SILVA, I. D. S.; SILVA, INGRIDY DAYANE DOS SANTOS.; DOS SANTOS SILVA, INGRIDY DAYANE.; http://lattes.cnpq.br/5675817448715747; SILVA, Ingridy Dayane dos Santos.
Resumen:
The commercial and scientific applications of epoxy resins depend on the
combination and reaction characters among resin/hardener/catalyst, forming a very
complex reactive system. In this work, the epoxy compound based on diglycidyl ether
of bisphenol A (DGEBA), methyl tetrahydrophthalic anhydride (MTHPA) as hardener
and 2,4,6-tris (dimethylaminomethyl) phenol (DEH 35) as catalyst, at fixed
concentration 100 / 87/5 was initially processed. In order to develop a workable
epoxy system, poly (lactic acid) (PLA) was added at contents of 10, 20, 30 and 90
phr to the epoxy compound. Analysis of hydrogen nuclear magnetic resonance (H-
NMR), Fourier transform infrared spectroscopy (FTIR) and differential scanning
calorimetry (DSC), were performed in order to obtain evidence of chemical
interactions and curing kinetics of investigated compositions. From the H-NMR and
FTIR spectra, partial miscibility between epoxy and PLA can be considered, mainly
due to the hydrogen bonds between the PLA carbonyl and epoxy hydroxyls. The
curing kinetics followed by the released heat during DSC scans indicated decrease in
the crosslink density after PLA addition, as well as lower Tg related to neat epoxy.
The epoxy network forbidden PLA crystallization, whereas neither exotherms nor
endotherms were displayed in DSC scans, regarding its crystallization and melting,
respectively. Partial solubility between the thermoplastic-thermosetting phases is also
suggested as driving force for the complex PLA structural organization/reorganization.
Increased curing temperatures, decreased conversion rate and decreased curing
enthalpy were obtained in epoxy/PLA compounds. By defining the guidelines for
chemical reactions and kinetics parameters of curing, the great control is achieved,
which allows manipulation of the operating system and definition of properties,
expanding the field of final products application.