Comparing Strategies for the Synthesis of Polyolefinic Thermoplastic Elastomers via Macromonomer Incorporation
✍ Scribed by Monica C. Haag; Leonardo C. Simon; Joao B. P. Soares
- Publisher
- John Wiley and Sons
- Year
- 2003
- Tongue
- English
- Weight
- 278 KB
- Volume
- 12
- Category
- Article
- ISSN
- 1022-1344
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✦ Synopsis
Abstract
The microstructure of polyolefinic thermoplastic elastomers made with a combination of two single‐site catalysts was analyzed by Monte Carlo simulation. The model can be used to describe the crystallizable fraction for both long‐chain branched polypropylene (__a__PP‐g‐__i__PP) and long‐chain branched ethylene/α‐olefin copolymers (PE__α__O‐g‐PE). The simulations showed that at levels of 7.5% of comonomer incorporation, PE__α__O‐g‐PE samples reach a similar crystallizability level of __a__PP‐g‐__i__PP. From a topological point of view, it was demonstrated that the fraction of free arms and inner segments tend to the limit of ½ for highly branched chains and that the fraction of free arms reaches its maximum value when the Y‐type chains are the predominant population. A mathematical correlation between the linear‐ and LCB catalyst probabilities was proposed to ensure the production of symmetrical branched chains.
Long‐chain branch architecture of PE__α__O‐g‐PE.
magnified imageLong‐chain branch architecture of PE__α__O‐g‐PE.