This work reported a NMR investigation on the structural and
chemical changes responsible for the degradation of carbon black
filled natural rubber due to long term contact with biodiesel.
Carr-Purcell-Meiboom-Gill and double-quantum time domain
NMR experiments revealed that network swelling occurs in different
ways when the rubber is placed in contact with both petrodiesel
and biodiesel. The biodiesel seems to be more effective for
creating network defects which was attributed to the stronger
interaction of biodiesel with the polymer chains. Using high resolution
13C NMR spectroscopy and 1
H Magic Sandwich Echoes Refocused
FIDs we showed the presence of immobilized isoprene
residues in biodiesel after contact with the rubber which was
absent in the case of petrodiesel. These results were interpreted
as result of the exudation of carbon black aggregates, which create
micro voids in the rubber systems leading to the loss of its
mechanical resistance. Therefore, these data indicate that efforts
must be made in order to optimize filler-matrix compatibility to
increase the durability of the rubber.