sources for MMCFs to supple-ment other fiber types.However,introducing new feedstocks with different compositions may require different biomass conversion methods.Therefore,based on existing work,this review ad-dresses the technical feasibility of various alternative feedstocks for conversion to textile-grade fibers.First,alternative feedstocks are introduced,and then conventional(dissolving pulp)and emerging(fibrillated cellulose and recycled material)conversion technologies are evaluated to help select the most suitable and promising processes for these emerging alternative sources of cellulose.It is important to note that for alternative feedstocks to be adopted on a meaningful scale,high biomass availability and proximity of conversion facilities are critical factors.In North America,soybean,wheat,rice,sorghum,and sugarcane residues are widely available and most suitable for conventional conversion through various dissolving pulp production methods(pre-hydrolysis kraft,acid sulfite,soda,SO2-ethanol-water,and potassium hydroxide)or by emerging cellulose fibrillation methods.While dissolving pulp conversion is well-established,fibrillated cel-lulose methods could be beneficial from cost,efficiency,and environmental perspectives.Thus,the authors strongly encourage more work in this growing research area.However,conducting thorough cost and sustainability assessments is important to determine the best feedstock and technology combinations.
基金This work is financially supported by National Natural Science Foundation of China(Nos.51773018,51973018 and 31700829)Key Research and Development Projects of People’s Liberation Army(BWS17J036).
文摘Uncontrollable hemorrhage leads to high mortality and thus effective bleeding control becomes increasingly important in the military field and civilian trauma arena.However,current hemostats not only present limitation when treating major bleeding,but also have various side effects.Here we report a self-expanding porous composites(CMCP)based on novel carboxymethyl cellulose(CMC)fibers and acetalized polyvinyl alcohol(PVA)for lethal hemorrhage control.The CMC fibers with uniform fibrous structure,high liquid absorption and procoagulant ability,are evenly interspersed inside the composite matrix.The obtained composites possess unique fiber-porous network,excellent absorption capacity,fast liquid-triggered self-expanding ability and robust fatigue resistance,and their physicochemical performance can be fine-tuned through varying the CMC content.In vitro tests show that the porous composite exhibits strong blood clotting ability,high adhesion to blood cells and protein,and the ability to activate platelet and the coagulation system.In vivo hemostatic evaluation further confirms that the CMCP presents high hemostatic efficacy and multiple hemostatic effects in swine femoral artery major hemorrhage model.Additionally,the CMCP will not fall off from the injury site,and is also easy to surgically remove from the wound cavity after the hemostasis.Importantly,results of CT tomography and 3D reconstruction indicate that CMCP can achieve shape adaptation to the surrounding tissues and the wound cavities with different depths and shapes,to accelerate hemostasis while protecting wound tissue and preventing infection.
基金China Natural Science Foundation under Grant No.51376162Key Laboratory of Recycling and Eco-treatment of Waste Biomass of Zhejiang Province under Grant No.2016REWB30.
文摘Centrifugal cleaners are commonly used in the pulp and paper industry to separate contaminates from pulp fibers.To reveal the separation mechanism of cellulose fibers and impurities in a centrifugal cleaner,three-dimensional computational fluid dynamics(CFD)models were established based on experimental analyses with the inlet flow rate and outlet diameter as the variables.The incompressible three-dimensional Navier-Stokes equations were applied to describe the fluid motion.Numerical simulation results showed that an increased inlet flow rate could improve the efficiency by enhance of the centrifugal force on particles.Secondary swirling patterns were predominant for centrifugal cleaners with smaller lower outlets.The crowding effect played an important role in the separation of heavy contaminants,and the separating efficiency was proportional to the inlet flow rate and inverse proportional to the lower outlet diameter.
基金the National Natural Science Foundation of China(No.22078184)China Postdoctoral Science Foundation(No.2019M653853XB)Natural science advance research foundation of Shaanxi University of Science and Technology(No.2018QNBJ-03).
文摘Recent research efforts in the field of electromagnetic interference shielding(EMI)materials have focused on biomass as a green and sustainable resource.More specifically,wood and cellulose nano fiber(CNF)have many advantages,some of which include lightweight,porosity,widespread availability,low cost,and easy processing.These favorable properties have led researchers to consider these types of biomass as an EMI shielding material with great potential.At present,while many excellent published works in EMI shielding materials have investigated wood and CNF,this research area is still new,compared with non-biomass EMI shielding materials.More specifically,there is still a lack of in-depth research and summary on the preparation process,pore structure regulation,component optimization,and other factors affecting the EMI shielding of wood and CNF based EMI shielding materials.Thus,this review paper presents a comprehensive summary of recent research on wood and CNF based EMI shielding materials in recent three years in terms of the preparation methods,material structure design,component synergy,and EMI mechanism,and a forward future perspective for existing problems,challenges,and development trend.The ultimate goal is to provide a comprehensive and informative reference for the further development and exploration of biomass EMI shielding materials.
基金The authors are grateful for the financial support from National Natural Science Foundation of China(Nos.31270625 and 21506105)Major Program of Natural Science Foundation of Shandong Province(No.ZR2018ZC0842).
文摘Transparent paper with good hydrophobicity and flexibility was expected to act as an alternative substrate in fabrication of flexible electronics.However,conventional paper made of cellulose fibers was opaque and hydrophilic without undergoing special processing.Herein,cellulose fiber paper was treated by impregnating with hydrolyzed tetraethyl orthosilicate(TEOS)followed by coating with hydrophobic polydimethylsiloxane(PDMS)to prepare hydrophobic transparent pa-per.The results showed that silica nanoparticles produced by the TEOS hydrolysis improved the paper transparency to some extent,increased the paper thermal stability,but still remained the hydrophilicity of paper.After the paper was further coated with the PDMS and the PDMS was consolidated,the paper became clearly transparent and hydrophobic.The processed paper had a transmittance of more than 90%at 550 nm.The water contact angle of the paper reached about 110°.This work provided a new approach for the fabrication of hydrophobic transparent paper with conventional cellulose fiber paper.
文摘The use of magnesium hydroxide(Mg(OH)_(2))was proposed as a filler to replace part of the calcium carbonate(CaCO_(3))in cigarette paper and reduce the toxicity of the smoke from cigarettes.Physical property changes and smoke reducing ability of this possible substitution were effectively studied.The results showed that adding 10%Mg(OH)_(2) could meet the requirements of the physical property of the cigarette paper.Moreover,with the addition of Mg(OH)2 as a filler in the cigarette paper,the pyrolysis temperature of the cigarette paper decreased,while the porosity and specific surface area increased.As a result,the main-stream smoke had a lower smoke total particle matter(STMP),tar,nicotine and carbon monoxide content,and the side-stream smoke also had a lower STMP.
基金supported by Key Laboratory of Recycling and Eco-treatment of Waste Biomass of Zhejiang Province (No.2016REWB33).
文摘Ammonium polyphosphate-diatomite composite filler(APP-diatomite composite filler)was modified with silane coupling agent KH550 to improve the flame retardancy of filled paper.Cone calorimeter was used to analyze the heat and smoke releasing rates,as well as smoke toxicity of the filled paper.The distribution of the composite filler particles in paper and the morphology of the charred residues after combustion were investigated by scanning electron microscope(SEM),and the chemical structure of the charred residues was studied with fourier transform infrared spectroscopy(FTIR).Results show that the peak heat releasing rate(PHRR),total heat release(THR)and peak mass loss rate(PMLR)of the filled paper with the modified APP-diatomite decreased markedly,compared with those for the control paper,while the charred residue after combustion increased.In addition,the filled paper had an increased peak rate of smoke release(RSR)and increased total smoke release(TSR)and peak CO production rates,but a decreased peak CO_(2) production rate.It was also found that part of the carbon element in the charred residue of the paper loaded with the modified APP-diatomite was in the forms of C=C=C,C≡C and C≡N,and the charred residue had a relatively more intact structure without apparent fiber breakage and longitudinal cracks.