Microcrystalline cellulose(MCC)is one of the cellulose derivatives produced as a result of the depolymerization of a part of cellulose to achieve high crystallinity.When implemented in other polymers,high crystallinit...Microcrystalline cellulose(MCC)is one of the cellulose derivatives produced as a result of the depolymerization of a part of cellulose to achieve high crystallinity.When implemented in other polymers,high crystallinity correlates with greater strength and stiffnes,but it can reduce the water-holding capacity.The acid concentration and hydrolysis time will affect the acquisition of crystallinity and water absorption capacity,both of which have significance as properties of hydrogel filler.The study aimed to evaluate the properties and select the MCC generated from varying the proportion of hydrochloric acid(HCl)and the appropriate hydrolysis time as a filler for film hydrogel.MCC was produced by hydrolyzing cellulose of oil palm empty fruit bunches(OPEFB)with the HCl solution at varied concentrations and periods.The results show that the longer hydrolysis times and higher HCl concentrations increase crystallinity and density while lowering yield and water absorption.The extensive acid hydrolysis reduces the amorphous area significantly,allowing the depolymerization to occur and extend the crystalline area.The morphological properties of the MCC,which are smaller but compact,indicate the presence of disintegrating and diminishing structures.A 2.5 N HCl concentration and a 45-min hydrolysis time succeed in sufficient crystallinity as well as maintaining good water absorption capacity.The treatment produced MCC with absorption capacity of 4.03±0.26 g/g,swelling capacity of 5.03±0.26 g/g,loss on drying of 1.44%±0.36,bulk and tapped density of 0.27±0.031 g/cm^(3) and 0.3±0.006 g/cm^(3),respectively,with a crystallinity index of 88.89%±4.76 and a crystallite size of 4.23±0.70 nm.The MCC generated could potentially be utilized as a hydrogel film filler,since a given proportion will be able to maintain the strength of the hydrogel,not readily dissolve but absorb water significantly.展开更多
Polyvinyl alcohol (PVA) colloid stabilized Polyvinyl acetate (PVAc) based wood adhesive has poor performance in highly humid conditions. Currently, the addition of natural fillers in the wood adhesive is one of the mo...Polyvinyl alcohol (PVA) colloid stabilized Polyvinyl acetate (PVAc) based wood adhesive has poor performance in highly humid conditions. Currently, the addition of natural fillers in the wood adhesive is one of the most effective ways to enhance the performance of PVAc wood adhesive in highly moist conditions. Microcrystalline cellulose (MCC) are strong renewable, bio-based material and has great potential in a reinforcement of the polymeric matrix. Hence, the present work investigates the applicability of microcrystalline cellulose incorporated 3% and 5% in situ emulsion polymerization PVAc wood adhesives. Effect on physical, thermal and mechanical properties was studied by viscosity, pH, contact angle measurement, differential scanning calorimetry (DSC) and pencil hardness test of films. Emulsions with different proportions of MCC were prepared and the shear strength of the applied adhesive on wood was measured. The viscosity of the adhesives was increased by increasing the concentration of MCC. The mechanical properties like tensile strength of adhesives with MCC were measured by universal tensile machine (UTM). Thermal stability was studied by differential scanning calorimetry (DSC). The tensile shear strength demonstrates that MCC can improve bonding strength as compared to PVAc Homo based adhesive in the wet condition which was validated through a contact angle study. The hardness of PVAc films were also changed positively by the addition of MCC. Here, we studied the effect of the addition of different concentrations of MCC materials in situ polymerization of PVAc on their performance properties.展开更多
In this study, we modified microcrystalline cellulose by cross-linking it with epichlorohydrin to obtain a rapid and efficient adsorbent for the removal of Reactive Blue 4 dye from aqueous solution. Evidences of the c...In this study, we modified microcrystalline cellulose by cross-linking it with epichlorohydrin to obtain a rapid and efficient adsorbent for the removal of Reactive Blue 4 dye from aqueous solution. Evidences of the cross-linking of the microcrystalline cellulose were obtained by Fourier transform infrared spectroscopy, X-ray diff raction, Brunauer–Emmett–Teller analysis, thermogravimetric analysis, and scanning electron microscopy. We investigated the eff ects of adsorbent dosage, p H, initial dye concentration, temperature, and contact time on the dye adsorption capacity. The results showed that the adsorption equilibrium time was just 20 min and the maximum adsorption capacity was 69.79 mg/g. The adsorption isotherm data fitted the Langmuir isotherm model well, and the adsorption kinetics data followed the pseudo-second-order kinetic model. The results of the thermodynamic analysis suggest that the adsorption process was spontaneous and exothermic. Recyclability experiments demonstrated the good reusability of this adsorbent. Electrostatic interaction was found to dominate the adsorption process.展开更多
The design of astonishing combinations of benzoxazine resins with various fillers is nowadays of great interest for high quality products,especially in ballistic armors.The objective of this study is to investigate a ...The design of astonishing combinations of benzoxazine resins with various fillers is nowadays of great interest for high quality products,especially in ballistic armors.The objective of this study is to investigate a new hybrid material prepared as multi-layered composite plate by hand lay-up technique.Different composites were manufactured from Kevlar fabrics reinforced polybenzoxazine,which was filled with silane treated microcrystalline cellulose(MCC Si)at various amounts in the interlayers.The developed materials were tested for their flexural,dynamic mechanical and ballistic performance.The aim was to highlight the effect of adding different amounts of MCC Si on the behavior of the different plates.Compared to the baseline,the dynamic mechanical and bending tests revealed an obvious decrease of the glass transition of 21℃and a notable increase in storage modulus and flexural strength of about 180%and17%,respectively,upon adding 1%MMC Si as filler.Similarly,the ballistic test exhibited an enhancement in kinetic energy absorption for which the composite supplemented with 1%MCC Si had the maximal energy absorption of 166.60 J.These results indicated that the developed panels,with interesting mechanical and ballistic features,are suitable to be employed as raw materials to produce body armor.展开更多
The main purpose of this study is to prepare highly stable diclofenac potassium(DP)pellet with microcrystalline cellulose(MCC)by extrusionespheronization.Using MCC,DP pellets were prepared and the stability was invest...The main purpose of this study is to prepare highly stable diclofenac potassium(DP)pellet with microcrystalline cellulose(MCC)by extrusionespheronization.Using MCC,DP pellets were prepared and the stability was investigated.Related compounds of DP pellets were analyzed by High Pressure Liquid Chromatography(HPLC).After stability test of 60℃/75%RH for 10 d,the values of two main related compounds were 0.94%and 2.17%,respectively.Compatibility tests show that instability of DP was mainly caused by MCC.To improve the stability of DP in presence of MCC,different kinds of stabilizers were investigated.Upon addition of 1.5%(w/w)sodium hydroxide,the primary related compound of pellets was reduced to be 0.159%after stability test of 60℃/75%RH for 50 d.This study demonstrated that MCC induced decomposition of DP upon exposure to moisture could be prohibited by addition of sodium hydroxide.The mechanisms were discussed and residual hydroxyl free radicals in excipients were responsible for decomposition of DP.Finally,this formulation of DP is highly stable with sustained-release behavior.展开更多
This study was aimed to determine the mechanical strength of composites made from Agave cantala with an unsaturated polyester matrix and microcrystalline cellulose.Cantala fiber(CF)was treated with 6%Na OH with immers...This study was aimed to determine the mechanical strength of composites made from Agave cantala with an unsaturated polyester matrix and microcrystalline cellulose.Cantala fiber(CF)was treated with 6%Na OH with immersion times of 0 h(UF),3 h(AK3),6 h(AK6),9 h(AK9),and12 h(AK12).Thermogravimetric analysis(TGA)analysis shows that treated CF has higher thermal stability than CF without treatment.Cantala fiber was tested by X-ray diffraction.After alkali treatment with a 6-h soaking,it had a crystallinity index of 73.65%.Scanning electron microscopy(SEM)showed that the fibers were cleaner after alkali treatment because hemicellulose,wax,and other impurities were removed.Examination of the contact angle and surface energy showed that treated CF has smaller contact angles and greater surface energy.展开更多
In recent years, there has been a growing discussion about the problems related to the massive use of many synthetic plastic materials, which inevitably leads to an increase in environmental pollution caused by the in...In recent years, there has been a growing discussion about the problems related to the massive use of many synthetic plastic materials, which inevitably leads to an increase in environmental pollution caused by the inappropriate disposal of these materials. In this sense, biodegradable materials have been a subject of great interest, as they are a real alternative to replace these materials and tackle this issue. In this work, fully biodegradable composites were prepared by solution casting method. Microcrystalline cellulose (MCC) and treated microcrystalline cellulose (TMCC) were separately incorporated into biodegradable PLA and PHB matrices at ratios of 3, 5 and 7 wt% and the properties of the obtained biocomposites were evaluated by TGA, DSC, XRD and TD-NMR. From thermal analyses, it was seen that TMCC resulted in better thermal stability and 3 wt% of filler, in general, promoted a more pronounced thermal improvement. Furthermore Tg, Tc and Tm remained practically unchanged after MCC and TMCC addition. From XRD it was seen that the cellulose fillers influence in different ways the matrices, promoting increase or decrease in the degree of crystallinity. Finally, the results obtained by TD-NMR showed a decrease in the T<sub>1</sub>H values for all prepared biocomposites, indicating a good dispersion of the cellulose fillers in the matrices and pointed that the systems containing 3 wt% of cellulose fillers were the most homogeneous formulations.展开更多
Low molecular aromatic compounds are detrimental to the enzymatic hydrolysis of lignocellu-lose.However,the specific role of their functional groups remains unclear.Here,a series of nine aromatic compounds as additive...Low molecular aromatic compounds are detrimental to the enzymatic hydrolysis of lignocellu-lose.However,the specific role of their functional groups remains unclear.Here,a series of nine aromatic compounds as additives were tested to understand their effect on the hydrolysis yield of microcrystalline cellulose(MCC)and alkaline pretreated wheat straw.Based on the results,the inhibition of aldehyde groups on MCC was greater than that of carboxyl groups,whereas for the alkaline pretreated wheat straw case,the inhibitory effect of aldehyde groups was lower than that of carboxyl groups.Increased methoxyl groups of aromatic compounds reduced the inhibitory ef-fect on enzymatic hydrolysis of both substrates.Stronger inhibition of aromatic compounds on MCC hydrolysis was detected in comparison with the alkaline pretreated wheat straw,indicating that the substrate lignin can offset the inhibition to a certain extent.Among all aromatic com-pounds,syringaldehyde with one aldehyde group and two methoxyl groups improved the glucan conversion of the alkaline pretreated wheat straw.展开更多
A strategy for fabricating microcrystalline cellulose–Ti_(3)C_(2)T_(x)(MCC–MXene)nanocomposite films with high relative permittivity,high thermal conductivity,and excellent mechanical properties was developed.The MC...A strategy for fabricating microcrystalline cellulose–Ti_(3)C_(2)T_(x)(MCC–MXene)nanocomposite films with high relative permittivity,high thermal conductivity,and excellent mechanical properties was developed.The MCC–MXene nanocomposite film was fabricated by casting a solution containing N,N-dimethylacetamide/lithium chloride(DMAc/LiCl)-soluble MCC and DMAcdispersible MXene nanosheets,followed by humidity control drying.The MXene nanosheets greatly enhanced the permittivity of the nanocomposite films owing to interfacial polarization.Thus,the nanocomposite film with 20 wt.%MXene content achieved a desirable permittivity of 71.4 at 102 Hz(a 770%improvement against that of neat cellulose),while the dielectric loss only increased by 1.8 times(from 0.39 to 0.70).The obtained nanocomposite films with 20 wt.%and 30 wt.%MXene exhibited remarkable in-plane thermal conductivities of 8.523 and 9.668 W∙m^(−1)∙K^(−1),respectively,owing to the uniform dispersion and selfalignment of the MXene layered structure.Additionally,the uniformly dispersed MXene nanosheets in the MCC network with interfacial interaction(hydrogen bonding)and mechanical entanglement endowed the nanocomposite films with excellent mechanical properties and flexibility.Furthermore,the thermal stability,water resistance,and antibacterial properties of the nanocomposite films were effectively improved with the introduction of MXene.Moreover,using DMAc/LiCl as the solvent system not only improves the compatibility between MCC and MXene but also avoids the problem of easy oxidation of MXene in aqueous systems.With the high stability of the MCC–MXene solution and enhanced properties of the MCC–MXene films,the proposed strategy manifests great potential for fabricating natural biomass-based dielectric materials.展开更多
This study focused on the manufacture of microcrystalline cellulose(MCC)from wheat straw using environmentally-friendly solvents.Raw cellulose was separated from wheat straw after thermal decomposition of lignin follo...This study focused on the manufacture of microcrystalline cellulose(MCC)from wheat straw using environmentally-friendly solvents.Raw cellulose was separated from wheat straw after thermal decomposition of lignin followed by dissolution of lignin using a recyclable ethanol/acetic acid/water solvent system.Then,pure cellulose was produced using a four-step refining process,including chelating,O_(3),H_(2)O_(2),and xylanase treatments.Finally,MCC was obtained through hydrolysis,drying,and mechanical treatments.The effects of acetic acid,O_(3),H_(2)O_(2),NaOH,pretreatment time,and temperature on the properties of wheat straw cellulose(including Kappa number,yield,α-cellulose content,crystallinity,KMnO4 value,degree of polymerization(DP),and brightness)were investigated.The results showed that the addition of acetic acid enhanced lignin removal and hemicellulose degradation,improving the purity of the raw cellulose.The optimized acetic acid dosage in the wheat straw thermal decomposition step was 2%(w/w).The optimized O_(3)dosage was 1.2%(w/w).The optimized conditions for H_(2)O_(2)treatment were found to be 3%(w/w)H_(2)O_(2)and 1.8%(w/w)NaOH at 70°C for 120 min.The KMnO4 value was 2.0,brightness was 84.1%ISO,the viscosity was 934 mL/g,and the DP was 626 for refined cellulose.Xylanase effectively improved theα-cellulose content of wheat straw cellulose.With an optimized xylanase dosage of 1.5 IU/g,theα-cellulose content was 94.7%,the brightness was 85.6%ISO,and the DP was 615 for wheat straw cellulose.展开更多
To tackle the challenge of producing highly filled polymer composites using the traditional injection molding technique,which is characterized by the fairly high melt viscosity that makes mold filling difficult,the au...To tackle the challenge of producing highly filled polymer composites using the traditional injection molding technique,which is characterized by the fairly high melt viscosity that makes mold filling difficult,the authors propose a solution based on dynamic covalent chemistry.As demonstrated by the proof-of-concept experiments,the 4-arm starshaped polycaprolactone(PCL)oligomers and microcrystalline cel-lulose(MCC)are crosslinked by the reversible Diels-Alder(DA)bonds.The flowability of the compounds greatly decreases due to the dissociation of the intercomponent DA bonds at the retro-reaction tempera-ture,and the networked architecture is reconstructed during cooling as a result of the forward DA reaction.Consequently,the high-loading MCC fillers are well distributed in the matrix and covalently bonded to the nearby PCL,forming a striking contrast to the control in which linear PCL acts as the matrix.The DA bonds crosslinked biodegradable PCL composites exhibit decent mechanical strength(20.7 MPa)even at the MCC fraction of 65 wt%,which is superior to those(5-12.2 MPa)of the highly filled PCL composites(with filler contents of 50-63.8 wt%)reported so far.The proposed approach has sufficient expansibility for the fabrication of the highly filled polymer composites constructed by other types of matrix and fillers.展开更多
This work presents a strategy for the mesoscopic engineering of hierarchically structured sodium alginate(SA)aerogels to enhance the macroscopic performance.The strategy was implemented by meso-functionalizing and reo...This work presents a strategy for the mesoscopic engineering of hierarchically structured sodium alginate(SA)aerogels to enhance the macroscopic performance.The strategy was implemented by meso-functionalizing and reorganizing SA aerogels via controlled heterogeneous nucleation,in which microcrystalline cellulose-manganese dioxide(MCC-MnO_(2))nano-crystallites worked as template.Due to the short rod-like structure and abundant hydroxyl groups of MCC-MnO_(2),the organized mesostructure of SA aerogels was reconstructed during the assembly of SA molecule chains,which gave rise to a significant enhancement in macroscopic performance of SA areogels.For instance,the functionalized and reconstructed MCC-MnO_(2)/SA aerogels acquired a more than 70%increase in mechanical strength with an excellent deformation recovery.Furthermore,an almost double enhancement of removal capacity for metal ions(i.e.,Cu^(2+)and Pb^(2+))and organic dyes(i.e.,congo red and methylene blue)was obtained for MnO_(2)/SA aerogels,with an 87%repossession of the pollutants removal performance after 5 operation cycles.展开更多
The present work mainly focuses on the estimation of various components and the extraction of microcrystalline cellulose(MCC)from non-wood sources like Country Almond/Badam shell through acid hydrolysis.This hydrolyze...The present work mainly focuses on the estimation of various components and the extraction of microcrystalline cellulose(MCC)from non-wood sources like Country Almond/Badam shell through acid hydrolysis.This hydrolyzed MCC was successfully used as reinforcement for development of biocomposites.Country Almond/Badam trees are found all over Kerala,India and they give nuts once in a year.Usually the nut shells are discarded and are becoming one of the sources of agricultural waste.During this investigation various components were isolated from the Country Almond shells and they were characterised using different spectral and analytical techniques thereby the composition of Country Almond shells was successfully determined for the first time.The properties of MCC especially the crystalline nature depends on the source from which is isolated.FT-IR spectra give evidence for the chemical structure of MCC.Morphology of MCC was evidenced from scanning electron microscopy.Transmission electron microscopy and atomic force microscopy reveal the agglomerated bundles of particles and rough surface of MCC.The extracted MCC was found to contain Cellulose I and Cellulose II polymorphs,and this was confirmed from the X-ray diffraction(XRD)studies.The MCC extracted from Country Almond shells has reasonably good thermal stability.Solution casting method was adopted for the development of green composite of Poly(vinyl alcohol)reinforced with MCC extracted from Country Almond shell.The mechanical property of developed composites has been enhanced by the addition of MCC.The dispersion of MCC in the PVA matrix and flocculation of MCC significantly influence the mechanical strength.展开更多
As the most favorable alternative to petroleum-based polymers,polylactic acid(PLA)which is the most promising degradable polymer has attracted increasing attention.However,the addition of cellulose to improve its stre...As the most favorable alternative to petroleum-based polymers,polylactic acid(PLA)which is the most promising degradable polymer has attracted increasing attention.However,the addition of cellulose to improve its strength often results in a reduction in its toughness.In this work,microscale cellulose is first prepared from pulp fibers by using a deep eutectic solvent,and then is used as the reinforcement of PLA.A microcrystalline cellulose(MCC)/PLA sheet with uniform texture is obtained by the solution mixing,melt blending,hot-pressing and cold-pressing process.The effects of MCC on the crystallization,thermal stability and mechanical properties of the PLA matrix were studied.Upon the addition of 1%cellulose fiber,the tensile strength of MCC/PLA composite sheet increased by 27%,and the elongation at break did not shown an evident decrease.The strength enhancement mechanism was elucidated using scanning electron microscopy,differential scanning calorimetry,and dynamic thermomechanical analysis.The energy dissipation during the deformation process and the compatibility of AMCC and rougher surface of MCC play important role in the strength enhancement.Additionally,UV spectroscopy showed that the composite material absorbed some ultraviolet light.Our results show that the combined use of a deep eutectic solvent and solution mixing is an effective approach for improving the strength of PLA while maintaining its toughness.展开更多
基金the Universitas Gadjah Mada’s financial support for this research.This research was conducted using the Final Project Recognition Grant Universitas Gadjah Mada Indonesia Number of 5075/UN1.P.II/DitLit/PT.01.01/2023.
文摘Microcrystalline cellulose(MCC)is one of the cellulose derivatives produced as a result of the depolymerization of a part of cellulose to achieve high crystallinity.When implemented in other polymers,high crystallinity correlates with greater strength and stiffnes,but it can reduce the water-holding capacity.The acid concentration and hydrolysis time will affect the acquisition of crystallinity and water absorption capacity,both of which have significance as properties of hydrogel filler.The study aimed to evaluate the properties and select the MCC generated from varying the proportion of hydrochloric acid(HCl)and the appropriate hydrolysis time as a filler for film hydrogel.MCC was produced by hydrolyzing cellulose of oil palm empty fruit bunches(OPEFB)with the HCl solution at varied concentrations and periods.The results show that the longer hydrolysis times and higher HCl concentrations increase crystallinity and density while lowering yield and water absorption.The extensive acid hydrolysis reduces the amorphous area significantly,allowing the depolymerization to occur and extend the crystalline area.The morphological properties of the MCC,which are smaller but compact,indicate the presence of disintegrating and diminishing structures.A 2.5 N HCl concentration and a 45-min hydrolysis time succeed in sufficient crystallinity as well as maintaining good water absorption capacity.The treatment produced MCC with absorption capacity of 4.03±0.26 g/g,swelling capacity of 5.03±0.26 g/g,loss on drying of 1.44%±0.36,bulk and tapped density of 0.27±0.031 g/cm^(3) and 0.3±0.006 g/cm^(3),respectively,with a crystallinity index of 88.89%±4.76 and a crystallite size of 4.23±0.70 nm.The MCC generated could potentially be utilized as a hydrogel film filler,since a given proportion will be able to maintain the strength of the hydrogel,not readily dissolve but absorb water significantly.
文摘Polyvinyl alcohol (PVA) colloid stabilized Polyvinyl acetate (PVAc) based wood adhesive has poor performance in highly humid conditions. Currently, the addition of natural fillers in the wood adhesive is one of the most effective ways to enhance the performance of PVAc wood adhesive in highly moist conditions. Microcrystalline cellulose (MCC) are strong renewable, bio-based material and has great potential in a reinforcement of the polymeric matrix. Hence, the present work investigates the applicability of microcrystalline cellulose incorporated 3% and 5% in situ emulsion polymerization PVAc wood adhesives. Effect on physical, thermal and mechanical properties was studied by viscosity, pH, contact angle measurement, differential scanning calorimetry (DSC) and pencil hardness test of films. Emulsions with different proportions of MCC were prepared and the shear strength of the applied adhesive on wood was measured. The viscosity of the adhesives was increased by increasing the concentration of MCC. The mechanical properties like tensile strength of adhesives with MCC were measured by universal tensile machine (UTM). Thermal stability was studied by differential scanning calorimetry (DSC). The tensile shear strength demonstrates that MCC can improve bonding strength as compared to PVAc Homo based adhesive in the wet condition which was validated through a contact angle study. The hardness of PVAc films were also changed positively by the addition of MCC. Here, we studied the effect of the addition of different concentrations of MCC materials in situ polymerization of PVAc on their performance properties.
文摘In this study, we modified microcrystalline cellulose by cross-linking it with epichlorohydrin to obtain a rapid and efficient adsorbent for the removal of Reactive Blue 4 dye from aqueous solution. Evidences of the cross-linking of the microcrystalline cellulose were obtained by Fourier transform infrared spectroscopy, X-ray diff raction, Brunauer–Emmett–Teller analysis, thermogravimetric analysis, and scanning electron microscopy. We investigated the eff ects of adsorbent dosage, p H, initial dye concentration, temperature, and contact time on the dye adsorption capacity. The results showed that the adsorption equilibrium time was just 20 min and the maximum adsorption capacity was 69.79 mg/g. The adsorption isotherm data fitted the Langmuir isotherm model well, and the adsorption kinetics data followed the pseudo-second-order kinetic model. The results of the thermodynamic analysis suggest that the adsorption process was spontaneous and exothermic. Recyclability experiments demonstrated the good reusability of this adsorbent. Electrostatic interaction was found to dominate the adsorption process.
文摘The design of astonishing combinations of benzoxazine resins with various fillers is nowadays of great interest for high quality products,especially in ballistic armors.The objective of this study is to investigate a new hybrid material prepared as multi-layered composite plate by hand lay-up technique.Different composites were manufactured from Kevlar fabrics reinforced polybenzoxazine,which was filled with silane treated microcrystalline cellulose(MCC Si)at various amounts in the interlayers.The developed materials were tested for their flexural,dynamic mechanical and ballistic performance.The aim was to highlight the effect of adding different amounts of MCC Si on the behavior of the different plates.Compared to the baseline,the dynamic mechanical and bending tests revealed an obvious decrease of the glass transition of 21℃and a notable increase in storage modulus and flexural strength of about 180%and17%,respectively,upon adding 1%MMC Si as filler.Similarly,the ballistic test exhibited an enhancement in kinetic energy absorption for which the composite supplemented with 1%MCC Si had the maximal energy absorption of 166.60 J.These results indicated that the developed panels,with interesting mechanical and ballistic features,are suitable to be employed as raw materials to produce body armor.
文摘The main purpose of this study is to prepare highly stable diclofenac potassium(DP)pellet with microcrystalline cellulose(MCC)by extrusionespheronization.Using MCC,DP pellets were prepared and the stability was investigated.Related compounds of DP pellets were analyzed by High Pressure Liquid Chromatography(HPLC).After stability test of 60℃/75%RH for 10 d,the values of two main related compounds were 0.94%and 2.17%,respectively.Compatibility tests show that instability of DP was mainly caused by MCC.To improve the stability of DP in presence of MCC,different kinds of stabilizers were investigated.Upon addition of 1.5%(w/w)sodium hydroxide,the primary related compound of pellets was reduced to be 0.159%after stability test of 60℃/75%RH for 50 d.This study demonstrated that MCC induced decomposition of DP upon exposure to moisture could be prohibited by addition of sodium hydroxide.The mechanisms were discussed and residual hydroxyl free radicals in excipients were responsible for decomposition of DP.Finally,this formulation of DP is highly stable with sustained-release behavior.
文摘This study was aimed to determine the mechanical strength of composites made from Agave cantala with an unsaturated polyester matrix and microcrystalline cellulose.Cantala fiber(CF)was treated with 6%Na OH with immersion times of 0 h(UF),3 h(AK3),6 h(AK6),9 h(AK9),and12 h(AK12).Thermogravimetric analysis(TGA)analysis shows that treated CF has higher thermal stability than CF without treatment.Cantala fiber was tested by X-ray diffraction.After alkali treatment with a 6-h soaking,it had a crystallinity index of 73.65%.Scanning electron microscopy(SEM)showed that the fibers were cleaner after alkali treatment because hemicellulose,wax,and other impurities were removed.Examination of the contact angle and surface energy showed that treated CF has smaller contact angles and greater surface energy.
文摘In recent years, there has been a growing discussion about the problems related to the massive use of many synthetic plastic materials, which inevitably leads to an increase in environmental pollution caused by the inappropriate disposal of these materials. In this sense, biodegradable materials have been a subject of great interest, as they are a real alternative to replace these materials and tackle this issue. In this work, fully biodegradable composites were prepared by solution casting method. Microcrystalline cellulose (MCC) and treated microcrystalline cellulose (TMCC) were separately incorporated into biodegradable PLA and PHB matrices at ratios of 3, 5 and 7 wt% and the properties of the obtained biocomposites were evaluated by TGA, DSC, XRD and TD-NMR. From thermal analyses, it was seen that TMCC resulted in better thermal stability and 3 wt% of filler, in general, promoted a more pronounced thermal improvement. Furthermore Tg, Tc and Tm remained practically unchanged after MCC and TMCC addition. From XRD it was seen that the cellulose fillers influence in different ways the matrices, promoting increase or decrease in the degree of crystallinity. Finally, the results obtained by TD-NMR showed a decrease in the T<sub>1</sub>H values for all prepared biocomposites, indicating a good dispersion of the cellulose fillers in the matrices and pointed that the systems containing 3 wt% of cellulose fillers were the most homogeneous formulations.
基金thankful to National Natural Science Foundation of China(No.31730106,No.21704045)Jiangsu Provincial Key Research and Development Program,China(No.BE2021368)for supporting the work.
文摘Low molecular aromatic compounds are detrimental to the enzymatic hydrolysis of lignocellu-lose.However,the specific role of their functional groups remains unclear.Here,a series of nine aromatic compounds as additives were tested to understand their effect on the hydrolysis yield of microcrystalline cellulose(MCC)and alkaline pretreated wheat straw.Based on the results,the inhibition of aldehyde groups on MCC was greater than that of carboxyl groups,whereas for the alkaline pretreated wheat straw case,the inhibitory effect of aldehyde groups was lower than that of carboxyl groups.Increased methoxyl groups of aromatic compounds reduced the inhibitory ef-fect on enzymatic hydrolysis of both substrates.Stronger inhibition of aromatic compounds on MCC hydrolysis was detected in comparison with the alkaline pretreated wheat straw,indicating that the substrate lignin can offset the inhibition to a certain extent.Among all aromatic com-pounds,syringaldehyde with one aldehyde group and two methoxyl groups improved the glucan conversion of the alkaline pretreated wheat straw.
基金supported by the National Research Foundation of Korea(NRF)Grant funded by the Ministry of Science and ICT,Korea(NRF-2021R1I1A3060098,NRF-2021R1I1A3059777)supported by the Brain Korea 21 Plus Program(4199990414196)+1 种基金the Korea Institute for Advancement of Technology funded by the Ministry of Trade,Industry and Energy(P0017531)Y.Z.Y.was partially supported by the China Scholarship Council(No.201908260073).
文摘A strategy for fabricating microcrystalline cellulose–Ti_(3)C_(2)T_(x)(MCC–MXene)nanocomposite films with high relative permittivity,high thermal conductivity,and excellent mechanical properties was developed.The MCC–MXene nanocomposite film was fabricated by casting a solution containing N,N-dimethylacetamide/lithium chloride(DMAc/LiCl)-soluble MCC and DMAcdispersible MXene nanosheets,followed by humidity control drying.The MXene nanosheets greatly enhanced the permittivity of the nanocomposite films owing to interfacial polarization.Thus,the nanocomposite film with 20 wt.%MXene content achieved a desirable permittivity of 71.4 at 102 Hz(a 770%improvement against that of neat cellulose),while the dielectric loss only increased by 1.8 times(from 0.39 to 0.70).The obtained nanocomposite films with 20 wt.%and 30 wt.%MXene exhibited remarkable in-plane thermal conductivities of 8.523 and 9.668 W∙m^(−1)∙K^(−1),respectively,owing to the uniform dispersion and selfalignment of the MXene layered structure.Additionally,the uniformly dispersed MXene nanosheets in the MCC network with interfacial interaction(hydrogen bonding)and mechanical entanglement endowed the nanocomposite films with excellent mechanical properties and flexibility.Furthermore,the thermal stability,water resistance,and antibacterial properties of the nanocomposite films were effectively improved with the introduction of MXene.Moreover,using DMAc/LiCl as the solvent system not only improves the compatibility between MCC and MXene but also avoids the problem of easy oxidation of MXene in aqueous systems.With the high stability of the MCC–MXene solution and enhanced properties of the MCC–MXene films,the proposed strategy manifests great potential for fabricating natural biomass-based dielectric materials.
基金the Doctoral Program of Higher Education Projects(for the priority development areas)by Ministry of Education of China(Grant No.20126125130001)State Key Laboratory of Pulp and Paper Engineering open foundation(Grant No.201505)the Doctoral Scientific Research Foundation(Grant No.BJ13-02)by Shaanxi University of Science and Technology.
文摘This study focused on the manufacture of microcrystalline cellulose(MCC)from wheat straw using environmentally-friendly solvents.Raw cellulose was separated from wheat straw after thermal decomposition of lignin followed by dissolution of lignin using a recyclable ethanol/acetic acid/water solvent system.Then,pure cellulose was produced using a four-step refining process,including chelating,O_(3),H_(2)O_(2),and xylanase treatments.Finally,MCC was obtained through hydrolysis,drying,and mechanical treatments.The effects of acetic acid,O_(3),H_(2)O_(2),NaOH,pretreatment time,and temperature on the properties of wheat straw cellulose(including Kappa number,yield,α-cellulose content,crystallinity,KMnO4 value,degree of polymerization(DP),and brightness)were investigated.The results showed that the addition of acetic acid enhanced lignin removal and hemicellulose degradation,improving the purity of the raw cellulose.The optimized acetic acid dosage in the wheat straw thermal decomposition step was 2%(w/w).The optimized O_(3)dosage was 1.2%(w/w).The optimized conditions for H_(2)O_(2)treatment were found to be 3%(w/w)H_(2)O_(2)and 1.8%(w/w)NaOH at 70°C for 120 min.The KMnO4 value was 2.0,brightness was 84.1%ISO,the viscosity was 934 mL/g,and the DP was 626 for refined cellulose.Xylanase effectively improved theα-cellulose content of wheat straw cellulose.With an optimized xylanase dosage of 1.5 IU/g,theα-cellulose content was 94.7%,the brightness was 85.6%ISO,and the DP was 615 for wheat straw cellulose.
基金the support of the National Natural Science Foundation of China(Grants:52033011,51973237,and 52173092)Natural Science Foundation of Guangdong Province(Grants:2019B1515120038,2020A1515011276,2021A1515010417)+1 种基金Science and Technology Planning Project of Guangzhou City(Grant:202201011568)Fundamental Research Funds for the Central Universities,Sun Yatsen University(Grant:23yxqntd002).
文摘To tackle the challenge of producing highly filled polymer composites using the traditional injection molding technique,which is characterized by the fairly high melt viscosity that makes mold filling difficult,the authors propose a solution based on dynamic covalent chemistry.As demonstrated by the proof-of-concept experiments,the 4-arm starshaped polycaprolactone(PCL)oligomers and microcrystalline cel-lulose(MCC)are crosslinked by the reversible Diels-Alder(DA)bonds.The flowability of the compounds greatly decreases due to the dissociation of the intercomponent DA bonds at the retro-reaction tempera-ture,and the networked architecture is reconstructed during cooling as a result of the forward DA reaction.Consequently,the high-loading MCC fillers are well distributed in the matrix and covalently bonded to the nearby PCL,forming a striking contrast to the control in which linear PCL acts as the matrix.The DA bonds crosslinked biodegradable PCL composites exhibit decent mechanical strength(20.7 MPa)even at the MCC fraction of 65 wt%,which is superior to those(5-12.2 MPa)of the highly filled PCL composites(with filler contents of 50-63.8 wt%)reported so far.The proposed approach has sufficient expansibility for the fabrication of the highly filled polymer composites constructed by other types of matrix and fillers.
基金Project supported by the National Natural Science Foundation of China (Grant No. 12074322)Shenzhen Science and Technology Plan Project (Grant No. JCYJ20180504170208402)+1 种基金Science and Technology Project of Xiamen City (Grant No. 3502Z20183012)Science and Technology Planning Project of Guangdong Province,China (Grant No. 2018B030331001)
文摘This work presents a strategy for the mesoscopic engineering of hierarchically structured sodium alginate(SA)aerogels to enhance the macroscopic performance.The strategy was implemented by meso-functionalizing and reorganizing SA aerogels via controlled heterogeneous nucleation,in which microcrystalline cellulose-manganese dioxide(MCC-MnO_(2))nano-crystallites worked as template.Due to the short rod-like structure and abundant hydroxyl groups of MCC-MnO_(2),the organized mesostructure of SA aerogels was reconstructed during the assembly of SA molecule chains,which gave rise to a significant enhancement in macroscopic performance of SA areogels.For instance,the functionalized and reconstructed MCC-MnO_(2)/SA aerogels acquired a more than 70%increase in mechanical strength with an excellent deformation recovery.Furthermore,an almost double enhancement of removal capacity for metal ions(i.e.,Cu^(2+)and Pb^(2+))and organic dyes(i.e.,congo red and methylene blue)was obtained for MnO_(2)/SA aerogels,with an 87%repossession of the pollutants removal performance after 5 operation cycles.
文摘The present work mainly focuses on the estimation of various components and the extraction of microcrystalline cellulose(MCC)from non-wood sources like Country Almond/Badam shell through acid hydrolysis.This hydrolyzed MCC was successfully used as reinforcement for development of biocomposites.Country Almond/Badam trees are found all over Kerala,India and they give nuts once in a year.Usually the nut shells are discarded and are becoming one of the sources of agricultural waste.During this investigation various components were isolated from the Country Almond shells and they were characterised using different spectral and analytical techniques thereby the composition of Country Almond shells was successfully determined for the first time.The properties of MCC especially the crystalline nature depends on the source from which is isolated.FT-IR spectra give evidence for the chemical structure of MCC.Morphology of MCC was evidenced from scanning electron microscopy.Transmission electron microscopy and atomic force microscopy reveal the agglomerated bundles of particles and rough surface of MCC.The extracted MCC was found to contain Cellulose I and Cellulose II polymorphs,and this was confirmed from the X-ray diffraction(XRD)studies.The MCC extracted from Country Almond shells has reasonably good thermal stability.Solution casting method was adopted for the development of green composite of Poly(vinyl alcohol)reinforced with MCC extracted from Country Almond shell.The mechanical property of developed composites has been enhanced by the addition of MCC.The dispersion of MCC in the PVA matrix and flocculation of MCC significantly influence the mechanical strength.
基金supported by the Natural Science Foundation of China(No.32071704).
文摘As the most favorable alternative to petroleum-based polymers,polylactic acid(PLA)which is the most promising degradable polymer has attracted increasing attention.However,the addition of cellulose to improve its strength often results in a reduction in its toughness.In this work,microscale cellulose is first prepared from pulp fibers by using a deep eutectic solvent,and then is used as the reinforcement of PLA.A microcrystalline cellulose(MCC)/PLA sheet with uniform texture is obtained by the solution mixing,melt blending,hot-pressing and cold-pressing process.The effects of MCC on the crystallization,thermal stability and mechanical properties of the PLA matrix were studied.Upon the addition of 1%cellulose fiber,the tensile strength of MCC/PLA composite sheet increased by 27%,and the elongation at break did not shown an evident decrease.The strength enhancement mechanism was elucidated using scanning electron microscopy,differential scanning calorimetry,and dynamic thermomechanical analysis.The energy dissipation during the deformation process and the compatibility of AMCC and rougher surface of MCC play important role in the strength enhancement.Additionally,UV spectroscopy showed that the composite material absorbed some ultraviolet light.Our results show that the combined use of a deep eutectic solvent and solution mixing is an effective approach for improving the strength of PLA while maintaining its toughness.
