Abstract  To study the surface structure of MgCl(2) support and its interaction with other active components in Ziegler-Natta catalyst, such as electron donors, we prepared a thin film analogue for Ziegler-Natta ethylene polymerization catalyst support by spin-coating a solution of MgCl(2) in ethanol, optionally containing a diester internal donor (diisobutyl-ortho-phthalate, DIBP) on a flat Si crystal surface. The donor content of these films was quantified by applying attenuated total internal reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). Changes in the interaction of DIBP with MgCl(2) at various temperatures were monitored by in situ ATR-FTIR. Upon increasing the temperature, a shift in the (C═O) band toward lower wavenumbers was observed together with the depletion of (O-H) stretching band due to the desorption of residual ethanol. We assign this shift to gradual redistribution of adsorbed DIBP from adsorption sites on the MgCl(2) (104) surface toward the more acidic MgCl(2) (110) surface. The morphologies of MgCl(2) and MgCl(2)/DIBP films were studied by transmission electron microscopy (TEM) revealing a preferential orientation of ClMgCl layers (001) parallel to the lateral film dimensions. This orientation becomes more pronounced upon annealing. In the absence of donor, the MgCl(2) grow in to large crystals aligned in large domains upon annealing. Both crystal growth and alignment is impeded by the presence of donor.

Abstract  CH-type catalysts were prepared by reacting MgC12.ROH, where ROH was 2-ethylhexanol(EH), (R)-2-octanol(R-2O) and (S)-2-octanol(S-2O), with titanium tetrachloride in the presence of diisobutyl phthalate (BP) , diisobutyl terephthalate(BT), (-)-dimenthyl phthalate(MP) or (-) -dimenthyl terephthalate(MT). The CH(EH,BP) catalyst was found to be five times more active than the CH(EH,MT) catalysts and to produce PP which was 97% isotactic, as compared with 84.7% for the latter. The catalysts derived from 2-octanols were much less active than the corresponding catalysts prepared with EH due to lack of reactivity with phthalic anhydride which permitted excessive incorporation of titanium tetrachloride to form non-stereospecific catalytic sites as well as inactive Ti species. 11 refs.

Abstract  The effect of internal and external bases on the copolymerisation of propylene with 1-butene was investigated. Catalytic systems used were magnesium chloride/titanium tetrachloride-triethylaluminium, magnesium chloride/titanium tetrachloride-triethylaluminium/tetramethylpiperidine(TMP), magnesium chloride/titanium tetrachloride-triethylaluminium /triethoxyphenylsilane(TPS), magnesium chloride/diisobutyl phthalate(DIBP)/titanium tetrachloride-triethylaluminium/TMP and magnesium chloride/DIBP/titanium tetrachloride-triethylaluminium /TPS. A series of copolymers of different compositions was produced using each catalytic system and the copolymers obtained were fractionated by sequential extraction with boiling solvents and the fractions characterised by means of carbon-13 NMR. The effect of the Lewis bases on the fraction distribution and on composition and the number-average sequence lengths of all fractions were analysed. 15 refs.

Abstract  The effects of ethers alone and in combination with alkoxysilanes as external donors on propylene polymerisation carried out in the presence of a MgCl"2/TiCl"4/diisobutyl phthalate catalyst system were investigated. It was found that ethers alone did not improve the isotacticity of PP but a combination of the ethers with an alkoxysilane resulted in increased propylene polymerisation activity and isotacticity index but a decrease in melting temperature and melting enthalpy of polypropylene. An analysis of active centre distribution by deconvolution of the MWD curves showed that the ether/silane combinations increased the activity of the active centres and provided PP with medium molecular weight. 22 refs.

Abstract  Supported titanium catalysts were prepared by chlorination of magnesium stearate with silicon tetrachloride or titanium tetrachloride, followed by treatment of the product with diisobutyl phthalate and titanium tetrachloride. The catalysts were used for the polymerisation of propylene and their productivity and isospecificity were examined. 10 refs.

Abstract  The effects of injecting ethylene, propylene, 1-hexene, 2-methylpropene, 3,3-dimethyl-1-butene, cis-2-butene, trans-2-butene, 2,3-dimethyl-2-butene, cyclopentene, styrene, 1,3-butadiene and 1,4-pentadiene during polymerisations of ethylene and propylene were investigated. Catalysts used were a supported magnesium chloride/ethyl benzoate/titanium tetrachloride ballmilled catalyst and precipitated magnesium chloride /2-ethylhexanol/titanium tetrachloride/diisobutyl phthalate catalysts activated with triethylaluminium in the presence of ethyl benzoate. The instantaneous polymerisation rate was observed by continuous monitoring of the monomer consumption, the time resolution of the measurements being less than one second. 40 refs.

Abstract  11 refs.

Abstract  Carbon-13 NMR analysis of PP fractions of differing tacticities, obtained using a catalyst system involving magnesium chloride /titanium tetrachloride/diisobutyl phthalate-triethylaluminium-diether, provided further evidence that the active species in this system were similar to those in which the ether was used as an 'internal' rather than 'external' donor. Chain-end analysis of relatively low molec.wt. polymer fractions indicated, for polymers of similar molec.wt., similar proportions of butyl-terminated chain-ends, indicative of chain transfer with hydrogen following regioirregular (2,1-) insertion. The relatively high hydrogen response of diether-containing catalyst systems could, therefore, be largely ascribed to this phenomenon, irrespective of whether the diether was used as internal or external donor. At relatively low hydrogen concentrations, chain transfer to hydrogen took place predominantly after the occasional secondary insertion, while the additional presence of vinylidene chain ends in certain xylene-soluble fractions indicated that chain transfer via beta-H transfer took place mainly after primary insertion. 17 refs.

Abstract  Active centre determinations for Ziegler-Natta catalysts for propylene polymerisation were made by quenching the polymerisation with tritiated ethanol, and subjecting the polymers to radiochemical analysis. The objective was to investigate the high activities of the catalyst system of magnesium chloride and titanium tetrachloride with a diether, 9,9-bis(methoxymethyl)fluorene, as internal catalyst, by comparing the performance with that obtained using a phthalate ester, diisobutyl phthalate, as internal catalyst. Triethyl aluminium was used as the co-catalyst. Active centre contents were 2-8% of the total Ti present, and there was good correlation between the catalyst activity and activity centre content. It was proposed that the high activity of diether-containing catalysts was due to the increased proportion of active centres rather than to a difference in propagation rate coefficients. 30 refs.

Abstract  Using triisobutylaluminium as the cocatalyst and diethyl zinc as the chain transfer agent in ethylene/1-hexene copolymerisation carried out with a Ziegler-Natta catalyst (magnesium chloride/titanium tetrachloride/diisobutyl phthalate) resulted in significantly higher comonomer incorporation than was obtained when triethylaluminium was used with diethyl zinc. However, using 2,6-dimethylpyridine as an external donor in this system had relatively little effect on the comonomer incorporation and distribution. The results were discussed. 24 refs.

Abstract  A MgCl2-supported catalyst containing diisobutyl phthalate (DIBP) and 2,4-pentadiol dibenzoate (PDDB) as internal donors was prepared. Propylene polymerizations were carried out using the catalyst in the absence or presence of an external donor. The resulting polymers were characterized by C-13-NMR, crystallization analysis fraction (CRYSTAF) and gel permeation chromatography (GPC). The performance of the catalyst was compared with that of other catalysts containing donor-free, DIBP and PDDB as internal donors respectively. The results demonstrated that the catalyst containing mixed internal donors not only had high activity and stereospecificity but also produced the polymer with relatively broad molecular weight distribution and the highest [mmmm] value. C-13-NMR analysis results indicated that strongly coordinating donors gave more stereoregular polymers, which was further confirmed by CRYSTAF data. The effects of mixed internal donors on the catalyst properties were discussed systematically. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120: 36-42, 2011

Abstract  Two different monoethers, CH3CH2CH2CH2OCH3 (NBME) and (CH3)(2)CHCH2-OCH3 (IBME), and Ph2Si(OCH3)(2) were used as external donors in propylene polymerization using MgCl2/TiCl4/DIBP catalyst (DIBP: diisobutyl phthalate) activated by triethylaluminium (TEA). The monoethers alone showed no improvement in the isotacticity index of polypropylene (PP). When one of the ethers and Ph2Si(OCH3)(2) were added together in the polymerization system as composite external donors, the propylene polymerization activity and isotacticity index were increased as compared to those of the systems with only silane as external donor, though the melting temperature and melting enthalpy of PP decreased. The effects of the external donors on the active center distribution of the catalyst system are demonstrated by deconvolution analysis of the PP molecular weight distribution into multiple Flory components, and the mechanism of external donor regulation effects is discussed. All the results show that adding monoether in MgCl2/TiCl4/DIBP-TEA/silane catalyst system can reduce the stereoregularity of the isotactic chains of the polymer while, it maintains the atactic PP fractions at a very low level.

Abstract  Prediction of reaction yield as the most important characteristic process of a slurry polymerization industrial process of propylene has been carried out. Stacked neural network as an effective method for modeling of inherently complex and nonlinear systems-especially a system with a limited number of experimental data points-was chosen for yield prediction. Also, effect of operational parameters on propylene polymerization yield was modeled by the use of this method. The catalyst system was Mg(OEt)(2)/DIBP/TiCl(4)/PTES/AlEt(3), where Mg(OEt)(2), DIBP (diisobutyl phthalate), TiCl(4), PTES (phenyl triethoxy silane), and triethyl aluminum (AlEt(3)) (TEAl) were employed as support, internal electron donor (ID), catalyst precursor, external electron donor (ED), and co-catalyst, respectively. The experimental results confirmed the validity of the proposed model. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 116: 1237-1246, 2010

Abstract  A model was derived for the glass transition temperature of plasticised polymers with up to 30% plasticiser by weight. The model was derived from the Sanchez-Lacombe equation of state and the Gibbs-DiMarzio criterion which states that the total system entropy is zero at the glass transition. The model was compared with empirical results for the glass transitions and efficiency parameters for polyvinyl chloride (PVC) plasticised with various dialkyl phthalates and polystyrene (PVC) plasticised with various aliphatic esters and non-polar solvents. It was discovered that the plasticiser efficiency parameter is parabolic with respect to the plasticiser molecular weight for PVC/phthalate and PS/ester systems. 34 refs.

Abstract  Two new ethers were synthesized using the Williamson reaction from related alcohols and were used as external donors in propylene polymerization in the presence of the industrial diisobutyl phthalate-based MgCl2-supported Ziegler-Natta catalyst. For comparison the propylene polymerization was carried out in the presence of silane and in the absence of external donors. The produced polymers were characterized by differential scanning calorimetry, xylene extraction, melt flow index, scanning electron microscopy and gel permeation chromatography. The isotacticity, molecular weight and molecular weight distribution, melt flow index, crystallinity degree and thermal properties of polypropylenes were influenced by the type of external donors.

Abstract  The role of two different internal donors [a phthalate (diisobutylphthalate) and a 1,3-diether (2,2-diisobutyl-1,3-dimethoxypropane)] on the formation of surface structure in MgCl2-supported Ziegler-Natta catalysts and their catalytic performance of propylene polymerization was investigated by comparing and correlating the catalyst structures and the polymerization characteristics. In the catalyst formation, the 1,3-diether had better affinity for the MgCl2 surface than the phthalate and the 1,3-diether generated the (110) surface more than the (104) surface while the phthalate generated both the (110) and (104) surfaces of MgCl2. With both donors introduced, the (110) and (104) surfaces were generated simultaneously, although the (110) surface was dominant due to the higher affinity via the 1,3-diether. In addition, it seemed probable that the active sites formed on the (110) plane showed isospecific characteristics in the presence of a donor while those formed on the (104) plane could be isospecific regardless of a donor. (c) 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40536.

Abstract  Ziegler-Natta catalysts supported on MgCl2 have been studied by CP-MAS (cross-polarization, magic-angle spinning) 13C NMR spectroscopy. The support was activated mechanically and chemically, and then treated with a monoester (ethyl benzoate) or a diester (diisobutyl phthalate). Catalytic species were obtained by a treatment with TiCl4. Complexation and crystal disordering phenomena are clearly observed as changes in the chemical shifts and line broadenings. Line splittings were observed, especially for the diester due to nonequivalent crystal coordination sites. The diester shows a different behaviour compared to the monoester thus reflecting its better ability as a stereoselectivity-controlling agent. The titanation led to the formation of a new, estercontaining and ordered complex on the surface of the carrier. The mobility of the surface complexes is restricted, crystalline complexes being more constrained.

Abstract  An examination is made of the composition and activity of high yield magnesium chloride supported Ziegler-Natta catalysts for olefin polymerisation.

Abstract  The composition distribution (CD) and microisotacticity distribution (ID) of propene/1-hexene copolymer synthesised by MgCl2/DIBP/TiCl4 (DIBP:diisobutyl phthalate) are determined by fractionating the copolymers according to crystallinity and characterising the fractions by 13C NMR. The effects of two alkoxysilane donors, triethoxyphenylsilane (PTES) and dimethoxydi-tert-butylsilane (TBMS), on CD and ID of the copolymers are compared. Three main parts in the CD diagram of each copolymer are distinguished, which are correlated to active centre distribution (ACD) based on three groups of different active centres. By studying the changes in 1-hexene content, microisotacticity and reactivity ratio product of three typical fractions, the effects of external donor on ACD are better elucidated. It is found that TBMS shows much stronger effects on ACD than PTES. In the former system, most fractions are produced on active centres with relatively lower r1r2, higher reactivity to 1-hexene, and higher stereospecificity as compared to the system without external donor. It is concluded that the observed very extensive changes in ACD mainly result from the formation of new types of active centres, possibly by co-ordination of external donor to certain positions on the catalyst. 16 refs.

Abstract  The role of ethers in the synthesis of a highly active and stereospecific catalyst for propylene polymerisation was studied. Diisoamyl ether and THF were used as electron donors in the beta-titanium trichloride treatment during the three-step synthesis. Dibutyl ether was employed as a first internal base complexed with TiCl4 and Et2ClAl in isooctane solution in the one-step synthesis. The effects of ethyl benzoate, tributyl phosphate and diisobutyl phthalate as second internal bases on the crystalline modification, activity and stereospecificity of TiCl3 were also investigated. 9 refs.

Abstract  It is demonstrated that plasticisers such as phthalates could be replaced by soft copolymer emulsions in formulations of water-based packaging adhesives, without loss of properties, and for some combinations, synergistic effects with reference to setting speed, adhesion and heat resistance, could be observed. Combinations of suitable soft copolymers and hard VAE copolymers are tested. Six copolymer emulsions based on different monomer systems and with Tgs below 0 degrees C were selected. Blends were compared to the properties of an externally plasticised hard VAE emulsion using diisobutyl phthalate as the plasticiser.

Abstract  The effect of electron donors on the catalytic composition of the catalyst system (I) consisting of a soluble vanadium complex tris(2-methyl-1,3-butandionato)vanadium/diethyl aluminium chloride, with the aim of increasing the number of active sites was studied. The rate of formation of these sites was greatly accelerated by addition of an ester or ether, the effect being dependent on the electron donor oxygen atom charge density (as calculated by MOPAC). The maximum charge density activation occurred at a charge density of -0.34, irrespective of the type of donor oxygen. Analysis of the stereoregularity of the polymers obtained indicated that the additives had no effect on the nature of the active sites but did increase their number. 5 refs.

Abstract  Propylene was polymerised by a new generation of magnesium-supported Ziegler-Natta catalysts which contained dialkylpropane diethers as external donors. They were capable of producing highly active and stereospecific catalysts without any external donor. The behaviour of three different diethers (2,2-diisobutyl-1,3-dimethoxypropane, 2,2-dicyclopentyl-1,3-dimethoxypropane and 2-ethyl-2-butyl-1,3-dimethoxypropane) as internal donors was compared with the behaviour of the same diethers when they were used as external donors with a catalyst containing diisobutyl phthalate as internal donor. The results show that the same isospecific centres are produced when the same diether donor is present as an internal donor or replaces diisobutyl phthalate during polymerisation when it is added as an external donor. The present results are collated with previous results to provide conclusions on the role and reciprocal behaviour of internal and external donors. Isotacticity index and isotactic productivity data are shown. 29 refs.

Abstract  Polymerisation inhibition with radioactive carbon monoxide was used to determine the number of active centres and the propagation rate constant in the isospecific polymerisation of propene with the catalytic system titanium tetrachloride/diisobutyl phthalate /magnesium chloride-triethylaluminium-phenyltriethoxysilane. The presence of hydrogen decreased the number of active centres (by a factor of 2) and increased the propagation rate constant (by a factor of about 4). In the absence of hydrogen, a considerable part of the active centres (titanium-polymer bonds) reacting with the carbon-14 monoxide seemed to be inactive in the propene polymerisation for steric reasons. Hydrogen was able to transform such centres into an active state. Thus a propagation rate constant value of 2500 L/(mol s) at 70C for propene polymerisation in the presence of hydrogen seems to be correct, since the portion of centres in the active state is maximum. The influence of polymerisation time, external donors and internal donors on the number of active centres and the propagation rate constant was studied. 25 refs.