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The reactor blends (RBs) with bimodal molecular weight distribution on the base of ultrahigh molecular weight polyethylene (UHMWPE) and low molecular weight random ethylene/1-hexene copolymers (CEH) were synthesized by two-step processes including ethylene polymerization followed by ethylene/1-hexene copolymerization over rac-(CH 3 ) 2 Si(Ind) 2 ZrCl 2 /methylaluminoxane catalyst. The four series of blends differed in a composition of copolymer fraction that was varied in a wide range (from 3.0 to 37.0 mol % of 1-hexene). The differential scanning calorimetric study shows the double melting behavior of the net semicrystalline CEHs, which can be attributed to intramolecular heterogeneity in chain branch distribution. The introduction of CEHs leads to the modification of nascent RB crystalline and amorphous phases. Physical and tensile properties as well as melting indexes of the materials depend not only on the percentage of copolymer fraction that varied from 6.9 to 35.8 wt % but also on its composition. The increase of copolymer fraction with high content of 1-hexene (11.0 mol %) in the blends leads to the change of the character of stress-strain curves; the materials behave as elastomers. Controlled regulation of copolymer fraction characteristics in the synthesis yields RBs combining the enough high strength, good plastic properties with enhanced melting indexes as compared with the net UHMWPE.

Reactor polymer compositions (RPC) of ultrahigh molecular weight polyethylene (UHMWPE) with Mw = 1,000 kg/mol and low molecular weight high density polyethylene (LMWPE) with Mw = 160 kg/mol were synthesized in a two‐stage ethylene polymerization with a rac‐Me2Si(Ind)2ZrCl2/methylaluminoxane catalyst. The conditions of the stages that ensure the formation of UHMWPE and LMWPE fractions with the desired molecular weight and properties were selected based on the study of one‐stage ethylene polymerization over this catalyst in a wide temperature range. The order of fraction synthesis in RPC preparation was changed. Two series of compositions UHMWPE/LMWPE and LMWPE/UHMWPE with UHMWPE content from 20 to 90 wt% were obtained. The SEM method was used to study the morphology of the nascent polymer particles. It was shown that RPC physical and mechanical properties depend not only on the UHMWPE content, but also on the morphology of the particles of reactor powders, which is determined by the order of polymer fraction synthesis. Materials of LMWPE/UHMWPE series have higher tensile properties compared to UHMWPE/LMWPE of the same composition. The LMWPE/UHMWPE compositions containing ≤50 wt% of UHMWPE flow even at a load of 10.5 kg.

Two Ti complexes with bidentate ligands derived from pinacol and perfluoropinacol and activated with a binary Al(C 2 H 5 ) 2 Cl -Mg(C 4 H 9 ) 2 cocatalyst are efficient catalysts for polymerization of lightest alkenes, ethylene and propylene, and for their copolymerization. They produce linear polyethylene of moderate molecular weight and essentially atactic amorphous polypropylene. Ethylene/propylene copolymers prepared with these catalysts are compositionally uniform resins with a very low crystallinity degree which can be used as synthetic EPM rubbers.

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