Observation of Different Catalytic Activity of Various 1-Olefins during Ethylene/1-Olefin Copolymerization with Homogeneous Metallocene Catalysts

Abstract

This research aimed to investigate the copolymerization of ethylene and various 1-olefins. The comonomer lengths were varied from 1-hexene (1-C6) up to 1-octadecene (1-C18) in order to study the effect of comonomer chain length on the activity and properties of the polymer in the metallocene/MAO catalyst system. The results indicated that two distinct cases can be described for the effect of 1-olefin chain length on the activity. Considering the short chain length comonomers, such as 1-hexene, 1-octene and 1-decene, it is obvious that the polymerization activity decreased when the length of comonomer was higher, which is probably due to increased steric hindrance at the catalytic center hindering the insertion of ethylene monomer to the active sites, hence, the polymerization rate decreased. On the contrary, for the longer chain 1-olefins, namely 1-dodecene, 1-tetradecene and 1-octadecene, an increase in the comonomer chain length resulted in better activity due to the opening of the gap aperture between Cp(centroid)-M-Cp-(centroid), which forced the coordination site to open more. This effect facilitated the polymerization of the ethylene monomer at the catalytic sites, and thus, the activity increased. The copolymers obtained were further characterized using thermal analysis, X-ray diffraction spectroscopy and 13C-NMR techniques. It could be seen that the melting temperature and comonomer distribution were not affected by the 1-olefin chain length. The polymer crystallinity decreased slightly with increasing comonomer chain length. Moreover, all the synthesized polymers were typical LLDPE having random comonomer distribution.

Crystallization behaviour and lamellar thickness distribution of metallocene‐catalyzed polymer: Effect of 1‐alkene comonomer and branch length

“…Increased activities of 18 %, 19 %, and 15 % were recorded with just a single millilitre addition of comonomers 1‐hexene, 1‐octene, and 1‐ decene respectively (see Table ). A slight decrease in activity of DEC‐4 compared to OCT‐4 is due to the steric hindrance caused by 1‐decene (1‐C 10 ) atoms . Furthermore, higher amounts of comonomer added up the short chain branching (SCB) to the copolymers, and correspond to lower DOC and T m .…”

Solvent-free aerobic oxidation of 1-octene using graphite-supported gold–palladium nanoparticle catalysts

“…To test the influence of the preparation methods on 1-octene oxidation, 1 % Au/graphite was prepared using three different methods: sol-immobilization (SI), deposition-precipitation (DP), and the impregnation method (IM). Previous studies [19][20][21][22] have shown that the activity of the gold catalyst decreases dramatically when the gold particle size is increased. The smallest Au particles have demonstrated much higher activity in 1-octene oxidation.…”

“…As there is a significant difference between the alkenes with the chain length of C 6 and C 10 , we are interested in studying 1-octene (alkene with the chain length of C 8 ) to understand the effect of chain length on catalytic activity. Interestingly, the chain length has been reported to play a significant role in the catalytic activity during ethylene/1-olefin copolymerization [19]. Thus, the aim of this study is to investigate the oxidation of 1-octene using supported gold nanoparticles as a catalyst under solvent-free conditions and air as the oxidant.…”

Metallocene-catalyzed ethylene−α-olefin isomeric copolymerization: A perspective from hydrodynamic boundary layer mass transfer and design of MAO anion

“…We shall discuss the influence of this comonomer effect on copolymer intra-chain compositional heterogeneity in Section 3.5. The above findings can be attributed to the following: The above factors variedly influenced the following chemically intrinsic phenomena: (i) the zirconocenium−MAO anion separation [20,[44][45][46][47][48] (in ethylene homopolymerization) and (ii) the activation of the dormant/sleeping Zr + −H catalytic sites [20,[49][50][51][52][53][54][55][56][57]] by 1-hexene and 4M1P (in ethylene copolymerization). Hence, we observe varying homopolymerization catalyst productivities and comonomer effects, respectively.…”

“…Hence, we observe varying homopolymerization catalyst productivities and comonomer effects, respectively. Note that the closer is the ion-pair separation, the higher is the energy barrier associated with each polymerization step; hence, the less is the catalyst productivity [20,[44][45][46][47][48].…”