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Melt Polycondensation (melt + polycondensation)
Selected AbstractsKinetics and Modeling of Melt Polycondensation for Synthesis of Poly[(butylene succinate)- co -(butylene terephthalate)], 1 , EsterificationMACROMOLECULAR REACTION ENGINEERING, Issue 9-10 2010Lixia Hu Abstract The kinetics of the tetrabutyl titanate-catalyzed homogeneous succinic acid/1,4-butylenediol (BDO) and heterogeneous terephthalic acid/BDO esterifications were investigated experimentally and theoretically. A unified kinetic model considering two main esterifications as well as one reversible polycondensation and two THF-forming side reactions has been developed for the two esterification systems. The model agrees well with the experimental results. The effects of reaction temperature, diol/diacid ratio, catalyst amount, and heterogeneity on the esterification kinetics are simulated and discussed. [source] Unexpected fluorescence emission of poly(,,,- L -malic acid) in aqueous mediumJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007Yaofeng Fan Abstract Unexpected fluorescence of poly(,,,- L -malic acid) (,,,-PMA) without traditional fluorophore was observed firstly. This fluorescent polymer was synthesized via melt polycondensation of L -malic acid. The polymer was characterized by gel permeation chromatography (GPC), nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), thermogravimetry (TG), Fourier transform infrared spectroscopy (IR), Fourier transform Raman spectroscopy (Raman), and X-ray powder diffractometry (XRD). The high molecular weight ,,,-PMA was synthesized by the optimum polycondensation at 130°C for 15 h, followed by fractional precipitation with diethyl ether and petroleum ether. The degree of branching of ,,,-PMA was from 10% to 20% according to the reaction condition. Terminal group of ,,,-PMA was mainly hydroxycarboxylic group companied with a few CHCHCOOH groups owing to dehydration of a normal terminal during the melt polycondensation. A fluorescence emission maximum of ,,,-PMA in water appeared at 420 nm when it was excited at 340 nm. Further study indicated that the fluorescence intensity was concentration-dependent, pH-dependent, and molecular-weight-dependent. The fluorescence formation may result from multichain aggregations, which was formed readily in aqueous solution due to intermolecular hydrogen bonds between branched ,,,-PMA. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [source] Synthesis, characterization, and in vitro degradation of liquid-crystalline terpolyesters of 4-hydroxyphenylacetic acid/3-(4-hydroxyphenyl)propionic acid with terephthalic acid and 2,6-naphthalene diolJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 11 2002V. S. Prasad Abstract Melt-processable liquid-crystalline terpolyesters of 4-hydroxyphenylacetic acid (HPAA) and 3-(4-hydroxyphenyl)propionic acid (HPPA) with terephthalic acid and 2,6-naphthalene diol were synthesized by one-step acidolysis melt polycondensation followed by postpolymerization and were characterized with viscosity studies, Fourier transform infrared (FTIR) and NMR spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), polarized light microscopy, and wide-angle X-ray diffraction. The melting behaviors and liquid-crystalline transition temperatures of the terpolyesters were dependent on the composition of the HPAA/HPPA content. The transition temperatures of the polyesters could be effectively reduced by the introduction of an even number of built-in short methylene spacers in combination with the 2,6-naphthalene offset structure. A terpolyester with an HPPA content of 33% (NTP33) showed optimum properties for the glass-transition temperature, around 71 °C, and the melting temperature, near 240 °C, with a Schlieren nematic texture. The polymer showed excellent flow behavior in a Brabender plasticorder. It was also thermally stable up to 400 °C. NTP33 showed 2.5% in vitro hydrolytic degradation in buffer solutions of pH 10 at 60 °C after 540 h. Considerable enzymatic degradation was also observed with porcine pancreas lipase/buffer solutions in comparison with Candida rugosa lipase after 60 days. The degradation was also followed with FTIR, DSC, and TGA. Apart from the temperature and pH of the buffer solution, several structural parameters, such as the aromatic content, crystallinity percentage, and composition of the polymer, affected the degradation behavior. FTIR studies indicated the involvement of chain scission during degradation. Scanning electron microscopy studies further showed that surface erosion also played a major role in the degradation. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1845,1857, 2002 [source] Synthesis of Poly(ester-anhydrides) Based on Different Polyester PrecursorsMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 7 2004Harri Korhonen Abstract Summary: Poly(ester-anhydrides) were synthesised from poly(L -lactide), poly(D,L -lactide), and poly(, -caprolactone) prepolymers prepared by ring-opening polymerisation of cyclic esters in the presence of 1,4-butanediol or ricinoleic acid as co-initiator. The hydroxyl group end functionality of the prepolymers was converted to carboxylic acid functionality by reaction with succinic anhydride, and the polyester precursors were coupled by melt polycondensation to give poly(ester-anhydrides). 1,4-Butanediol was used as co-initiator to study the properties of poly(ester-anhydrides) prepared from different monomers, whereas ricinoleic acid was used as co-initiator to introduce a hydrophobic fatty acid moiety to the polyester precursor. In hydrolysis tests, the poly(ester-anhydrides) showed a two-stage degradation comprising a rapid hydrolysis of anhydride linkages within three days, followed by the slower hydrolysis of the remaining polyester oligomer. Weight loss of the poly(ester-anhydrides) depended most importantly on molecular weight and thermal properties of the polyester precursors; thus, poly(ester-anhydrides) prepared from low molecular weight prepolymers having thermal transitions below 37,°C showed very fast weight loss. [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] Lithocholic-acid-containing poly(ester,anhydride)sPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 11-12 2003Michal Y. Krasko Abstract New degradable poly(ester-anhydride)s were prepared by melt polycondensation of poly(sebacic acid) (PSA), transesterified by different amounts (30,90%) of lithocholic acid (LCA), a natural hydroxy bile acid. Transesterification of PSA is a one-pot reaction that starts with a high-molecular-weight polymer based on anhydride bonds and yields polymer based on random anhydride,ester bonds. A systematic study of the synthesis, characterization, degradation in vitro, drug release, and stability of these polymers was performed. Polymers with molecular weights (Mw) in the range of 12,000,115,000 and melting points in the range of 55,112,°C were obtained for 30,90% of lithocholic acid content. NMR and IR spectroscopic analyses indicate the formation of ester bonds in the polyanhydride backbone. The experimental results fit the calculated molecular weight, with the highest Mw obtained for a 4:6 PSA,LCA ratio. The study shows that some of these new degradable copolymers can be potentially used as carriers for the controlled release of drugs. Copyright © 2003 John Wiley & Sons, Ltd. [source] | ||||||||||