Study On The Molecular Motion Of Thermoplastic Elastomer/thermoplastic Systerms

Thermoplastic elastomers have special molecule structure, whose molecule chains contain both the soft rubber segments and the hard plastic micro-sections, therefore the molecule motions of thermoplastic elastomers are different from those of the none thermoplastic polymers. In this thesis, a typical thermoplastic Polystyrene (TPS) was modified with Polypropylene (PP) in order to improve the elasticity of the elastomers, and the molecule motion of modified TPS systems, such as SEBS/PP, SEPS/PP, SBS/PP and the fillers modified SEBS/PP were studied thoroughly.First, the mathematic model for the deformation and relaxation of SEBS/PP elastomers, set up by studying the compression deformation properties of SEBS/PP systems, is validated and corrected. The applications of this model to the broader TPS systems are studied.A new method based on Dynamic Mechanical Analyzers (DMA) is developed for the sake of accurately studying the deformational characteristic of elstomers and of getting over the disadvantages of the standard method currently ruled by Chinese Internal Code. The systems used are SEBS/PP, SEPS/PP and SBS/PP.The effects of super- fine fillers, such as organomontmorillon, glass beads and super- fine CaCO₃, on the deformational characteristics of elastomers are studied, and the deformation recoveries are characterized. The results showed that by adding organomontmorillonite, glass beads and super- fine CaCO₃, the molecule motion of systems are influenced. The deformation recoveries of the systems were at the different levels with respect to the fillers used. It was shown that organomontmorillonite gave the best modifying effect.At last, the initial study on the tropism of SEBS/PP molecule chains during the inject molding process is carried out and the result showed that the tropism of SEBS/PP molecule chains is along the direction of injection and the tropism of the crystal of PP also existed.