Browsing by Author "Tagle, L.H."

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    Thermal stability of aromatic poly(monoitaconates)
    (GORDON BREACH SCI PUBL LTD, 1996) Radic, D.; Tagle, L.H.; 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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    THERMOGRAVIMETRIC ANALYSIS OF COPOLY(CARBONATE THIOCARBONATE)S
    (ELSEVIER SCIENCE BV, 1991) Tagle, L.H.; Diaz, F.R.
    The thermal stability and the kinetics parameters of copoly(carbonate-thiocarbonate)s from two diphenols and for three different compositions were studied. No clear relation between the thermal decomposition temperature and the carbonate content was found for the two series of copolymers. The kinetics parameters of the thermal decomposition were determined using the Arrhenius relationship and indicated a two-step degradation process, the first step being of zero kinetic order and the second of first order. The steps were associated with two different decomposition mechanisms.
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    THERMOGRAVIMETRIC ANALYSIS OF POLY(ETHER-ESTER)S DERIVED FROM BISACID A-2 AND RELATED DIACIDS AND DIPHENOLS
    (ELSEVIER SCIENCE BV, 1991) Tagle, L.H.; Diaz, F.R.; Vargas, M.A.
    The thermogravimetric behaviour of nine poly(ether-ester)s derived from three acid dichlorides and three diphenols was studied by dynamic thermogravimetry. The thermal decomposition temperatures (TDT), the temperature at which the poly(ether-ester)s lost 10% of their weight, were also determined; they are within 30-degrees-C of each other. The kinetics parameters of the thermal decomposition were also determined. The poly(ether-ester)s in which the structures of the acid dichloride and the diphenol were the same, showed a 0 kinetic order, but when those structures were different the kinetic order was 0.5, which means that the degradation is a complex process.
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    THERMOGRAVIMETRIC STUDIES OF POLY(OXYMETHYLENE-CO-DIMETHYLSILOXANE) COPOLYMERS
    (ELSEVIER SCIENCE BV, 1993) Rodriguez Baeza, M.; Zapata, M.; Cardenas, G.; Tagle, L.H.
    The thermal stability and kinetic parameters of a series of poly(oxymethylene-co-dimethylsiloxane) copolymers have been studied by thermogravimetry from 303 to 846K under nitrogen flow. The new copolymers, obtained by ring-opening copolymerization of 1,3,5-trioxane and hexamethylcyclotrisiloxane, contain different concentrations of oxymethylene and dimethylsiloxane comonomer units. The results of the thermal studies were compared with data corresponding to pure poly(oxymethylene) and poly(dimethyl-siloxane). The copolymers with low concentration of dimethylsiloxane comonomer units show only one degradation process, but copolymers richer in this co-unit degrade in two stages. Copolymers with an even higher concentration of dimethylsiloxane co-unit have three decomposition processes. The TGA results indicate that the molecular structure of the copolymers correspond to block copolymers and random copolymers bonded to segments formed by both pure poly(oxymethylene) and poly(dimethylsiloxane). The structures depend on the composition of the copolymers. The pre-exponential factors, the reaction orders and the activation energies have been determined from non-isothermal thermogravimetric data.