Preparation of Poly(1,6-Hexanediol) Carbonate Diols Catalyzed by Ti(OBu)_4
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Poly(1,6-hexanediol) carbonate diols (PCDL) was synthesized using 1,6-hexanediol (HDO) and diethyl carbonate(DEC) in the presence of Ti(OBu)4 as catalyst. The polymerization reaction was carried out in a two-stage process,including atmospheric pressure and vacuum. All reaction conditions were investigated based on Ti(OBu)4. The experiment results show that it exhibits the best catalytic activity with Ti(OBu)4 accounting for 0.05 weight percent of HDO. PCDL of expected number average molecular weight is prepared rapidly with raising the reaction temperature. It is available for controlling the molecular weight and polydispersity of PCDL to alter the vacuum time. The characters of PCDL were determined by Fourier transform infrared spectrum(FT-IR),1H nuclear magnetic resonance spectrum(1H-NMR),gel permeation in chromatography(GPC) and differential scanning calorimetry (DSC). It is concluded that Ti(OBu)4 is evidenced to be an effective catalyst for transesterification. The possible reaction mechanism of Ti(OBu)4 was offered.Keywords:
Dispersity
Gel permeation chromatography
Molar mass distribution
Diethyl carbonate
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Poly(L-lactic acid) (PLLA) was produced by the melt polycondensation of L-lactic acid. For the optimization of the reaction conditions, various catalyst systems were examined at different temperature and reaction times. It was discovered that Sn(II) catalysts activated by various proton acids can produce high molecular weight PLLA [weight-average molecular weight (Mw ) ≥ 100,000] in a relatively short reaction time (≤15 h) compared with simple Sn(II)-based catalysts (SnO, SnCl2 · 2H2O), which produce PLLA with an Mw of less than 30,000 after 20 h. The new catalyst system is also superior to the conventional systems in regard to racemization and discoloration of the resultant polymer. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1673–1679, 2000
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Abstract In this paper we report the employment of Ti(acac) 2 (O‐ i Pr) 2 (titanium bisacetylacetonate diisopropylate) as a novel catalyst for the synthesis of poly(butylene terephthalate) (PBT). Large scale synthesis of several polymers with the new catalytic system and with the standard catalyst Ti(O‐ n Bu) 4 (titanium tetra‐ n ‐butylate) have been performed in a 20 L pilot plant. In the optimized reaction conditions, Ti(acac) 2 (O‐ i Pr) 2 has shown significantly higher activity than standard catalyst, Ti(O‐ n Bu) 4. Furthermore, a stabilized PBT has been synthesized in the presence of Ti(O‐ n Bu) 4 as catalyst with the addition of the stabilizer U626. Then, the stability of the synthesized polymers toward thermo‐oxidation has been tested in a forced circulating air oven. The polymers obtained in the presence of Ti(acac) 2 (O‐ i Pr) 2 system showed higher stability towards thermo‐oxidation than stabilized and not stabilized PBT, synthesized in the presence of Ti(O‐ n Bu) 4 . © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Stabilizer (aeronautics)
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Abstract Copolymerization of styrene and 1‐butene was first conducted at 50°C with a novel Ti catalyst by using Al(iBu) 3 (iBu = isobutyl) as cocatalyst. The Ti catalyst is composed of MgCl 2 /TiCl 4 /PhCOOEt/Ph 2 SiCl 2 /SiCl 4 /NdCl x (OR) y /Al(iBu) 3 (assigned as SN‐1 catalyst), which gave mixtures of poly(1‐butene), polystyrene, and a copolymer of both monomers. The catalytic efficiency is 1 200 ‐ 4 000 g p /(g Ti · h). The monomer reactivity ratios were estimated to be r s = 0.47 and r b = 29.1. The polymers produced were fractionated successively, and a styrene‐1‐butene copolymer was obtained which was characterized in detail.
Polystyrene
Reactivity
1-Butene
Butene
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The high molecular weight poly(L-lactic acid)was synthesized from L-lactic acid by means of melt polycondensation with the improved process of dehydration,catalyst and lactide reflux.The influences of the OLLA,apparatus,catalysts,temperature and time of polymerrization on the molecular weight,yield and color of the products were discussed.The Molecular structure of the products was also characterized.After the(improvement) of apparatus,taking Sn(Ot)_2/SnCl_2·2H_2O/TSA as the catalyst and polymerized at 170℃for 12 h,the viscosity average molecular weight(M_η) and the yield of PLLA reached 10.6×10~4 and 76% respectively.
Lactide
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Molecular mass
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Abstract Highly active catalysts for copolymerization have been prepared by the precipitation of MgCl 2 /ToCl 4 complex with or without high surface area silica. Copolymerization of ethylene and 1‐butene has been tested by using the prepared catalysts at various concentrations of 1‐butene. The catalytic activities are 20–80 kg/g Ti h. The rate of copolymerization is strongly affected by the addition of 1‐butene. The decay rate of copolymerization is first order with respect to time. Analyses of copolymers with solvent extraction, DSC, IR, XRD, and NMR were performed. Ethylene reactivity ratio ( k 11 ) for TiCl 4 /MgCl 2 /THF catalyst is calculated to be about 26 by NMR spectrum. © 1994 John Wiley & Sons, Inc.
1-Butene
Butene
Reactivity
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Abstract Bis(hexamethylene carbonate) (HC) and bis(2,2,3,3,4,4,5,5‐octafluorohexamethylene carbonate) (FHC) were synthesized starting from the corresponding diols and diphenyl carbonate in a two‐step reaction: (i) first polycondensation occurs, (ii) then ring‐closing depolymerization leads to HC and FHC, respectively. The polymerization of HC is performed with sec ‐butyllithium in toluene solution, and the corresponding polymer is obtained in high yield. Polymerization of FHC is perfomed either in tetrahydrofuran solution with dibutylmagnesium as initiator or in the melt with dibutyltin dimethoxide as initiator. Poly(HC) is a semicrystalline polymer with a melting point of 54.0°C and a glass transition temperature of −51.3°C. Poly(FHC) was obtained either as a semicrystalline material with a melting point of 40.8°C or an amorphous material with a glass transition temperature of −39.8°C. Copolymers of HC and FHC with a diad ratio of 19:60:21 were obtained by melt polymerization with dibutyltin dimethoxide as initiator. The ringchain equilibrium established during polymerization was studied for HC in toluene solution and for FHC in the melt. The concentration of the cyclic oligomers at equilibrium was determined, and for poly(HC) the characteristic ratio was calculated to be 10.0 ± 1.0.
Trimethylene carbonate
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L-Lactide Ring-Opening Polymerization with Tris(acetylacetonate) Titanium(IV) for Renewable Material
A new Ti-type of catalyst for L-lactide polymerization was synthesized by reaction of titanium(IV) isopropoxide (TTIP) with acetylacetone (AA). Moreover, PLA was prepared by the bulk ring-opening polymerization using synthesized Ti catalyst. Polymerization behaviors were examined depending on monomer/catalyst molar ratio, polymerization temperature and time. The structure of synthesized catalysts was verified with FT-IR and 1H NMR and the properties of poly(L-lactide) (PLLA) were examined by GPC, DSC and FT-IR. There existed about 30 minutes of induction time at the monomer/catalyst molar ratio of 300. The molecular weight (MW) increased as monomer/catalyst molar ratio increased. The MW increased almost linearly as polymerization progressed. Increasing polymerization temperature increased the molecular weight of PLLA as well as monomer/catalyst molar ratio. The melting point (T(m)) of polymers was in the range of 142 to 167 degrees C. Lower T(m) was expected to be resulted from relatively lower molecular weight.
Coordination polymerization
Molar mass distribution
Chain-growth polymerization
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The polymerization of isoprene with supported titanium catalyst modified by n-octanol was carried out.The effect of levels of catalyst,Al(i-Bu)_3 and temperature on polymerization was studied.The structure and crystalline morphology of polyisoprenes were characterized with ((~1 )H)-NMR and DSC.The experimental results showed that the optimum catalyst efficiency was obtained at n(Ti)/n(Ip)=5×10~(-4)∶1,n(Al)/n(Ti)=50∶1,temperature 60?℃.The relative molecular weight of the polymers decreased with the increasing levels of catalyst.And the effect of levels of Al(i-Bu)_3 and temperature on the relative molecular weight was typically the same as the effect on catalyst activity.The mass fraction of 3,4-units of polyisoprene was 26.8%,trans-1,4-units 73.2%;and the melting point and crystalline contents were lower than TPI.
Isoprene
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Molar mass distribution
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The alumina supported heteropoly-acid catalysts were prepared and used in the polymerization of THF in the presence of epichlorohydrin(ECH) to obtained the poly-tetrahydrofuran(PTHF) containing ECH moieties.The effects of the preparation conditions,the dosage of ECH and reaction temperature on the yield and number-average molecular mass of PTHF were investigated as well.The reaction results indicated that the acid amount corresponding to +0.8H_0≤+3.3 on catalysts related to the yield of PTHF with the number-average molecular mass in the range of 700-3000 with narrow distribution M_w/M_n2.0,that is,the more the acid amount of +0.8H_0≤+3.3,the higher the yield of PTHF. The optimal reaction conditions were n(ECH)/n(THF)=0.12,the reaction temperature of 50℃,the reaction time of 4 h and the catalyst with a 35%(mass fraction) loading of heteropoly-acids.
Epichlorohydrin
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Tetrahydrofuran
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