Crystal Structure and Morphology of Syndiotactic Polystyrene Nanocomposites.

• Main Authors: Sung-Fu Hsu, 徐崧富
• Other Authors: Tzong-Ming Wu
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/31674737316940632560

碩士 === 義守大學 === 材料科學與工程學系 === 89 === Abstract Syndiotactic polystyrene (sPS) has received considerable attention due to its high melting temperature, fast crystallization rate, low dielectric constant and permeability to gases and excellent chemical resistance. Structural studies by XRD, FTIR and NMR have revealed a complex polymorphic behavior. The various crystalline structures, namely α, β, γ, δ, differ with respect to the chain conformation as well as for the chain packing within unit cell. The α and β forms, containing trans planar zigzag chains, can be obtained from the melt or the glassy state of sPS under different thermal conditions, while the γ and δ forms are formed under conditions where the solvent induced. Polymer nanocomposites defined by the particle size of the dispersed phase containing at least one dimension less than 100 nm have relatively high aspect ratio and increase much interest due to their excellent physical, mechanical and thermal behavior over their conventional microcomposites. The preparation of synthetic nanocomposites is the intercalation of monomers or polymers into swellable layer silicate hosts. In this thesis, we have used montmorillonite as the dispersed phase to prepare sPS/clay nanocomposites. Both x-ray diffraction data and transmission electron microscopy of sPS/clay nanocomposites show the layered montmorillonite are intercalated with sPS at least in the scale of 3.81nm. X-ray data also indicates the presence of polymorphism in sPS/clay nanocomposites. This polymorphic behavior is dependent on the thermal history of sPS/clay nanocomposites from the melt and on the content of clay in sPS/clay nanocomposites. The quenching from the melt induces the crystallization into the α crystalline form for pure sPS as well as sPS/MMT nanocomposites. The effect of crystallization temperature, melting temperature and cooling condition on the temperature range of α-β crystalline transformation is also discussed.