Novel binary chlorides containing TiCl3 as components of coordination catalysts for ethylene polymerization. II. Behavior of the resulting catalyst systems

Binary chlorides described in part I yielded very active catalyst systems for HDPE synthesis when they were associated with (i-C₄H₉)₃Al. Very high initial polymerization rates were observed for systems bases on MnCl₂·TiCl₃, MnCl₂·2TiCl₃, or FeCl₂·2TiCl₃ (III), but high yields, i.e., above 30 kg polymer/g Ti, could be reached only using moderate pressure of ethylene. Hydrogen consumption during ethylene polymerization was observed in the case of catalysts based on AlCl₃·3TiCl₃, CrCl₃·3TiCl₃, and other binary chlorides containing elements of the VIII group. Relevant amounts of ethane were found in the case of systems III, V, and VIII. All the mixed chlorides studied were able to reduce cyclohexene in the presence of H₂ and (i-C₄H₉)₃Al, even though with different kinetic courses. Compounds II, III, V, and VIII and (MgCl₂)_1.5·TiCl₃ and AlCl₃·3TiCl₃ were very active. The results have been explained on the basis of solubilization processes involving the heterogeneous catalysts which actually were experimentally verified during cyclohexene reduction. Analogous processes may occur also during HDPE synthesis.     

New crystalline complex chlorides containing transition metal chlorides or oxychlorides as components of coordination catalysts

Novel complex chlorides have been obtained by reacting TiCl₄, VOCl₃, MoOCl₄, WOCl₄, or AlCl₃, with Be, Mg, Ca, or Sr chlorides in the presence of electron donors such as POCl₃ (L) or C₆H₅POCl₂, (L′). The resulting products, obtained with good yield, show defined stoichimetry, ionic character, and crystalline structure, and may be considered reference systems for high-yield catalysts in the low-pressure polymerization of ethylene (HDPE). Complexes (TiCl₆)MgL₆, (TiCl₅L′)₂ MgL′₆, and (Ti₂Cl₁₀)MgL₆ associated with (i-C₄H₉)₃Al were found very active in HDPE synthesis, but completely unable to polymerize propylene. This result and other evidence suggest that part of the catalytic activity of these systems is displayed by soluble species. The role played by the Mg ion in high-yield catalysts is displayed by soluble species. The role played by the Mg ion in high-yield catalysts is discussed in the light of the peculiar behavior shown by the complex chlorides containing this earth-alkali metal.     

Kinetics of ethylene polymerization over supported TiCl4SiO2 Ziegler catalyst modified with binary metal chlorides

The polymerization of ethylene over metal chloride-exchanged silica-gel has been studied. Basic, amphoteric and electropositive metals on the surface of the silica-gel were found to promote the polymerization reaction. I.r., e.s.r. and kinetic studies suggest that the active sites were highly dispersed in a solid solution of TiCl₃ and MCl₂ formed from the supporting TiCl₄. The influence of polymerization time, temperature and pressure on the polymerization rate were also investigated.     

Active centers of TiCl3 catalysts for propene polymerization

Summary Publications reporting numbers of active centers in TiCl₃ propylene polymerization catalysts are very contradictory. Experimental data from the beginning of the sixties are reevaluated by the author. It is concluded that TiCl₃-catalysts from the Hoechst type (and probably from the Stauffer AA-type) have, after an initial period of polymerization, numbers of active centers in the range of percentage of total TiCl₃. This value increases with temperature. By cooling during polymerization some metal polymer bonds, probably active centers, disappear.Conversion versus time and molecular weight versus conversion for propene polymerization     

Novel polyaryletherketones containing various pendant groups. I. Synthesis and characterization

Novel high glass transition temperature polyaryletherketones, containing pendant amido, alkyl, and carboxyl groups with reduced viscosity above 0.54 dL/g, were synthesized via solution nucleophilic polycondensation reaction of phenolphthalin, 2′,2′-diisopropyl-5′,5′-dimethylphenolphthalin, and 3,3′-bis (4-hydroxyphenyl) isobenzopyrrolidone with bis(4-nitrophenyl)ketone in the presence of potassium carbonate. By ion exchange with Na⁺ and K⁺, four ionomers were also prepared. A new monomer simultaneously containing carboxyl and alkyl substituents was synthesized by reduction reaction of 2′,2′-diisopropyl-5′,5′-dimethyl-phenolphthalein. The resulting polymers were soluble in a few polar aprotic solvents; transparent, colorless, and tough films could easily be cast from DMF or DMSO solution. The mechanical properties of the films were excellent; and their tensile strength, elongation at break, and tensile moduli were in the range of 67.1–97.1 MPa, 7.8–165%, and 1.47–2.27 GPa, respectively. The prepared polymers showed fairly good thermal stability and resonably high glass transition temperatures above 210°C. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1127–1135, 1997     

Novel nickel(II)-based catalysts for the polymerization of ethylene

A series of Ni(II)-based bidentate -diimine complexes bearing two alkyl (alkyl = methyl, ethyl and isopropyl) substituents on each imine aryl group were studied as precatalysts for the polymerization of ethylene. These new catalysts were observed to show high activity in combination with methyl aluminoxane (MAO) and produced high molecular weight polyethylenes. The effects of the steric bulk of ortho-aryl substituents of the ligand on the catalytic activity and the resulting polyethylene microstructure were investigated. Kinetics of polymerization was also studied by changing important parameters such as temperature and MAO concentration. The polymerization activity, polymer molecular weight and resulting polymer microstructure were drastically changed according to the catalyst structure modification and polymerization parameters.     

Kinetic study for the decay rate of ethylene polymerization catalyzed over silica supported TiCl4/MgCl2 catalysts

The kinetics for decay rate of ethylene polymerization catalyzed with TiCl₄/MgCI₂/Si0₂ has been investigated in the range of temperatures between 40 and 90°C and in the range of ethylene pressures between 4 and 12.4 atm. The decay of polymerization rale was fitted well by the type of first order decay. The decay rale constant caused by monomer could be expressed by k _d ^/′ = C ·[M]^−1/2. Some plausible speculations have been proposed on the deactivation mechanism caused by monomer. The activation energy for the deactivation reaction is 9.8 kcal/mole.     

新型树枝状镍系催化剂的合成、表征及催化乙烯聚合的性能

合成了一种含有强供电子、较大空间位阻的新型树枝状水杨醛亚胺配体及其镍配合物,利用1H NMR、元素分析、FT-IR、UV进行了表征。以配合物为催化剂,甲基铝氧烷（MAO）为助催化剂对乙烯齐聚反应进行了研究,详细考察了聚合反应温度、Al/Ni摩尔比、反应压力及时间对催化剂活性及产物分布的影响。结果表明,齐聚产物为不同碳链的烯烃,在温度为25℃、Al/Ni=500、压力为0.5MPa、时间为0.5h的条件下,树枝状催化剂的活性最高,达到4.93?105g/(mol Ni?h),C10～C18的含量为54.17%。     

Nanocapsules containing binary phase change material obtained via miniemulsion polymerization with reactive emulsifier: Synthesis,characterization, and application in fabric finishing

The nanocapsules containing n‐butyl stearate (BS) and n‐octadecane (C18) as binary phase change material and polyacrylate as shell were synthesized via miniemulsion polymerization using reactive emulsifier. The phase transition (change) temperatures and phase change enthalpies of the phase change material can be adjusted by regulating the composition of BS and C18. Moreover, the influences of emulsification method and reactive emulsifier dosage were studied. SEM and TEM analysis showed the nanocapsules were a spherical shape with core‐shell structure and the average size was about 170 nm. DSC and FT‐IR analysis indicated the binary phase change material was encapsulated with polyacrylate shell, and the fusing and crystallizing temperatures and latent heats of nanocapsules were determined as 26.07 °C and 24.85 °C, 56.89 J g^?1 and 54.02 J g^?1 respectively, and the encapsulation efficiency was above 55.09%. In addition, the results of thermoregulating and durability property revealed that the finished cotton fabric had temperature‐regulated and durability properties. POLYM. ENG. SCI., 59:E42–E51, 2019. © 2018 Society of Plastics Engineers     

Synthesis and characterization of low- and medium-molecular-weight hyperbranched polyethylenes by chain walking ethylene polymerization with Pd-diimine catalysts

We report in this article the synthesis and characterization of a range of hyperbranched polyethylenes having various low and medium molecular weights by chain walking ethylene polymerization with Pd-diimine catalysts of reduced ligand steric crowdedness, which are intended for potential applications as novel synthetic base stocks. Four Pd-diimine catalysts featured with different ligand crowdedness, ([(RC₆H₃NC(R′)-C(R′)NC₆H₃R)Pd(CH₃) (NCMe)]SbF₆) (1, R = 2,6-(iPr)₂, R′ = CH₃; 2, R = CH₃, R′ = H; 3, R = 2,6-(iPr)₂, R′ = H; 4, R = CH₃, R′ = CH₃), were employed herein for ethylene polymerizations at different conditions. Generally, reducing ligand steric crowdedness (in the order 1 > 4 > 3 > 2) leads to decreased catalyst activity and dramatically reduced polymer molecular weight. As opposed to high-molecular-weight polymers (weight-average molecular weight (M_w): about 150 kg/mol) obtained with catalyst 1, low-molecular-weight polymers (M_w: below 1.0 kg/mol) were obtained with 2 and 3, and medium-molecular-weight polymers (M_w: about 25 kg/mol) were produced with 4. Despite their various reduced molecular weights, the polymers are all featured with highly branched chain structures with a total branching density of above 100 branches per 1000 carbons. The low- and medium-molecular-weight hyperbranched polymers synthesized with 2-4 display good potential for applications as synthetic base stocks. In comparison with three commercial poly(α-olefin) based synthetic base stocks, they exhibit similar thermal and viscosity properties. Meanwhile, it is also discovered that a subsequent one-pot hydrogenation step can be incorporated in the process after the Pd-diimine catalyzed polymerization step to render nearly fully saturated hyperbranched polymers without the use of additional hydrogenation catalysts.     

Synthesis and activity of zirconocene catalysts supported on silica-type sol-gel carrier for ethylene polymerization

Summary Synthesis and activity of bis(cyclopentadienyl)zirconium dichloride catalyst supported on unconventional silica-type material obtained in sol-gel process and activated by organoaluminium co-catalyst were studied. The effect of support modification conditions (thermal dehydration and/or modification by organoaluminium compound) and a type of co-catalyst on an activity of the catalytic system in ethylene polymerization and properties of resulting polymers were investigated and compared with results obtained earlier for vanadium catalysts supported on mentioned sol-gel carrier. The most appropriate method of the sol-gel silica-type support preparation is thermal pre-treating (200°C) followed by modification with AlEt₂Cl. Metallocene catalyst supported on such sol-gel product and activated by MAO appeared to be most active among studied systems. Studied Cp₂ZrCl₂/MAO supported on silica-type sol-gel carrier allow to obtain polyethylene (at 50°C polymerization temperature) with yield up to 30·10⁶ g/(mol_Zr·h), molecular weight below 300 000 and MWD=2−4. Received: 4 September 2000/Revised version: 3 January 2001/Accepted: 3 January 2001     

Synthesis and characterization of telechelic polymers obtained by micellar polymerization

Summary The synthesis, characterization and rheological properties in aqueous solution of two telechelic polymers of different structures and size are reported: they are water soluble polyacrylamides, hydrophobically modified with linear and di-substituted hydrophobic initiators. The polymers were prepared via free radical micellar polymerization. The results of static light scattering (SLS), showed similar weight-average molecular weights (M_w) in all of the synthesized polymers. No signal corresponding to the presence of the hydrophobic group of the initiator could be observed by ¹H NMR; however, the presence of these hydrophobic groups was demonstrated using rheological measurements.     

Synthesis and characterization of first‐ and second‐generation polyamide pyridylimine nickel dihalide metallodendrimers and their uses as catalysts for ethylene polymerization

First‐ and second‐generation pyridylimine‐terminated dendrimeric ligands were prepared by the reaction of the corresponding amine‐terminated aromatic polyamide dendrimers with 2‐acetylpyridine. The pyridylimine terminal groups were used as bidentate N,N ligands of nickel halide to prepare the corresponding first‐generation and second‐generation nickel dihalide metallodendrimers C1 and C2 , respectively. The synthesized dendrimers and metallodendrimers were characterized by elemental and spectral analyses. C1 and C2 were evaluated as catalyst precursors for ethylene oligomerization after being activated with methylaluminoxane (MAO) and diethylaluminum chloride (Et₂AlCl) under 1 atm and 5 atm pressure of ethylene. In both cases, the use of 1 atm or 5 atm pressure of ethylene and a 1500:1 Al:Ni molar ratio for C1 and C2 resulted in high catalytic activities toward ethylene polymerization. Upon activation with MAO and Et₂AlCl, C1 exhibited promising activities toward ethylene polymerization and produced linear chain structures that were associated with high density polyethylene. In contrast, C2 produced a polymer with the branching nature of low density polyethylene under similar conditions. © 2014 Society of Chemical Industry     

Preparation of soluble TiCl3 catalysts by reduction of TiCl4 with Grignard reagents and their use for copolymerization of ethylene with propylene

Summary Preparations of soluble TiCl₃ catalysts by reduction of TiCl₄ with some types of Grignard reagents were carried out in halogenated hydrocarbon solvents by using appropriate ethers as donor. The soluble TiCl₃·MgX₂·ether complex catalysts and triisobutylaluminum as co-catalyst showed high activities for the copolymerization of ethylene with propylene. It was first found that the soluble TiCl₃·MgX₂·ether complex catalysts enhance the activities for the copolymerizations in the same manner as solid titanium catalysts supported on MgCl₂ which show high activities for homopolymerizations of olefin monomers. The copolymers obtained possessed low crystallinities. Also, the copolymers seem to contain microblock sequences and have outstandingly high tensile strength and elongation at break compared to copolymers by the conventional VOCl₃/Al(Et)_1.5Cl_1.5 catalyst system.     

Particle control of Ziegler–Natta catalysts based on TiCl3 for propylene polymerization. Effect of prepolymerization

Prepolymerizations employing an extremely high stereospecific and high active catalyst based on TiCl₃ modified by di-n-butyl ether (DBE) were carried out with different monomers (styrene, propylene, hexene-1, cyclopentadiene). The influence of prepolymerization on the morphology of polypropylene obtained with TiCl₃ catalyst was investigated. The catalyst was synthesized by TiCl₄ reduction in toluene solution with A1Et₃·DBE complex. The polymer morphology was evaluated through optical and scanning electron microscopies and polymer bulk density and particle size distribution. © 1994 John Wiley & Sons, Inc.     

A structural model for the catalytic polymerization of ethylene using chromium catalysts. Part I: Description and solution

A mathematical model for the polymerization of ethylene using silica-supported chromium catalysts is presented. The fundamentals for the physical and chemical representation of the phenomenon are detailed. The emerging mathematical problem is attached and solved using a multiple moving-boundary numerical scheme. Predictions are made using the model for the cases of low and high activity catalysts tested by experiments, and the results used to evaluate the model. The main feature of the model is its structural nature: catalyst characterization and morphology data are used to create a physical scheme that does not require the assumptions concerning particle geometry, usually made in models. The initial catalyst fragmentation process is modeled using a pore-structure scheme based upon porosimetry data. The whole fragmentation sequence is treated as a set of steps that follow the actual rupture process of the initial solid into fragments with irregular shapes. Parameters are evaluated from data for the initial support, and time evolution is followed using a realistic interpretation of the pore filling process. A novel application of moving-boundary solution techniques permits a relatively simple mathematical scheme to handle the transport and reaction processes that take place in the polymerizing particle. Only the results obtained for the experimental laboratory conditions are analyzed. In subsequent parts, the case of thermal effects typical of industrial conditions will be discussed. The results obtained are in excellent agreement with the experimental data.     

Preparation,characterization and testing of Cr/AlSBA-15 ethylene polymerization catalysts

Ethylene polymerization catalysts have been prepared by grafting chromium(III) acetylacetonate onto AlSBA-15 (Si/Al = ∞, 156, 86 and 30) mesoporous materials. A combination of XRD, nitrogen adsorption, TEM, ICP-atomic emission spectroscopy, H₂-TPR, TGA, UV–vis and FT-IR spectroscopy, were used to characterize the prepared Cr–AlSBA-15 catalysts. By reducing the Si/Al ratio of the AlSBA-15 supports increases the amount of chromium anchored, promotes the stabilization of chromium species as chromate and decreases the reduction temperature of Cr⁶⁺ ions determined by H₂-TPR. Attachment of Cr species onto AlSBA-15 surface results from the interaction of hydroxyl groups with the acetylacetonate ligands through H-bonds. On the contrary, a ligand exchange reaction may occur over siliceous SBA-15.The polymerization activity of Cr–AlSBA-15 catalysts is significantly improved by increasing aluminium content of the AlSBA-15 supports. Particularly, the chromium catalyst prepared with AlSBA-15 (Si/Al = 30) support is almost four times more active than a conventional Cr/SiO₂ Phillips catalyst. Polymers obtained with all the catalysts showed melting temperatures, bulk densities and high load melt indexes indicating the formation of linear high-density polyethylene.     

The influence of aluminum alkyls on the polymerization of ethylene with SiO2/MgCl2-supported TiCl4 catalysts

The influence of different aluminum alkyls (diethylaluminum chloride, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum and isoprenylaluminum) on the ethylene polymerization activity of a laboratory prepared high-activity SiO₂/MgCl₂-supported TiCl₄ catalyst has been investigated. A slurry reactor (decane diluent) was used for measuring rates of polymerization. The average molar mass, the breadth of the molar mass distribution, the polymerization activity, and the shapes of the activity-time profiles, were strongly dependent on the nature of the aluminum alkyl. For several of the cocatalysts used, the catalytic activity approached a constant value after a certain amount of time under reaction conditions. In this constant activity region, a first-order dependence of the polymerization rate on the monomer concentration was found for all of the systems examined. However, the activation energy of the polymerization reaction was found to depend strongly on the type of cocatalyst which was used.