Studies On Preparation And Properties Of Styrene-Ethylene Butylene-Styrene(SEBS) Based Elastomer System Modified With Polypropylene (PP)

Thermoplastic elastomers form a new class of polymeric materials with the unique combination of mechanical properties and processability. It is called "the third generation rubber". Their modulus level is comparable to that of the reinforced rubber vulcanized at the working conditions. At high temperature, thermoplastic elastomers are in the melt state so that they can be processed with plastic processing equipment. One kind of these materials is styrene-ethylene butylenes-styrene (SEBS) block copolymer. Its mechanical properties, thermal properties and rheological properties will be improved when blended with additives such as oil, thermoplastic, resin, etc. Even though they have been widely used from daily life, medical equipments, to industry fields, the researches are only limited in the simple corresponding relationship between the component changes and properties.By studying the modification of SEBS elastomer system with additives, the objective of the thesis is to set up the relationship between composition, morphology, properties and use efficiency. Accordingly, the design of specific material can be supervised and achieved.A series of blends SEBS/PP and SEBS/PP/fillers are prepared. Then their properties and microstructure are studied in detail in this thesis. And an elementary relationship between microstructure and properties of these blends is discussed.1. The influence of mechanical properties of SEBS with oil content is studied. And the quality proportion between SEBS and oil is then determined. PP is used to modify SEBS because of its excellent mechanical and rheological properties.2.The mechanical properties of the blends, such as tensile strength, elongation, rheological properties, permanent compressed deformation, dynamic mechanical property, and relaxation property are studied. The relationship of the mechanical properties and PP contents are obtained. A mathematical model explaining the relaxation properties of the blending system is proposed for the first time.3. The rheological properties are studied by torsion rheometer. The results will be useful in improving the processibility of elastomer materials.4. The crystallization behaviors PP in blends have been studied by X-radial diffraction and thermo-polarize microscope. It can be concluded that the morphology of blends is related to the content of PP and a basic relationship between microstructure and properties of these blends is set up. This is beneficial for designing the blending materials with special properties.