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Thermal Decomposition Temperature (thermal + decomposition_temperature)
Selected AbstractsNanoclay-reinforced syntactic foams: Flexure and thermal behaviorPOLYMER COMPOSITES, Issue 8 2010Mrinal C. Saha Syntactic foams containing 60 vol% of hollow glass microballoons in epoxy matrix are modified with untreated nanoclays using combined mechanical and ultrasonication methods. Effects of nanoclays on flexure and thermal behavior of syntactic foams are investigated by adding different amount of nanoclays in the range of 1,3% by weight. Microscopic examinations and physical property characterization are performed to determine the interactions among constituent materials and the void formation during fabrication. It is found that the syntactic foams with 2 wt% nanoclays show the highest improvement in flexural properties (,42% strength and ,18% modulus) and dynamic mechanical properties (,30% storage modulus and ,28% loss modulus) properties. Thermal decomposition temperature is found to be unaffected by the addition of nanoclays, whereas a continuous reduction in the coefficient of thermal expansion (CTE) is observed. An examination of failure surface indicates that the failure is initiated on the tension side of the flexure sample due to fracturing of microballoons. POLYM. COMPOS., 31:1332,1342, 2010. © 2009 Society of Plastics Engineers [source] Synthesis of organic,inorganic hybrid polymeric nanocomposites for the hard coat applicationJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007Chuan Hsiao Shu Abstract An organic,inorganic hybrid polymeric nanocomposite has been synthesized for making UV-curable hard coats. This nanocomposite consists of nano-sized colloidal silica functionalized with vinyltriethoxysilane (VTES) and dendritic acrylic oligomers (DAO) which have been formed earlier via a reaction of ethylenediamine (EDA) with trimethylopropane triacrylate (TMPTA). Applied as a hard coat on top of a polyethylene terephthalate (PET) film, this nanocomposite has a short UV-cure time and the cured coat has an enhanced thermal decomposition temperature (Td), 89,90% transparency, increased hardness up to 3H, better adhesion up to 4B, and a flat surface with a root mean square roughness of 2,4 nm. The preparation as well as the characterization of the constituting species and the final hybrid are described in detail. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3985,3993, 2007 [source] Living cationic polymerization of 2-adamantyl vinyl etherJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 5 2008Tamotsu Hashimoto Abstract Living cationic polymerization of 2-adamantyl vinyl ether (2-vinyloxytricyclo[3.3.1.1]3,7decane; 2-AdVE) was achieved with the CH3CH(OiBu)OCOCH3/ethylaluminum sesquichloride/ethyl acetate [CH3CH(OiBu)OCOCH3/Et1.5AlCl1.5/CH3COOEt] initiating system in toluene at 0 °C. The number-average molecular weights (Mn's) of the obtained poly(2-AdVE)s increased in direct proportion to monomer conversion and produced the polymers with narrow molecular weight distributions (MWDs) (Mw/Mn = ,1.1). When a second monomer feed was added to the almost polymerized reaction mixture, the added monomer was completely consumed and the Mn's of the polymers showed a direct increase against conversion of the added monomer. Block and statistical copolymerization of 2-AdVE with n -butyl vinyl ether (CH2CHOCH2 CH2CH2CH3; NBVE) were possible via living process based on the same initiating system to give the corresponding copolymers with narrow MWDs. Grass transition temperature (Tg) and thermal decomposition temperature (Td) of the poly(2-AdVE) (e.g., Mn = 22,000, Mw/Mn = 1.17) were 178 and 323 °C, respectively. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1629,1637, 2008 [source] Organosoluble and transparent polyimides derived from alicyclic dianhydride and aromatic diaminesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2002J. G. Liu Abstract Organosoluble polyimides were synthesized with the alicyclic dianhydride 1,8-dimethylbicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride and aromatic diamines. The polyimides possessed good solubility both in strong dipolar solvents and in common solvents; the thermal decomposition temperature of the polyimides exceeded 420 °C. Strong and flexible films of the polyimides, with the cutoff of ultraviolet,visible absorption lower than 310,320 nm, exhibited good features as the alignment layers for nematic liquid crystals with pretilt angles of 1.5,2.9°. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 110,119, 2002 [source] The effect of copper(II) on the thermal and mechanical properties of poly(vinyl alcohol)/silica hybridPOLYMER ENGINEERING & SCIENCE, Issue 8 2009Juan Li A novel copper-poly(vinyl alcohol) (PVA)/silica complex was prepared and its chemical structure, thermal, and mechanical properties were studied. The results showed that the crystallinity of PVA first increased and then decreased by the addition of copper chloride, whereas, the thermal decomposition temperature increased dramatically. For PVA/silica hybrid, the decomposition temperature associated with the removal of water molecules in PVA chains was 262°C. But the temperature increased to 361°C when the content of copper chloride was 2 wt%. The intelligent electronic tensile tester was used to investigate the mechanical properties of these complexes. The results suggested that the tensile strength of the complexes is improved with negligible decrease in the plasticity. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers [source] Preparation and characterization of polyurethane,gold nanocomposites prepared using encapsulated gold nanoparticlesPOLYMER INTERNATIONAL, Issue 7 2010Chao-Ching Chang Abstract Gold nanoparticles (GNPs) have been widely studied due to their unique properties. Although many research groups have developed the synthesis of GNPs using various polymers as stabilizing or reducing agents, the effects of GNPs on the structures and properties of polymer matrices have been less reported. We propose a new design for the preparation of polyurethane,gold (PU,Au) nanocomposites. 11-Mercapto-1-undecanol-coated GNPs acted as the chain extenders and reacted with isocyanates to form covalent bonds between PU and GNPs. PU,Au nanocomposites were successfully synthesized, and the effects of multifunctional GNPs on the structures, morphology and properties of poly(ester urethane) were investigated. Scanning electron microscopy images suggested the GNPs can be dispersed uniformly in the PU matrix. Maltese-cross of spherical crystals was observed in the PU,Au nanocomposites, and the size of the crystals decreased with an increase in gold content. As the gold content increased, the thermal decomposition temperature and the temperature of the maximum decomposition rate increased. The glass transition temperature, crystal melting temperature and melting enthalpy of the soft segment also increased progressively. The results showed that multifunctional GNPs concentrated hard segments and resulted in an increase of heterogeneous nucleation, phase separation and elasticity. Copyright © 2010 Society of Chemical Industry [source] Preparation, characterization, and thermal properties of hydrophilic copolymers: p -chlorophenylmaleimides with hydroxylethyl methacrylate and ,-methyl itaconatePOLYMER INTERNATIONAL, Issue 9 2007Guadalupe del C Pizarro Abstract This work describes the synthesis, characterization, and thermal behavior of copolymers of p -chlorophenylmaleimide (Cl-PhMI) with ,-methyl itaconate (,-MHI) and 2-hydroxyethyl methacrylate (HEMA). Copolymerization was carried out with a radical initiator by varying the feed mole fraction of Cl-PhMI from 0.25 to 0.75. The copolymer composition was determined from the N/C ratio based on elemental analysis data and with 1H NMR spectroscopy for poly(Cl-PhMI- co -HEMA) using a proton signal attributed to the CH3 of HEMA (, = 0.7,1.4 ppm) and the area of aromatic ring protons (, = 7.2,7.8 ppm), where the proton/area relationship confirmed the copolymer compositions calculated by elemental analysis. The monomer reactivity ratios r1 and r2 were determined using the Kelen,Tüdös method. These values demonstrated that copolymerization produced random copolymers with an alternation tendency. The molecular weight and polydispersity were also determined. The thermal behavior can be correlated with the copolymer composition. An increase of the thermal decomposition temperature occurred when the content of Cl-PhMI increased. The glass transition temperature and thermal stability of poly(,-MHI) or poly(HEMA) increased with an increasing amount of Cl-PhMI in the polymer backbone. Copyright © 2007 Society of Chemical Industry [source] The influence of metallic substitution on the physical properties of manganese mercury thiyocyanate crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 3 2007G. P. Joseph Abstract Good optical grade single crystals of pure, Cd2+ and Mg2+ doped Manganese Mercury Thiyocyanate (MMTC) crystals are grown by slow solvent evaporation technique at room temperature. Single crystal XRD studies reveal that the incorporation of metallic dopants has not changed the structure of the parent crystal. The SHG efficiencies of the pure and doped samples of MMTC are measured by Kurtz Perry powder method and the results are compared with urea. It is evident from microhardness study that the presence of dopants has increased the mechanical strength of MMTC crystal. The TG/DTG studies confirm that the thermal decomposition temperatures of pure (353°C), Mg2+ doped (363°C) and Cd2+ doped (365°C) MMTC are relatively high when compared to other NLO crystals of the same family. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Synthesis and applications of low-bandgap conjugated polymers containing phenothiazine donor and various benzodiazole acceptors for polymer solar cellsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2010Harihara Padhy Abstract A series of soluble donor-acceptor conjugated polymers comprising of phenothiazine donor and various benzodiazole acceptors (i.e., benzothiadiazole, benzoselenodiazole, and benzoxadiazole) sandwiched between hexyl-thiophene linkers were designed, synthesized, and used for the fabrication of polymer solar cells (PSC). The effects of the benzodiazole acceptors on the thermal, optical, electrochemical, and photovoltaic properties of these low-bandgap (LBG) polymers were investigated. These LBG polymers possessed large molecular weight (Mn) in the range of 3.85,5.13 × 104 with high thermal decomposition temperatures, which demonstrated broad absorption in the region of 300,750 nm with optical bandgaps of 1.80,1.93 eV. Both the HOMO energy level (,5.38 to ,5.47 eV) and LUMO energy level (,3.47 to ,3.60 eV) of the LBG polymers were within the desirable range of ideal energy level. Under 100 mW/cm2 of AM 1.5 white-light illumination, bulk heterojunction PSC devices containing an active layer of electron donor polymers mixed with electron acceptor [6,6]-phenyl-C61 -butyric acid methyl ester (PC61BM) or [6,6]-phenyl-C71 -butyric acid methyl ester (PC71BM) in different weight ratios were investigated. The best performance of the PSC device was obtained by using polymer PP6DHTBT as an electron donor and PC71BM as an acceptor in the weight ratio of 1:4, and a power conversion efficiency value of 1.20%, an open-circuit voltage (Voc) value of 0.75 V, a short-circuit current (Jsc) value of 4.60 mA/cm2, and a fill factor (FF) value of 35.0% were achieved. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 [source] Incorporation of Multi-Walled Carbon Nanotubes into Biodegradable Telechelic PrepolymersMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 3 2008Wenhui Song Abstract Biodegradable lactic-acid-based telechelic prepolymers incorporating CNTs were prepared. The products were characterized by FTIR, TGA, DSC, POM, 1H and 13C NMR, TEM, and FESEM. The results indicated that hydroxy-terminated telechelic prepolymers were obtained. According to the TGA curves, the initial thermal decomposition temperatures of the prepolymers incorporating carboxylic CNTs were higher than those of the pure prepolymers. Amorphous and crystalline prepolymers incorporating CNTs were obtained, while the spherocrystal morphologies were not changed by the addition of the CNTs. The carboxylic CNTs were coated with PLA polymers after polymerization and well dispersed in the prepolymer matrix. [source] Phenylethynyl End-Capped Fluorinated Imide Oligomer AFR-PEPA- N: Morphology and Processibility CharacteristicsMACROMOLECULAR MATERIALS & ENGINEERING, Issue 1 2007Yuntao Li Abstract Two phenylethynyl phthalic anhydride-capped imide oligomers, AFR-PEPA-2 and AFR-PEPA-8, with molecular weights of 1,601 and 4,699 g,·,mol,1, respectively, were synthesized and characterized. The AFR-PEPA- N oligomers show higher glass transition temperatures and higher thermal decomposition temperatures than phenylethynyl-terminated imide PETI-5. After curing for 1 h at 390,°C, AFR-PEPA-2 and AFR-PEPA-8 have Tgs of 370 and 358,°C, respectively. AFR-PEPA- N oligomers demonstrated lower minimum complex melt viscosities than PETI-5 due to the presence of CF3 group in the backbone structure. 1,601 g,·,mol,1 AFR-PEPA-2 imide oligomer has a complex melt viscosity of 10 Pa,·,s at 340,°C, and 4,699 g,·,mol,1 AFR-PEPA-8 imide oligomer has a complex melt viscosity of 227 Pa,·,s at 371,°C. AFR-PEPA- N film's crystal morphology was observed using polarized optical microscopy and the AFR-PEPA-8 oligomer did not show crystallinity. AFR-PEPA-2 film exhibits semicrystalline behavior and the crystallinity does not disappear until the film is cured above 375,°C. [source] | ||||||||||