Water-resistant films were prepared by coating the surface of regenerated cellulose films with castor oil-based polyurethane (PU)/ poly-(methacrylate-co-styrene) [P (MA-St)]. The effects of the ratio of PU to P (MA-St...Water-resistant films were prepared by coating the surface of regenerated cellulose films with castor oil-based polyurethane (PU)/ poly-(methacrylate-co-styrene) [P (MA-St)]. The effects of the ratio of PU to P (MA-St) copolymer on tensile strength (dry and wet states), vapor permeability, size stability, and water resistivity of the coated films were studied. The interfacial interaction between cellulose and the PU/P (MA-St) coating was analyzed using infrared (IR), ultraviolet (UV), scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential thermal analysis (DTA), and electron probe microanalysis (EPMA). The results indicated that the mechanical properties and water resistivity of the coated films significantly enhanced, and the biodegradability was displayed, when the ratio of PU to P (MA-St) was 8∶2 by weight. The chemical bonds and hydrogen bonds between the cellulose, PU, and the copolymer exist in the coated films. It is regarded that PU/P (MA-St) semi-interpenetrating polymer networks (IPNs) were formed, and a shared network of PU with both the cellulose and the coating in the coated film occurred simultaneously resulting in a strong bonding between the coating layer and the film.展开更多
A series of cellulose acetate membranes were prepared by using formamide as additive, and then were hydrolyzed in 4 wt% aqueous NaOH solution for 8 h to obtain regenerated cellulose membranes. The dependence of degree...A series of cellulose acetate membranes were prepared by using formamide as additive, and then were hydrolyzed in 4 wt% aqueous NaOH solution for 8 h to obtain regenerated cellulose membranes. The dependence of degree of substitution, structure, porous properties, solubility and thermal stability on hydrolysis time was studied by chemical titration, Fourier transform infrared spectroscopy, scanning electron microscopy, wide-angle X-ray diffraction, and differential scanning calorimetry, respectively. The results indicated that the pore size of the regenerated cellulose membranes was slightly smaller than that of cellulose acetate membrane, while solvent-resistance, crystallinity and thermostability were significantly improved. This work provides a simple way to prepare the porous cellulose membranes, which not only kept the good pore characteristics of cellulose acetate membranes, but also possessed solvent-resistance, high crystallinity and thermostability. Therefore, the application range of cellulose acetate membranes can be expanded.展开更多
Regenerated cellulose films with water-resistance were obtained by an improved method ofpreparing cellulose cuoxam solution from pulps of agricultural wastes (linters, wheat straw, reedand Bamao). Experimental results...Regenerated cellulose films with water-resistance were obtained by an improved method ofpreparing cellulose cuoxam solution from pulps of agricultural wastes (linters, wheat straw, reedand Bamao). Experimental results showed that the mechanical properties of both the dry. and wetfilms were excellent. Data from IR, SEM and tensile strength measurements implied that thesignificant improvement of water-resistance of the films was due to the cohesion between the thinTung oil covers with hydrophobicity and the regenerated cellulose films. The films werecompletely biodegraded after being buried in soil for 100 days. The transmittance of the filmsderived from linter and reed in visible band range were 80-90%.展开更多
The biodegradability of Aspergillus niger (A. niger), Mucor (M-305) and Trichoderma (T-311) strains on regenerated cellulose films in media was investigated. The results showed that T-311 strain isolated from soil adh...The biodegradability of Aspergillus niger (A. niger), Mucor (M-305) and Trichoderma (T-311) strains on regenerated cellulose films in media was investigated. The results showed that T-311 strain isolated from soil adhered on the cellulose film fragments has stronger degradation effect on the cellulose film than A. niger strain. The weights, molecular weights and tensile strengths of the cellulose films in both shake culture and solid media decreased with incubation time, accompanied by producing CO2 and saccharides. HPLC, IR and released CO2 analysis indicated that the biodegradation products of the regenerated cellulose films mainly contain oligosaccharides, cellobiose, glucose, arabinose, erythrose, glycerose, glycerol, ethanal, formaldehyde and organic acid, the end products were CO2 and water. After a month, the films were completely decomposed by fungi in the media at 30 degrees C.展开更多
Derivatization has great potential for the high-value utilization of cellulose by enhancing its processability and functionality.However,due to the low reactivity of natural cellulose,it remains challenging to rapidly...Derivatization has great potential for the high-value utilization of cellulose by enhancing its processability and functionality.However,due to the low reactivity of natural cellulose,it remains challenging to rapidly prepare cellulose derivatives with high degrees of substitution.The“cavitation effect”of ultrasound can reduce the particle size and crystalline index of cellulose,which provides a possible method for preparing cellulose derivatives.Herein,a feasible method was proposed for efficiently converting regenerated cellulose to cellulose oleate with the assistance of ultrasonic treatment.By adjusting the reaction conditions including ultrasonic intensity,feeding ratios of oleic acid,reaction time,and reaction solvent,a series of cellulose oleates with degrees of substitution ranging from 0.37 to 1.71 were synthesized.Additionally,the effects of different reaction conditions on the chemical structures,crystalline structures,and thermal behaviors were investigated thoroughly.Cellulose oleates with degrees of substitution exceeding 1.23 exhibited amorphous structures and thermoplasticity with glass transition temperatures at 159.8 to 172.6℃.This study presented a sustainable and practicable method for effectively derivatizing cellulose.展开更多
Polymer-based thermally conductive composites have attracted tremendous interest in thermal management of electronics.However,it remains challenging to achieve high thermal conductivity partly because the difficulty t...Polymer-based thermally conductive composites have attracted tremendous interest in thermal management of electronics.However,it remains challenging to achieve high thermal conductivity partly because the difficulty to obtain favorable distribution and orientation of conductive fillers within the polymer matrix.Herein,networked boron nitride(BN)conductive pathway was realized within the poly(lactic acid)(PLA)matrix,via regenerated cellulose(RC)-assisted assembly of BN on Pickering emulsion interface based on the noncovalent interaction,followed by solvent evaporation and hot-compressing.The strong noncovalent interactions between BN and RC were found critical to enhance the wettability and stability of BN in aqueous media with a lowest mass ratio of 1:40 of RC and BN.The obtained PLA/BN composites feature a thermal conductivity of 1.06 W/(m K)at 28.4 wt%BN loading,representing an enhancement of 430%comparing to neat PLA,and the crystallinity of the composites could increase significantly from11.7%(neat PLA)to 43.7%.This simple,environmentally friendly and effective strategy could be easily extended for effective construction of thermally conductive composites.展开更多
As the global population grows,the demand for textiles is increasing rapidly.However,this puts immense pressure on manufacturers to produce more fiber.While synthetic fibers can be pro-duced cheaply,they have a negati...As the global population grows,the demand for textiles is increasing rapidly.However,this puts immense pressure on manufacturers to produce more fiber.While synthetic fibers can be pro-duced cheaply,they have a negative impact on the environment.On the other hand,fibers from wool,sisal,fique,wood pulp(viscose),and man-made cellulose fibers(MMCFs)from cotton can-not alone meet the growing fiber demand without major stresses on land,water,and existing markets using these materials.With a greater emphasis on transparency and circular economy practices,there is a need to consider natural non-wood alternative sources for MMCFs to supple-ment other fiber types.However,introducing new feedstocks with different compositions may require different biomass conversion methods.Therefore,based on existing work,this review ad-dresses the technical feasibility of various alternative feedstocks for conversion to textile-grade fibers.First,alternative feedstocks are introduced,and then conventional(dissolving pulp)and emerging(fibrillated cellulose and recycled material)conversion technologies are evaluated to help select the most suitable and promising processes for these emerging alternative sources of cellulose.It is important to note that for alternative feedstocks to be adopted on a meaningful scale,high biomass availability and proximity of conversion facilities are critical factors.In North America,soybean,wheat,rice,sorghum,and sugarcane residues are widely available and most suitable for conventional conversion through various dissolving pulp production methods(pre-hydrolysis kraft,acid sulfite,soda,SO2-ethanol-water,and potassium hydroxide)or by emerging cellulose fibrillation methods.While dissolving pulp conversion is well-established,fibrillated cel-lulose methods could be beneficial from cost,efficiency,and environmental perspectives.Thus,the authors strongly encourage more work in this growing research area.However,conducting thorough cost and sustainability assessments is important to determine the best feedstock and technology combinations.展开更多
文摘Water-resistant films were prepared by coating the surface of regenerated cellulose films with castor oil-based polyurethane (PU)/ poly-(methacrylate-co-styrene) [P (MA-St)]. The effects of the ratio of PU to P (MA-St) copolymer on tensile strength (dry and wet states), vapor permeability, size stability, and water resistivity of the coated films were studied. The interfacial interaction between cellulose and the PU/P (MA-St) coating was analyzed using infrared (IR), ultraviolet (UV), scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential thermal analysis (DTA), and electron probe microanalysis (EPMA). The results indicated that the mechanical properties and water resistivity of the coated films significantly enhanced, and the biodegradability was displayed, when the ratio of PU to P (MA-St) was 8∶2 by weight. The chemical bonds and hydrogen bonds between the cellulose, PU, and the copolymer exist in the coated films. It is regarded that PU/P (MA-St) semi-interpenetrating polymer networks (IPNs) were formed, and a shared network of PU with both the cellulose and the coating in the coated film occurred simultaneously resulting in a strong bonding between the coating layer and the film.
基金This work was supported by the National Natural Science Foundation of China (No. 59933070) and Laboratory of Cellulose and Lignocellulosic Chemistry, Guangzhou Institute of Chemistry, Chinese Academy of Sciences.
文摘A series of cellulose acetate membranes were prepared by using formamide as additive, and then were hydrolyzed in 4 wt% aqueous NaOH solution for 8 h to obtain regenerated cellulose membranes. The dependence of degree of substitution, structure, porous properties, solubility and thermal stability on hydrolysis time was studied by chemical titration, Fourier transform infrared spectroscopy, scanning electron microscopy, wide-angle X-ray diffraction, and differential scanning calorimetry, respectively. The results indicated that the pore size of the regenerated cellulose membranes was slightly smaller than that of cellulose acetate membrane, while solvent-resistance, crystallinity and thermostability were significantly improved. This work provides a simple way to prepare the porous cellulose membranes, which not only kept the good pore characteristics of cellulose acetate membranes, but also possessed solvent-resistance, high crystallinity and thermostability. Therefore, the application range of cellulose acetate membranes can be expanded.
文摘Regenerated cellulose films with water-resistance were obtained by an improved method ofpreparing cellulose cuoxam solution from pulps of agricultural wastes (linters, wheat straw, reedand Bamao). Experimental results showed that the mechanical properties of both the dry. and wetfilms were excellent. Data from IR, SEM and tensile strength measurements implied that thesignificant improvement of water-resistance of the films was due to the cohesion between the thinTung oil covers with hydrophobicity and the regenerated cellulose films. The films werecompletely biodegraded after being buried in soil for 100 days. The transmittance of the filmsderived from linter and reed in visible band range were 80-90%.
基金The work ws supported by the State Economy and Trade Commission of China.
文摘The biodegradability of Aspergillus niger (A. niger), Mucor (M-305) and Trichoderma (T-311) strains on regenerated cellulose films in media was investigated. The results showed that T-311 strain isolated from soil adhered on the cellulose film fragments has stronger degradation effect on the cellulose film than A. niger strain. The weights, molecular weights and tensile strengths of the cellulose films in both shake culture and solid media decreased with incubation time, accompanied by producing CO2 and saccharides. HPLC, IR and released CO2 analysis indicated that the biodegradation products of the regenerated cellulose films mainly contain oligosaccharides, cellobiose, glucose, arabinose, erythrose, glycerose, glycerol, ethanal, formaldehyde and organic acid, the end products were CO2 and water. After a month, the films were completely decomposed by fungi in the media at 30 degrees C.
基金The authors are grateful for financial support from the National Natural Science Foundation of China(Grant Nos.52273040 and 51873128)Yunnan Fundamental Research Projects(Grant No.202301AT070232).
文摘Derivatization has great potential for the high-value utilization of cellulose by enhancing its processability and functionality.However,due to the low reactivity of natural cellulose,it remains challenging to rapidly prepare cellulose derivatives with high degrees of substitution.The“cavitation effect”of ultrasound can reduce the particle size and crystalline index of cellulose,which provides a possible method for preparing cellulose derivatives.Herein,a feasible method was proposed for efficiently converting regenerated cellulose to cellulose oleate with the assistance of ultrasonic treatment.By adjusting the reaction conditions including ultrasonic intensity,feeding ratios of oleic acid,reaction time,and reaction solvent,a series of cellulose oleates with degrees of substitution ranging from 0.37 to 1.71 were synthesized.Additionally,the effects of different reaction conditions on the chemical structures,crystalline structures,and thermal behaviors were investigated thoroughly.Cellulose oleates with degrees of substitution exceeding 1.23 exhibited amorphous structures and thermoplasticity with glass transition temperatures at 159.8 to 172.6℃.This study presented a sustainable and practicable method for effectively derivatizing cellulose.
基金supported by the One Belt and One Road Innovative Talent Exchange Program for Foreign Experts[Grant No.DL20200009005]the Fundamental Research Funds for the Central Universities[Grant No.2232021G-02]Fundamental Research Funds for the Central Universities[Grant No.2232020G-04]。
文摘Polymer-based thermally conductive composites have attracted tremendous interest in thermal management of electronics.However,it remains challenging to achieve high thermal conductivity partly because the difficulty to obtain favorable distribution and orientation of conductive fillers within the polymer matrix.Herein,networked boron nitride(BN)conductive pathway was realized within the poly(lactic acid)(PLA)matrix,via regenerated cellulose(RC)-assisted assembly of BN on Pickering emulsion interface based on the noncovalent interaction,followed by solvent evaporation and hot-compressing.The strong noncovalent interactions between BN and RC were found critical to enhance the wettability and stability of BN in aqueous media with a lowest mass ratio of 1:40 of RC and BN.The obtained PLA/BN composites feature a thermal conductivity of 1.06 W/(m K)at 28.4 wt%BN loading,representing an enhancement of 430%comparing to neat PLA,and the crystallinity of the composites could increase significantly from11.7%(neat PLA)to 43.7%.This simple,environmentally friendly and effective strategy could be easily extended for effective construction of thermally conductive composites.
文摘As the global population grows,the demand for textiles is increasing rapidly.However,this puts immense pressure on manufacturers to produce more fiber.While synthetic fibers can be pro-duced cheaply,they have a negative impact on the environment.On the other hand,fibers from wool,sisal,fique,wood pulp(viscose),and man-made cellulose fibers(MMCFs)from cotton can-not alone meet the growing fiber demand without major stresses on land,water,and existing markets using these materials.With a greater emphasis on transparency and circular economy practices,there is a need to consider natural non-wood alternative sources for MMCFs to supple-ment other fiber types.However,introducing new feedstocks with different compositions may require different biomass conversion methods.Therefore,based on existing work,this review ad-dresses the technical feasibility of various alternative feedstocks for conversion to textile-grade fibers.First,alternative feedstocks are introduced,and then conventional(dissolving pulp)and emerging(fibrillated cellulose and recycled material)conversion technologies are evaluated to help select the most suitable and promising processes for these emerging alternative sources of cellulose.It is important to note that for alternative feedstocks to be adopted on a meaningful scale,high biomass availability and proximity of conversion facilities are critical factors.In North America,soybean,wheat,rice,sorghum,and sugarcane residues are widely available and most suitable for conventional conversion through various dissolving pulp production methods(pre-hydrolysis kraft,acid sulfite,soda,SO2-ethanol-water,and potassium hydroxide)or by emerging cellulose fibrillation methods.While dissolving pulp conversion is well-established,fibrillated cel-lulose methods could be beneficial from cost,efficiency,and environmental perspectives.Thus,the authors strongly encourage more work in this growing research area.However,conducting thorough cost and sustainability assessments is important to determine the best feedstock and technology combinations.
