Budrugeac, P.; Badea, E.; Della Gatta, G.; Miu, L.; Comanescu, A.; “A DSC study of deterioration caused by environmental chemical pollutants to parchment, a collagen-based material”, Thermochimica Acta 500 (1-2) (2010) 51-62
DOI:10.1016/j.tca.2009.12.010 (restricted access)
DOI:10.1016/j.tca.2009.12.010 (restricted access)
Abstract:
A DSC study of new parchments exposed at 25
degrees C for 1-16 weeks to controlled atmospheres containing 50 ppm of gaseous
chemical pollutants (NO2, SO2, NO2 + SO2)
and 50% relative humidity (RH) was performed. Samples were exposed to chemical
pollutants alone, as well as after previous heating at 100 C for 2-16 days
and/or irradiating with visible light (1.7 x 10(5) lx) for 4-16 h. DSC
measurements were performed in both sealed crucibles in static air atmosphere
at 25-200 degrees C and open crucibles under gas flow (nitrogen, oxygen,
synthetic air) at 25-280 degrees C. Analysis of DSC curves provided the
variation induced by ageing on the thermodynamic parameters associated with
both parchment denaturation and softening of collagen crystalline fraction. All
the ageing procedures decreased both temperature and enthalpy of denaturation
and increased broadness of DSC peak in function of ageing time. The occurrence
of thermal oxidation peaks and/or lower temperature endothermic peaks was
observed. The temperature of the first softening peak always indicated a
general tendency to decrease as a function of ageing time. Shrinkage
temperature of collagen fibres measured by thermomicroscopy also decreased as a
result of accelerated ageing treatments.