CIOP   05384
CENTRO DE INVESTIGACIONES OPTICAS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
SHRINKAGE MEASUREMENT OF BIS-GMA RESINS BY EMBEDED FBG
Autor/es:
NELIDA ARACELI RUSSO; GUSTAVO ARENAS; SERGIO NORIEGA; RICARDO DUCHOWICZ
Lugar:
Lima
Reunión:
Congreso; RIAO OPTILAS 2010; 2010
Institución organizadora:
Pontificia Universidad Católica de Peru
Resumen:
Polymeric shrinkage in photo-curing resins is a considerable source of strain and residual stresses that holds permanently on final state of such materials. Knowing of this characteristic is a remarkable issue on latter designs and optimizations of various formulations. In addition, exothermic nature of these photo-polymeric reactions complicates measurements due to thermal expansion can competes with polymeric contraction. On the other hand, a thermal shrinkage takes place at samples cooling (post-curing), despite being small can distort actual net values. In this work we present a method that uses a Fiber Bragg Grating (FBG) embedded in the inside of samples containing photo-curing BIS-GMA resins (with Camphorquinone 1%), and a K-type thermocouple close up one each other. All FBG´s presents spectral response highly sensible to strain and stress (either longitudinal and/or transversal) and to temperature. The primary aim is the determination of shrinkage samples from the measurement of polymeric strain over the Bragg grating. Thermal effects are removed from the data using the thermocouple readings with post-processing allowing in such a way a more precise and sensitive value of shrinkage. Results are compatible with previous ones obtained by an interferometric technique. The technique gives us a more detailed information about what is happening in the inner of samples during the photo-curing reaction. Moreover, thermal expansion coefficients and the beginning of the vitrification process was estimated successfully.