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  • 1 Swinburne University of Technology School of Engineering and Science PO Box 218 Hawthorn Victoria 3122 Australia PO Box 218 Hawthorn Victoria 3122 Australia
  • 2 CSIRO Molecular Science Private Bag 10 Clayton South MDC Victoria 3169 Australia Private Bag 10 Clayton South MDC Victoria 3169 Australia
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Abstract  

Differential scanning calorimetry(DSC) was used to study the effects of varying NaOH concentrations on the thermochemical curing properties of 2,4-dimethylol phenol (2,4-DMP), and 2,6-dimethylol phenol(2,6-DMP). Analysis of the DSC curves showed significant differences in the thermochemical curing behavior of these compounds with increasing NaOH:DMP molar ratios, in terms of the peak shape, position of the reaction peaks, (Tp), along the temperature scale and energy of activation, E. The curves consisted of either a single, two or three exothermic peaks which indicated the occurrence of multiple reactions. One of these peaks was observed for the entire range of NaOH molar ratios, and is attributed to the self-condensation reaction. For the 2,4-DMP, NaOH had the effect of lowering the Tp of curing from 212C in the uncatalyzed state to135C between 0.15–0.75 molar ratios. The lowest value of E, however, was 111 kJ mole−1, only through 0.45–0.60 molar ratios and this combined with the above, points to this concentration range as the optimum NaOH level. Similarly, the Tp of curing for the 2,6-DMP was lowered from 211C in the uncatalyzed state, to a minimum of 116C at the NaOH:2,6-DMP molar ratio of 0.45. At this ratio, Ealso had the lowest value of 117 kJ mole−1 and this suggests that 0.45 molar ratio is the optimum NaOH level.

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