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Eric Nield - One of the best experts on this subject based on the ideXlab platform.
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reactions induced by triphenyl phosphite addition during melt mixing of pet pbt blends chromatographic evidence of a molecular weight increase due to the creation of bonds of two different natures
Polymer, 1997Co-Authors: B Jacques, Jacques Devaux, Roger Legras, Eric NieldAbstract:A detailed chromatographic investigation has been carried out on the influence of triphenyl phosphite addition in molten poly(ethylene Terephthalate) or poly(ethylene Terephthalate)/poly(butylene Terephthalate) blends. The observed molecular weight evolution corresponds to torque and viscosity observations and fully confirms the occurrence of high temperature reactions between polyester and phosphite. The reaction mechanisms deduced from model compound studies are successfully applied to polymers. The formation of bonds of different types is verified: phosphite reactions with hydroxyl chain ends lead to the incorporation of significant quantities of phosphorus into the polyester backbone. A high sensitivity of these phosphorus containing links towards water, phenol or m-cresol has been observed. Subsequent carboxyl chain end attack on the phosphorus linkages leads to stable ester bonds. (C) 1997 Elsevier Science.
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reactions induced by triphenyl phosphite addition during melt mixing of poly ethylene Terephthalate poly butylene Terephthalate blends influence on polyester molecular structure and thermal behaviour
Polymer, 1996Co-Authors: B Jacques, Jacques Devaux, Roger Legras, Eric NieldAbstract:The influence of triphenyl phosphite addition in molten poly(ethylene Terephthalate) or poly(ethylene Terephthalate)/poly(butylene Terephthalate) blends has been investigated. Torque measurements during polyester processing and corresponding intrinsic viscosity values confirm an expected chain extension. Chromatographic results similarly indicate a molecular-weight increase. The precise nature of this chain extension mechanism is questioned. Chromatographic and calorimetric observations strongly suggest the formation of ester bonds and of bonds including phosphorus atoms. The enhanced reactivity of these new links towards phosphorous by-products or phenolic solvents at high temperature could explain the degradation observed in specific conditions.
Ramon Vicente - One of the best experts on this subject based on the ideXlab platform.
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five coordinate cobalt ii complexes of tris 2 pyridylmethyl amine tpa synthesis structural and magnetic characterization of a terephthalato bridged dinuclear cobalt ii complex
Inorganica Chimica Acta, 2008Co-Authors: Salah S Massoud, Franz A Mautner, Ramon Vicente, Kendra T Broussard, Manas K Saha, Ivan BernalAbstract:Abstract The cobalt(II) complexes [Co(TPA)Cl]ClO 4 ( 1 ), [Co(TPA)Br]ClO 4 ( 2 ), [Co(TPA)(H 2 O)]Cl(ClO 4 ) ( 3 ) and [Co 2 (TPA) 2 (μ-tp)](ClO 4 ) 2 · 2H 2 O ( 4 ) (TPA = tris(2-methylpyridyl)amine and tp = Terephthalate dianion) were synthesized and structurally characterized by UV–vis and IR spectroscopy. The molecular structures of complexes 1 and 4 were determined by X-ray crystallography and their magnetic properties were measured over the temperature range 2–300 K. The coordination geometry around the central Co(II) in these compounds has a distorted trigonal bipyamidal geometry with four nitrogen atoms from the TPA ligand and the fifth coordination site is occupied by Cl − ion in 1 , Br − ion in 2 , coordinated oxygen atom from H 2 O in 3 and by an oxygen atom supplied by the carboxylate group of the bridged terephthalato ligand in 4 . The visible spectra of the complexes 1 – 3 in MeOH show strong distortion toward tetrahedral geometry. For complex 4 , analysis of the infrared spectral data for the ν (COO − ) stretching frequencies of the tp-carboxalato groups reveals the existence of the bis(monodentate) coordination mode for the bridged tp. X-ray data for 1 and 4 show that the former is mononuclear while the latter is dinuclear. The electronic spectrum of 4 in MeOH is in complete agreement with the assigned X-ray geometry around the Co(II) centers. The magnetic behavior of the mononuclear complex 1 is indicative of a high-spin compound with zero-field splitting. The best fit was obtained with ∣ D ∣ = 7.3 cm −1 , g = 2.25. The dinuclear complex 4 exhibits weak antiferromagnetic coupling with a coupling constant J = −0.8 cm −1 . The magnetic properties and the structural parameters of 4 are discussed in relation to the other related μ-terephthalato dinuclear Co(II) compounds. The geometry of the coordination sphere around 4 is unique – the CSD compilation listing only one other compound with such a geometry around the dinuclear Co(II) complex and its composition is far different from that in 4 . However, they share a common feature of having a weakly antiferromagnetic coupling between Co(II) centers.
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syntheses structures and magnetic properties of the dicyanamide dca polynuclear compounds mn ac terpy μ1 5 dca n mn pdz 2 μ1 5 dca 2 n and mn dca terpy meoh 2 μ Terephthalate
Inorganica Chimica Acta, 2002Co-Authors: Albert Escuer, Franz A Mautner, Nuria Sanz, Ramon VicenteAbstract:Abstract Dicyanamide, (dca, N(CN) 2 − ) is found to form, as bridging ligand, two compounds of formula [Mn(ac)(terpy)(μ 1,5 -dca)] n ( 1 ) and [Mn(pdz) 2 (μ 1,5 -dca) 2 ] n ( 2 ) (ac=acetate; terpy=2,2′:6′,2″-terpyridine; pdz=pyridazine). The X-ray diffraction analysis reveals one-dimensional systems, with single dca bridges the compound 1 and double dca bridges the compound 2 . The manganese atom in 1 is heptacoordinated, with a MnN 5 O 2 pentagonal bipyramid environment, whereas in 2 the manganese atom is hexacoordinated. The susceptibility measurements of 1 and 2 indicate slight antiferromagnetic coupling. In an attempt to obtain a double chain with Terephthalate and dicyanamide bridges, the dinuclear Terephthalate bridged compound [{Mn(dca)(terpy)(MeOH)} 2 (μ-Terephthalate)] ( 3 ) was obtained. The manganese atom in 3 is heptacoordinated, with a MnN 4 O 3 pentagonal bipyramid environment. The susceptibility measurements of 3 indicate also slight antiferromagnetic coupling.
C F King - One of the best experts on this subject based on the ideXlab platform.
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new diol processes 1 3 propanediol and 1 4 butanediol
Applied Catalysis A-general, 2005Co-Authors: T Haas, Bernd Jaeger, R Weber, S F Mitchell, C F KingAbstract:Abstract More than 1000 t of polyester resins and fibers are produced every hour in the world. The highest fraction of this amount is contributed by the oldest polyester, polyethylene Terephthalate (PET). This material is based on the diol ethylene glycol (EG). Beside ethylene glycol butanediol (BDO) gained increasing demand in the polyester business, especially because of the use of polybutylene Terephthalate (PBT) in the automotive industry as an engineering plastic. In the last 5 years also 1,3-propanediol (PDO) joined its homologues as an interesting polyester raw material. This development was caused by the finding of unique properties of the corresponding polyester, polypropylene Terephthalate (PPT) in fiber application. Because of the increasing new market demand for PPT and PBT new production technologies were developed for 1,3-propanediol and 1,4-butanediol. A review will be presented whereby the production of 1,3-propanediol via fermentation of glucose will be not considered.
N E Ikladious - One of the best experts on this subject based on the ideXlab platform.
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depolymerization of poly ethylene Terephthalate wastes using 1 4 butanediol and triethylene glycol
Polymer Testing, 2002Co-Authors: S H Mansour, N E IkladiousAbstract:Abstract Polyethylene Terephthalate (PET) wastes were depolymerized using 1,4-butanediol (BD) and triethylene glycol (TEG) in the presence of zinc acetate as a transesterification catalyst. The glycolyzed products were analyzed for hydroxyl and acid values and identified by elemental analysis, GPC, 1 HNMR, 13 CNMR, differential scanning calorimeter (DSC) and mass spectra techniques. It was found that the glycolyzed products consist mainly of bis- (hydroxybutyl Terephthalate) monomer and dimer by using 1,4-butanediol. The depolymerization using TEG resulted in products of TEG–(TPA–TEG) n for n =1–3. All glycolyzed products had low acid value indicating the presence of a minor fraction of Terephthalate oligoesters.
B Jacques - One of the best experts on this subject based on the ideXlab platform.
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reactions induced by triphenyl phosphite addition during melt mixing of pet pbt blends chromatographic evidence of a molecular weight increase due to the creation of bonds of two different natures
Polymer, 1997Co-Authors: B Jacques, Jacques Devaux, Roger Legras, Eric NieldAbstract:A detailed chromatographic investigation has been carried out on the influence of triphenyl phosphite addition in molten poly(ethylene Terephthalate) or poly(ethylene Terephthalate)/poly(butylene Terephthalate) blends. The observed molecular weight evolution corresponds to torque and viscosity observations and fully confirms the occurrence of high temperature reactions between polyester and phosphite. The reaction mechanisms deduced from model compound studies are successfully applied to polymers. The formation of bonds of different types is verified: phosphite reactions with hydroxyl chain ends lead to the incorporation of significant quantities of phosphorus into the polyester backbone. A high sensitivity of these phosphorus containing links towards water, phenol or m-cresol has been observed. Subsequent carboxyl chain end attack on the phosphorus linkages leads to stable ester bonds. (C) 1997 Elsevier Science.
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reactions induced by triphenyl phosphite addition during melt mixing of poly ethylene Terephthalate poly butylene Terephthalate blends influence on polyester molecular structure and thermal behaviour
Polymer, 1996Co-Authors: B Jacques, Jacques Devaux, Roger Legras, Eric NieldAbstract:The influence of triphenyl phosphite addition in molten poly(ethylene Terephthalate) or poly(ethylene Terephthalate)/poly(butylene Terephthalate) blends has been investigated. Torque measurements during polyester processing and corresponding intrinsic viscosity values confirm an expected chain extension. Chromatographic results similarly indicate a molecular-weight increase. The precise nature of this chain extension mechanism is questioned. Chromatographic and calorimetric observations strongly suggest the formation of ester bonds and of bonds including phosphorus atoms. The enhanced reactivity of these new links towards phosphorous by-products or phenolic solvents at high temperature could explain the degradation observed in specific conditions.
