Influence of Topology Structure on the Stability of Konjac Glucomannan Nano Gel Microfibril

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.

Microfibril angle variability in Masson Pine (Pinus massoniana Lamb.) using X-ray diffraction

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.

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

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

Preparation and Application of Microfibrillated Cellulose-modified Ground Calcium Carbonate

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

Cellulose Microfibril from Banana Peels as a Nanoreinforcing Fillers for Zein Films

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.

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

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

Isolation and Characterization of Cellulose Microfibrils and Nanocrystals from Corn Silk

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.

The Arrangement and Size of Cellulose Microfibril Aggregates in the Cell Walls of Sclerenchyma Fibers and Parenchyma Tissue in Bamboo

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.

Biocomposites of Polylactic Acid Reinforced by DL-Lactic Acid-Grafted Microfibrillated Cellulose

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.

Effect of Y-Methacryloxypropyltrimethoxysilane (MPS) and Tetraethoxysilane (TEOS) Towards Preparation of Oil Absorbent Foams from Polyvinyl Alcohol (PVA) Reinforced with Microfibrillated Cellulose (MFC)

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.

Thermal Insulation Properties of Microfibrillated Cellulose Aerogel

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.

基于遗传效应和气候变量的日本落叶松微纤丝角预测

【目的】分析遗传效应和气候变量对日本落叶松木材微纤丝角的影响,建立预测模型,预测终端收获木材的质量,旨在提高遗传材料的选育效率和促进目标材种的定向培育。【方法】以20个日本落叶松无性系为研究对象,通过木芯取样测定了林龄从4年到15年连续12个年轮的微纤丝角,分析了微纤丝角与林龄和年轮宽度的关系,建立了微纤丝角基础预测模型,然后对微纤丝角和气候变量进行相关性分析,采用混合效应模型构建了含有遗传效应和气候变量的日本落叶松微纤丝角预测模型。【结果】(1)微纤丝角随着林龄的增加呈减小趋势,随年轮宽度的增加呈增加趋势,不同无性系间微纤丝角变化规律明显不同。(2)含有林龄和年轮宽度的基础模型确定系数(R^(2))为0.43,均方根误差(RMSE)为4.391;加入平均年降水量和冬季平均降水量后模型R2为0.54,RMSE为4.039;采用混合模型建立的含遗传效应和平均年降水量、冬季平均降水量的微纤丝角预测模型R^(2)为0.81,RMSE为3.061。(3)平均年降水量和冬季平均降水量增加会增大日本落叶松微纤丝角,两个气候变量解释了微纤丝角变异的11%;遗传效应对日本落叶松微纤丝角变异有重要影响,可解释微纤丝角变异的27%。【结论】相较于平均年降水量和冬季平均降水量,遗传效应对木材微纤丝角影响更大。而且不同无性系的微纤丝角对气候因素变化的响应不同,无性系I6-7-075、I8-4-30和J28-6对于气候变化更钝化,是生态适应性更强的无性系,适合进一步在日本落叶松适生区推广应用。

玻璃体内注射原纤维蛋白-2(FBN2)重组蛋白对FBN2缺陷型视网膜病变的影响

目的探讨玻璃体内注射原纤维蛋白-2(FBN2)重组蛋白对FBN2缺陷型视网膜病变的影响。方法取SPF级C57BL/6J小鼠32只,随机分为4组:正常对照组、阴性对照组、FBN2敲减组、FBN2重组蛋白组,每组8只小鼠,取右眼作为实验眼。入组后,正常对照组小鼠不进行干预,阴性对照组小鼠玻璃体内注射3μL空载体(1 mg·L^(-1)),FBN2敲减组及FBN2重组蛋白组小鼠玻璃体内注射3μL腺相关病毒(AAV)(1 mg·L^(-1)),4周后FBN2重组蛋白组小鼠玻璃体内注射3μL FBN2重组蛋白(1 mg·L^(-1))。采用视网膜电图(ERG)视觉电生理仪和光学相干断层扫描(OCT)仪分别检测小鼠视网膜Rod-b、Max-a波振幅和视网膜结构变化;RT-PCR、Western blot检测小鼠视网膜中FBN2、微原纤维相关糖蛋白(MAGP-2)、Ⅰ型胶原蛋白(COL1)mRNA和蛋白表达变化。结果ERG检测结果显示,与阴性对照组和正常对照组相比,FBN2敲减组和FBN2重组蛋白组小鼠视网膜ERG Rod-b、Max-a波振幅均变小(均为P<0.05);与FBN2敲减组相比,FBN2重组蛋白组视网膜ERG Rod-b、Max-a波振幅均明显增加(均为P<0.05)。OCT检测结果显示,与FBN2敲减组相比,FBN2重组蛋白组小鼠视网膜色素上皮层组织结构恢复正常,光反射变规则。RT-PCR检测结果显示,与FBN2敲减组相比,FBN2重组蛋白组小鼠视网膜组织FBN2 mRNA表达明显升高,COL1、MAGP-2 mRNA表达均明显降低(均为P<0.05)。Western blot检测结果显示,与FBN2敲减组相比,FBN2重组蛋白组小鼠视网膜组织FBN2蛋白表达明显升高,COL1、MAGP-2蛋白表达均明显降低(均为P<0.05)。结论玻璃体内注射FBN2重组蛋白可以弥补FBN2缺陷型视网膜病变小鼠FBN2内源性缺失,通过调控COL1、MAGP-2表达可达到治疗疾病的作用。

聚己内酰胺-己内酯微球/PA6原位微纤化复合材料的制备及性能研究

原位微纤化是提高复合材料强度和韧性的有效方法,但传统原位微纤化材料是基于两相体系的不相容特点。为了探究在相容体系下,两相粘度比对微纤化行为及复合材料性能的影响,通过阴离子聚合制得聚己内酰胺-己内酯(P (CL-CLO))共聚微球,并与PA6切片于双螺杆挤出机中通过共混纺丝,得到P(CL-CLO)/PA6原位微纤化复合材料。分别考察了CLO含量、共混比和牵伸比对共聚微球和微纤的形貌以及P(CL-CLO)/PA6的性能影响。通过SEM观察到,CLO含量为25 wt%以下时,能得到形貌规则的P(CL-CLO)共聚微球。旋转流变仪测结果表明,通过调控CLO含量实现了P(CL-CLO)与PA6的粘度比在1.25~1.65之间调控。对微纤形貌的观察发现,粘度比为1.45~1.65时所形成的微纤尺寸均匀。同时当共混比为2:8、牵伸比为4时,微纤复合材料伸长率和断裂强度分别比纯PA6提高了31.6%和2.96%。这表明微纤与基体间有良好的界面作用力,实现了复合纤维的增强增韧。

DIFFERENT TYPES OF MICROFIBRILLATED CELLULOSE AS FILLER MATERIALS IN POLYSODIUM ACRYLATE SUPERABSORBENTS

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.

广西10种野生竹材的纤维形态及结构研究

对广西10种野生竹材:青皮竹、沙罗单竹、撑篙竹、大绿竹、壮绿竹、清甜竹、花吊丝竹、油竹、耳垂竹、甲竹的纤维形态及结构进行了研究。结果表明,广西10种野生竹材纤维整体直且细长,花吊丝竹的纤维长度(3.19 mm)最长;10种野生竹材的纤维密度分布在1.20~1.45 g/cm^(3)之间,其中青皮竹纤维的密度最小,为1.21 g/cm^(3);10种野生竹材纤维的微纤丝角分布在8°~11°之间。

PBAT/PA6原位微纤复合材料的性能

为了对聚己二酸-对苯二甲酸丁二酯(PBAT)进行增强改性,选择尼龙6(PA6)作为分散相,采用自制的多级挤出拉伸装置制备了PBAT/PA6原位微纤复合材料。通过扫描电子显微镜、万能试验机、差示扫描量热仪与旋转流变仪对PBAT/PA6原位微纤复合材料的微观结构、力学性能、结晶性能及流变性能进行研究。结果表明,分散相PA6在PBAT基体中形成了微纤,当PA6质量分数为4%时,在PBAT-4试样的断面中PA6分散相呈短棒状形状,随着PA6含量的增大,PA6微纤平均直径逐渐增大,其直径分布范围也增大;当PA6质量分数为12%时,PBAT-12试样中的PA6微纤长度较长,大部分PA6微纤的长度大于30μm。PA6的加入提高了PBAT的结晶温度及屈服强度,PA6微纤对PBAT的结晶起到明显异相成核作用,使PBAT的结晶温度提高了14℃左右,PBAT/PA6原位微纤复合材料的玻璃化转变温度随PA6含量增加而逐渐向高温方向移动;随着PA6含量的增加,PBAT/PA6原位微纤复合材料的屈服强度及拉伸弹性模量先增大后减小,PBAT-12试样的屈服强度及拉伸弹性模量最大,分别为10.3MPa和233.5MPa。随着PA6微纤含量增加,PBAT/PA6复合材料的储能模量(G′)、损耗模量(G′′)和复数黏度(η*)值先增大后减小,PBAT-12试样呈现出最高的G′,G′′和η^(*)值。

CONCENTRATION DEPENDENCE OF Se EFFECT ON THE CYTOSKELETON AND COLLAGEN MICROFIBRILS OF CHICKEN EMBRYO CHONDROCYTE AND ITS EXTRACELLULAR MATRIX

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 Na2SeO3 has been effective in preventing such a disease. The main pathological changes of KBD are the necrosis of cartilage, early

Fast self-assembled microfibrillated cellulose@MXene film with high-performance energy storage and superior mechanical strength

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.

Effect of microfibrillated cellulose(MFC)on the properties of gelatin based composite films

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.