Study On Synthesis,characterization And Mechanical Performances Of Geopolymer-based Fiber Composites

Plant fiber board has wide application.But because most of substrate material is organic,its fire resistance is poorer,and harmful substances will be released into environment,which limit its application.Cement-based plant fiber composite board can overcome these defects,and it has been applied.But because of using wood pulp cellulose,its production process is relatively complex.Geopolymer is a kind of inorganic cementing material with low CO2 emission,low energy consumption,and environment friendly.It can overcome the problem in the preparation of cement-based plant fiber board.Therefore,the research on preparation of geopolymer-based plant fiber board and performance is important.Cellulose content,fiber structure,and the geopolymer-based structure have a big effect on the mechanical properties of composite materials.Therefore,the research on the structure characterization using analysis techniques,and the relationship between structure and properties is meaningful.The cellulose content in plants can be measured by two methods: nitric acid ethanol and infrared spectroscopy.By comparing the two analysis results,it can be concluded that the determination of cellulose content by infrared spectroscopy is feasible.It is not only accurate,but also easy to operate and environment friendly.Therefore,it has practical application value to determine the content of cellulose and hemicelluloses and choose plant fiber by them.In this paper,rice husk or straw fiber and metakaolin were used as raw materials to prepare the plant fiber-kaolin based geopolymer composites at room temperature by alkali excitation.The effects of the modulus of water glass,the ratio of water to cement,the alkali treatment and the size of plant fiber on the properties of geopolymer fiber composites were systematically studied.The research results on material property show that: the modulus of water glass is 1.5,water cement ratio is 0.55,the rice husk fiber content is 18%,and the rice husk size is 40-60 mesh,the preparation of the performance of geopolymer based rice husk fiber composites is better.By comparing the static bending strength of the materials before and after alkali treatment,we can draw a conclusion that the property of geopolymer made using the rice husk soaked 24 hours with 1% sodium hydroxide as one of raw material is best.The preparation processes of geopolymer materials were researched and the optimal processconditions were established by means of single-factor experiments.They were that the ratio of water to binder was 0.5,the modulus of water glass is 1.5,and the straw fiber content is 10%.If the geopolymer materials were made using the rice straw treated with alkali solution,the mass fraction of sodium hydroxide is 4%,soaking time is 24 hours,the property of composite material is best.Three kinds of analysis methods,FTIR,X-ray diffraction(XRD),and scanning electron microscopy(SEM),were used to study the structure of geopolymer-based straw fiber composites material.The analysis results of FTIR showed that: the modulus of water glass was 1.5,the ratio of water to binder was 0.5,and the content of rice straw was about 10%,both the effect of polymerization and the mechanical properties of the material are the best.The analytical results of XRD and SEM are consistent with the analysis results of FTIR.In addition,the structure of geopolymer materials made using the rice straw treated with alkali solution was analyzed by FTIR,we can draw the conclusion that the dissolution of hemicelluloses in rice straw soaked in4% NaOH for 24 h is more complete,the damage degree of cellulose is the least,and the properties of the geopolymer materials obtained is also optimum.