Polymerization of methyl methacrylate using bis(imine)cobalt, a polyolefin catalyst

A mono-nuclear catalyst of bis-imine cobalt (MC) was synthesized with using 2,6-dibenzhydryl-4-ethoxy phenyl as a ligand. The so huge ligand was prepared via the reaction of 2,6-dibenzhydryl-4-ethoxy phenyl)-N=(CH3)-C(CH3)=O with diacetyl with equal mole stoichiometry in presence of formic acid catalysis. The catalyst was synthesized via a reaction between the ligands and cobalt salt (CoCl2). The catalyst was used for polymerization of methyl methacrylate (MMA), (a polar monomer) in the presence of modified methylaluminoxane (MMAO). The highest polymerization activity (8.6 g PMMA/mmol cat. h) was obtained at [cocatalyst]/[catalyst]=1000:1 molar ratio and at room temperature reaction. For the prepared PMMA, Polymer with branching density of 263/1000C was obtained using 1H NMR technique calculation. The microstructure of one of the produced PMMA was as follow: 48% syndiotactic, 29% isotactic and 23% atactic. GPC analysis of the polymer showed a number average molecular weight of about 5.7 × 105 g/mol and a narrow molecular weight distribution of 1.57

Synthesis of high molecular weight polyethylene using FI catalyst

A FI Zr-based catalyst of bis[N-(3,5-dicumylsalicylidene)-2′,6′­diisopropylanilinato]zirconium(IV) dichloride was prepared and used for polymerization of ethylene. The effects of reaction conditions on the polymerization were examined in detail. The increase in ethylene pressure and rise in polymerization temperature up to 35 oC were favorable for catalyst/MAO to raise the catalytic activity as well as the viscosity-average molecular weight (Mv) of polyethylene. The activity of the catalyst was linearly increased with increasing MAO concentration and no optimum activity was observed in the range studied. Although introduction of the bulky cumyl and 2′,6′-diisopropyl alkyl substitution groups on ortho positions to the phenoxy-oxygen and on phenyl ring on the N, respectively enhanced the viscosity average molecular weight (Mv) of the obtained polymer strongly, diminished the activity of the catalyst. Neither the activity of the catalyst nor the (Mv) of the obtained polymer were sensitive to hydrogen concentration. However, higher amount of hydrogen could slightly increase the activity of the catalyst. The (Mv) of polyethylene ranged from 2.14×106 to 2.77×106 at the monomer pressure of 3 and 5 bar respectively which are much higher than that of the reported FI Zr-based catalysts

An Integrated AHP-PROMETHEE Method for Selecting the most Suitable Ethylene Propylene Diene Termonomer

This paper considers the problem of selecting the most appropriate ethylene propylene diene monomer (EPDM), which is a polyolefin with a variety of usages in different areas. The metallocene catalyst, bis(2-phenyl indenyl) zirconium dichloride ((2-PhInd)2ZrCl2) was synthesized by a modified method and applied to the terpolymerization of ethylene, propylene, and 5-ethylidiene-2-norbornene (ENB). The methylaluminoxane (MAO) was used as a cocatalyst. It showed an appropriate activity, a high incorporation ability of the comonomers, and good performance in terpolymerization. The compounded EPDM showed good thermal stability with time. Proper criteria were chosen for the selection of the best EPDM, and a hybrid of the analytical hierarchy process (AHP) and preference ranking organization method for enrichment evaluations (PROMETHEE) was used for prioritizing 15 different synthesized EPDM species. The sensitivity and Genetic Association Interaction Analysis (GAIA) analysis were also performed. Finally, one of the polymers, which had a very high quality and moderate yield, cost, and curing time was selected

Study of Ziegler-Natta/(2-PhInd)2ZrCl2 hybrid catalysts performance in slurry propylene polymerization

Several types of hybrid catalysts are made through mixing of 4th generation Ziegler-Natta (ZN) and (2-PhInd)2ZrCl2  metallocene catalysts using triethylaluminum (TEA) as coupling agent. Response surface methodology (RSM) is used to evaluate the interactive effects of different parameters including amounts of metallocene and TEA and temperature on metallocene loading. Analyzing the amounts of Al and Zr elements in the hybrid catalysts through ICP-OES and EDXA reveals that temperature plays a crucial role on anchoring of the metallocene catalyst on ZN while TEA has the least determining effect. The ICP analysis shows that as the concentration of Al goes up in the hybrid catalyst the concentration of Zr passes a maximum, while EDXA shows a direct relationship between the Al and Zr contents. Using triisobutylaluminum (TIBA) and methylaluminoxane (MAO) as the coupling agents, almost similar metallocene loadings are observed. Finally, the performance of hybrid catalysts is investigated in propylene polymerization and the obtained polymers are characterized using DSC and DMTA through which the presence of two types of polymers in the final product are confirmed

Comparison of Ethylene/1-Hexene Copolymers Microstructures Synthesized by Homogeneous and Heterogeneous Metallocene Catalysts

The substituted (bis-2-PhIndZrCl2) and non-substituted (bis-IndZrCl2) indenylbased metallocene catalysts were synthesized and used in homogenous and heterogeneous forms for copolymerization of ethylene and 1-hexene. The MCM-41 nano silica was used as support in heterogenization of the catalysts. The substituted (bis-2-PhIndZrCl2) metallocene catalyst in homogenous and heterogeneous forms showed lower activities in comparison to non-substituted (bis-IndZrCl2) metallocene catalyst. The microstructures of the obtained copolymers were investigated by techniques such as DSC, CNMR and TRRF. The kinetic study showed that the decay index (DI) was decreased for both homogeneous catalysts due to unstable kinetic behaviors. However, the decay index contents approached one, using heterogeneous forms of catalyst which was an indication of stable kinetic behaviors. The kinetic results also displayed negative effect on the catalysts activities both in the homogeneous and heterogeneous forms by addition of comonomer on the polymerization. The triad distributions of obtained polymer by NMR technique exhibited the higher ratio of EEH, EHE, EEE triads than the other triads. The comonomer incorporationacceptability of substituted metallocene catalyst (bis-2-PhIndZrCl2) was higher than non-substituted catalyst (bis-IndZrCl2) as its comonomer acceptability increased from 1.3% to 5.4% by substitution mechanism. Microstructures of copolymers obtained by supported metallocene catalyst showed more non-uniform comonomer distribution in comparison with unsupported catalyst. The lamella thickness distributions for polymer obtained by supported substituted metallocene catalyst (bis-2-PhIndZrCl2) were in the ranges (3-8 ). However, for supported metallocene non-substituted catalysts (bis-IndZrCl2) the lamella thickness were in the ranges (3-16 )

Effect of Polysulfone and Graphene Nanosheets on the Flexibility of Epoxy Coatings

Epoxy resin has remarkable properties including excellent mechanical and electrical properties, thermal and chemical stability, and resistance to creep. On the other side, these resins are brittle with low resistance toward crack initiation and its growth. In order to solve this problem, thermoplastic polysulfone and graphene nanosheets have been used as filler for improving the flexibility of epoxy coatings. The effect of adding different amounts (1, 0.5, 2.5, 5 wt%) of polysulfone and 0.5 wt% of graphene nanosheets on the epoxy properties was investigated by thermal analysis (DSC), tensile strength, impact resistance and determining the gel content of samples. The results showed that the tensile strength of epoxy resin increased by adding polysulfone, and the graphene nanosheets could improve flexibility of the sample containing 1 wt% polysulfone. The study of thermal properties of cured samples by means of DSC analysis showed that the addition of polysulfone into the epoxy network resulted in changing the glass transition (Tg) of the resin. With incorporation of graphene nanosheets into the polymer matrix, the modulus decreased due to the reduction in number of crosslinks. The study in impact resistance of the samples showed that those containing 1 wt% polysulfone and 0.5 wt% graphene displayed high strength and impact resistance. These types of compounds can be used in flexible and anticorrosion coatings

Polymerization of Ethylene Using α-Diimine Nickel Catalyst

The late transition metal catalysts based on end group of transition metals in the periodic table like Ni, Fe, Co, Pd, Pt were developed rapidly in polyolefin industrial productions. These metals with suitable ligands exhibited specific properties and appropriate activities in the production of polyolefins. These catalysts based on bulky bisimine ligands usually depend on the structures of the ligands and the ortho group position on the aryl ligands show very interesting behaviors in olefin polymerization. When these groups, located in the ortho positions of aryl ligands, become larger, it would have lesser chance in leading to β hydrogen elimination reactions. The ligand 1,4-bis (2,6-diisopropyl phenyl) acenaphthene was synthesized by reaction of 2,6- diisopropyl aniline and acenaphthene quinone. The synthesized ligand was then added on nickel (II) dibromide salt that produced the 1,4-bis(2,6-diisopropyl phenyl) acenaphthene nickel (II) dibromide catalyst. The structure of the catalyst was fully characterized by IR, NMR techniques. Ethylene polymerization was performed using the prepared catalyst and the effects of parameters such as, polymerization temperature, cocatalyst, to catalyst molar ratio and monomer pressure, were investigated. One of experimental design methods (Box Behnken) was used to minimize the number of tests. The highest activity of catalyst [1420 kgPE/molNih] was obtained at monomer pressure 5 atm, [Al]:[Ni] = 1000 and polymerization temperature of 25°C. Some of the produced polymers were characterized by DSC and 13CNMR. The branched structures with higher methyl branch contents were observed in some polyethylene products