Structural and Morphological Inhomogeneity of Short-Chain Branched Polyethylenes in Multiple-Step Crystallization
| Autor: | Eric Tsu-Yin Hsieh, Qiang Fu, Benjamin S. Hsiao, Stephen Z. D. Cheng, Fang Chyou Chiu, Qiang Wang, Paul S. Honigfort, Fengji Yeh, Chung C. Tso, M. Y. Keating |
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| Rok vydání: | 2000 |
| Předmět: |
Materials science
Polymers and Plastics Comonomer General Chemistry Polyethylene Condensed Matter Physics Endothermic process Butene Isothermal process law.invention chemistry.chemical_compound Crystallography Differential scanning calorimetry chemistry law Materials Chemistry Orthorhombic crystal system Crystallization |
| Zdroj: | Journal of Macromolecular Science, Part B. 39:317-331 |
| ISSN: | 1525-609X 0022-2348 |
| DOI: | 10.1081/mb-100100388 |
| Popis: | Three commercial metallocene-catalyst synthesized short-chain branched polyethylene (SCBPE) samples with similar molecular weights and molecular weight distributions were investigated in terms of their molecular structural (comonomer sequences and compositions) inhomogeneity and crystal morphology. Two of these samples [SCBPE(B1) and SCBPE(B2)] contained different ratios of a butene comonomer (20.7 and 26.8 SCB/1000 carbons, respectively), while the third sample, SCBPE(H), contained a branched hexane comonomer (7.8 SCB/1000 carbons). A linear PE fraction was also investigated for comparison. Differential scanning calorimetry (DSC) results indicate that multiple-step isothermal (thermal segregation) experiments lead to multiple endothermic melting processes in these SCBPEs during heating, a phenomenon that was not observed in the linear PE. Wide-angle X-ray diffraction (WAXD) experiments show that all of these SCBPEs possess an orthorhombic crystal lattice with different crystallinities. Linear coefficient... |
| Databáze: | OpenAIRE |
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