2024-03-28T10:41:06Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/1413652017-09-20T04:30:41Zcom_10261_98com_10261_3col_10261_351
2016-12-13T11:37:45Z
urn:hdl:10261/141365
Combined TGA-MS kinetic analysis of multistep processes. Thermal decomposition and ceramification of polysilazane and polysiloxane preceramic polymers.
García-Garrido, Cristina
Sánchez-Jiménez, P.E.
Pérez-Maqueda, Luis A.
Perejón, Antonio
Criado Luque, J.M.
Kinetics
Deconvolution
Frasier-Suzuki
Polymer-Derived Ceramics
Thermal decomposition
The polymer-to-ceramic transformation kinetics of two widely employed ceramic
precursors; 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane (TTCS) and
polyureamethylvinylsilazane (CERASET) have been investigated using coupled
thermogravimetry and mass spectrometry (TG-MS), Raman, XRD and FTIR. The
thermally induced decomposition of the pre-ceramic polymer is the critical step in the
synthesis of Polymer Derived Ceramics (PDCs) and an accurate kinetic modeling is key
to attain a complete understanding of the underlying process and to attempt any
behavior predictions. However, obtaining a precise kinetic description of processes of
such complexity, consisting of several largely overlapping physico-chemical processes
comprising the cleavage of the starting polymeric network and the release of organic
moieties, is extremely difficult. Here, using the evolved gases detected by MS as a
guide it has been possible to determine the number of steps that compose the overall
process, which was subsequently resolved using a semiempirical deconvolution method
based on the Frasier-Suzuki function. Such function is more appropriate that the more
usual Gaussian or Lorentzian functions since it takes into account the intrinsic
asymmetry of kinetic curves. Then, the kinetic parameters of each constituent step was
independently determined using both model-free and model-fitting procedures, finding
the processes obey mostly diffusion models that can be attributed to the diffusion of the
released gases through the solid matrix. The validity of the obtained kinetic parameters
was tested not only by the successful reconstruction of the original experimental curves
but also by predicting the kinetic curves of the overall processes yielded by different
thermal schedules and by a mixed TTCS-CERASET precursor
2016-12-13T11:37:45Z
2016-12-13T11:37:45Z
2016
artículo
Physical Chemistry Chemical Physics, 18, 29348-29360 (2016)
http://hdl.handle.net/10261/141365
10.1039/C6CP03677E
eng
Postprint
http://dx.doi.org/10.1039/C6CP03677E
Sí
openAccess
Royal Society of Chemistry (UK)