Determination of Polymeric Microstructure by Small-Angle Scattering
| Autor: | Wei-Po Liao, 廖巍博 |
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| Rok vydání: | 2002 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 90 The research is separated into three parts. In the first part, small-angle X-ray scattering (SAXS) is used to analyze the microstructure of syndio tactic polystyrene (sPS)/atatic polystyrene (aPS) and metallocene polyethylene (mPE1)/polypropylene (PP) blends in different ratios. A procedure in dealing with the raw data is established. In the second part, the internal crystal structures of sPS/aPS blends were carried out by observing the changes of Hv patterns obtained from small-angle light scattering (SALS). In the final part, charged coupled device (CCD) and a polarized optical microscope (POM) were used to measure the change of light intensities in the growth or melting of the sPS/aPS blends. The melting process of positive or negative spherulites can also be observed. In the study of microstructure, zero-angle scattering can be detected by SAXS in sPS/aPS and mPE1/PP blends. The values of long period remain constant with increasing aPS in sPS/aPS blends, implying that the addition of aPS can’t reach the level of interlamellar segregation. Only single distribution of the long period can be found in mPE1/PP blends. Apparent cloverleaf patterns can’t be observed by small-angle light scattering (SALS) in the sPS system. The scattering intensity decays with q (scattering vector). According to this, we can conclude that the Hv patterns obtained are from the contribution of both spherulites and axilites. On the other hand, the longer time or higher crystallization temperature, the smaller scattering patterns. The same melting behavior is found in positive and negative spherulites of sPS by CCD and POM. Melting points computed from POM experiment are close to the differential scanning calorimeter (DSC) results. The melting points obtained from DSC and POM are 292oC and 286oC, respectively. The difference may result from different heat transfer mechanism. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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