中文摘要：

通过广角X射线衍射（WAXD）和小角X射线散射（SAXS）方法研究了PEO-b-PCL在CO2中的结晶形貌和片晶厚度的变化,利用高压示差扫描量热仪（HP DSC）考察了压力对熔融和等温结晶过程的影响.结果表明,PEO-b-PCL的结晶度、片晶厚度、熔融温度均随压力的升高而减小,结晶结构变得不完善.在等温结晶过程中,结晶速率随压力的升高而下降,结晶过程处于成核控制区,Avrami指数n在3.7~4.7,表明晶体的生长方式为三维生长.

英文摘要：

The crystallization morphology and lamellae thickness of poly（ ethylene oxide）-b-poly（ ε-caprolactone）（ PEO-b-PCL） under high pressure CO2 was studied by means of wide-angel X-ray diffraction（ WAXD） and small-angel X-ray scattering（ SAXS）. For the sample of PEO0. 5 k-b-PCL24. 5 k,only PCL blocks crystallized under 1 ~ 3 MPa CO2 and the lamellae thickness of PCL segment decreased with increasing CO2 pressure. The melting behavior and isothermal crystallization kinetics were investigated by using high pressure differential scanning calorimetry（ HP DSC）. The results indicated that only the melting peak of PCL segments can be observed and the melting peaks widened with increasing pressure. The crystallinity degree（ Xc） and melting temperature（ Tm） of PEO-b-PCL decreased with increasing CO2 pressure. Xcof PCL in the sample decreased from 46. 9% to 36. 6% and Tmdecreased from 54. 5 ℃ to 47. 2 ℃ under 0 MPa and 3 MPa respectively. The Avrami analysis was performed to obtain the kinetics parameters. The overall crystallization rate decreased with increasing pressure and the crystallization process was controlled by nucleation rate. The half crystallization time（ t1 /2） of the sample increased from 2. 23 min at 0 MPa to 5. 83 min at 3 MPa. The value of Avrami index n,is between 3. 7 and 4. 7,demonstrating a three-dimensional spherulitic growth in the process of isothermal crystallization. The decreasing crystallinity degree and crystallization rate illustrated that pressurized CO2 hindered the crystallization of PEO-b-PCL.