KINETICS OF CURING OF UNSATURATED POLYESTERS IN THE PRESENCE OF ORGANIC AND INORGANIC FILLERS

The curing of unsaturated polyesters in the presence of organic and in organic fillers was studied by rheology and differential scanning calo rimetry (DSC). A commercial resin was used as unsaturated polyester an d pressed olive stones, which are an agricultural by-product, talc and quartz in different concentrations were used as fillers. The viscosit y versus time at different temperatures was recorded and the gel time (G) was determined by the sharp increase of viscosity, which involves the beginning of the crosslinking reaction. DSC records the exothermic peak due to the double bonds breaking to give crosslinked macromolecu les. The results of both methods were treated kinetically. The activat ion energy E-v and the pre-exponential factor A' from the rheological method remained almost constant in the case of talc and quartz compare d with the neat unsaturated polyester. With pressed olive stones as fi ller, both parameters increased. On the other hand. the DSC results fo r the resins with inorganic and organic fillers showed a decreased act ivation energy E-a,E-D and frequency factor k(o,D) compared with the n eat unsaturated polyester, whose activation energy E-a,E-D. and freque ncy factor k(o,D) were calculated to be 23.5 kcal mol(-1) and 9.5 x 10 (9) s(-1), respectively. The order of reaction was calculated to be cl ose to 1, The olive stones influenced the curing reaction, acting as a n auxiliary accelerator.