A polysaccharide: poly sugar These OH groups bond with water
Gum Arabic: A polysaccharide: poly sugar Gum on acacia tree Gums:
soluble in water; form viscous (mucilinous) "solutions"; of C, H
and O only. Are typically organic carboyhydrate acids as Ca, Mg or
K salts.
Slide 3
Drying oils: lipids 5 Views of Linoleic Acid = C 18 H 32 O 2 2
unsaturated bonds (2 double bonds) Carbons only Carbons and
Hydrogens Note bend: due to Double bond
Slide 4
Other drying oils: Linoleic Acid = C 18 H 32 O 2 : 2
unsaturated bonds (2 double bonds) Oleic = C 18 H 34 O 2 Linolenic
= C 18 H 30 O 2 1 unsaturated bonds (1 double bonds) 3 unsaturated
bonds (3 double bonds)
Slide 5
The drying reaction: Drying is not just evaporation of solvent
(like fresco drying wasn't). Is a chemical reaction: oxidation
(here, addition of O 2 ); Double bonds are reactive (unstable) and
that is where O 2 adds Oxidation by O 2 can be catalyzed by Co, Mn
other metals (siccants)
Slide 6
Acrylics: are polymers monomer unit = Acrylic Acid: CH 2 =CHOOH
picture of polymer Methyl Methacrylate: monomer unit CH 2 =C(CH 3
)COOCH 3
Tempera (egg yolk): Protein, fat/oil, lecithin lecithin Fatty
acid Example of protein
Slide 10
So whats the bottom line regarding binders? Theyre all BIG
molecules Theyre all organic molecules Theyre most often bio
molecules They bind using Intermolecular Forces