Nucleation and Crystallization of PLDA-b-PE and PLLA-b-PE Diblock Copolymers
| Autor: | Reina Verónica Castillo, Alejandro J. Müller, Marc A. Hillmyer |
|---|---|
| Rok vydání: | 2006 |
| Předmět: |
Materials science
Lactide Polymers and Plastics Organic Chemistry Nucleation Condensed Matter Physics law.invention Amorphous solid chemistry.chemical_compound Crystallinity Optical microscope Chemical engineering chemistry law Polymer chemistry Materials Chemistry Copolymer Lamellar structure Crystallization |
| Zdroj: | Macromolecular Symposia. 242:174-181 |
| ISSN: | 1521-3900 1022-1360 |
| DOI: | 10.1002/masy.200651025 |
| Popis: | The nucleation and crystallization of two types of strongly segregated poly(lactide)-block-polyethylene diblock copolymers with an approximate 50/50 composition has been investigated. One material contains an amorphous PLDA block (PLDA-b-PE) and the other contains a semicrystalline PLLA block (PLLA-b-PE). The overall isothermal crystallization rate of the PLLA block was slowed down as compared to homo-PLLA by the covalently bonded PE chains that were molten at the PLLA crystallization temperatures. This crystallization rate depression of the PLLA block produces a coincident crystallization process when PLLA-b-PE is cooled down from the melt at rates larger than 2°C/min. The overall crystallization rate of the PE block is faster when it is covalently bonded to previously crystallized PLLA than when it is attached to a rubbery PDLA block, this results from a nucleation effect of PLLA on the PE block. Polarized Light Optical Microscopy (PLOM) confirmed the confined nature of the crystallization process within lamellar microdomains for both diblock copolymers, since neither PLLA nor PE are capable of breaking out and spherulites can not be formed. |
| Databáze: | OpenAIRE |
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