Study On The Preparation And Performance Of Stress Sensor Based On Natural Rubber And Cellulose Materials

Using biomass materials to prepare composite materials with special functions is of great scientific significance and social value for the development of environmental-friendly renewable resources.Natural rubber,a green environmental protection material,has the characteristics of high elasticity,and it is easy to bond with other materials.Cellulose is a kind of carbon-rich material with low cost,abundant sources and renewable.In this thesis,functional sensors are constructed.They are based on natural rubber used as matrix and cellulose for conductive element.The properties and performances of the materials are systematically analyzed and discussed by means of various characterization methods.The main research contents are as follows:Firstly,the natural rubber/waste carbonized cotton fabric composites were introduced,and the composite fabrics were prepared by three types of composite methods(vacuum bagging method,negative pressure adsorption method and drop coating method).The results of optical photographs and scanning electron microscopy(SEM)show that the fabric retains the original fabric structure after carbonization and combination with rubber,which lays the foundation for the stable conductivity of the composite material.Through the stress-strain test and analysis of the samples,it can be found that the strength of the carbonized fabric sample was greatly improved by the rubber compound,but also the sample exhibited a certain strain hysteresis effect.The samples were tested by repeated tension at fixed length,and the results suggest that the samples had stable sensing ability at different strains,and it could maintain a certain stability even after repeated cycling.In addition,the sensor was applied to the monitoring of finger bending and arm bending.Secondly,natural rubber/carbonized kapok fiber composites were developed based on the preparation of natural rubber/carbonized fabric.The kapok fiber aggregates were successfully prepared by vacuum filtration.After carbonization of kapok fiber,the natural rubber was successfully combined with the carbonized kapok fiber aggregates by negative pressure method.The results show that natural rubber only coats the surface of the carbonized fibers and does not make the aggregates into rubber blocks.In terms of material properties,a series of characterization and performance tests have been carried out to prove that the material has stable conductivity and compressive strain capacity.Repeated quantitative compression tests further show that the material has stable and reliable compression strain sensing ability.Thirdly,a natural rubber/polyaniline/kapok fiber composite system was developed based on the natural rubber/carbonized kapok fiber compression sensing materials.The polyaniline/kapok fiber aggregates were successfully prepared on kapok fibers by using hydrochloric acid,ammonium persulfate and aniline monomers.And then natural rubber was used as binder to compound into the fiber aggregates.The preparation method maintains the original mechanical properties of the kapok fiber,but at the same time makes the kapok fiber have the conductive capacity.Polyaniline has a limited amount of polymerization on fibers,which makes it possible for the prepared sample to be used as an electrical switch because the sample can only conduct electricity under compression.When the sample is given a certain pressure,repeated compression tests show that the sample can still show a relatively stable resistance change.And the resistance change rate measured by different weights can correspond to the stress curve of the material,which proves that the material also has stable compressive strain sensing performance.