Study On The Synthesis Process And Performance Of Graphite/Expandable Polystyrene

Along with our country energy-saving and emission-reduction strategy deeply, expandable polystyrene (EPS) board as thermal insulation material has some advantages, attracted much people's attention. Thermal insulation materials EPS has a low thermal conductivity coefficient, a certain strength and toughness, forming easily, mature technology and so on. In order to further reduce the thermal conductivity, after 10 years hard work, BASF of Germany firstly pushed out Graphite/Expandable Polystyrene (G-EPS) composite material to the market in 2010, but the process of synthesis is still confidential, in order to control the market of the low thermal conductivity of G-EPS. Therefore, how to use existing production process of EPS to prepare a low coefficient of thermal conductivity of G-EPS is the main research content of this paper.The second chapter realizes the suspension polymerization of linear low density polyethylene (LLDPE) and styrene monomer using styrene monomer swelling method. The toughening modification mechanism adout LLDPE to PS is expatiated. The optimum process conditions for different ratios of LLDPE and styrene monomer were compared and identified. The polystyrene particles (PS) with symmetrical particle size distribution are obtained.The effect of LLDPE quantity added on the grafting polymerization efficiency ,the ball ratio,particle morphology, average particle size, particle size distribution and the copolymer glass transition temperature properties has been studied by IR, SEM and DSC.In the third chapter, the main purpose is to find a convenient graphite modified process, which can make the modified graphite disperse well in styrene monomer. The effect of graphite type and particle size is discussed in detail by the sedimentation experiment of the graphite in styrene monomer, and the solvent of modifying graphite are selected. In addition, the dispersing stability of modified graphite in water, monomer and the mixture of monomer and water were characterized. The results show that the modified graphite and styrene has good compatibility. The effect of adding order of modified graphite on its dispersion in styrene are examined by SEM. Furthermore, the equipment of modifying graphite process was designed and put into industrial production. A modified graphite production process of annual output 800 tons is set up, which can provide a basis and guarantee for the synthesis of G-EPS.In the fourth chapter, based on the modified graphite, one-step preparation process of graphite/polystyrene is studied, and composite particles with the black uniform G-EPS are prepared. In this chapter the effect of the water-oil ratio of G-EPS polymerization reaction system on viscosity and graphite addition quantity on the G-EPS particle size distribution are discusseed detailedly. The effects of initiator concentration on the molecular weight of G-EPS and reaction cycle changes are also discussed. The morphology of G-EPS original and foam tablets are analized using the scanning electron microscope (SEM) .Thermal conductivity and flame resistant properties determined, and the mechanism of G-EPS with low thermal conductivity and high flame retardant from are discussed.In the fifth chapter, the one-step preparation manufacturing process of composite graphite/expandable polystyrene (G-EPS) particles is investigated. The main problems solved in this chapter are as follows: Process parameters, production process as well as equipment in industrial production are optimized, a production process of G-EPS with annual output of 90,000 tons is achieved, and performances of the industrial products are tested by both national authorities and manufacturers of insulation materials. Moreover, the economic benefits of industrial production of G-EPS are analysed integratively.The studies are focused on different processes, such as the manufacturing process of modified graphite, the pilot process and the manufacturing process of composite graphite/expandable polystyrene (G-EPS). Performances of the industrial products are evaluated systematically. Fourthermore, the production technology of G-EPS is self-developed, which filled the void of domestic industry. As a result of this breakthrough, the monopoly position of BASF and South Korea Kumho Group in low thermal conductive G-EPS market is broken.