ON- POLYMERS - ezio martuscelli

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FIGURE 9: Model showing the layer structure of a painting [15]. Binders are defined in reference [17] as follows: < A resin or other cement like material used to hold particles together and provide mechanical strength or to ensure uniform consistency, solidification, or adhesion to a surface coating; typical binder are resin, glue, gum, and casein > [17]. In painting art the binders, while are hardening forming a transparent coat, should be able to fix the pigments and dyes to the preparation layer without influencing their colors. Binders should also have the capability to: --- give to paints a high chromatic yield, brightness and brilliancy; --- implement the solidity of the paints against the physical and chemical factors of deterioration [15,16]. Varnish formulations, used for coating the surfaces of the paintings, according to reference [17] can be defined as follows: < A transparent surface coating which is applied as a liquid and then changes to a hard solid; all varnishes are solutions of resinous materials in a solvent > [17]. Varnishes have not only the role of render more homogeneous and brilliant the surface but also that of protecting the underlying painting, including pigments, against the action of water, light and chemical pollutant agents. Before the development of synthetic resins several types of natural substances that derived from animal or vegetal world were used as binders in the painting art (as example, terpenes, proteins, polysaccharides, drying oils, etc. ). Just before the Second World War the chemistry industry developed several types of synthetic binders with innovative performances and properties and tailored to be used also in the field of painting art.
Such a new products very soon began to replace natural materials. According to R. Mustalish this substitution process happened essentially because: < They were cheaper and more readily available, especially during World War II, when natural raw materials were difficult to obtain. They also appealed to artists who wanted to experiment with non traditional materials to create non traditional art > [18]. Some of the characteristics of synthetic binders are hereafter summarized: i) can be easily used; ii) are able to induce brightness; iii) their hardening is very fast; iv) the painting film is high elastic; v) they may be applied directly on no pre-treated canvas; vi) in some cases they may be used also as protective surface varnish. The denomination and the chemical structure of monomers and of repetitive units of polymers that are the constituents of the most common synthetic binders are shown in figures 10 [16]. Among those reported in figure 10 the most used synthetic binders for artistic paints definitely were the alkyd, vinyl and acrylic resins whose molecular structures are depicted in figure 11 [19]. In 1946 the Bocour Artists Colors Inc developed a line of paints specific for artistic use, based on acrylic resin dissolved in organic solvent , marketed as Magna. < these highly pigmented paints, which could be thinned with turpentine and used with oils, made them immediately attractive to modern artists such as Morris Louis, Kenneth Noland, Jules Olitski, and Roy Liechtenstein > [18]. In 1955 the Permanent Pigments Inc. commercialized the first paint for artists based on acrylic resins dispersed in water ( marketed as Liquitex ). < Andy Warhol and Helen Frankenthaler were among the first artists to use this new medium > [18]. The most relevant peculiarities of paints, based on water emulsions of acrylic resins, have been summarized as follows by R. Mustalish [18]: < --- They can be diluted in water instead of turpentine or paint thinner, --- they dry very quickly, and, unlike Magna color, they do not resolubilize with the addition of other layers of acrylic. This allows the artist to paint layer upon layer without disturbing the previously applied paint. --- Acrylics also cause less change to paper and textiles, giving the artist more freedom in choosing supports for the work of art > [18]. Starting from 1950s the acrylic water emulsion based paints were more and more used by artists substituting most of polyvinyl acetate emulsion paints. According to G. Martinez the introduction of acrylic resins represented a revolution in the field of artistic paintings comparable only to the first use of oil painting by the Flemish painter Van Eyck [14]. It is interesting to point out that now a days most of commercial canvas are prepared by using acrylic emulsion able to impart an higher flexibility in comparison to more traditional substances [20].
Page 1 and 2: WITH THE GROWTH OF POLYMER INDUSTRY
Page 3 and 4: Early attempts in using plastics as
Page 5: FIGURE 8: Sculpture in epoxy resin
Page 9 and 10: FIGURE 11: Molecular structure of t
Page 11 and 12: This phase of imitation and substit
Page 13 and 14: vibration of the recording stylus w
Page 15 and 16: iv) Plastic applications in the sec
Page 17 and 18: FIGURE 21: Left, Handsome mahogany
Page 19 and 20: Objects in plastics attesting event
Page 21 and 22: REFERENCES 1 ) E. Martuscelli, La C

ON- POLYMERS - ezio martuscelli

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