| Autor: |
Suwier, D. R., Steeman, P. A. M., Teerenstra, M. N., Schellekens, M. A. J., Vanhaecht, B., Monteiro, M. J., Koning, C. E. |
| Zdroj: |
Macromolecules; July 2002, Vol. 35 Issue: 16 p6210-6216, 7p |
| Abstrakt: |
High molecular weight poly(styrene-co-N-substituted-maleimide)-block-poly(tetrahydrofuran) multiblock copolymers with an excellent thermal stability were synthesized using the polymeric iniferter technique. Evidence for the existence of these multiblock copolymers was obtained by submitting them to gradient polymer elution chromatography and by snipping the chemical bonds between the SMI blocks and the PTHF blocks, after which the molecular weight distribution of the remaining SMI blocks was determined. Only one glass transition temperature was observed in a modulated temperature DSC scan of the segmented copolymers, typical for a homogeneous material. The Tg of these flexibilized, single-phase multiblock copolymers is still high enough to qualify them as engineering plastics. The entanglement density, which is closely related to the toughness of materials, of a styrene-N-phenylmaleimide copolymer flexibilized by 12 wt % PTHF was raised by a factor 1.6 as compared to the unflexibilized styrene-N-phenylmaleimide copolymer. These entanglement densities were deduced from the respective rubber plateau moduli, which were corrected for the nonentangled low molar mass fraction by applying the Wasserman−Graessley model. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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