Taraxacum Kok-saghyz(TKS) Rubber Engineering Process Design And Optimization

Natural rubber(NR)is widely used in the automotive industry,aerospace,rail transportation,shipbuilding and medical and health care because of its excellent properties and irreplaceability.The vast majority of natural rubber comes from the rubber tree(Hevea brasiliensis)in Southeast Asia.The tropical rainforest environment in these regions,as well as factors such as labor shortages,politics,climate,disease and pests,can make long-term production of NR unsustainable.In recent years,China’s natural rubber output has only accounted for less than 20%of its demand,and its foreign dependence has been more than 80%.Therefore,the development of new rubber-producing plants with commercial prospects has become an urgent need.At present,the most popular rubber-producing plants in the world mainly include Guayule,Eucommia ulmoides and Taraxacum koksaghyz(TKS).The international research on TKS rubber is mainly focused on the upstream aspects such as seed selection and breeding technology and gene proteomics,while the extraction process of TKS rubber has yet to be explored in depth.In this paper,a more comprehensive investigation is conducted on the extraction process of TKS rubber in small trials.The study is divided into four parts,firstly,the design and optimization of the equipment of TKS rubber production line in small trials,followed by the optimization study of the extraction process of TKS rubber in small trials,then the morphological and compositional analysis of TKS rubber and residues,and finally the characterization of several rubber structures and properties.1.Drawing on the devices used in the laboratory-grade TKS rubber extraction process,the key equipment and auxiliary equipment of the pilot line were designed and scaled up and optimized,making the pilot line capable of stable production of TKS rubber.The working principles of the homemade loosening machine and strong water shear kettle were highlighted.These equipments are indispensable for the quality improvement of TKS rubber.The homemade loosening machine can increase the rubber content of raw material root from 5.40%to 8.58%,and the rubber extraction efficiency is increased by 60%;the homemade strong water shear kettle can extract rubber purity up to 90.2%,while the rubber extraction efficiency is over 35%.2.In the extraction process of rubber,a more complete small pilot extraction process route of TKS rubber was proposed and optimized.The small pilot process route is divided into three main parts,namely pretreatment unit,water-based extraction unit and solvent purification unit.In the pretreatment process,about 40%of impurities are removed by mechanical treatment of the whole root,and the rubber content of the material is increased by about 60%,which effectively reduces energy consumption and increases efficiency,and achieves initial enrichment of rubber.The water-based extraction process was the core of the pilot route,and the four parameters,namely extraction frequency,extraction temperature,extraction speed and material-liquid ratio,were optimized through single-factor and four-factor three-level orthogonal experiments.However,the purity of the rubber after water-based extraction was about 90%,which could not meet the industrial requirements,so the solvent purification process was designed and optimized for the crude rubber and bagasse.Finally,the purity and rubber yield reached up to 99%and 98%respectively,which met the standard of rubber industrialization.3.The TKS rubber and water-based residue before and after purification were analyzed morphologically,and it was found that the rubber and bagasse extracted before purification had the characteristics of "bagasse in rubber and rubber in bagasse".The impurities in the crude rubber are significantly weakened by the solvent purification.The content of water-soluble molecule,pigments,resins,rubber,lignocellulose and ash in the bagasse was also measured,and it was found that the rubber content was as high as 12.4%,which was the reason for increasing the bagasse purification process;the lignocellulose content was nearly 50%,which was the main component of impurities.4.TKS rubber,TSR20#and IR were characterized by GPC,FTIR,NMR,TGA,DSC and mechanical properties.The results showed that the heavy average molecular weight of TKS rubber reached about 177 W,which was slightly smaller than that of TSR20#(about 213 W)and slightly larger than that of IR(about 152 W).The results of both the molecular structure and thermal property analysis show that the three rubbers have similar chemical structures and similar decomposition and glass transition temperatures,which also expand the application prospects of TKS rubber.In terms of mechanical properties,TKS rubber has the largest elongation at break among the three rubbers,and its modulus of elasticity is also in the range of the other two,smaller than that of TSR20#and IR.In addition,similar to IR,TKS rubber did not show strain-induced crystallization.Overall,the performance of TKS rubber extracted by the small pilot process is slightly inferior to that of Hevea rubber and superior to that of synthetic IR,which fully meets the requirements of industrial application.