Promotion of self-nucleation with latent Form I nuclei in polybutene-1 and its copolymer
The formation of Form I nuclei of polybutene-1 (PB-1) and its copolymer with polyethylene (PB1-ran-PE) has been studied by means of modified self-nucleation protocols. Even when the self-nucleation temperature was high enough and all Form II crystals melt, re-crystallization can be accelerated if th...
| Autores: | , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2018 |
| País: | España |
| Institución: | Universidad del País Vasco |
| Repositorio: | Addi. Archivo Digital para la Docencia y la Investigación |
| OAI Identifier: | oai:addi.ehu.eus:10810/33073 |
| Acceso en línea: | http://hdl.handle.net/10810/33073 |
| Access Level: | acceso abierto |
| Palabra clave: | Polybutene-1 Butene-1/ethylene copolymer polymorphic transformation self-nucleation crystalline memory |
| Sumario: | The formation of Form I nuclei of polybutene-1 (PB-1) and its copolymer with polyethylene (PB1-ran-PE) has been studied by means of modified self-nucleation protocols. Even when the self-nucleation temperature was high enough and all Form II crystals melt, re-crystallization can be accelerated if the melt-crystallized sample was annealed at low temperatures (below 60 oC for PB-1 and 75 oC for PB1-ran-PE) for just 3 min. These results suggest the formation of latent Form I nuclei within Form II crystals. This hypothesis is consistent with the observed growth of a small amount of Form I crystals during heating, after previous annealing at temperature lower than 20 °C. In addition, a peculiar phenomenon was found in PB1-ran-PE, as both Form II and Form I′ can be induced by the presence of latent Form I nuclei, due to cross-nucleation and self-nucleation effects, respectively. The final ratio of the two kinds of crystal Forms is a result of the competition between the two nucleation rates, which strongly depend on crystallization temperature. In this work, we have shown that careful design of novel self-nucleation protocols can yield evidence of the early stages of Form II to Form I transition, even when the degree of transformed crystals is below the limit of detection of conventional techniques sensitive to crystalline order (DSC, WAXD, FTIR). |
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