Home About us Contact
|
Home About us Contact | ||
|
|
||
Dimethyl Terephthalate (dimethyl + terephthalate)
Selected AbstractsPoly(ethylene terephthalate) recycling and recovery of pure terephthalic acid by alkaline hydrolysisADVANCES IN POLYMER TECHNOLOGY, Issue 4 2002G. P. Karayannidis Abstract Poly(ethylene terephthalate) (PET) taken from postconsumer soft-drink bottles was subjected to alkaline hydrolysis after cutting it into small pieces (flakes). The reaction took place in an autoclave at 120,200°C with aqueous NaOH solutions and at 110,120°C with a nonaqueous solution of KOH in methyl Cellosolve. The disodium or dipotassium terephthalate received was treated with sulfuric acid and terephthalic acid (TPA) of high purity was separated. The 1H NMR spectrum of the TPA revealed an about 2% admixture of isophthalic acid together with the pure 98% TPA. The purity of the TPA obtained was tested by determining its acidity and by polymerizing it with ethylene glycol by using tetrabutyl titanate as catalyst. A simple theoretical model was developed to describe the hydrolysis rate. The activation energy calculated was 99 kJ/mol. This method is very useful in recycling of PET bottles and other containers because nowadays TPA is replacing dimethyl terephthalate (the traditional monomer) as the main monomer in the industrial production of PET. © 2002 Wiley Periodicals, Inc. Adv Polym Techn 21: 250,259, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.10029 [source] Synthesis and characterization of poly(butylene terephthalate)/mica nanocomposite fibers via in situ interlayer polymerizationJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2007Jin-Hae Chang Abstract Intercalated nanocomposites consisting of poly(butylene terephthalate) (PBT) incorporated between mica layers were synthesized from dimethyl terephthalate (DMT) and 1,4-butanediol (BD) by in situ interlayer polymerization. PBT nanocomposites of varying organoclay content were melt-spun to produce monofilaments. The samples were characterized using wide angle X-ray diffraction, electron microscopy, thermal analysis, and tensile testing. Some of the clay particles were found to be well dispersed in the PBT matrix, but other clay particles were agglomerated at a size level greater than approximately 20 nm. The glass transition temperatures (Tg) and the thermal degradation properties (TDi) of undrawn PBT hybrid fibers were found to improve with increases in the clay content. At draw ratio (DR) = 1, the ultimate tensile strengths of the hybrid fibers increased with the addition of clay up to a critical content and then decreased. However, the initial moduli monotonically increased with increases in the amount of organoclay in the PBT matrix. The ultimate strengths were found to decrease linearly with increases in DR from 1 to 18. In contrast to the trend for the tensile strengths, the initial moduli of the hybrid fibers increased only slightly with increases in DR up to 18. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source] Safety of Polyethylene Terephthalate Food Containers Evaluated by HPLC, Migration Test, and Estimated Daily IntakeJOURNAL OF FOOD SCIENCE, Issue 6 2008H.-J. Park ABSTRACT:, A comparative high-pressure liquid chromatography (HPLC) analysis of monomers, terephthalic acid (TPA), isophthalic acid (IPA), and dimethyl terephthalate (DMT) from polyethylene terephthalate (PET) food containers was conducted. Monomer linearities and sensitivities were calibrated between established and novel HPLC analyses. Safety of PET containers was evaluated with newly established detection methods for TPA, IPA, and DMT. Migration of the 3 monomers into food simulants (water, 4% acetic acid, 20% alcohol, and n-heptane) from 56 PET containers collected from open markets was monitored. Migrated monomers were not detected over 0.1 ppm of detection limit. The corresponding estimated daily intake was measured to confirm the safety of these publicly available PET containers and to permit comparison to the specific migration limit of the European Union. The estimated daily intake of 3 monomers migrating from PET was 0.0384 mg/kg each. This represented only 0.6% of the European Union's specific migration limit, confirming the safety of the examined containers. [source] Poly(ethylene terephthalate) terpolyesters containing isophthalic and 5- tert -butylisophthalic unitsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2003Darwin P. R. Kint Abstract Poly(ethylene terephthalate- co -isophthalate- co -5- tert -butylisophthalate) (PETItBI) terpolymers were investigated with reference to poly(ethylene terephthalate) (PET) homopolymer and poly(ethylene terephthalate- co -isophthalate) (PETI) copolymers. Three series of PETItBI terpolyesters, characterized by terephthalate contents of 90, 80, and 60 mol %, respectively, with different isophthalate/5- tert -butylisophthalate molar ratios, were prepared from ethylene glycol and mixtures of dimethyl terephthalate, dimethyl isophthalate, and 5- tert -butylisophthalic acid. The composition of the terpolymers and the composition of the feed agreed. All terpolymers had a random microstructure and number-average molecular weights ranging from 10,000 to 20,000. The PETItBI terpolyesters displayed a higher glass-transition temperature and a lower melting temperature than the PETI copolymers having the same content of terephthalic units. Thermal stability appeared essentially unchanged upon the incorporation of the 5- tert -butylisophthalic units. The PETItBIs were crystalline for terephthalate contents higher than 80 mol %, and they crystallized at lower rates than PETI. The crystal structure of the crystalline terpolymers was the same as that of PET with the 1,3-phenylene units being excluded from the crystalline phase. Incorporation of isophthalate comonomers barely affected the tensile modulus and strength of PET, but the brittleness of the terpolymers decreased for higher contents in 5- tert -butylisophthalic units. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 124,134, 2003 [source] Poly(ethylene terephthalate) reinforced by N,N,-diphenyl biphenyl-3,3,,4,4,-tetracarboxydiimide moietiesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 7 2002Jun Xiao Abstract Starting with 3,3,,4,4,-biphenyltetracarboxylic dianhydride and methyl aminobenzoate, we synthesized a novel rodlike imide-containing monomer, N,N,-bis[p -(methoxy carbonyl) phenyl]-biphenyl-3,3,,4,4,-tetracarboxydiimide (BMBI). The polycondensation of BMBI with dimethyl terephthalate and ethylene glycol yielded a series of copoly(ester imide)s based on the BMBI-modified poly(ethylene terephthalate) (PET) backbone. Compared with PET, these BMBI-modified polyesters had higher glass-transition temperatures and higher stiffness and strength. In particular, the poly(ethylene terephthalate imide) PETI-5, which contained 5 mol % of the imide moieties, had a glass-transition temperature of 89.9 °C (11 °C higher than the glass-transition temperature of PET), a tensile modulus of 869.4 MPa (20.2 % higher than that of PET), and a tensile strength of 80.8 MPa (38.8 % higher than that of PET). Therefore, a significant reinforcing effect was observed in these imide-modified polyesters, and a new approach to higher property polyesters was suggested. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 852,863, 2002; DOI 10.1002/pola.10169 [source] Solubility of terephthalic acid in the reaction system oligomeric bishydroxybutyl terephthalates,1,4-butanediolPOLYMER ENGINEERING & SCIENCE, Issue 4 2009Hainan Huang The physical solubilities of terephthalic acid (TPA) in the reaction system oligomeric bishydroxybutyl terephthalates,1,4-butanediol (BD) are measured using an analytic method from 449 to 507 K. The reaction system is obtained by transesterification of dimethyl terephthalate and excess BD. These results are fitted with the solubility model based on the Margules equation, and the average deviation of the model is 1.20%; the fusion enthalpies ,Hfus of TPA and infinite-dilution activity coefficients ,,2 in the system are obtained by regressing of the experimental data. In addition, synthetic method is chosen to determine the total solubility which is complicated by chemical reaction, the results indicate that the chemical reaction start at 452,472 K. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers [source] Copolymers based on poly(butylene terephthalate) and polycaprolactone- block -polydimethylsiloxane- block -polycaprolactonePOLYMER INTERNATIONAL, Issue 6 2010Vesna V Anti Abstract A series of novel thermoplastic elastomers, based on poly(butylene terephthalate) (PBT) and polycaprolactone- block -polydimethylsiloxane- block -polycaprolactone (PCL-PDMS-PCL), with various mass fractions, were synthesized through melt polycondensation. In the synthesis of the poly(ester-siloxane)s, the PCL blocks served as a compatibilizer for the non-polar PDMS blocks and the polar comonomers dimethyl terephthalate and 1,4-butanediol. The introduction of PCL-PDMS-PCL soft segments resulted in an improvement of the miscibility of the reaction mixture and therefore in higher molecular weight polymers. The content of hard PBT segments in the polymer chains was varied from 10 to 80 mass%. The degree of crystallinity of the poly(ester-siloxane)s was determined using differential scanning calorimetry and wide-angle X-ray scattering. The introduction of PCL-PDMS-PCL soft segments into the polymer main chains reduced the crystallinity of the hard segments and altered related properties such as melting temperature and storage modulus, and also modified the surface properties. The thermal stability of the poly(ester-siloxane)s was higher than that of the PBT homopolymer. The inclusion of the siloxane prepolymer with terminal PCL into the macromolecular chains increased the molecular weight of the copolymers, the homogeneity of the samples in terms of composition and structure and the thermal stability. It also resulted in mechanical properties which could be tailored. Copyright © 2010 Society of Chemical Industry [source] Kinetic and thermodynamic study of methanolysis of poly(ethylene terephthalate) waste powderPOLYMER INTERNATIONAL, Issue 3 2003S Mishra Abstract Depolymerization of poly(ethylene terephthalate) waste (PETW) was carried out by methanolysis using zinc acetate in the presence of lead acetate as the catalyst at 120,140,°C in a closed batch reactor. The particle size ranging from 50 to 512.5,µm and the reaction time 60 to 150,min required for methanolysis of PETW were optimized. Optimal percentage conversion of PETW into dimethyl terephthalate (DMT) and ethylene glycol (EG) was 97.8% (at 120,°C) and 100% (at 130 and 140,°C) for the optimal reaction time of 120,min. Yields of DMT and EG were almost equal to PET conversion. EG and DMT were analyzed qualitatively and quantitatively. To avoid oxidation/carbonization during the reaction, methanolysis reactions were carried out below 150,°C. A kinetic model is developed and the experimental data show good agreement with the kinetic model. Rate constants, equilibrium constant, Gibbs free energy, enthalpy and entropy of reaction are also evaluated at 120, 130 and 140,°C. The methanolysis rate constant of the reaction at 140,°C (10.3 atm) was 1.4,×,10,3,g PET mol,1 min,1. The activation energy and the frequency factor for methanolysis of PETW were 95.31,kJ,mol,1 and 107.1,g PET mol,1 min,1, respectively. © 2003 Society of Chemical Industry [source] Synthesis, thermal, and rheological properties of poly(trimethylene terephthalate)/BaSO4 nanocompositesPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 10 2009Chenguang Yao Abstract A novel method was developed for fabricating poly(trimethylene terephthalate) (PTT)/BaSO4 nanocomposites using in situ polymerization. A nano-BaSO4 suspension was prepared by reacting H2SO4 with Ba(OH)2 in 1,3-propanediol (PDO). The mean size of original nano-BaSO4 is 15,23,nm. PTT matrix was synthesized by condensation polymerization of bis(3-hydroxypropyl terephthalate) after the completion of transesterification of dimethyl terephthalate (DMT) with PDO. It was found that the addition of BaSO4 had little influence on the synthesis of PTT. The properties of nanocomposites with a wide range of BaSO4 fraction were systematically studied. The morphologies of the composites were investigated by transmission electron microscopy (TEM), which showed that agglomerate structures did not form until BaSO4 content higher than 8,wt%. The thermal properties of the nanocomposites were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The DSC results revealed that the triple endothermic melting phenomenon is only observed for the nanocomposites which contained 4,wt% BaSO4, other samples exhibit double endothermic melting. These results indicated that nano-BaSO4 could induce a microcrystal to form more perfect morphology and restrain the formation of much thicker lamellar crystallinity, that is, nano-BaSO4 could induce the formation of more uniform crystallinity. Besides, the crystallization ability of the composites was greatly improved by loading nano-BaSO4. The TGA results suggested that nano-BaSO4 slightly increased the maximum-decomposing-rate temperature 1 (Tmax1), but markedly increased the maximum-decomposing-rate temperature 2 (Tmax2). Furthermore, the steady-state shear behavior of samples was investigated by a parallel-plate rheometer. The storage modulus (G') and loss modulus (G") curves shifted to higher modulus upon addition of 2,16,wt% of nano-BaSO4. All of the samples investigated exhibited the expected shear-thinning behavior. Proper contents of nano-BaSO4 would decrease the shear viscosity of nanocomposites, whereas superfluous amounts would greatly increase the viscosity of nanocomposites and the composites which loaded 8,wt% nano-BaSO4 revealed an equivalent shear viscosity compared to pure PTT. Copyright © 2008 John Wiley & Sons, Ltd. [source] Synthesis and Characterization of Poly(butylene adipate- co - terephthalate) Catalyzed by Rare Earth StearatesCHINESE JOURNAL OF CHEMISTRY, Issue 10 2007Kui ZHU Abstract Rare earth (Nd, Y, La, Dy) stearates have been synthesized and used as single component catalysts for the polycondensation of dimethyl terephthalate, adipic acid and 1,4-butanediol for the first time preparing biodegradable poly(butylene adipate- co -terephthalate) (PBAT) with high molecular weight. The microstructures of PBAT were characterized by 1H NMR spectra. The PBAT exhibits good mechanical properties such as high tensile strength (ca. 20 MPa) and long break elongation (>700%). [source] | |||||||||||||