INFLUENCE OF BIOMASS ON THE CURING OF NOVOLAC-COMPOSITES

Novolac resin (N) was cured with hexamethylenetetramine (hexa) without or with biomass (B). The agricultural/industrial by-product of olive stones was used as biomass. The curing was followed by DSC and i.r.-sp ectroscopy and the kinetic of curing was performed based on DSC scans. For the cured composites having high amounts of hexa (28.6%), the cha racteristic peaks of hexa were present, whereas for the material havin g low amounts of hexa (10%) these peaks disappeared. The composites co ntaining high proportions of novolac (N = 70%) exhibit the same values of the enthalpy changes Delta H and Delta H-m, the latter calculated from the law of mixtures, whereas the composites with high proportion of biomass (B = 30%) show different values of Delta H and Delta H-m. T he kinetic parameters of activation energy E and frequency factor k(o) of the total curing reaction of novolac with hexa are almost the same for high amounts of hexa (20%, 28.6%) but are slightly increased with decreased amounts of hexa (10%, 5%). The incorporation of biomass in the mass of novolac-hexa leads to an increase of E and k(o). Generally , the curing reaction for all materials is a first order reaction. Cop yright (C) 1996 Elsevier Science Ltd