The microfibril angle of seven poplar clones was determined by using X-ray diffraction technique. Microfibril angle, wood basic density, fiber length, fiber width and cellulose content were assessed for every growth r...The microfibril angle of seven poplar clones was determined by using X-ray diffraction technique. Microfibril angle, wood basic density, fiber length, fiber width and cellulose content were assessed for every growth ring at breast height for all sample trees. Significant variation in microfibril angle was observed among growth rings. Mean microfibril angle (MFA) at breast height varied from 7.8?to 28?between growth rings with cambial age and showed a consistent pith-to-bark trend of decline an-gles. Analysis of variance also indicated that there were significant differences in wood basic density, fiber length, fiber width and cellulose content between the growth rings, which had an increasing tendency from pith to bark. Correlations between MFA and examined wood properties were predominantly large and significant negative (?0.01), and the coefficients were -0.660 for cellulose content, -0.586 for fiber length, -0.516 for fiber width and -0.450 for wood basic density, respectively. Regression analysis with linear and curve estimation indicated that a quadratic function showed the largest R2 and the least standard error for describing the relationships between microfibril angle and measured wood properties, and the correlation coefficients were over -0.45 (n=125). The results from this study suggested that microfibril angle would be a good characteristic for improvement in the future breeding program of poplars.展开更多
Konjac glucomannan nano gel microfibrils were prepared by using electrospinning method. Topology structures were analyzed by Fourier transform infrared spectroscopy （FT-IR） and Field emission scanning electron micro...Konjac glucomannan nano gel microfibrils were prepared by using electrospinning method. Topology structures were analyzed by Fourier transform infrared spectroscopy （FT-IR） and Field emission scanning electron microscopy （FESEM）, while the differential scanning calorimetry （DSC） was carried out to check the thermal stability of the structure. Results reveal that the interaction of KGM intermolecular hydrogen bonds and topological tangle rate are increased by electrospirming, while stable structures of nano gel microfibrils are formed without altering the molecular groups of origin, These structures compose of topological networks of clustered nano fibers with lower porosity and higher density.展开更多
Three types of microfibrillated cellulose （MFC） with differences in structure and surface charge were used at low concentration as filler materials in polysodium acrylate superabsorbents （SAPs）. The swelling of th...Three types of microfibrillated cellulose （MFC） with differences in structure and surface charge were used at low concentration as filler materials in polysodium acrylate superabsorbents （SAPs）. The swelling of the composite hydrogels was determined in 0.9% NaCl solution as well as in deionized water. The shear modulus of the samples was determined through uniaxial compression analysis after synthesis and after swelling in 0.9% NaC1 solution. Furthermore, the ability to retain filler effects after washing was investigated. The results showed that all of the investigated MFCs had a strong reinforcing effect on the shear modulus after synthesis. The filler effect on swelling and on the associated shear modulus of swollen samples showed a more complicated dependence on structure and surface charge. Finally, it was found that the filler effects were reasonably retained after washing and subsequent drying. The results confirm that MFC holds great potential as a filler material in superabsorbent applications. Furthermore, the results provide some insight on how the structural properties and surface charge of MFC will affect gel properties depending on swelling conditions. This information should be useful in evaluating the use of different types of MFC in future applications.展开更多
Microfibrillated cellulose(MFC)is often added to polylactic acid(PLA)matrixes as a reinforcing filler to obtain fully-biodegradable composites with improved mechanical properties.However,the incompatibility between MF...Microfibrillated cellulose(MFC)is often added to polylactic acid(PLA)matrixes as a reinforcing filler to obtain fully-biodegradable composites with improved mechanical properties.However,the incompatibility between MFC and the PLA matrix limits the mechanical performance of MFC-reinforced PLA composites.In this paper,DL-lactic acid-grafted-MFC(MFC-g-DL)was used to improve the compatibility with PLA.Reinforced composites were prepared by melt extrusion and hot-cold pressing.The tensile strength of the PLA/MFC-g-DL composite increased by 22.1%compared with that of PLA after adding 1%MFC-g-DL.Scanning electron microscopy(SEM),differential scanning calorimetry(DSC),and dynamic thermomechanical analysis(DMA)were used to explore the enhancement mechanism.The energy dissipation in the MFC network and the improved compatibility between PLA and MFC-g-DL played important roles in the reinforcement.The SEM results showed that there was a closer combination between PLA and MFC-g-DL.The DSC results showed that the addition of cellulose changed the glass transition temperature,melting temperature,and crystallization temperature of PLA.The TG results showed that the initial and maximum decomposition temperature were lower than those of PLA.The ultraviolet spectra showed that the composite had good transparency at a low concentration of MFC-g-DL.展开更多
The microfibril angle of fiber walls is an ultra-mieroscopic feature affecting the performance of wood products. It is therefore essential to get more definitive information to improve selection and utilization. X-ray...The microfibril angle of fiber walls is an ultra-mieroscopic feature affecting the performance of wood products. It is therefore essential to get more definitive information to improve selection and utilization. X-ray diffraction is a rapid method for measuring microfibril angles. In this paper, the variability of microfibril angle in plantation-grown Masson pine was investigated by peak-fitting method. This method was compared with the traditional hand-drawn method, 40% peak height method and half peak height method. X-ray diffraction measurements indicated that the microfibril angle changed as a function of the position in the tree. The mean microfibril angle decreased more gradually as the distance increased from the pith and reached the same level in mature wood. The microfibril angle also seemed to decrease clearly from the base upward. Differences of angle-intensity curves between heartwood and sapwood were also examined.展开更多
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 measur...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).展开更多
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...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.展开更多
Cellulose microfibril (CMF) was the extraction with acid mixture from peel of Musa sapientum Linn type of banana (Kluai Nam Wa). The fibrous-shape of CMF interconnected weblike structure with the average diameter 26 n...Cellulose microfibril (CMF) was the extraction with acid mixture from peel of Musa sapientum Linn type of banana (Kluai Nam Wa). The fibrous-shape of CMF interconnected weblike structure with the average diameter 26 nm were observed by TEM. In order to prepare zein/CMF nanocomposite films, 16% wt zein solution was prepared by dissolved in 80% ethanol aqueous solution which contain glycerol 20% w/w. The suspension of CMF and zein solution was mixed with 0% - 5% weight fractions of solid CMF in zein matrix. The morphology of the zein films is more roughness by increased amount of cellulose microfibrils. It was found that as CMF content increase from 0 to 5% wt results in increasing tensile strength and Young’s modulus of zein nanocomposite films. The highest strength obtains at 4% wt CMF.展开更多
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 di...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.展开更多
The trade-off between the electrochemical performance and mechanical strength is still a challenge for Ti_(3)C_(2)T_(x)free-standing electrode.Herein,a facile approach was proposed to fabricate a Microfibrillated cell...The trade-off between the electrochemical performance and mechanical strength is still a challenge for Ti_(3)C_(2)T_(x)free-standing electrode.Herein,a facile approach was proposed to fabricate a Microfibrillated cellulose@Ti_(3)C_(2)T_(x)(MFC@Ti_(3)C_(2)T_(x))self-assembled microgel film by means of hydrogen bonding linkage.Benefiting from the rich hydroxyl groups on the MFC,the Ti_(3)C_(2)T_(x)nanosheets coated on the MFC in a time scale of minutes(within 1 min)instead of hours.The ultralong 1D frame of MFC effectively mitigated the re-aggregation of Ti_(3)C_(2)T_(x)nanosheet.The fluffy MFC@Ti_(3)C_(2)T_(x)film structure and the constructed 1D/2D conducting Ti_(3)C_(2)T_(x)pathways in horizontal and vertical directions endowed the fast ion transport of the electrolytes and the improved accessibility to the Ti_(3)C_(2)T_(x)surface.As a result,the freestanding MFC@Ti_(3)C_(2)T_(x)microgel film delivered a high specific capacitance of 451F/g.And the rate performance was increased to 71%from the 64%of that of pristine Ti_(3)C_(2)T_(x)film.Furthermore,the tensile strength of MFC@Ti_(3)C_(2)T_(x)film was also promoted to 46.3 MPa,3 folds of that of the pristine Ti_(3)C_(2)T_(x)film,due to the high strength of MFC and the hydrogen bonding effect.展开更多
For the value-added utilization of discarded agricultural wastes,corn silk( CS) obtained abundantly in the farming field has been tested as a new source of cellulosic materials. Cellulose microfibril( CMF) and cellulo...For the value-added utilization of discarded agricultural wastes,corn silk( CS) obtained abundantly in the farming field has been tested as a new source of cellulosic materials. Cellulose microfibril( CMF) and cellulose nanocrystal( CNC) were isolated from CS by ethanol and alkali pretreatments,and acid hydrolysis.The characterization was performed by scanning electron microscopy( SEM),Fourier transform infrared spectroscopy( FT-IR),X-ray diffraction( XRD), thermogravimetric analysis( TGA) and transmission electron microscopy( TEM). After chemical pretreatments,the lignin,hemicelluloses and other non-structural components were removed. The degree of crystallinity and thermal stability of CMF and CNC were increased compared to raw CS. The crystallinity indexes of CS,CMF and CNC were 45. 90%,65. 77%,and 73. 75% respectively. The CNC was flat and rod like shape with diameter and aspect ratio range of 13. 96-33. 69 nm and 34. 34-23. 02 nm respectively. The nanocrystals had an alternative potential to be used as reinforcing filler for bio-nanocomposites preparation.展开更多
Understanding the assembly and spatial arrangement of bamboo cell wall components is crucial for its optimal utilization.Bamboo cell walls consist of aggregates of cellulose microfibrils and matrix.In the present stud...Understanding the assembly and spatial arrangement of bamboo cell wall components is crucial for its optimal utilization.Bamboo cell walls consist of aggregates of cellulose microfibrils and matrix.In the present study,the size and arrangement of cellulose microfibril aggregates in the cell walls of sclerenchyma fibers and parenchyma cells in moso bamboo were investigated with NMR and FE-SEM.The NMR measurement showed that the characteristic sizes of the microfibril aggregates of fibers and parenchyma cells were approximately 25.8 nm and 18.8 nm,respectively.Furthermore,high-resolution SEM showed the size of microfibril aggregates varied little across the cell wall of sclerenchyma fiber.However,there were significant size differences between the broad and narrow lamellae both in fiber and parenchyma cells,which is thought to be closely related to the orientation of microfibrils in these layers.The microfibril aggregates in the fibers mainly appear in a random arrangement,although occasionally in a radial or tangential arrangement in individual cell.Parenchyma cells have a relatively thinner cell wall layers,in which microfibril aggregates appear in a concentric lamellar arrangement.展开更多
Increasing usage of foams in various industry sectors had causing serious disposal problems once it reaches the end of its life-cycle.Herein,PVA-MFC foam was prepared by freeze-drying using polyvinyl alcohol(PVA)and m...Increasing usage of foams in various industry sectors had causing serious disposal problems once it reaches the end of its life-cycle.Herein,PVA-MFC foam was prepared by freeze-drying using polyvinyl alcohol(PVA)and microfibrillated cellulose(MFC)as a reinforced material from sugarcane bagasse(SCB).In this study,the PVA-MFC foam was chemically silylated with Y-methacryloxypropyltrimethoxysilane(MPS)and tetraethoxysilane(TEOS).The wetting ability and mechanical strength of the silylated_(2,20)PVA-MFC foam was greatly enhanced compared with unmodified_(2,20)PVA-MFC foam.The silane chemicals(MPS and TEOS)had been confirmed grafted on_(2,20)PVA-MFC foam due to the presence of Si-C and Si-O-C stretching vibration as showed in Fourier Transform Infrared(FTIR)spectra and cloud-like coating of porous pore was observed in scanning electron microscopy(SEM)images.The silylated_(2,20)PVA-MFC foam(MPS and TEOS)exhibited a series of desirable properties such as lower swelling ratio and high absorption capacity of solvents and oils but had low thermal stability in thermogravimetric(TGA)analysis.The characterization of_(2,20)PVA-MFC foam using TEOS was further investigated.A significant difference in morphology was clearly observed between the unmodified and silylated_(2,20)PVA-MFC-TEOS foam through field emission scanning electron microscopy(FESEM)images.The X-ray photoelectron(XPS)analysis of silylated_(2,20)PVA-MFC-TEOS foam confirmed the presence of C,O and trace amount of Si elements.These synthesized_(2,20)PVA-MFC foam could be a promising material for broad range of polymer foam applications.展开更多
Microfibrillated cellulose(MFC)aerogels are bio-based materials with high thermal resistance.In this study,MFC aerogels and MFC-kapok composite aerogels were prepared.A series of experiments were carried out in a clim...Microfibrillated cellulose(MFC)aerogels are bio-based materials with high thermal resistance.In this study,MFC aerogels and MFC-kapok composite aerogels were prepared.A series of experiments were carried out in a climate chamber to study the influence of MFC concentration,the temperature gradient,testing methods and introduction of kapok fibers on the thermal insulation properties of aerogels.The results suggested that the density of MFC aerogels was less than 10 mg/cm3 and the porosity was higher than 99%.Besides,the minimum thermal conductivity of MFC aerogels was 0.0357 W·m-1·K-1 observed at 0.8%MFC aerogels.The minimum thermal conductivity of MFC-kapok composite aerogels was 0.0382 W·m-1·K-1 when the ratio of MFC to kapok was 2∶6.展开更多
For promising applications such as soft robotics,flexible haptic monitors,and active biomedical devices,it is important to develop ultralow voltage,highly-performant artificial muscles with high bending strains,rapid ...For promising applications such as soft robotics,flexible haptic monitors,and active biomedical devices,it is important to develop ultralow voltage,highly-performant artificial muscles with high bending strains,rapid response times,and superior actuation endurance.We report a novel highly performant and low-cost artificial muscle based on microfibrillated cellulose(MFC),ionic liquid(IL),and polyvinyl alcohol(PVA),The proposed MFC-IL-PVA actuator exhibits excellent electro-chemical performance and actuations characteristics with a high specific capacitance of 225 mF/cm2,a large bending strain of 0.51%,peak displacement up to 7.02 mm at 0.25 V ultra-low voltage,outstanding actuation flexural endurance(99.1%holding rate for 3 h),and a wide frequency band(0.1-5 Hz).These attributes stem mainly from its high specific surface area and porosity,tunable mechanical properties,and the strong ionic interactions of cations and anions with MFC and PVA in ionic liquids.Furthermore,bionic applications such as bionic flytraps,bionic butterflies with vibrating wings,and smart circuit switches have been successfully realized using this technology.These specific bionic applications demonstrate the versatility and potential of the MFC-IL-PVA actuator,highlighting its important role in the fields of bionic engineering,robotics,and smart materials.They open up new possibilities for innovative scientific research and technological applications.展开更多
Microfibrillated cellulose(MFC)was functionalised using a reactive ionic liquid monomer,i.e.,glycidyltriethylammonium chloride(GTEAC),via chain-growth polymerisation,resulting in a novel cationic polyelectrolyte-graft...Microfibrillated cellulose(MFC)was functionalised using a reactive ionic liquid monomer,i.e.,glycidyltriethylammonium chloride(GTEAC),via chain-growth polymerisation,resulting in a novel cationic polyelectrolyte-grafted quaternised MFC(QMFC).The degree of quaternisation and maximum ion exchange capacity of the resulting QMFC were 2.13 mmol/g(i.e.,132 mg/g)and 1.51 mmol/g(i.e.,94 mg/g),respectively.Small-angle X-ray scattering(SAXS)and wide-angle X-ray scattering(WAXS)experiments confirmed the retention of monoclinic crystalline structure for cellulose I with the corresponding decrease in the degree of crystallinity from 85%to 56%and the increase in the spacing between cellulose crystallites by 35%.The presence of the amorphous and grafted polymers was confirmed by microscopy,thermal analysis,and water sorption exper-iments.QMFC filter cartridges were prepared and tested under dynamic flow conditions with a pressure of 0.2 MPa(retention time of 0.5 min).These cationic polyelectrolytes enhanced multi-site ion exchange interactions as evidenced by the Freundlich sorption isotherm.The QMFC filter cartridges demonstrated high anion removal efficiency values of 83.2%,98.1%,and 94.9%for NO_(3)^(−),SO_(4)^(2−),and PO_(4)^(3−),respectively.This system achieved a process mass efficiency of 2.79,an E-factor of 1.97,and an energy efficiency score of 66.3,which conforms to the green chemistry principles and demonstrates high potential for sustainable water purification.展开更多
Kaschin-Beck disease （KBD）, endemic in China, occurs along a low selenium belt where the Se contents of water, soil, crops and patients’ blood and hair are all in a low state. Supplementation of Na<sub>2</...Kaschin-Beck disease （KBD）, endemic in China, occurs along a low selenium belt where the Se contents of water, soil, crops and patients’ blood and hair are all in a low state. Supplementation of Na<sub>2</sub>SeO<sub>3</sub> has been effective in preventing such a disease. The main pathological changes of KBD are the necrosis of cartilage, early展开更多
Bone,renowned for its elegant hierarchical structure and unique mechanical properties,serves as a constant source of inspiration for the development of synthetic materials.However,achieving accurate replication of bon...Bone,renowned for its elegant hierarchical structure and unique mechanical properties,serves as a constant source of inspiration for the development of synthetic materials.However,achieving accurate replication of bone features in artificial materials with remarkable structural and mechanical similarity remains a significant challenge.In this study,we employed a cascade of continuous fabrication processes,including biomimetic mineralization of collagen,bidirectional freeze-casting,and pressure-driven fusion,to successfully fabricate a macroscopic bulk material known as artificial compact bone(ACB).The ACB material closely replicates the composition,hierarchical structures,and mechanical properties of natural bone.It demonstrates a lamellated alignment of mineralized collagen(MC)microfibrils,similar to those found in natural bone.Moreover,the ACB exhibits a similar high mineral content(70.9%)and density(2.2 g/cm^(3))as natural cortical bone,leading to exceptional mechanical properties such as high stiffness,hardness,and flexural strength that are comparable to those of natural bone.Importantly,the ACB also demonstrates excellent mechanical properties in wet,outstanding biocompatibility,and osteogenic properties in vivo,rendering it suitable for a broad spectrum of biomedical applications,including orthopedic,stomatological,and craniofacial surgeries.展开更多
Properties of gelatin composite films(with 4%glycerol as plasticizer)with different mass concentrations of microfibrillated cellulose(MFC)(0.2-1.0%)were investigated.The prepared composite films with 1.0%MFC showed th...Properties of gelatin composite films(with 4%glycerol as plasticizer)with different mass concentrations of microfibrillated cellulose(MFC)(0.2-1.0%)were investigated.The prepared composite films with 1.0%MFC showed the highest tensile strength(12.32 MPa)with the lowest water absorption rate(391.1%).The composite films can be dissolved in hot water of 95℃ in less than 5 minutes.However,the addition of MFC had insignificant effect on the heat shrinkage and light transmittance of the resultant composite films.展开更多
Microfibrilled cellulose(MFC) is a new kind of nanoscale cellulose functional materials, having broad application prospects in many fields like food,medicine,cosmetic,paint,paper and pulp engineering,composite materia...Microfibrilled cellulose(MFC) is a new kind of nanoscale cellulose functional materials, having broad application prospects in many fields like food,medicine,cosmetic,paint,paper and pulp engineering,composite materials,et al.The research on MFC has been extensively conducted for the past 30 years in some developed countries,and even some relevant products have appeared in the market.On the contrast,similar studies in China were rather limited.This paper firstly introduced the properties and application of MFC briefly,and then gave more detailed description on the preparation technology of MFC and its important performance indexes. Several suggestions on the future study on MFC were also proposed.展开更多
基金This research was supported by National Natural Science Foundation of China (Grant No. 30070616).
文摘The microfibril angle of seven poplar clones was determined by using X-ray diffraction technique. Microfibril angle, wood basic density, fiber length, fiber width and cellulose content were assessed for every growth ring at breast height for all sample trees. Significant variation in microfibril angle was observed among growth rings. Mean microfibril angle (MFA) at breast height varied from 7.8?to 28?between growth rings with cambial age and showed a consistent pith-to-bark trend of decline an-gles. Analysis of variance also indicated that there were significant differences in wood basic density, fiber length, fiber width and cellulose content between the growth rings, which had an increasing tendency from pith to bark. Correlations between MFA and examined wood properties were predominantly large and significant negative (?0.01), and the coefficients were -0.660 for cellulose content, -0.586 for fiber length, -0.516 for fiber width and -0.450 for wood basic density, respectively. Regression analysis with linear and curve estimation indicated that a quadratic function showed the largest R2 and the least standard error for describing the relationships between microfibril angle and measured wood properties, and the correlation coefficients were over -0.45 (n=125). The results from this study suggested that microfibril angle would be a good characteristic for improvement in the future breeding program of poplars.
基金supported by the National Natural Science Foundation of China(31471704 and 31271837)major projects of industries,university and research in Fujian Province(2013N5003)
文摘Konjac glucomannan nano gel microfibrils were prepared by using electrospinning method. Topology structures were analyzed by Fourier transform infrared spectroscopy （FT-IR） and Field emission scanning electron microscopy （FESEM）, while the differential scanning calorimetry （DSC） was carried out to check the thermal stability of the structure. Results reveal that the interaction of KGM intermolecular hydrogen bonds and topological tangle rate are increased by electrospirming, while stable structures of nano gel microfibrils are formed without altering the molecular groups of origin, These structures compose of topological networks of clustered nano fibers with lower porosity and higher density.
基金This project is part of the VINN Excellence Centre SuMo Biomaterials(Supermolecular Biomaterials-Structure dynamics and properties)
文摘Three types of microfibrillated cellulose （MFC） with differences in structure and surface charge were used at low concentration as filler materials in polysodium acrylate superabsorbents （SAPs）. The swelling of the composite hydrogels was determined in 0.9% NaCl solution as well as in deionized water. The shear modulus of the samples was determined through uniaxial compression analysis after synthesis and after swelling in 0.9% NaC1 solution. Furthermore, the ability to retain filler effects after washing was investigated. The results showed that all of the investigated MFCs had a strong reinforcing effect on the shear modulus after synthesis. The filler effect on swelling and on the associated shear modulus of swollen samples showed a more complicated dependence on structure and surface charge. Finally, it was found that the filler effects were reasonably retained after washing and subsequent drying. The results confirm that MFC holds great potential as a filler material in superabsorbent applications. Furthermore, the results provide some insight on how the structural properties and surface charge of MFC will affect gel properties depending on swelling conditions. This information should be useful in evaluating the use of different types of MFC in future applications.
基金the Natural Science Foundation of China(No.32071704).
文摘Microfibrillated cellulose(MFC)is often added to polylactic acid(PLA)matrixes as a reinforcing filler to obtain fully-biodegradable composites with improved mechanical properties.However,the incompatibility between MFC and the PLA matrix limits the mechanical performance of MFC-reinforced PLA composites.In this paper,DL-lactic acid-grafted-MFC(MFC-g-DL)was used to improve the compatibility with PLA.Reinforced composites were prepared by melt extrusion and hot-cold pressing.The tensile strength of the PLA/MFC-g-DL composite increased by 22.1%compared with that of PLA after adding 1%MFC-g-DL.Scanning electron microscopy(SEM),differential scanning calorimetry(DSC),and dynamic thermomechanical analysis(DMA)were used to explore the enhancement mechanism.The energy dissipation in the MFC network and the improved compatibility between PLA and MFC-g-DL played important roles in the reinforcement.The SEM results showed that there was a closer combination between PLA and MFC-g-DL.The DSC results showed that the addition of cellulose changed the glass transition temperature,melting temperature,and crystallization temperature of PLA.The TG results showed that the initial and maximum decomposition temperature were lower than those of PLA.The ultraviolet spectra showed that the composite had good transparency at a low concentration of MFC-g-DL.
基金This study was financially supported by the National Natural Science Foundation of China （Grant Nos. 30371125 and 30400337）.
文摘The microfibril angle of fiber walls is an ultra-mieroscopic feature affecting the performance of wood products. It is therefore essential to get more definitive information to improve selection and utilization. X-ray diffraction is a rapid method for measuring microfibril angles. In this paper, the variability of microfibril angle in plantation-grown Masson pine was investigated by peak-fitting method. This method was compared with the traditional hand-drawn method, 40% peak height method and half peak height method. X-ray diffraction measurements indicated that the microfibril angle changed as a function of the position in the tree. The mean microfibril angle decreased more gradually as the distance increased from the pith and reached the same level in mature wood. The microfibril angle also seemed to decrease clearly from the base upward. Differences of angle-intensity curves between heartwood and sapwood were also examined.
文摘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).
文摘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.
文摘Cellulose microfibril (CMF) was the extraction with acid mixture from peel of Musa sapientum Linn type of banana (Kluai Nam Wa). The fibrous-shape of CMF interconnected weblike structure with the average diameter 26 nm were observed by TEM. In order to prepare zein/CMF nanocomposite films, 16% wt zein solution was prepared by dissolved in 80% ethanol aqueous solution which contain glycerol 20% w/w. The suspension of CMF and zein solution was mixed with 0% - 5% weight fractions of solid CMF in zein matrix. The morphology of the zein films is more roughness by increased amount of cellulose microfibrils. It was found that as CMF content increase from 0 to 5% wt results in increasing tensile strength and Young’s modulus of zein nanocomposite films. The highest strength obtains at 4% wt CMF.
基金The authors are grateful for financial support from the National Key Research and Development Program of China(2017YFE0102500 and 2017YFB0307901).
文摘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.
基金supported by National Natural Science Foundation of China(No.51571076)Open project of State Key Laboratory of Urban Water Resource and Environment of Harbin Institute of Technology(No.HCK202115).
文摘The trade-off between the electrochemical performance and mechanical strength is still a challenge for Ti_(3)C_(2)T_(x)free-standing electrode.Herein,a facile approach was proposed to fabricate a Microfibrillated cellulose@Ti_(3)C_(2)T_(x)(MFC@Ti_(3)C_(2)T_(x))self-assembled microgel film by means of hydrogen bonding linkage.Benefiting from the rich hydroxyl groups on the MFC,the Ti_(3)C_(2)T_(x)nanosheets coated on the MFC in a time scale of minutes(within 1 min)instead of hours.The ultralong 1D frame of MFC effectively mitigated the re-aggregation of Ti_(3)C_(2)T_(x)nanosheet.The fluffy MFC@Ti_(3)C_(2)T_(x)film structure and the constructed 1D/2D conducting Ti_(3)C_(2)T_(x)pathways in horizontal and vertical directions endowed the fast ion transport of the electrolytes and the improved accessibility to the Ti_(3)C_(2)T_(x)surface.As a result,the freestanding MFC@Ti_(3)C_(2)T_(x)microgel film delivered a high specific capacitance of 451F/g.And the rate performance was increased to 71%from the 64%of that of pristine Ti_(3)C_(2)T_(x)film.Furthermore,the tensile strength of MFC@Ti_(3)C_(2)T_(x)film was also promoted to 46.3 MPa,3 folds of that of the pristine Ti_(3)C_(2)T_(x)film,due to the high strength of MFC and the hydrogen bonding effect.
基金Fundamental Research Funds for the Central Universities,China(Nos.16D310102,2232018A3-04)
文摘For the value-added utilization of discarded agricultural wastes,corn silk( CS) obtained abundantly in the farming field has been tested as a new source of cellulosic materials. Cellulose microfibril( CMF) and cellulose nanocrystal( CNC) were isolated from CS by ethanol and alkali pretreatments,and acid hydrolysis.The characterization was performed by scanning electron microscopy( SEM),Fourier transform infrared spectroscopy( FT-IR),X-ray diffraction( XRD), thermogravimetric analysis( TGA) and transmission electron microscopy( TEM). After chemical pretreatments,the lignin,hemicelluloses and other non-structural components were removed. The degree of crystallinity and thermal stability of CMF and CNC were increased compared to raw CS. The crystallinity indexes of CS,CMF and CNC were 45. 90%,65. 77%,and 73. 75% respectively. The CNC was flat and rod like shape with diameter and aspect ratio range of 13. 96-33. 69 nm and 34. 34-23. 02 nm respectively. The nanocrystals had an alternative potential to be used as reinforcing filler for bio-nanocomposites preparation.
基金The authors gratefully acknowledge the National Natural Science Foundation(31770600)for its financial support.
文摘Understanding the assembly and spatial arrangement of bamboo cell wall components is crucial for its optimal utilization.Bamboo cell walls consist of aggregates of cellulose microfibrils and matrix.In the present study,the size and arrangement of cellulose microfibril aggregates in the cell walls of sclerenchyma fibers and parenchyma cells in moso bamboo were investigated with NMR and FE-SEM.The NMR measurement showed that the characteristic sizes of the microfibril aggregates of fibers and parenchyma cells were approximately 25.8 nm and 18.8 nm,respectively.Furthermore,high-resolution SEM showed the size of microfibril aggregates varied little across the cell wall of sclerenchyma fiber.However,there were significant size differences between the broad and narrow lamellae both in fiber and parenchyma cells,which is thought to be closely related to the orientation of microfibrils in these layers.The microfibril aggregates in the fibers mainly appear in a random arrangement,although occasionally in a radial or tangential arrangement in individual cell.Parenchyma cells have a relatively thinner cell wall layers,in which microfibril aggregates appear in a concentric lamellar arrangement.
基金support provided by the Ministry of Education of Malaysia under grant FRGS 16-044-0543 and FRGS19-091-0700.
文摘Increasing usage of foams in various industry sectors had causing serious disposal problems once it reaches the end of its life-cycle.Herein,PVA-MFC foam was prepared by freeze-drying using polyvinyl alcohol(PVA)and microfibrillated cellulose(MFC)as a reinforced material from sugarcane bagasse(SCB).In this study,the PVA-MFC foam was chemically silylated with Y-methacryloxypropyltrimethoxysilane(MPS)and tetraethoxysilane(TEOS).The wetting ability and mechanical strength of the silylated_(2,20)PVA-MFC foam was greatly enhanced compared with unmodified_(2,20)PVA-MFC foam.The silane chemicals(MPS and TEOS)had been confirmed grafted on_(2,20)PVA-MFC foam due to the presence of Si-C and Si-O-C stretching vibration as showed in Fourier Transform Infrared(FTIR)spectra and cloud-like coating of porous pore was observed in scanning electron microscopy(SEM)images.The silylated_(2,20)PVA-MFC foam(MPS and TEOS)exhibited a series of desirable properties such as lower swelling ratio and high absorption capacity of solvents and oils but had low thermal stability in thermogravimetric(TGA)analysis.The characterization of_(2,20)PVA-MFC foam using TEOS was further investigated.A significant difference in morphology was clearly observed between the unmodified and silylated_(2,20)PVA-MFC-TEOS foam through field emission scanning electron microscopy(FESEM)images.The X-ray photoelectron(XPS)analysis of silylated_(2,20)PVA-MFC-TEOS foam confirmed the presence of C,O and trace amount of Si elements.These synthesized_(2,20)PVA-MFC foam could be a promising material for broad range of polymer foam applications.
基金National Natural Science Foundation of China(No.51903034)Fundamental Research Funds for the Central Universities,China(No.2232019D3-12)。
文摘Microfibrillated cellulose(MFC)aerogels are bio-based materials with high thermal resistance.In this study,MFC aerogels and MFC-kapok composite aerogels were prepared.A series of experiments were carried out in a climate chamber to study the influence of MFC concentration,the temperature gradient,testing methods and introduction of kapok fibers on the thermal insulation properties of aerogels.The results suggested that the density of MFC aerogels was less than 10 mg/cm3 and the porosity was higher than 99%.Besides,the minimum thermal conductivity of MFC aerogels was 0.0357 W·m-1·K-1 observed at 0.8%MFC aerogels.The minimum thermal conductivity of MFC-kapok composite aerogels was 0.0382 W·m-1·K-1 when the ratio of MFC to kapok was 2∶6.
基金supported by National Natural Science Foundation of China(51525504,51905487,12102393)Bellwethers Research and Development Plan of Zhejiang Province of China(Grant No.2023C01045)+2 种基金Fundamental Research Funds of Zhejiang Sci-Tech University(24242115-Y)Natural Science Foundation of Zhejiang Province(LY21E050023)Zhejiang Provincial General Scientific Research Projects Fund of China under Grant Y202353093.
文摘For promising applications such as soft robotics,flexible haptic monitors,and active biomedical devices,it is important to develop ultralow voltage,highly-performant artificial muscles with high bending strains,rapid response times,and superior actuation endurance.We report a novel highly performant and low-cost artificial muscle based on microfibrillated cellulose(MFC),ionic liquid(IL),and polyvinyl alcohol(PVA),The proposed MFC-IL-PVA actuator exhibits excellent electro-chemical performance and actuations characteristics with a high specific capacitance of 225 mF/cm2,a large bending strain of 0.51%,peak displacement up to 7.02 mm at 0.25 V ultra-low voltage,outstanding actuation flexural endurance(99.1%holding rate for 3 h),and a wide frequency band(0.1-5 Hz).These attributes stem mainly from its high specific surface area and porosity,tunable mechanical properties,and the strong ionic interactions of cations and anions with MFC and PVA in ionic liquids.Furthermore,bionic applications such as bionic flytraps,bionic butterflies with vibrating wings,and smart circuit switches have been successfully realized using this technology.These specific bionic applications demonstrate the versatility and potential of the MFC-IL-PVA actuator,highlighting its important role in the fields of bionic engineering,robotics,and smart materials.They open up new possibilities for innovative scientific research and technological applications.
基金support received from the Deutscher Akademische Austauchsdienst(DAAD)in the form of the Short-term Research(No.57693450)that partially funded his research stay at the time of this research.
文摘Microfibrillated cellulose(MFC)was functionalised using a reactive ionic liquid monomer,i.e.,glycidyltriethylammonium chloride(GTEAC),via chain-growth polymerisation,resulting in a novel cationic polyelectrolyte-grafted quaternised MFC(QMFC).The degree of quaternisation and maximum ion exchange capacity of the resulting QMFC were 2.13 mmol/g(i.e.,132 mg/g)and 1.51 mmol/g(i.e.,94 mg/g),respectively.Small-angle X-ray scattering(SAXS)and wide-angle X-ray scattering(WAXS)experiments confirmed the retention of monoclinic crystalline structure for cellulose I with the corresponding decrease in the degree of crystallinity from 85%to 56%and the increase in the spacing between cellulose crystallites by 35%.The presence of the amorphous and grafted polymers was confirmed by microscopy,thermal analysis,and water sorption exper-iments.QMFC filter cartridges were prepared and tested under dynamic flow conditions with a pressure of 0.2 MPa(retention time of 0.5 min).These cationic polyelectrolytes enhanced multi-site ion exchange interactions as evidenced by the Freundlich sorption isotherm.The QMFC filter cartridges demonstrated high anion removal efficiency values of 83.2%,98.1%,and 94.9%for NO_(3)^(−),SO_(4)^(2−),and PO_(4)^(3−),respectively.This system achieved a process mass efficiency of 2.79,an E-factor of 1.97,and an energy efficiency score of 66.3,which conforms to the green chemistry principles and demonstrates high potential for sustainable water purification.
文摘Kaschin-Beck disease （KBD）, endemic in China, occurs along a low selenium belt where the Se contents of water, soil, crops and patients’ blood and hair are all in a low state. Supplementation of Na<sub>2</sub>SeO<sub>3</sub> has been effective in preventing such a disease. The main pathological changes of KBD are the necrosis of cartilage, early
基金supported by the National Key R&D Program of China(No.2023YFC2412300 and 2020YFC1107600)the Key R&D Program in Shandong Province(No.2019JZZY011106)the Foshan-Tsinghua Industry-University-Research Cooperation Collaborative Innovation Project.
文摘Bone,renowned for its elegant hierarchical structure and unique mechanical properties,serves as a constant source of inspiration for the development of synthetic materials.However,achieving accurate replication of bone features in artificial materials with remarkable structural and mechanical similarity remains a significant challenge.In this study,we employed a cascade of continuous fabrication processes,including biomimetic mineralization of collagen,bidirectional freeze-casting,and pressure-driven fusion,to successfully fabricate a macroscopic bulk material known as artificial compact bone(ACB).The ACB material closely replicates the composition,hierarchical structures,and mechanical properties of natural bone.It demonstrates a lamellated alignment of mineralized collagen(MC)microfibrils,similar to those found in natural bone.Moreover,the ACB exhibits a similar high mineral content(70.9%)and density(2.2 g/cm^(3))as natural cortical bone,leading to exceptional mechanical properties such as high stiffness,hardness,and flexural strength that are comparable to those of natural bone.Importantly,the ACB also demonstrates excellent mechanical properties in wet,outstanding biocompatibility,and osteogenic properties in vivo,rendering it suitable for a broad spectrum of biomedical applications,including orthopedic,stomatological,and craniofacial surgeries.
基金support of the Natural Science Foundation of Qinghai Province,China,Grant No.2015-ZJ-909.
文摘Properties of gelatin composite films(with 4%glycerol as plasticizer)with different mass concentrations of microfibrillated cellulose(MFC)(0.2-1.0%)were investigated.The prepared composite films with 1.0%MFC showed the highest tensile strength(12.32 MPa)with the lowest water absorption rate(391.1%).The composite films can be dissolved in hot water of 95℃ in less than 5 minutes.However,the addition of MFC had insignificant effect on the heat shrinkage and light transmittance of the resultant composite films.
文摘Microfibrilled cellulose(MFC) is a new kind of nanoscale cellulose functional materials, having broad application prospects in many fields like food,medicine,cosmetic,paint,paper and pulp engineering,composite materials,et al.The research on MFC has been extensively conducted for the past 30 years in some developed countries,and even some relevant products have appeared in the market.On the contrast,similar studies in China were rather limited.This paper firstly introduced the properties and application of MFC briefly,and then gave more detailed description on the preparation technology of MFC and its important performance indexes. Several suggestions on the future study on MFC were also proposed.
