Model development for semicontinuous production of ethylene and norbornene copolymers having uniform composition

Abstract

in Wiley InterScience (www.interscience.wiley.com).Terminal and penultimate models for controlling copolymer composition distribution (CCD) in ethylene and norbornene (NB) copolymerization were developed by taking into account the variation of active site concentration with the initial comonomer ratio. The models were validated by batch polymerization experimental data. The terminal model gave better correlation with the composition data whereas the penultimate model had a better fit to the rate data. The terminal model was then used to design NB feeding policies in semicontinuous processes for targeted CCD profiles. Based on the model results, a series of ethylene-NB copolymers with various NB contents were prepared. With the same NB content, the semicontinuous process produced a uniform composition, whereas the batch process yielded broad CCD. The batch samples had lower T g values and broader transition ranges, even yielded crystalline materials. In contrast, the semicontinuous samples overcame the disadvantages. (a) Copolymer yield vs. reaction time; (b) NB conversion vs. reaction time. Conditions: catalyst concentration 5 4 3 10 25 mol/l, Al/Zr 5 1500, toluene 5 50 ml, P 5 1 atm, T 5 708C, initial NB/E 5 19.6, total reaction time 5 90 min. Conditions: catalyst concentration 5 4 3 10 25 mol/l, Al/Zr 5 1500, toluene 5 50 ml, P 5 1 atm, T 5 708C.Figure 5. Copolymer yield/NB conversion vs. reaction time in the batch process for initial NB/E 5 1.3 (For the model calculation, c * varies with the initial NB/E according to Figure 4). (a) Copolymer yield vs. reaction time; (b) NB conversion vs. reaction time. Conditions: catalyst concentration 5 4 3 10 25 mol/l, Al/Zr 5 1500, toluene 5 50 ml, P 5 1 atm, T 5 708C, initial NB/E 5 1.3, total reaction time 5 10 min.

Influence of chain microstructure on ethylene–norbornene copolymer film properties

“…To study the effects of copolymer composition and its distribution (CCD) on optical properties of E‐NB copolymers, the transparency and refractive index of E‐NB copolymers with five different NB contents (20, 35, 45, 55, and 60 mol %) were compared. These copolymers were obtained from our previous work 23. There were two kinds of the samples for each composition: one with uniform composition prepared by semibatch process and the other with broad CCD prepared by batch process.…”

“…In this Figure, T − T ′ meant the transparency difference between uniform composition copolymer and broad CCD copolymer having the same average NB content. The instantaneous NB content drifts were estimated by the model calculation combined with the thermal properties 23. Their values denoted the breadth of CCD.…”

“… Effect of NB content drift on the transparency of E‐NB copolymers. ( T − T ′: The transparency difference between uniform composition copolymer and broad composition distribution copolymer with the same average NB content; NB max : NB content of copolymer fraction with instantaneous maximum NB composition drift based on the model calculation23; NB min : NB content of copolymer fraction with instantaneous minimum NB composition drift based on the model calculation23). [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]…”

“…The preparation of the E‐NB copolymer and E‐NB‐P terpolymer samples used in this work had been reported in literature 21–24. The composition, molecular weight, and PDI data were cited from the sources.…”