Resins, fossil

Natural resins are generally described as solid or semisolid amorphous, fusible, organic substances that are formed in plant secretions. They are usually transparent or translucent yeUow-to-brown colored, and are soluble in organic solvents but not in water. The principal uses for natural resins are in varnishes, printing inks, adhesives, paper size, and polymer compositions. The term natural resins includes tree and plant exudates, fossil resins, mined resins, and shellac. They often have been altered from their original state during isolation and processing. For some appHcations, the resins have been chemically modified to increase their industrial utiUty. 

Ka.un. This fossil resin, classified as a copal, is found in the South Pacific, primarily in New Zealand. It formerly was used in protective coatings. It is still used in the Kauri-butanol test (ASTM D1133) to determine the volume of thinner that can be added to a varnish formulation without causing turbidity. 

In Ancient Rome, Pliny the Elder (c. a.d. 23-79) dedicated 37 volumes of Natural History to the emperor Titus. In the last of these books, dealing with gems and precious stones, he describes the properties of the fossil resin, amber. The ability of amber to attract dust was recognised and in fact the word electricity is derived from elektron, the Greek for amber. 

One resin, however, can be considered as an exception to this. Although rarely recognised as a plastics material it can be fabricated into pipe mouthpieces, cigarette holders and various forms of jewellery. It may also be compression moulded and extruded. It is the fossil resin amber. 

Erdharz, n. asphalt, bitumen fossil resin. — gelbes —, amber,... 

Amber Organic Origin Fossil resin Yellow//brown/red... 

Poinar, G. O. and R. Milki (2001), Lebanese Amber The Oldest Insect Ecosystem in Fossilized Resin, Oregon State University, Corvallis, OR. 

Resins older than 40 000 years are considered to be fossil resins. The fossilization of resins begins with polymerisation and forms ambers and copals. Most of the ambers are derived from components of diterpenoid resins with a labdanoid structure other ambers are based on polymers of sesquiterpene hydrocarbons such as cadinene, and may include triterpenoids less common ambers from phenolic resins derive from polymers of styrene. Figure 1.4 shows the skeletal structures of the components which make up the polymers occurring in fossil resins [141]. 

Figure 1.4 Main structures of polymeric fossil resins...

Copals, sometimes referred to as immature amber, originate from Africa, Asia or central American countries and derive from the Araucariaceae and Leguminosae families. Polymerised communic acid and agathic acid are found as the main compounds in these fossil resins. The extreme hardness of copal results from polymers of resin acids such as ozoic acid, an enantiomer of communic acid that can polymerize and thus enable fossilization [86]. They are still commonly used today for varnishing and protecting wood. 

I. Pastorova, T. Weeding, J.J. Boon, 3 Phenylpropanylcinnamate, a copolymer unit in siegbur gite fossil resin a proposed marker for the Hamamelidaceae, Organic Geochemistry, 29, 1381 1393 (1998). 

K.B. Anderson, J.C. Crelling (Eds), Amber, Resinite, and Fossil Resins, American Chemical Society, Washington, DC, 1995. 

Some high molecular weight substances, such as highly polymerized terpenic resins or fossil resins, cannot be directly analysed by GC/MS. In these cases online analytical pyrolysis combined with GC/MS can be used. Pyrolysis-GC/MS applications are described in Chapters 11 and 12. 

K.B. Anderson, New evidence concerning the structure, composition, and maturation of Class I (polylabdanoid) resinites, in Amber, Resinite and Fossil Resins, K.B. Anderson and J.C. Crelling (Eds), vol.617, American Chemical Society, Washington, DC 105 129 (1995). 

Grimalt, J.O., Simoneit, B.R.T. and Hatcher, P.G. (1989). Chemical affinities between the solvent extractable and bulk organic matter of fossil resin associated with an extinct podocarpaceae. Phytochemistry 28 1167-1171. 

Anderson KB, LePage BA, Analysis of fossil resins from Axel Heiberg Island,... 

Otto A, Simoneit BRT, Wilde V, Kimzmann L, Piittmann W, Terpenoid composition of three fossil resins from Tertiary and Cretaceous conifers, Review of Palaeobotany and Palynology 2452 1—13, 2001. 

Grantham PJ, Douglas AG, The nature and origin of sesquiterpenoids in some Tertiary fossil resins, Geochim Cosmochim Acta 1980. 

Another promising application of NMR spectrometry to archaeological problems deals with fossil resins. These terpenoid polymers, the best known of which is amber, have played a large role in trade relations during prehistoric times since at least the neolithic era, and the determination of their geographic and botanical origin can contribute to our knowledge of this early commerce. 

Unfortunately, fossil resins are largely insoluble because of their polymeric character, and a dissolved sample is a prerequisite for a well resolved NMR spectrum. We have therefore carried out comparative NMR studies on the soluble pyrolysates of amber and of pine resins. 

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