Editing Guar gum (section)

==Industrial applications==
{{More citations needed section|date=February 2021}}
* [[Textile]] industry – [[sizing]], [[finishing (textiles)|finishing]] and [[textile printing|printing]]
* [[Paper]] industry – improved sheet formation, folding and denser surface for printing
* [[Explosive]]s industry – as waterproofing agent mixed with [[ammonium nitrate]], [[nitroglycerin]], etc.
* [[Pharmaceutical]] industry – as binder or as disintegrator in tablets; main ingredient in some bulk-forming [[laxative]]s
* [[Cosmetics]] and toiletries industries – thickener in [[toothpaste]]s, conditioner in [[shampoo]]s (usually in a chemically modified version{{Which|date=January 2025}})
* [[Hydraulic fracturing]] – Shale oil and gas extraction industries consumes about 90% of guar gum produced from India and Pakistan.<ref>{{cite web |url=https://www.law.upenn.edu/blogs/regblog/2012/08/8-narayan-guar-gum.html |title=From Food to Fracking: Guar Gum and International Regulation |author=Ram Narayan |date=8 August 2012 |work=RegBlog |publisher=[[University of Pennsylvania Law School]] |access-date=15 August 2012 |archive-date=22 August 2012 |archive-url=https://web.archive.org/web/20120822153712/https://www.law.upenn.edu/blogs/regblog/2012/08/8-narayan-guar-gum.html |url-status=dead }}</ref>
Fracturing fluids normally consist of many additives that serve two main purposes, firstly to enhance fracture creation and proppant carrying capability and secondly to minimize formation damage. Viscosifiers, such as polymers and crosslinking agents, temperature stabilizers, pH control agents, and fluid loss control materials are among the additives that assist fracture creation. Formation damage is minimized by incorporating breakers, biocides, and surfactants. More appropriate gelling agents are linear polysaccharides, such as guar gum, cellulose, and their derivatives.

Guar gums are preferred as thickeners for enhanced oil recovery (EOR). Guar gum and its derivatives account for most of the gelled fracturing fluids. Guar is more water-soluble than other gums, and it is also a better emulsifier, because it has more galactose branch points. Guar gum shows high low-shear viscosity, but it is strongly shear-thinning. Being non-ionic, it is not affected by ionic strength or pH but will degrade at low pH at moderate temperature (pH 3 at 50&nbsp;°C). Guar's derivatives demonstrate stability in high temperature and pH environments. Guar use allows for achieving exceptionally high viscosities, which improves the ability of the fracturing liquid to transport proppant. Guar hydrates fairly rapidly in cold water to give highly viscous pseudoplastic solutions of, generally, greater low-shear viscosity than other hydrocolloids. The colloidal solids present in guar make fluids more efficient by creating less filter cake. Proppant pack conductivity is maintained by utilizing a fluid that has excellent fluid loss control, such as the colloidal solids present in guar gum.

Guar has up to eight times the thickening power of starch. Derivatization of guar gum leads to subtle changes in properties, such as decreased hydrogen bonding, increased solubility in water-alcohol mixture, and improved electrolyte compatibility. These changes in properties result in increased use in different fields, like textile printing, explosives, and oil-water fracturing applications.

=== Crosslinking guar ===

Guar molecules have a tendency to aggregate during the hydraulic fracturing process, mainly due to intermolecular hydrogen bonding. These aggregates are detrimental to oil recovery because they clog the fractures, restricting the flow of oil. Cross-linking guar polymer chains prevents aggregation by forming metal–hydroxyl complexes. The first crosslinked guar gels were developed in the late 1960s. Several metal additives have been used for crosslinking; among them are chromium, aluminium, antimony, zirconium, and the more commonly used boron. Boron, in the form of B(OH)4, reacts with the hydroxyl groups on the polymer in a two-step process to link two polymer strands together to form bis-diol complexes.

1:1 1,2 diol complex and a 1:1 1,3 diol complex, place the negatively charged borate ion onto the polymer chain as a pendant group. Boric acid itself does not apparently complex to the polymer so that all bound boron is negatively charged. The primary form of crosslinking may be due to ionic association between the anionic borate complex and adsorbed cations on the second polymer chain . The development of cross-linked gels was a major advance in fracturing fluid technology. Viscosity is enhanced by tying together the low molecular weight strands, effectively yielding higher molecular weight strands and a rigid structure. Cross-linking agents are added to linear polysaccharide slurries to provide higher proppant transport performance, relative to linear gels.

Lower concentrations of guar gelling agents are needed when linear guar chains are cross-linked. It has been determined that reduced guar concentrations provide better and more complete breaks in a fracture. The breakdown of cross-linked guar gel after the fracturing process restores formation permeability and allows increased production flow of petroleum products.

* [[Mining]]
* [[Hydroseeding]] – formation of seed-bearing "guar tack"{{citation needed|date=March 2019}}
* Medical institutions, especially [[nursing homes]] - used to thicken liquids and foods for patients with [[dysphagia]]
* [[Fire retardant]] industry – as a thickener in [[Phos-Chek]]
* [[Nanoparticles]] industry – to produce silver or gold nanoparticles, or develop innovative medicine delivery mechanisms for drugs in pharmaceutical industry
* [[Slime (toy)]], based on guar gum crosslinked with sodium tetraborate