CURING OF NOVOLAC-LIGNOCELLULOSIC COMPOSITES

Novalac resin (N) with hexamethylenetetramine (HTA) was cured with bio mass (B) or Kraft lignin (KL) or hydroxymethylated Kraft lignin (KLH) or cellulose (GEL). The agricultural/industrial by-product of olive st ones was used as biomass. Kraft lignin, hydroxymethylated Kraft lignin and cellulose were isolated from the biomass. The cure was followed b y DSC and IR spectroscopy. Based on the IR spectra of cured materials and their characteristic bands, the proportion of N/B = 50/50 was chos en for the preparation of novolac mixtures with other components. Only N-KLH exhibited values of Delta H higher than Delta H-m, calculated f rom the law of mixtures, indicating that KLH participates in the cure reaction. The kinetic parameters E and k(0) of the total cure reaction s, calculated by DSC scans, increased in the order N < N-KLH < N-B < N -KL < N-CEL. The incorporation of KLH in the mass of N-HTA led to a sl ight increase in E and k(0). On the other hand, KL, CEL and B acted as diluents in the mass of novolac. Generally, the cure of all materials was a first order reaction, indicating that the cure mechanism of nov olac remains the same.