Morphological Structure of Crystalline Polymer Blend Probed by Small Angle X-ray Scattering
| Autor: | Shi-Fang Wang, 王世帆 |
|---|---|
| Rok vydání: | 1999 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 87 The effect of composition, molecular weight and crystalliztion history on the morphological structure of crystalline polymer blends have investigated by this research. Two systems were considered: (I)crystalline/amorphous polymer blends : polycaprolactone(PCL)/poly ( 4-vinyl phenol)(PVPh) and (II)crystalline/crystalline polymer blend : poly(ethylene oxide)(PEO)/poly(ethylene succinate). The misibility and growth rate of these systems were probed by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The morphological parameters associated with the lamellar stacks crystal thickness(lc), amorphous layer thickness(la), and long period(L=lc+la) were deduced from small angle X-ray scattering (SAXS). For PCL/PVPh system, it was found that the crystal growth rate of PCL was significantly depressed by the strong hydrogen bonding interaction between PCL and PVPh. The consequence of such a growth depression is that the noncrystalline PVPh was rejected predominantly out of the interlamellar regions. Increasing the molecular weight (MW) of PCL also depressed the growth rate and thus the blend containing higher MW PCL displayed a larger extent of extralamellar segregation. The segregation distance of PVPh was also promoted by increasing the diluent composition. For the two MW fractions of PVPh investigated, the extent of extralamellar segregation was relatively unaffect by MPVPh.For PEO/PES system, the melting point of PEO is ca. 60℃and that of PES is ca. 101℃.At temperature between the melting point of PEO and that of PES, the blend was a crystalline/amorphous state. Both crystallizations via direct cooling to 70℃(where only PES crystallized) and direct cooling to 41℃(where two components crystallized simultaneously)created a high extent of intefibrillar segregation coupled with a minor extent of interlamellar incorporation of amorphous PEO. A temperatures below the M.P. of PEO(Tc=41℃), where both components crystalliztion simultaneously, the SAXS profiles show two scattering peaks : one associated with almost pure PES lamellae and the other with mixed PES and PEO lamellae .Crystallization at 70℃ followed by cooling to room temperature (two-step crystallization) also yielded two separate LS domain, due to the crystallization of PEO within the interfibrillar region. Therefore, in the crystalline/crystalline state, PEO/PES system exhibited the "lamellar stacking"morphology, in contrast with the lamellar insertion mode in polycaprolactone/ polycarbonate blends. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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