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Back To In The Workshop or Choosing The Right Adhesive
[edit] In A Nutshell
Polyvinyl acetate (PVA or PVAc) is a rubbery #synthetic polymer. It is prepared by polymerization of #vinyl acetate monomer, also referred to as VAM. Partial or complete #hydrolysis of the polymer is used to prepare #polyvinyl alcohol. Hydroylized alcohol product is typically in the 87% to 99% range (converted PVA). It was discovered in Germany by Dr. Fritz Klatte in 1912.
As an emulsion in water, PVA is sold as an adhesive for porous materials, particularly wood, paper, and cloth. It is the most commonly used wood glue, both as "white glue" and the yellow "#carpenter's glue." PVA is widely used in bookbinding and book arts due to its flexibility, and because it is non-acidic, unlike many other polymers.
PVA is a common copolymer with more expensive acrylics, used extensively in paper, paint and industrial coatings, referred to as vinyl acrylics. It can also be used to protect cheese from fungi and humidity. It is slowly attacked by alkali, forming acetic acid as a hydrolysis product. Boron compounds like boric acid or #borax will form tackifying precipitates by causing the polymer to #cross-link.
PVA is also commonly recommended for use in making leather handcrafted works and papier-mâché.
[edit] Definitions
synthetic polymers
- Synthetic polymers are often referred to as "plastics", such as the well-known polyethylene and nylon. However, most of them can be classified in at least three main categories: thermoplastics, thermosets and elastomers.
- Man-made polymers are used in a wide array of applications: food packaging, films, fibers, tubing, pipes, etc. The personal care industry also uses polymers to aid in texture of products, binding, and moisture retention (e.g. in hair gel and conditioners).
vinyl acetate monomer
- Vinyl acetate is the organic compound with the formula CH3COOCH=CH2. This colorless liquid with a pungent odor is the precursor to an important polymer polyvinyl acetate. Like other industrially significant compounds, vinyl acetate has numerous names and acronymns. Want to know more
hydrolysis
- Hydrolysis is a chemical reaction or process in which a chemical compound is broken down by reaction with water. It is the type of reaction that is used to break down certain polymers, especially those made by step-growth polymerization. Such polymer degradation is usually catalysed by either acid or alkali attack, often increasing with their strength or pH. Want to know more
polyvinyl alcohol
- Polyvinyl alcohol (PVOH, PVA, or PVAL) is a water-soluble synthetic polymer. It has excellent film forming, emulsifying, and adhesive properties. It is also resistant to oil, grease and solvent. It is odorless and nontoxic. It has high tensile strength and flexibility, as well as high oxygen and aroma barrier properties. However these properties are dependent on humidity, in other words, with higher humidity more water is absorbed. The water, which acts as a plasticiser, will then reduce its tensile strength, but increase its elongation and tear strength. PVA is fully degradable and is a quick dissolver. Want to know more
carpenter's glue
- The most common wood glues are polyvinyl acetate (PVA), also known as "white glue" or "hobby and craft", and aliphatic resin emulsion, commonly referred to as "carpenter's glue" or "Yellow glue", which has similar relative ultimate strength. The two have different grip characteristics before initial set, with PVAs exibiting more slip during assembly and yellow glue having more initial grip.
borax
- Borax (from Persian burah), also known as sodium borate, sodium tetraborate, or disodium tetraborate, is an important boron compound, a mineral, and a salt of boric acid. It is usually a white powder consisting of soft colorless crystals that dissolve easily in water.
- Borax has a wide variety of uses. It is a component of many detergents, cosmetics, and enamel glazes. It is also used to make buffer solutions in biochemistry, as a fire retardant, as an anti-fungal compound for fiberglass, as an insecticide, as a flux in metallurgy, and as a precursor for other boron compounds. Want to know more
cross-link
- Cross-links are bonds that link one polymer chain to another. They can be covalent bonds or ionic bonds. "Polymer chains" can refer to synthetic polymers or natural polymers (such as proteins). When the term "cross-linking" is used in the synthetic polymer science field, it usually refers to the use of cross-links to promote a difference in the polymers' physical properties. When "crosslinking" is used in the biological milieu, it can be in reference to its use as a probe to link proteins together to check protein-protein interactions, as well as other creative cross-linking methodologies. Cross-linking is used in both synthetic polymer chemistry and in the biological sciences. Want to know more
