Natural resins main

Ageing of natural resins mainly proceeds by autoxidation and strong oxidation occurs within a very short time within weeks and months rather than years and decades. Oxidation is more pronounced in light, but it also proceeds in darkness. Reduced intensities of... 

From a chemical point of view, vegetable resins are a complex mixture of mono-, sesqui-, di- and triterpenes, which have, respectively, 10, 15, 20 and 30 carbon atoms per molecule. The mono- and sesquiterpenes are both present in most resins. The di- and triterpenes are rarely found together in the same resin, which means that terpenic resins can be divided into two main classes. Table 1.5 lists the botanical origin and the kind of terpenoid compounds of some natural resins. 

The collection of reviews to be published in ADVANCES IN POLYMER SCIENCE is devoted just to these fundamental problems. The epoxy resin-curing agent formulations are typical thermosetting systems of a rather high degree of complexity. Therefore, some of the formation-structure-properties relationships are still of empirical or semiempirical nature. The main objective of this series of articles is to demonstrate the progress in research towards the understanding of these relationships in terms of current theories of macromolecular systems. 

The natural resin most commonly used as a binder today is rosin, which is often tailored by chemical modification to suit specific applications. Also, many synthetic hard resins mainly based on cyclohexanone, acetophenone, or aldehydes, are used in the paints industry. Hard resin binders increase the solids content, accelerate drying, and improve surface hardness, luster, and adhesion. 

Initially, phenolic resins attracted a great deal of interest because they appeared to be the first synthetic products that could be used as a substitute for natural resins (rosin, copal resins, shellac). Nowadays attention is mainly focused on performance and technical-economic competition between the widely differing groups of resins. 

Whereas natural fibers, mainly in the form of short fibers and fabric chips, have foimd application above all in the curable phenoplast and aminoplast molding compounds, it was more than anything else the development of the polyesters and epoxy resins that made it necessary to develop new kinds of reinforcing fibers to optimize the properties of these products as well. Modem, high-strength, synthetic organic fibers are the results of these efforts [112]. 

Natural surfactants (mainly asphaltenes and resins) extracted from one crude are added to a lighter crude or a condensate. 

This natural resin is used in adhesives, e.g., adhesive tape, epilating wax, and as a tacky wax to prevent slipping (violinists, gymnasts). It is a residue after distilling oils from certain pine trees. Gum rosin and wood rosin are the two main types. They contain abietic acid which may be the sensitizer. Cross-reactions between rosin and balsam of Peru occur (Fisher 1973, p. 173 Hjorth 1961). 

Natural resin paints natural resins (e.g., shellac) or chemical modified natural resins (e.g., colophonium derivates), additions (e.g., methyl cellulose, natural latex, casein), inorganic, organic pigments (mainly natural origin), mineral fillers, additives (organic solvents alcohols, terpenes, oil of turpentine, limonenes), essential oils (eucalyptus oil, oil of rosemary, oil of bergamot) various applications... 

The main natural resins used as wood panel binders are vegetal tannin adhesives, lignin adhesives and more recently also soy protein adhesives [1]. Of these, tannin-based adhesives have been used commercially the longest, since 1971. They offer the advantage over the other two types of not needing any reinforcement with an oil-derived synthetic resin [1]. Lignin [2-5] and soy binders [1, 6-8], however, still require between 20% and 40% of the total resin to be either phenol-formaldehyde or most often PMDI (polymeric isocyanate) to satisfy the requirements of relevant board standards. 

The less volatile fraction of CTO distillation in comparison to TOFA which comprises roughly spoken 30% of CTO is tall oil rosin (TOR).TOR consists mainly of natural resin acids. The actual composition depends on the age and species of the trees and the growing region from which it was derived as well as the processing conditions under which it was manufactured. TOR is the second most important tree resin. It accounts for 31% of the 1.3 Mio mto (2011) world production (gum rosin 68%, wood rosin l%). Wood and tall oil rosin are similar to gum rosin but contain a different mixture of resin acids (Figure 3B.21).The primary monobasic... 

The production of renewable raw materials (carbohydrates/wood derivatives, fats and oils, proteins, plant extracts), and petrochemical base chemicals is of the same order of magnitude are similar, but one has to consider that the use of renewable raw materials for the production of chemicals and biofuels is limited by the available land area and affects food production. Fats and oils are mainly consumed as food 10% is used for production of surfactants, candles, and cosmetic products, and another 10% for biodiesel. Wood consists of cellulose, hemicellulose, and lignin. The majority is used as fuel, mainly in developing countries 14% is used puipwood for production of cellulose and paper. Other important renewable raw materials are starch and sugar, which are both mainly consumed as food. Extracts and excreta from plants are natural rubber, natural dyes, and natural resins. 

Various structures in a polymer molecule cause it to become more reactive and thus unstable (Figure 2.17). When they form part of the main chain of the molecule, they cause particular instability. Many natural resins contain these groups and are thus less stable. 

Acidolysis of fatty adds with diterpene abietic add (3-156), the main component of the so-called resin acids (see Section 8.2.14) is used, for example, to produce varnishes, where the exchange of fatty acids for phthaHc acid yields glyptals (polymers containing the ester functional group with properties of natural resins). 

Toxic 5-alkatrienyl, 5-alkadienyl, 5-alkenyl and 5-alkyl resorcinols, collectively known as cardol, occur in the cashew nutshell liquid (CNSL), also known as cashew shell oil, a natural resin found in the honeycomb structure of the cashew nutshell. It is a byproduct of cashew nuts processing (see Section 8.2.6.1.6). A typical solvent-extracted CNSL contains 15-20% of cardol. The main components are (8Z,llZ)-pentadeca-8,ll,14-trien-l-yl (10-1), (8Z,llZ)-pentadeca-8,ll-dien-l-yl, (8Z)-pentadeca-8-en-1-yl and pentadecyl derivatives. 

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