To overcome the shortcomings of traditional degumming process,an efficient and environmentally friendly ethylene glycol(EG) degumming process was adopted to degum hemp fibers.The surface morphology,chemical compositio...To overcome the shortcomings of traditional degumming process,an efficient and environmentally friendly ethylene glycol(EG) degumming process was adopted to degum hemp fibers.The surface morphology,chemical composition,chemical structures,and mechanical properties of the fiber samples were analyzed to explore the mechanism of the degumming process.It was found that the EG degumming process could be divided into the main degumming stage(heating) and the supplementary degumming stage(insulation).The removal rates of hemicellulose and lignin in the main degumming stage were 70.56% and 60.17%,respectively.In the supplementary degumming stage,9.95% hemicellulose and 25.39% lignin were removed.It is confirmed that EG can separate hemp fibers effectively with less damage,which holds great potential for the biomass fiber separation technology.展开更多
This present study deals with the reinforcement of thermosetting resin blends composed of cyanate ester(CE) and benzoxazine(BOZ) resins with natural hemp fibers(NHFs). These NHFs were initially treated by using a sila...This present study deals with the reinforcement of thermosetting resin blends composed of cyanate ester(CE) and benzoxazine(BOZ) resins with natural hemp fibers(NHFs). These NHFs were initially treated by using a silane coupling agent(SCA) in order to chiefly enhance their distributions as well as adhesions within the CE/BOZ resin matrix,then incorporated with various weight amounts ranging from 5 wt% to 20 wt% with a regular interval of 5 wt%. The obtained results showed that at the maximum treated fiber loading(20 wt%), distinctive enhancements in the mechanical properties in terms of flexural strength and microhardness were obtained. Besides, the thermal stability and glass transition temperature(Tg) were appreciably enhanced and were higher than those of the pure CE/BOZ resin properties. With respect to the astonishing properties of the NHFs, these enhancements could be possibly due to the good dispersion and adhesion of the treated NHFs inside the CE/BOZ resin achieved upon using the SCA. Therefore,we believe herein that these renewable and cheap NHFs have considerable potential to be used as reinfocer materials for CE/BOZ resin composites to be used in various industrial sectors.展开更多
Hemp fibers were treated with different pretreatments before being put into ionic liquid dissolved systems. NaOH,HCI,N,N-dimethylacetamide（ DMAc） solution and ultrasonic were utilized to activate fibers. Scanning el...Hemp fibers were treated with different pretreatments before being put into ionic liquid dissolved systems. NaOH,HCI,N,N-dimethylacetamide（ DMAc） solution and ultrasonic were utilized to activate fibers. Scanning electron microscopy（ SEM）,Fourier transform infrared spectroscopy（ FTIR） and X-ray diffraction（ XRD） were used to analyze the morphological and molecular structures of the fiber before and after activation for the comparative analysis. The pretreated fibers were dissolved and the dissolving process of fibers were observed until they were dissolved completely. Experimental studies found that NaOH solution made fibers crystal form change from cellulose Ⅰ to cellulose Ⅱ,and others didn＇t have this kind of change. By comparison,fibers treated by DMAc solution worked best, various methods which affected solubility could be sorted roughly as follows： DMAc ＆gt; ultrasonic ＆gt;HCI ＆gt; NaOH ＆gt; untreated.展开更多
Flax and hemp fibers were used as reinforcing materials to commingle with polypropylene(PP)fiber to realize the mixture of two materials at the stage of yarn.Meanwhile,PP filaments were introduced to produce a core-sp...Flax and hemp fibers were used as reinforcing materials to commingle with polypropylene(PP)fiber to realize the mixture of two materials at the stage of yarn.Meanwhile,PP filaments were introduced to produce a core-spun yarn with flax/PP as core and PP filament as outer sheath.The commingled yarns were woven into 2D fabric which was used as the prefabricated material.The composite laminates were prepared by hot press technology.The effects of manufacture technology,yarn structure,and fiber weight fraction on flexural properties of composites were investigated.展开更多
Natural plant fibers, including flax, kenaf, jute, bamboo, ramie and much more are renewable and sustainable resources and are considered good candidates for cost-effective alternatives to glass and carbon fibers. In ...Natural plant fibers, including flax, kenaf, jute, bamboo, ramie and much more are renewable and sustainable resources and are considered good candidates for cost-effective alternatives to glass and carbon fibers. In this research, cross ply biodegradable composites were fabricated by press-forming method. The biodegradable composites consist of Manila hemp textile as a reinforcement and starch-based biodegradable plastics as a matrix was fabricated and investigated about mechanical properties. The tensile strength increased with the fiber content until fiber content of about 50% and leveled off thereafter. This dependence on the fiber content is due to the decrease in fiber strength of loading direction caused by fiber damages introduced during hot-pressing. In order to decrease the damage of fibers aligned in loading direction, Manila hemp textile was produced by using Manila hemp fibers for warp and biodegradable resin thread for weft. As a result, the tensile strength of cross ply composites increased from 153 MPa to 202 MPa.展开更多
基金Fundamental Research Funds for the Central Universities of Ministry of Education of China(No.2232020A-07)。
文摘To overcome the shortcomings of traditional degumming process,an efficient and environmentally friendly ethylene glycol(EG) degumming process was adopted to degum hemp fibers.The surface morphology,chemical composition,chemical structures,and mechanical properties of the fiber samples were analyzed to explore the mechanism of the degumming process.It was found that the EG degumming process could be divided into the main degumming stage(heating) and the supplementary degumming stage(insulation).The removal rates of hemicellulose and lignin in the main degumming stage were 70.56% and 60.17%,respectively.In the supplementary degumming stage,9.95% hemicellulose and 25.39% lignin were removed.It is confirmed that EG can separate hemp fibers effectively with less damage,which holds great potential for the biomass fiber separation technology.
基金Supported by the National Natural Science Foundation of China(51773048)the Natural Science Foundation of Heilongjiang Province(E2016025)Fundamental Research Funds for the Central Universities(HEUCFP201724,HEUCFP201791)
文摘This present study deals with the reinforcement of thermosetting resin blends composed of cyanate ester(CE) and benzoxazine(BOZ) resins with natural hemp fibers(NHFs). These NHFs were initially treated by using a silane coupling agent(SCA) in order to chiefly enhance their distributions as well as adhesions within the CE/BOZ resin matrix,then incorporated with various weight amounts ranging from 5 wt% to 20 wt% with a regular interval of 5 wt%. The obtained results showed that at the maximum treated fiber loading(20 wt%), distinctive enhancements in the mechanical properties in terms of flexural strength and microhardness were obtained. Besides, the thermal stability and glass transition temperature(Tg) were appreciably enhanced and were higher than those of the pure CE/BOZ resin properties. With respect to the astonishing properties of the NHFs, these enhancements could be possibly due to the good dispersion and adhesion of the treated NHFs inside the CE/BOZ resin achieved upon using the SCA. Therefore,we believe herein that these renewable and cheap NHFs have considerable potential to be used as reinfocer materials for CE/BOZ resin composites to be used in various industrial sectors.
文摘Hemp fibers were treated with different pretreatments before being put into ionic liquid dissolved systems. NaOH,HCI,N,N-dimethylacetamide（ DMAc） solution and ultrasonic were utilized to activate fibers. Scanning electron microscopy（ SEM）,Fourier transform infrared spectroscopy（ FTIR） and X-ray diffraction（ XRD） were used to analyze the morphological and molecular structures of the fiber before and after activation for the comparative analysis. The pretreated fibers were dissolved and the dissolving process of fibers were observed until they were dissolved completely. Experimental studies found that NaOH solution made fibers crystal form change from cellulose Ⅰ to cellulose Ⅱ,and others didn＇t have this kind of change. By comparison,fibers treated by DMAc solution worked best, various methods which affected solubility could be sorted roughly as follows： DMAc ＆gt; ultrasonic ＆gt;HCI ＆gt; NaOH ＆gt; untreated.
文摘Flax and hemp fibers were used as reinforcing materials to commingle with polypropylene(PP)fiber to realize the mixture of two materials at the stage of yarn.Meanwhile,PP filaments were introduced to produce a core-spun yarn with flax/PP as core and PP filament as outer sheath.The commingled yarns were woven into 2D fabric which was used as the prefabricated material.The composite laminates were prepared by hot press technology.The effects of manufacture technology,yarn structure,and fiber weight fraction on flexural properties of composites were investigated.
文摘Natural plant fibers, including flax, kenaf, jute, bamboo, ramie and much more are renewable and sustainable resources and are considered good candidates for cost-effective alternatives to glass and carbon fibers. In this research, cross ply biodegradable composites were fabricated by press-forming method. The biodegradable composites consist of Manila hemp textile as a reinforcement and starch-based biodegradable plastics as a matrix was fabricated and investigated about mechanical properties. The tensile strength increased with the fiber content until fiber content of about 50% and leveled off thereafter. This dependence on the fiber content is due to the decrease in fiber strength of loading direction caused by fiber damages introduced during hot-pressing. In order to decrease the damage of fibers aligned in loading direction, Manila hemp textile was produced by using Manila hemp fibers for warp and biodegradable resin thread for weft. As a result, the tensile strength of cross ply composites increased from 153 MPa to 202 MPa.
