On the fractionation of homopolymers during crystallization from the pure melt
| Autor: | Leo Mandelkern, Raymond H. Glaser |
|---|---|
| Rok vydání: | 1988 |
| Předmět: |
chemistry.chemical_classification
Chromatography Materials science Polymers and Plastics Analytical chemistry Fractionation Polymer Polyethylene Condensed Matter Physics Isothermal process law.invention Gel permeation chromatography Linear low-density polyethylene chemistry.chemical_compound Differential scanning calorimetry chemistry law Materials Chemistry Physical and Theoretical Chemistry Crystallization |
| Zdroj: | Journal of Polymer Science Part B: Polymer Physics. 26:221-234 |
| ISSN: | 1099-0488 0887-6266 |
| DOI: | 10.1002/polb.1988.090260201 |
| Popis: | The question as to whether fractionation occurs during the crystallization of homopolymers from the pure melt has been addressed by studying linear polyethylene mixtures. Two methods were used. In one procedure, mixtures of well-defined fractions were crystallized under controlled conditions and the subsequent fusion process was analyzed. In the other procedure, a selective extraction was carried out on an isothermally crystallized polydisperse whole polymer, and the residue was analyzed by gel permeation chromatography. Both methods lead to the same conclusion, namely that during isothermal crystallization only the very low molecular weight species crystallize separately. An extreme upper limit to fractionation corresponds to M = 7000. More likely, fractionation in linear polyethylene during bulk crystallization is restricted to molecular weights of 5000 or less. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Plný text