Binder (material)

Source: Wikipedia, the free encyclopedia.

A binder or binding agent is any material or substance that holds or draws other materials together to form a cohesive whole mechanically, chemically, by adhesion or cohesion.

More narrowly, binders are liquid or dough-like substances that harden by a chemical or physical process and bind fibres,

thickening
.

Examples of mechanical binders are

tie beams
in timber framing.

Classification

Binders are loosely classified as organic (

glues, polymers) and inorganic (lime, cement, gypsum, liquid glass
, etc.). These can be either metallic or ceramic as well as polymeric depending on the nature of the main material. For example, in the compound WC-Co (Tungsten Carbide used in cutting tools) Co constitutes the binding agent for the WC particles.

Based on their chemical resistance, binders are classified by the field of use: non-hydraulic (

silicon fluoride cement, quartz cement), and autoclavable (harden at 170 to 300°С i.e. 8-16 atm pressure and, e.g., comprise CaSiO3
materials).

Physical properties

Some materials labeled as binders such as

tensile strength and need to be reinforced with fibrous material or rebar if tension and shear forces
will be applied.

Other binding agents such as

matrix and fiber as a reinforcement. Compressive strength can be improved by adding filling material
.

Uses

Binders hold together pigments and sometimes filling material to form

gum tragacanth, methyl cellulose, or proteins such as egg white or casein. Glue is traditionally made by the boiling of hoofs, bones, or skin of animals and then mixing the hard gelatinous residue with water. Natural gum-based binders are made from substances extracted from plants.[1] Larger amounts of dry substance are added to liquid binders in order to cast or model sculptures and reliefs.[2]

In cooking, various edible thickening agents are used as binders. Some of them, e.g. tapioca flour, lactose, sucrose, microcrystalline cellulose, polyvinylpyrrolidone and various starches are also used in pharmacology in making tablets. Tablet binders include lactose powder, sucrose powder, tapioca starch (cassava flour) and microcrystalline cellulose.

In

wattle-and-daub construction and in the building material cob
which would otherwise become brittle after drying. Sand is added to improve compressive strength, hardness and reduce shrinkage. The binding property of clay is also used widely to prepare shaped articles (e.g. pots and vases) or to bind solid pieces (e.g. bricks).

In

phenolic resins are common. In reinforced carbon–carbon, plastic or pitch resin is used as a source of carbon released through pyrolysis. Transite, hypertufa, papercrete and petecrete used cement
as a binder.

In

styrene-butadiene rubber are often used as binders for plastic explosives. For polymer-bonded explosives, various synthetic polymers
are used.

In

rocket fuels
.

Organic binders, designed to disintegrate by heat during baking, are used in sintering.

History

In the

Classical World painters used materials like egg, wax, honey, lime, casein, linseed oil or bitumen as binders to mix with pigment in order to hold the pigment particles together in the formation of paint.[3] Egg-based tempera was especially popular in Europe from the Middle Ages until the early 16th century.[4] However, since that time, the binder of choice for paint has been oil.[5]

See also

Look up binder or binding agent in Wiktionary, the free dictionary.

References

  1. ISBN 9780385041850
    . Retrieved 17 January 2012.
  2. ^ Arthur Williams (2005). The sculpture reference illustrated: contemporary techniques, terms, tools, materials, and sculpture. Sculpture Books. p. 40.
  3. ISBN 9780892367085
    . Retrieved 17 January 2012.
  4. ^ Collector's Guide. WingSpread. 1995. p. 109. Retrieved 17 January 2012.
  5. ISBN 9780823095223
    . Retrieved 17 January 2012.
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