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Polyvinyl acetate

Polyvinyl acetate

Overview
Polyvinyl acetate, PVA, PVAc, poly(ethenyl ethanoate), is a rubber
Rubber
Natural rubber, also called India rubber or caoutchouc, is an elastomer that was originally derived from latex, a milky colloid produced by some plants. The plants would be ‘tapped’, that is, an incision made into the bark of the tree and the sticky, milk colored latex sap collected and refined...

y synthetic polymer
Synthetic polymer
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....

 with the formula (C4H6O2)n. It belongs to the polyvinyl ester
Vinyl polymer
Vinyl polymers are a group of polymers derived from vinyl monomers. Their backbone is an extended alkane chain, made by polymerizing an alkene group into a chain . In popular usage, "vinyl" refers only to polyvinyl chloride...

s family with the general formula -[RCOOCHCH2]-. It is a type of thermoplastic
Thermoplastic
Thermoplastic, also known as a thermosoftening plastic, is a polymer that turns to a liquid when heated and freezes to a very glassy state when cooled sufficiently...

.

It should not be confused with the related polymer polyvinyl alcohol
Polyvinyl alcohol
Polyvinyl alcohol is a water-soluble synthetic polymer .-Properties:...

, which is called PVA also (PVAc could be considered a technically correct abbreviation for polyvinyl acetate and would aid in avoiding such confusion).

Polyvinyl acetate is a component of a widely-used type of glue, referred to variously as wood glue, white glue, carpenter's glue, school glue or PVA glue.

PVAc is a vinyl polymer.
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Encyclopedia
Polyvinyl acetate, PVA, PVAc, poly(ethenyl ethanoate), is a rubber
Rubber
Natural rubber, also called India rubber or caoutchouc, is an elastomer that was originally derived from latex, a milky colloid produced by some plants. The plants would be ‘tapped’, that is, an incision made into the bark of the tree and the sticky, milk colored latex sap collected and refined...

y synthetic polymer
Synthetic polymer
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....

 with the formula (C4H6O2)n. It belongs to the polyvinyl ester
Vinyl polymer
Vinyl polymers are a group of polymers derived from vinyl monomers. Their backbone is an extended alkane chain, made by polymerizing an alkene group into a chain . In popular usage, "vinyl" refers only to polyvinyl chloride...

s family with the general formula -[RCOOCHCH2]-. It is a type of thermoplastic
Thermoplastic
Thermoplastic, also known as a thermosoftening plastic, is a polymer that turns to a liquid when heated and freezes to a very glassy state when cooled sufficiently...

.

It should not be confused with the related polymer polyvinyl alcohol
Polyvinyl alcohol
Polyvinyl alcohol is a water-soluble synthetic polymer .-Properties:...

, which is called PVA also (PVAc could be considered a technically correct abbreviation for polyvinyl acetate and would aid in avoiding such confusion).

Polyvinyl acetate is a component of a widely-used type of glue, referred to variously as wood glue, white glue, carpenter's glue, school glue or PVA glue.

Preparation


PVAc is a vinyl polymer. Polyvinyl acetate is prepared by polymerization
Polymerization
In polymer chemistry, polymerization is a process of reacting monomer molecules together in a chemical reaction to form three-dimensional networks or polymer chains...

 of vinyl acetate monomer
Vinyl acetate
Vinyl acetate is an organic compound with the formula CH3COOCH=CH2. A colorless liquid with a pungent odor, it is the precursor to polyvinyl acetate, an important polymer in industry.-Production:...

 ( free radical
Radical (chemistry)
Radicals are atoms, molecules, or ions with unpaired electrons on an open shell configuration. Free radicals may have positive, negative, or zero charge...

 vinyl polymerization of the monomer
Monomer
A monomer is an atom or a small molecule that may bind chemically to other monomers to form a polymer; the term "monomeric protein" may also be used to describe one of the proteins making up a multiprotein complex...

 vinyl acetate).

Discovery


Polyvinyl acetate was discovered in Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 in 1912 by Dr. Fritz Klatte
Fritz Klatte
Fritz Klatte was a German chemist and the discoverer of polyvinyl acetate, with German patent for its preparation from acetylene gas....

.

The monomer, vinyl acetate, was on an industrial scale first produced by addition of acetic acid
Acetic acid
Acetic acid is an organic compound with the chemical formula CH3CO2H . It is a colourless liquid that when undiluted is also called glacial acetic acid. Acetic acid is the main component of vinegar , and has a distinctive sour taste and pungent smell...

 to acetylene
Acetylene
Acetylene is the chemical compound with the formula C2H2. It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is unstable in pure form and thus is usually handled as a solution.As an alkyne, acetylene is unsaturated because...

 with a mercury(I) salt but it is now primarily made by palladium catalyzed oxidative addition of acetic acid to ethylene
Ethylene
Ethylene is a gaseous organic compound with the formula . It is the simplest alkene . Because it contains a carbon-carbon double bond, ethylene is classified as an unsaturated hydrocarbon. Ethylene is widely used in industry and is also a plant hormone...

.

Properties


The degree of polymerization of polyvinyl acetate typically is 100 to 5000.
The ester groups of the polyvinyl acetate are sensitive for alkali
Alkali
In chemistry, an alkali is a basic, ionic salt of an alkali metal or alkaline earth metal element. Some authors also define an alkali as a base that dissolves in water. A solution of a soluble base has a pH greater than 7. The adjective alkaline is commonly used in English as a synonym for base,...

 and will slowly convert PVAc into polyvinyl alcohol and acetic acid
Acetic acid
Acetic acid is an organic compound with the chemical formula CH3CO2H . It is a colourless liquid that when undiluted is also called glacial acetic acid. Acetic acid is the main component of vinegar , and has a distinctive sour taste and pungent smell...

.

Under alkaline conditions, boron
Boron
Boron is the chemical element with atomic number 5 and the chemical symbol B. Boron is a metalloid. Because boron is not produced by stellar nucleosynthesis, it is a low-abundance element in both the solar system and the Earth's crust. However, boron is concentrated on Earth by the...

 compounds, such as boric acid
Boric acid
Boric acid, also called hydrogen borate or boracic acid or orthoboric acid or acidum boricum, is a weak acid of boron often used as an antiseptic, insecticide, flame retardant, as a neutron absorber, and as a precursor of other chemical compounds. It exists in the form of colorless crystals or a...

 or borax
Borax
Borax, 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...

 causes the polymer to cross-link
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 . When the term "cross-linking" is used in the synthetic polymer science field, it usually refers to the use of...

 forming tackifying precipitates or slime
Slime (toy)
Slime was a toy product manufactured by Mattel, sold in a plastic trash can and introduced in the winter of 1976 consisting of a non-toxic viscous, oozing green material made primarily from guar gum...

.

Applications and uses


As an emulsion
Emulsion
An emulsion is a mixture of two or more liquids that are normally immiscible . Emulsions are part of a more general class of two-phase systems of matter called colloids. Although the terms colloid and emulsion are sometimes used interchangeably, emulsion is used when both the dispersed and the...

 in water, PVAc emulsions are used as adhesive
Adhesive
An adhesive, or glue, is a mixture in a liquid or semi-liquid state that adheres or bonds items together. Adhesives may come from either natural or synthetic sources. The types of materials that can be bonded are vast but they are especially useful for bonding thin materials...

s for porous
Porosity
Porosity or void fraction is a measure of the void spaces in a material, and is a fraction of the volume of voids over the total volume, between 0–1, or as a percentage between 0–100%...

 materials, particularly for wood
Wood
Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...

, paper
Paper
Paper is a thin material mainly used for writing upon, printing upon, drawing or for packaging. It is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets....

, and cloth, and as a consolidant for porous building stone, in particular sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...

.
Uses:
  • as wood glue
    Wood glue
    Wood glue is an adhesive used to tightly bond pieces of wood together. Many substances have been used as glues.-Types of wood glue:* For many centuries animal glue, especially hide glue was the traditional glue for all kinds of woodwork. It is still used today, mainly for musical instruments and...

     PVAc is known as "white glue" and the yellow "carpenter's glue" or PVA glue.
  • as paper adhesive during paper packaging converting
  • in bookbinding
    Bookbinding
    Bookbinding is the process of physically assembling a book from a number of folded or unfolded sheets of paper or other material. It usually involves attaching covers to the resulting text-block.-Origins of the book:...

     and book arts, due to its flexible strong bond and non-acidic nature (unlike many other polymers). The use of PVAC on the Archimedes Palimpsest
    Archimedes Palimpsest
    The Archimedes Palimpsest is a palimpsest on parchment in the form of a codex. It originally was a copy of an otherwise unknown work of the ancient mathematician, physicist, and engineer Archimedes of Syracuse and other authors, which was overwritten with a religious text.Archimedes lived in the...

     during the 20th century greatly hindered the task of disbinding the book and preserving and imaging the pages in the early 21st century, in part because the glue was stronger than the parchment it held together.
  • for handcrafted works.
  • as envelop adhesives,
  • as wallpaper adhesive


The stiff homopolymer PVAc , but mostly the more soft copolymer a combination of vinyl acetate and ethylene, vinyl acetate ethylene (VAE), is used also in paper
Paper
Paper is a thin material mainly used for writing upon, printing upon, drawing or for packaging. It is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets....

 coatings, paint
Paint
Paint is any liquid, liquefiable, or mastic composition which after application to a substrate in a thin layer is converted to an opaque solid film. One may also consider the digital mimicry thereof...

 and other industrial coatings, as binder in nonwovens in glass fibers. sanitary napkins, filter paper
Filter paper
Filter paper is a semi-permeable paper barrier placed perpendicular to a liquid or air flow. It is used to separate fine solids from liquids or air.-Properties:Filter paper comes in various porosities and grades depending on the applications it is meant for...

 and in textile finishing

PVAc can also be used as coating to protect cheese
Cheese
Cheese is a generic term for a diverse group of milk-based food products. Cheese is produced throughout the world in wide-ranging flavors, textures, and forms....

 from fungi and humidity
Humidity
Humidity is a term for the amount of water vapor in the air, and can refer to any one of several measurements of humidity. Formally, humid air is not "moist air" but a mixture of water vapor and other constituents of air, and humidity is defined in terms of the water content of this mixture,...

.

Polyvinyl acetate is also the raw material to make other polymers like:
  • Polyvinyl alcohol
    Polyvinyl alcohol
    Polyvinyl alcohol is a water-soluble synthetic polymer .-Properties:...

     -[HOCHCH2]-: Polyvinyl acetate is partially or completely hydrolysed
    Hydrolysis
    Hydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...

     to give polyvinyl alcohol. This reversible saponification and esterification reaction was a strong hint for Hermann Staudinger
    Hermann Staudinger
    - External links :* Staudinger's * Staudinger's Nobel Lecture *....

     in the formulation of his theory of macromolecules.
  • Polyvinyl acetate phthalate
    Polyvinyl acetate phthalate
    Polyvinyl acetate phthalate is a commonly used polymer phthalate in the formulation of pharmaceuticals, such as the enteric coating of tablets or capsules. It is a vinyl acetate polymer that is partially hydrolyzed and then esterified with phthalic acid. Its main use in pharmaceutics is with...

     (PVAP): Polyvinyl acetate is partially hydrolyzed and then esterified with phthalic acid
    Phthalic acid
    Phthalic acid is an aromatic dicarboxylic acid, with formula C6H42. It is an isomer of isophthalic acid and terephthalic acid. Although phthalic acid is of modest commercial importance, the closely related derivative phthalic anhydride is a commodity chemical produced on a large...

    .

See also

  • Vinyl acetate
    Vinyl acetate
    Vinyl acetate is an organic compound with the formula CH3COOCH=CH2. A colorless liquid with a pungent odor, it is the precursor to polyvinyl acetate, an important polymer in industry.-Production:...

  • Polyvinyl alcohol
    Polyvinyl alcohol
    Polyvinyl alcohol is a water-soluble synthetic polymer .-Properties:...

  • Copolymer: Ethylene vinyl acetate
  • Polymerization
    Polymerization
    In polymer chemistry, polymerization is a process of reacting monomer molecules together in a chemical reaction to form three-dimensional networks or polymer chains...