Browsing by Author "Tagle, LH"

Now showing 1 - 6 of 6
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    Poly(p-phenylene-diselenocarbonate) and poly(p-phenylene-diselenothiocarbonate): New semiconducting polymers
    (1996) Diaz, FR; Godoy, A; Tagle, LH; Valdebenito, N; Bernede, JC
    New polymers which contain selenium in the main chain have been synthesized. Poly(p-phenylene-diselenocarbonate) and poly(p-phenylene-diselenothiocarbonate) have been studied by X-ray photoelectron spectroscopy (XPS). Electrical conductivity was measured on samples without dopant agent and on samples doped with AlCl3, FeCl3, SbF5 and I-2. The morphology of these compounds was studied using a scanning electron microscope (SEM). Copyright (C) 1996 Elsevier Science Ltd
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    Thermal stability of aromatic poly(monoitaconates)
    (GORDON BREACH SCI PUBL LTD, 1996) Radic, D; Tagle, LH; Opazo, A; Gargallo, L
    Thermogravimetric analysis of poly(mono-benzyl itaconate), (PMBzI) poly(mono-ethylphenyl itaconate) (PMEPI) and poly(mono-n-propyl itaconate) (PMPPI), were performed by dynamic thermogravimetry. The thermal stability of these polymers depends on the side chain structure. The kinetic analysis of the degradation data shows that the thermal decomposition of these polymers follows a 0.5 kinetic order in all the cases.
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    Thermal studies of poly(esters) containing silicon or germanium
    (SOCIEDAD CHILENA DE QUIMICA, 2001) Tagle, LH; Diaz, FR; Opazo, A
    The thermal properties of poly(esters) containing silicon or germanium in the main chain and derived from the diphenols bis(4-hydroxyphenyl)-diphenylsilane and bis(4-hydroxyphenyl)-diphenylgermane and isophthaloyl or terephthaloyl acid dichlorides were studied by differential scanning calorimetry and dynamic thermogravimetry. Poly(esters) derived from terephthalic acid showed higher Tg and thermal stability values than those derived from isophthalic acid. Poly(esters) containing Ge showed higher Tg values but lower thermal decomposition temperatures when compared with the analogous with Si.
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    Thermal studies of poly(esters) containing silicon or germanium in the main chain
    (2005) Tagle, LH; Terraza, C; Valenzuela, P; Leiva, A; Urzúa, M
    The thermal properties of poly(esters) containing Si and/or Ge in the main chain derived from the acid dichlorides bis(4-chloroformylphenyl)-dimethyl-silane, bis(4-chloroformyl-phenyl)-dimethyl-germane, bis(4-chlorofonnyt-phenyl)-diphenyl-silane and bis(4-chloroformyl-phenyl)-diphenyl-silane, and the diphenols bis(4-hydroxyphenyl)-dimethyl-silane, bis (4-hydroxyphenyl)-dimethyl-germane, bis(4hydroxyphenyl)-diphenyl-silane and bis(4-hydroxyphenyl)-diphenyl-germane were studied by differential scanning calorimetry and dynamic thermogravimetry. Poly(esters) with two Si atoms in the main chain showed higher values of Tg than those with two Ge atoms, and the same was observed for poly(esters) with phenyl groups bonded to the heteroatoms, instead of those with methyl groups. Thermal decomposition temperatures were also higher for those poly(esters) with two Si atoms in the main chain and those in which the heteroatom is bonded to phenyl groups, due to the higher polarity of the Si-C bond in front of the Ge-C. (C) 2004 Elsevier B.V. All rights reserved.
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    Thermogravimetric analysis of poly(ester-carbonates) and poly(ester-thiocarbonates)
    (GORDON BREACH SCI PUBL LTD, 1995) Tagle, LH; Diaz, FR
    The thermogravimetric behaviour of poly(ester-carbonates) and poly(ester-thiocarbonates) derived from the diphenol esters 4-hydroxy-phenyl-4-hydroxy-benzoate, 3-hydroxy-phenyl-4-hydroxy-benzoate, 4-hydroxy-phenyl-3-hydroxy-benzoate, and 3-hydroxy-phenyl-3-hydroxy-benzoate with phosgene and thiophosgene was studied by dynamic thermogravimetry. The thermal decomposition temperatures were determined, showing that poly(ester-carbonates) are more stable than poly(ester-thiocarbonates). The kinetics parameters, activation energy, reaction order and pre-exponential factor, were determined by using the Arrhenius relationship and a computer program.
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    Vinyltrimethylsilane-co-methylmethacrylate copolymers. Synthesis and reactivity ratios
    (MARCEL DEKKER INC, 2000) Gatica, N; Alegria, S; Tagle, LH; Diaz, F; Gargallo, L; Radic, D
    In order to obtain information about the copolymerization process of vinyltrimethyl silane with comonomers of different chemical structure, copolymers containing vinyltrimethylsilane and methyl methacrylate at different compositions were synthesized and characterized. Comparison of the reactivity ratios of the resulting copolymers with those containing N-vinyl-2-pyrrolidone and 2-vinylpyridine previously reported and other related comonomers with different chemical structure allows us to establish some reactivity structure relationship and a generalization for these systems. The monomer reactivity ratios r(1) and r(2) (MRR) were estimated by using the classical linear fitting procedures and also through a computer program based on a nonlinear minimization algorithm, starting from the r(1) and r(2) values obtained by the former procedures.