Summary: Linear and long‐chain branched high‐density polyethylenes with a molar mass $\overline M _{\rm w}$ between 1 700 and 1 150 000 g · mol−1 were synthesized using metallocene catalyst systems. Depending on the polymerization parameters the molar mass distribution reached values ranging from 2 to 12. The resins were characterized with various analytical methods. The branch detection took place via two independent methods, melt rheology and SEC‐MALLS. New relationships between catalyst structure, polymerization conditions, and the branching content of polyethylenes were established. Besides the branched materials strictly linear polymers are presented; for those no long‐chain branches were detected either by light scattering or by rheology. The viscosity function was observed to be strongly influenced by the molar mass distribution and the degree of long‐chain branching. The molar mass distribution was affected by the catalyst type and the polymerization conditions. A dependence of the melting point and the melting enthalpy on the molar mass was observed.
Summary: Copolymers of propylene and hexacosene (Cn = 26–28) were synthesized in the presence of three different metallocene catalysts activated by methylaluminoxane. The poly(propylene) copolymers were prepared with iso‐, syndio‐, and atactic backbone microstructures by using different symmetric metallocenes such as rac‐{Me2Si[2‐Me‐4‐(1‐Naph)Ind]2}ZrCl2 (1), [Ph2C(Cp)(Flu)]ZrCl2 (2), and [(H3C)2Si(9‐Flu)2]ZrCl2 (3) and up to 46.6 mol‐% comonomer content in the feed. The influence of the incorporated linear, ethylene‐based side chains into the poly(propylene) backbone were investigated by DSC, GPC, and 13C NMR. Generally, a decreasing content of comonomer in the feed enhances the activity of metallocene based catalysts. The determination of the branched microstructure by 13C NMR of the copolymers allows a smart identification of the amount of inserted hexacosene because of the separated backbone and side chain signals. Moreover, the relationship between the population of the side chains and the melting behavior of resulting copolymers were discussed. The melting point of the syndiotactic and isotactic poly(propylene) backbone decreases with increasing hexacosene content. When the inserted comonomer content exceeds 2 mol‐%, a second melting point of the crystallized ethylene based side chains can be observed which increases with an increasing amount of hexacosene.
Summary: Copolymers of propene and ethene-based macromers have been prepared in a direct copolymerization. First macromers in a range of 3000-11600 g/mol were synthesized by varying the polymerization temperature and ethene concentration with the metallocene catalyst [(CH 3 ) 2 CCp 2 ]ZrCl 2 /MAO. These vinyl terminated ethene oligomers were copolymerized with propene by C s symmetric catalyst [Ph 2 C(Cp)(Flu)]ZrCl 2 to a long-chain branched syndiotactic polypropylene. The LCB-sPP was separated from the bimodal product by a fractional crystallization with p-xylene and 2 -ethoxy ethanol at 130 8C. A detailed analysis of the purified copolymer was given by GPC, DSC and 13 C NMR spectroscopy.
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