| Conductive rubber sponge,owing to its low density,compressible and reboundable properties,has been widely used in people’s production and life.With the rapid development of human society,people have a growing demand for conductive rubber sponge.Due to a single conductive performance has not been able to meet the market demand for new generation of conductive rubber sponges.So,it needs to have good electrical conductivity and mechanical properties of conductive rubber sponge,but also to require divere properties of conductive rubber sponge for the different areas of demand.However,being limited by the latex foam molding technology,it is difficult to develop a multifunctional conductive rubber sponge to meet the market demand.Therefore,it is crucial to develop a rubber latex sponge molding technology that supports various types of filler filling and has characteristics such as simple operation,green sustainability,and low process cost.Owing to their green,degradable,renewable,good specific strength,low density,and abundant resources,biomass fibers have been widely used as fillers or reinforcing agents for polymer sponges.Therefore,by taking advantage of the green regenerability,excellent suspension ability,and its surface chemical properties of cellulose and inspired by the design and process technologies of porous and polymeric sponge materials,this thesis utilizes the ice-template method and hydrothermal vulcanization technology to prepare multifunctional biomass/rubber sponge composites,providing new technical guidelines for the development of the new generation of biomass/rubber sponges.The main research contents and results of this thesis are as follows.（1）Based on the hydrophilic property of cellulose microfiber（CMF）,CMF/NR sponge was obtained by freezing through ice-template method with the help of latex vulcanization additives and prepared by combined with hydrothermal vulcanization technique,which was inspired by the principle and molding technique of porous-structured aerogel and polymer sponge prepared by ice-template method.The introduction of CMF in latex rubber sponge could not only increase the lightness(0.1 g·cm-3),hydrophilicity,processability and softness of NR sponge,but also increase the hydrogenic shape memory and absorption properties of NR sponge.Compared with latex foaming technologies such as Dunlop method and Talalay method,ice-template method has the characteristics of simple operation,low equipment requirements,green sustainability and low cost,and the prepared sponges shows the good application potential in oil adsorption.（2）Based on the excellent pore structure of CMF/NR composite sponge,for the problems of the poor dispersion of conductive fillers,the low electrical conductivity and difficult molding in rubber sponge materials,significantly restricting their large-scale application.Inspired by the instantaneous ink absorption of paper and no ink loss in water,we choose graphite as conductive fillers,CMF as dispersion aid and NR as bonding binder,and the conductive rubber sponges were fabricated by ice-template method combined with hydrothermal vulcanization technology.The results showed that the introduction of CMF could not only improve the deposition of GP in NRL and the agglomeration and uneven dispersion in the latex sponge,but also improve the mechanical strength of the composite sponge.The frabricated GP/CMF/NR conductive sponge has excellent mechanical strength and electrical conductivity.When the addition amount of GP was 100 phr（100 phr of NR in the sponge and10 phr of CMF）,the compressive strength of latex composite sponge was increased by 1860%than that of CMF/NR sponge,and the electrical conductivity was 18.5 S/m at 50%strain,which was 133,000%higher than that of latex composite sponge with 20 phr GP.In addition,the prepared GP/CMF/NR conductive sponge has excellent sensing properties,showing the good potential in wearable electronic devices and piezoresistive sensors,etc.（3）Based on the excellent conductivity of GP/CMF/NR conductive sponge,in order to improve the single performance of conductive latex sponges,the broom-shaped MFC was prepared by high-speed shearing of CMF,and GP/MFC/NR conductive sponges were prepared by solution blending,ice-template method and hydrothermal vulcanization techniques.The technical design of GP/MFC/NR conductive sponges was based on the excellent conductivity of conductive rubber sponges and inspired by the excellent moisture absorption-desorption properties of fiber paper.The spatial distribution of GP on the"broom tail"of MFC and its suspension in solution could be directly observed by optical microscope,SEM and digital camera.The results showed that the microstructure of GP/MFC/NR conductive sponge prepared by high-speed shearing was more homogeneous,stronger mechanical strength and better electrical conductivity.After high-speed shearing of CMF for 60 min,the prepared GP/MFC/NR conductive sponges exhibited excellent pressure,temperature and humidity sensitivity as well as sensing properties,which have good prospects in the application and development of multifunctional flexible sponge sensors.（4）In order to meet the multi-functional demand of the flexible electronic materials in people’s daily wearable electronic products,based on the excellent piezoresistive sensing properties of GP/MFC/NR conductive sponges,the antibacterial rubber latex sponge（Zn O/MFC/NR sponge）was prepared by ice-template method and hydrothermal vulcanization technology,which was reinforced by the introduction of antibacterial Zn O nanoparticles.The antibacterial conductive rubber latex sponge with upper-lower layered structure was constructed by the step-freezing method.The results showed that Zn O/MFC/NR antibacterial layer and GP/MFC/NR conductive layer are compatible and stable with each other,and the introduce of Zn O could effectively improve the mechanical strength and antibacterial properties of the latex sponge.In addition,the latex sponge prepared by the distributed freezing method not only has the good mechanical strength and antibacterial ability of Zn O/MFC/NR sponge,but also has the excellent electrical conductivity and sensing properties of GP/MFC/NR sponge.In a word,this preparation and construction method of the multifunctional latex sponge shows the good development potential in the field of flexible electronic materials.（5）Based on the porous structures of CMF/NR,GP/CMF/NR,GP/MFC/NR and Zn O/MFC/NR composite sponge constructed by ice template-vulcanization method,in order to solve the problems that high-content fillers are difficult to disperse and to form in rubber composites as well as low mechanical strength,ice-template method was used to frozen MFC/NR mixture,which was based on the characteristics of rubber that can be gelled at low temperature but not cross-linked.The inorganic particles are used as functional fillers and MFC as functional particles.The frozen MFC/NR mixture was directly thawed in room temperature,and then pressed into the lamination by cold plate and dried at air drying to obtain the pre-formed latex composite film.Finally,the latex composite film was obtained by hot press vulcanization of flat plate.In addition,to meet the functional requirements of rubber materials,the lamellar GP micron particles,granular Zn O nanoparticles and Fe3O4 nanoparticles were introduced into the NRL solution with the assistance of MFC,and the conductive latex composites,magnetic latex composites,antibacterial latex composites,and antibacterial conductive films were prepared by the ice template-vulcanization method.The results showed that the prepared latex composites have homogeneous structure,uniform filler dispersion,good strength and universal applicability,which have good prospects in the application and development of multifunctional natural rubber latex composite materials. |
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