All-cellulose composites(ACCs)are composites that use non-derivatized cellulose as both the matrix and the reinforcement phase.ACC consists entirely of cellulose,and since the reinforcement phase and the matrix have e...All-cellulose composites(ACCs)are composites that use non-derivatized cellulose as both the matrix and the reinforcement phase.ACC consists entirely of cellulose,and since the reinforcement phase and the matrix have exactly the same chemical properties,they can overcome the problem of poor fiber-matrix adhesion in biocomposites.In this study,ACC was prepared by partially dissolving wood pulp in a cryogenic aqueous phosphoric acid solution,and the effects of dissolution temperature,dissolution time and pressing load on the properties of ACC were investigated.The results showed that a dissolution time of 45 min achieved the optimal reinforcement-matrix ratio.The use of an aqueous ethanol solution at an ethanol mass fraction of 50%as a coagulation bath and a pressing load of 3000 kg during the drying process achieved the best mechanical properties of ACC,with a tensile strength of 49.3 MPa(approximately 210%higher than that of the untreated wood pulp)and an elastic modulus of 1.6 GPa(approximately 122%higher than that of the untreated wood pulp).The composite’s compactness affected ACC’s mechanical properties.The air permeability analysis showed that the barrier performance of ACC was also significantly better than that of the untreated wood pulp.With a pressing load of 3500 kg,the surface water contact angle(WCA)increased to 110.3°(approximately 94%higher than that of the untreated wood pulp),and the air permeability was significantly reduced to 1.1 mm/s,showing its good application prospects in the field of green packaging materials.展开更多
Cellulose nanofibrils(CNFs)were obtained through one-step mechano-partial dissolution by ball milling in N,N-dimethyl acetamide with a low concentration of LiCl from agricultural waste bagasse pith(BP).Compared with f...Cellulose nanofibrils(CNFs)were obtained through one-step mechano-partial dissolution by ball milling in N,N-dimethyl acetamide with a low concentration of LiCl from agricultural waste bagasse pith(BP).Compared with fibrous cellulose,parenchyma cellulose(PC)is less uniform in diameter and less aligned,causing PC to dissociate into CNFs during this process without pretreatment.The results showed that the CNFs prepared from PC of BP had a diameter of 30-200 nm and a length of several micrometers.The as-obtained CNFs,along with dissolved cellulose,formed a wet-stable and highly transparent nanopaper in a sorbitol aqueous solution bath,which exhibited a high strain of 101%and a low Young's modulus of 4.3 MPa owing to the addition of the plasticizer sorbitol.This type of nanopaper with favorable transparency,high tensile property,and low Young's modulus has great potential for use as electronic skin and medical dressing material.展开更多
基金Fundamental Research Funds for the Central Universities,China(No.2232023G-04)。
文摘All-cellulose composites(ACCs)are composites that use non-derivatized cellulose as both the matrix and the reinforcement phase.ACC consists entirely of cellulose,and since the reinforcement phase and the matrix have exactly the same chemical properties,they can overcome the problem of poor fiber-matrix adhesion in biocomposites.In this study,ACC was prepared by partially dissolving wood pulp in a cryogenic aqueous phosphoric acid solution,and the effects of dissolution temperature,dissolution time and pressing load on the properties of ACC were investigated.The results showed that a dissolution time of 45 min achieved the optimal reinforcement-matrix ratio.The use of an aqueous ethanol solution at an ethanol mass fraction of 50%as a coagulation bath and a pressing load of 3000 kg during the drying process achieved the best mechanical properties of ACC,with a tensile strength of 49.3 MPa(approximately 210%higher than that of the untreated wood pulp)and an elastic modulus of 1.6 GPa(approximately 122%higher than that of the untreated wood pulp).The composite’s compactness affected ACC’s mechanical properties.The air permeability analysis showed that the barrier performance of ACC was also significantly better than that of the untreated wood pulp.With a pressing load of 3500 kg,the surface water contact angle(WCA)increased to 110.3°(approximately 94%higher than that of the untreated wood pulp),and the air permeability was significantly reduced to 1.1 mm/s,showing its good application prospects in the field of green packaging materials.
基金The authors are grateful for the financial support from the National Natural Science Foundation of China(Grant No.51963012)Special Foundation for Excellent Youth Scholars of Yunnan Province,China(Nos.YNWR-QNBJ-2020-039 and YNWR-QNBJ-2020-045).
文摘Cellulose nanofibrils(CNFs)were obtained through one-step mechano-partial dissolution by ball milling in N,N-dimethyl acetamide with a low concentration of LiCl from agricultural waste bagasse pith(BP).Compared with fibrous cellulose,parenchyma cellulose(PC)is less uniform in diameter and less aligned,causing PC to dissociate into CNFs during this process without pretreatment.The results showed that the CNFs prepared from PC of BP had a diameter of 30-200 nm and a length of several micrometers.The as-obtained CNFs,along with dissolved cellulose,formed a wet-stable and highly transparent nanopaper in a sorbitol aqueous solution bath,which exhibited a high strain of 101%and a low Young's modulus of 4.3 MPa owing to the addition of the plasticizer sorbitol.This type of nanopaper with favorable transparency,high tensile property,and low Young's modulus has great potential for use as electronic skin and medical dressing material.
