A thermal analytical study of some modern and fossil resins from New Zealand
A thermal analytical study of some modern and fossil resins from New Zealand
- Thermochimica Acta, 326(1-2), p.143-149, 1999 .
Differential and thermogravimetric analyses of New Zealand modern, Pleistocene (<30 000 years)and Tertiary (>40 000 000 years)Agathis resins show a progressive change in their combustion pro®les with increasing age. Differences between modern resins and Pleistocene Kauri gums are minimal. Both exhibit thermal events in the low-temperature range, commencing near 1008C and extending to 3008C, that re¯ect the relative abundance of more reactive, undersaturated, carboxyl-rich, unpolymerized components in the younger samples. Diagenetic changes accompanying thermal maturation reveal a reduction in intensity of thermal responses below 2008C and a progression in the temperature of the major thermal combustion event, from 350±4508C in the younger resins, to 450±5808C in the 40 000 000-year-old copals. These variations in thermal behavior accord with a reduction in undersaturated bonds and functionalized groups, and an increase in the proportion of aromatized groups that characterize resin aging. Used judiciously, thermal behavior may indicate maturation histories and resin associations.
AGATHIS
NEW ZEALAND
RESIN
COPAL
THERMAL ANALYSIS
Differential and thermogravimetric analyses of New Zealand modern, Pleistocene (<30 000 years)and Tertiary (>40 000 000 years)Agathis resins show a progressive change in their combustion pro®les with increasing age. Differences between modern resins and Pleistocene Kauri gums are minimal. Both exhibit thermal events in the low-temperature range, commencing near 1008C and extending to 3008C, that re¯ect the relative abundance of more reactive, undersaturated, carboxyl-rich, unpolymerized components in the younger samples. Diagenetic changes accompanying thermal maturation reveal a reduction in intensity of thermal responses below 2008C and a progression in the temperature of the major thermal combustion event, from 350±4508C in the younger resins, to 450±5808C in the 40 000 000-year-old copals. These variations in thermal behavior accord with a reduction in undersaturated bonds and functionalized groups, and an increase in the proportion of aromatized groups that characterize resin aging. Used judiciously, thermal behavior may indicate maturation histories and resin associations.
AGATHIS
NEW ZEALAND
RESIN
COPAL
THERMAL ANALYSIS