1 / 18

Production of Controlled-Rheology Polypropylene Resins by Peroxide Promoted Degradation During Extrusion

Overview. IntroductionReaction MechanismsModelAssumptionsResults. Introduction . Commercial polypropylene (PP) resins are produced with conventional polymerization process using Ziegler-Natta catalyst systemsProducts have a weight average molecular weight in the range of 3x105 7x105Broad ran

blossom
Download Presentation

Production of Controlled-Rheology Polypropylene Resins by Peroxide Promoted Degradation During Extrusion

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

    1. Production of Controlled-Rheology Polypropylene Resins by Peroxide Promoted Degradation During Extrusion Based on paper by: C. Tzoganakis, J. Vlachopoulos, and A.E. Hamielec Presented by: Michelle Leung Ch E 720 Dynamic Modelling and Optimization

    2. Overview Introduction Reaction Mechanisms Model Assumptions Results

    3. Introduction Commercial polypropylene (PP) resins are produced with conventional polymerization process using Ziegler-Natta catalyst systems Products have a weight average molecular weight in the range of 3x105 7x105 Broad range generally believed to be due to broad distribution of active sites on the heterogeneous catalysts Molecular weight distribution (MWD) determines flow properties and performance of polymer melt in processing Polymers with varying MWDs are required in different end-uses MWD is difficult to control using Ziegler-Natta catalyst system

    4. Introduction Peroxide initiated degradation is a relatively flexible post-reactor method for the controlled-rheology resins with tailor-made properties Peroxide radicals preferential to attacking tertiary hydrogens Probability of attacking a certain chain proportional to the number of tertiary hydrogens in the chain Therefore, the longer the chain, the more likely it will be attacked, thus narrowing MWD Objective To propose a dynamic model and simulate peroxide promoted degradation of PP

    5. Polypropylene

    6. Reaction Mechanisms

    7. Model Equations

    8. Model Equations

    9. Method of Moments

    10. Closure Method

    11. Variables Independent variable Time, t Temperature, T Initial peroxide concentration, [I]o Dependent variables Reaction constants Initator efficiency, f Average molecular weight, Mn, Mw, Mz

    12. Assumptions Contributions from transfer, thermal degradation and termination reactions are negligible Steady state hypothesis for the radicals Average temperature used based on barrel temperature profile

    13. Simplified Model Let:

    14. Results

    15. Results

    16. Results

    17. Results

    18. Conclusions Peroxide-initiated degradation of PP is a post reactor method used to narrow the MWD of PP resins Model satisfactory in predicting Mn, and Mw but not Mz This can be attributed to experimental errors involved in the measurement of high molecular weight tail of the MWD Branching and crosslinking reactions can occur under chain degradation conditions, which can significantly increase Mz

    19. Work Cited Tzoganakis, C., J. Vlachopoulos, and A.E. Hamielec. "Production of Controlled-Rheology Polypropylene Resins by Peroxide Promoted Degradation During Extrusion." Polymer Engineering and Science February 1988: 170-180. Tzoganakis, C., J. Vlachopoulos, and A.E. Hamielec. "Modelling of the Peroxide Degradation of Polypropylene." International Polymer Processing 3 (1988): 141-150.

More Related