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.

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.

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.

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

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

Carboxyethylated Microfibrillated Cellulose Fibers Prepared from Different Raw Materials

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

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.

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.

MFC气凝胶的制备及其精油缓释性能研究

目的利用孔隙率高、比表面积大和吸附性能好的微纤化纤维素(MFC)气凝胶与百里香精油结合,解决抗菌保鲜包装中精油释放过快的问题,实现精油的缓慢释放。方法采用不同用量的内切纤维素酶预处理桉木漂白硫酸盐浆,通过高压均质制备MFC,经冷冻干燥制备MFC气凝胶,在基本性能表征的基础上,研究其精油缓释性能。结果由百里香精油的GC-MS分析得出其主要抑菌成分为麝香草酚。MFC气凝胶均为三维多孔结构,比表面积和平均孔径的变化范围分别为2.0~5.1m^2/g和5.0~22.0nm;当精油与MFC的质量比为1∶1时,MFC气凝胶的精油初始保留率为4.38mg/g(每克气凝胶中保留4.38mg精油),向密闭容器释放的精油量均呈现出先增大后减小,随后逐渐稳定的趋势,释放速率平均为3.1%。结论MFC气凝胶为高孔隙率、中孔材料,可延长精油释放时间,具有优异的缓释性能。

化学氧化预处理对MFC性能的影响

以漂白硫酸盐竹浆为原料,结合PFI磨的前期磨浆预处理和高压均质机的后期高压均质化处理制备微纤化纤维素(MFC),探讨了由2,2,6,6-四甲基哌啶氧化物自由基(TEMPO)、NaClO和NaBr组成的氧化体系的主要工艺参数(TEMPO、NaBr及NaOH用量)对竹浆MFC主要性能(如相对保水值)的影响,确定了最佳的化学预处理工艺。基于氧化后浆料的黏度与最终所得MFC的相对保水值之间的关系以及在优化氧化条件下NaOH用量与氧化后浆料黏度的关系,建立了预测MFC相对保水值的数学方程。

不同制备方式得到的MFC的增强应用对比

分别采用TEMPO诱导氧化预处理结合机械研磨法和PFI磨精浆法制备了2种微纤化纤维素(分别记作TO-MFC和PRMFC),比较了TO-MFC和PR-MFC作为增强剂对抄纸过程的影响及对纸张的增强效果。研究表明:加入3%的TO-MFC或PR-MFC后,浆料滤水速度变慢,填料留着率提高,纸张强度性能提高,其中,抗张强度增幅最大,TO-MFC的增强效果略好于PR-MFC。TOMFC和PR-MFC均为纳米级纤丝交织形成的网络状结构体,与纸浆纤维之间有很强的结合力,提高了纸张的强度性能。

PFI磨解对MFC及纳米纤维纸基材料性能的影响

微纤化纤维素(microfibrillated cellulose,MFC)是一种具有纳米尺度的新型纤维素纤维,具有极为广阔的应用前景。但工业化MFC产品存在尺寸分布和纤丝化程度不均一的问题,从而影响其使用。本文采用PFI磨解的方法对MFC进行后处理,结果表明:PFI磨解可显著提高MFC的均一性,磨解转数为20 000转时,小于200μm的组分含量可达到92.3%,纤维平均长度为42μm。MFC经PFI后处理可制备出具有更高性能的纸基材料,在磨解转数为60 000转时,紧度可提高66.13%,透明度可提高40.26%,吸收性下降45.83%。撕裂指数最高增幅为268.03%(10 000转),抗张指数可提高90.41%(20 000转)。

基于RSM模型对纤维素酶预处理制备MFC的参数优化

研究了响应曲面法(RSM)应用于纤维素酶预处理制备微纤化纤维素(MFC)的工艺条件优化,首先通过马尔文粒度仪、刚果红染色法等手段对MFC性能进行单因素分析,然后以MFC的粒径、比表面积为响应值,采用RSM对工艺条件进行优化和分析。结果表明,纸浆浓度、酶用量、酶处理时间的变化对于制备的MFC性能都具有一定的影响,依据单因素分析,利用RSM进行参数优化,预测得出酶预处理制备MFC的优化条件为:纸浆浓度为10%,酶用量为10.53 U/g,处理时间为24 h。

MFC增强碳纳米纸的制备及其电磁屏蔽效能

为提高碳纳米纸(BP)力学性能,将微纤化纤维素(MFC)与多壁碳纳米管(MWCNT)混合,采用真空抽滤的方法制备MFC/BP。详细研究了MFC/BP的微观形貌、力学性能、电学性能、电磁屏蔽效能。研究表明,MFC均匀分散在碳纳米管中,形成了纤维骨架,碳纳米管相互穿插缠绕分布在纤维骨架周围形成网状结构。随着MFC含量的增加,MFC/BP的力学性能明显提高。当MFC与MWCNT质量比为1/1时,碳纳米纸的拉伸强度为11.76 MPa,比纯碳纳米纸提升了979%;在8.2~12.4 GHz频段内,碳纳米纸(厚度约55μm)的电磁屏蔽效能为24~30 dB。

微纤化程度对MFC气凝胶的性质和包装性能的影响

目的 深入研究制备过程中微纤化程度对微纤化纤维素(MFC)气凝胶的性质及导热、保温、缓释等性能的影响。根据相应性能数据将该气凝胶应用于包装领域,解决精油在包装内释放速率过快而造成精油浓度过高和短时间内消耗完毕的问题。方法 采用TEMPO(2,2,6,6-四甲基哌啶-1-氧自由基)/NaBr/NaClO氧化体系预处理针叶木漂白硫酸盐浆,通过改变高压均质次数和低温真空冷冻干工艺制备不同微纤化程度的MFC气凝胶,利用FT-IR、XRD、SEM和BET等技术分析气凝胶的结构性质,运用应力-应变测试、导热系数测试、TGA测试和GC-MS分析等方法分别对气凝胶的压缩、保温、耐热和缓释性能进行研究。结果 随着微纤化程度的增加,MFC气凝胶的结晶度逐渐增加,气凝胶的比表面积呈现先减小后增加的趋势,范围为17.643~35.171m2/g;气凝胶的压缩强度呈现增加趋势,增幅为15.35%;均质次数为10的气凝胶的耐热性最好,均质次数为8的气凝胶次之。结论 均质次数的增加引起MFC微纤化程度提高,不同微纤化程度的MFC气凝胶具有不同的内部结构性质,以及压缩、保温、耐热和精油负载缓释性能。

喷涂阳离子化MFC对柴油滤纸原纸孔隙特性的影响研究

以漂白硫酸盐针叶木浆为原料制备不同直径的阳离子化微纤化纤维素(C-MFC),并将CMFC喷涂在单层柴油滤纸原纸(基纸)表面得到复合柴油滤纸原纸(复合原纸);通过扫描电子显微镜(SEM)分析其表面形貌,实验分析不同直径C-MFC对复合原纸孔隙特性、强度、透气度及紧度等性能的影响。结果表明,随着均质压力从10 MPa增加到70 MPa时,C-MFC的平均直径从154. 5 nm降至68. 3 nm;复合原纸的平均孔径由空白样的21. 3μm逐渐降低至14. 1μm,最大孔径由64. 2μm逐渐降低至38. 0μm,且孔径分布更加均一;喷涂C-MFC显著改善基纸的强度性能,在均质压力70MPa条件下获得的C-MFC用于复合原纸制备,其抗张指数和耐破指数相比于空白样分别提高了61. 2%和124. 6%。

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.

Effects of MFC-modified GCC as Filler on the Opacity of Pulp Handsheets

Microfibrillated cellulose(MFC)was obtained by mechanical grinding of different pulps.MFC-modified ground calcium carbonate(GCC)was prepared in two different ways,designated MFC-GCC composite filler and MFC-GCC flocs filler.The opacity of pulp handsheets loaded with MFCmodified GCC was measured.The effects of MFC originated from different pulps,pretreatment method,and filler modification on the opacity of handsheets loaded with MFC-modified GCC were discussed.The results show that MFC originated from alkaline peroxide mechanical pulp(APMP)was optimal for improving the opacity of the handsheets and PFI grinding pretreatment for MFC provided a denser structure in the corresponding MFCAPMP-GCC floc filler while enzyme pretreatment was more effective in increasing the opacity of the filled paper.Under the experimental conditions,the opacity of handsheets increased from 81.0%to 82.7%when the unmodified GCC was replaced by an equivalent amount of MFCAPMP-GCC composite filler,while other properties were unchanged.

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.

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.

微纤化纤维素及其制备技术的研究进展

微纤化纤维素(MFC)是一种主要由植物纤维制备而得的可再生高分子材料,兼具天然纤维和纳米材料的特点。近年来,有关MFC制备、改性及应用方面的研究越来越多,然而制备成本高、干燥以及再分散等仍然是MFC规模化生产所不可回避的问题。为了更全面地加深对MFC及其制备技术发展现状的认识,本文首先探讨了MFC物化特性及其命名,然后介绍了MFC机械制备方法,包括高压均质处理、微射流处理、超细研磨处理、冷冻破碎处理和高强超声处理等,并对MFC机械制备存在的问题进行了分析。本文还介绍了MFC制备过程中的预处理方法,包括纤维素酶预处理、酸-碱抽提预处理、羧甲基化预处理、TEMPO氧化预处理、高碘酸盐氧化预处理等。最后对MFC在规模化生产及干燥过程中存在的问题进行了总结。