Crystallization kinetics of poly(L‐lactide) in contact with pressurized CO<sub>2</sub>

Polymer Engineering and Science - Tập 44 Số 1 - Trang 186-196 - 2004
Mitsuko Takada1, Shigeki Hasegawa1, Masahiro Ohshima1
1Department of Chemical Engineering, Kyoto University, Kyoto 606–8501, Japan

Tóm tắt

AbstractThe effect of CO2 on the isothermal crystallization kinetics of poly(L‐lactide), PLLA, was investigated using a high‐pressure differential scanning calorimeter (DSC), which can perform calorimetric measurements while keeping the sample polymer in contact with pressurized CO2. It was found that the crystallization rate followed the Avrami equation. However, the crystallization kinetic constant was changed depending upon the crystallization temperature and concentration of CO2 dissolved in the PLLA. The crystallization rate was accelerated by CO2 at the temperature in the crystal‐growth rate controlled region (self‐diffusion controlled region), and depressed in the nucleation‐controlled region. CO2 has also decreased the glass transition temperature, Tg, and the melting temperature, Tm. As a result, the CO2‐induced change in the crystallization rate can be predicted from the magnitudes of depression of both Tg and the equilibrium melting temperature. The crystalline structure and crystallinity of polymers crystallized in contact with pressurized CO2 were also investigated using a wide angle X‐ray diffractometer (WAXD). The resulting crystallinity of the sample was increased with the pressure level of CO2, although the presence of CO2 did not change the crystalline structure.

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Tài liệu tham khảo

10.1021/ma9712209

10.1021/ma9712211

10.1016/0032-3861(87)90441-1

10.1002/polb.1991.090290513

10.1002/polb.1994.090321512

10.1002/(SICI)1099-0488(19961115)34:15<2635::AID-POLB11>3.0.CO;2-7

10.1002/(SICI)1099-0488(19980430)36:6<977::AID-POLB5>3.0.CO;2-D

10.1002/polb.1122

R.Gendron “Applied Rheology for the Extrusion of Thermoplastic Foams;”Proceedings of Foams'99(1999).

10.1002/pat.1991.220020303

10.1002/pen.10890

10.1002/app.1985.070300626

10.1002/app.1985.070300929

10.1002/polb.1987.090250713

10.1021/ma00097a035

10.1016/0896-8446(91)90026-3

10.1016/0009-2509(93)80280-4

10.1002/pen.10039

Operating Instruction for the DSC High Pressure Cell Perkin‐Elmer.

10.1107/S0365110X61003429

10.1063/1.1750380

10.1063/1.1750631

10.1063/1.1750872

10.1063/1.3051751

10.1007/BF01498927

10.1007/BF00263945

10.1002/(SICI)1097-4628(19961114)62:7<1079::AID-APP14>3.0.CO;2-1

10.1016/0032-3861(77)90134-3

10.1007/BF00658762

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Polymer Engineering and Science

Tập 44 Số 1

186-196

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