| Summary: | 碩士 === 國立雲林科技大學 === 工業化學與災害防治研究所 === 93 === Reactions of two aliphatic polyesters, semicrystalline poly(��-caprolactone) (PCL) and amorphous poly(D,L-lactide) (PLA), in supercritical CO2 fluids (SCF CO2) at 35℃ and 5000 psi were investigated. Blends of two PCLs with molecular weights of 80,000 (PCL8) and 10,000 (PCL1) and blends of PCL8 and PLA were used for this study. The compositions of the PCL8/PCL1 blend included 100/0, 85/15, and 70/30. GPC data found that PCL8 performed both solid-state polymerizations and transesterification reactions whereas PCL1 performed only solid-state polymerizations in SCF CO2. The trend of the molecular weight change of the 85/15 and 70/30 blends with treatment time was similar to that of pure PCL8. The level of the molecular weight change of the 70/30 blend, however, was less than that of the 85/15 blend. DSC data found that the crystallinity of PCL8 was increased whereas that of PCL1 was decreased by the SCF CO2 treatments. FTIR data found that the carbonyl band of the PCL samples shifted to higher wavenumbers after SCF CO2 treatments, suggesting that carbonate linkages were formed after reactions in SCF CO2. For the PCL8/PLA blends, GPC data found that PLA performed as well both solid-state polymerizations and transesterification reactions in SCF CO2. DSC data found that the SCF CO2 treatments could induce crystallization of the amorphous PLA. FTIR data found that the carbonyl band of the PLA samples shifted to higher wavenumbers as well after SCF CO2 treatments. This blue shift for the PLA samples was at a less level than that for the PCL samples.
|
|---|
