Gum, in botany, adhesive substance of vegetable origin, mostly obtained as exudate from the bark of trees or shrubs belonging to the family Fabaceae (Leguminosae) of the pea order Fabales. Some plant gums, such as gum arabic, dissolve in water to give clear solutions. Other gums, such as gum tragacanth, form mucilages by the absorption of large amounts of water.
Polysaccharides from plant exudates have been in use from many decades in immense quantities. Natural gums are natural polymers, which mainly consists of carbohydrates sometimes with small amounts of proteins and minerals. The appearance and properties of natural gums determine their commercial value and end use. Adhesive or sealant is a mixture in a liquid or semi-liquid state that is capable of holding materials together by surface attachment. Adhesives and sealants are used as a raw material for the manufacturing industry or for the service of different processing industries. An adhesive is any substance applied to the surfaces of materials that binds them together and resists separation. The term "adhesive" may be used interchangeably with glue, cement, mucilage, or paste. The use of adhesives offers many advantages over binding techniques such as sewing, mechanical fastening, thermal bonding, etc. Adhesives may be found naturally or produced synthetically. Although natural adhesives are less expensive to produce, most important adhesives are synthetic. Adhesives based on synthetic resins and rubbers excel in versatility and performance. The polymers used in synthetic adhesives fall into two general categories—thermoplastics and thermosets. The adhesives and sealants are two chemically similar but functionally different groups of formulated products.
Types of adhesives are- 1) epoxy 2) solvent cements 3) contact adhesives 4) polyurethane 5) cyanoacrylate .
According to a new market research, adhesives in global composites industry is likely to remain profitable over the forecast period (2014-2019) and expected to reach an estimated value of $1,170 million by 2019.The adhesives and sealants industry's development can best be explained by the economy-wide transition from conventional materials (glass, stone, wood, and metal) to lighter and more economical resources, mainly petroleum-based plastics. A generation of new products emerged to service this rapid growth area. The market for reactive adhesives grew as the automotive industry moved away from mechanical fasteners. Developments in reactive adhesives for the auto industry also brought benefits to other industrial sectors, including appliance manufacturing. Into the twenty-first century, products expected to see the most growth included electronics adhesives for printed wiring boards, hot melt systems, and automotive adhesives.
There is no end in sight to the new materials, new formulation, and new uses to which adhesives and sealants will be put in the future.
The industry is witnessing high growth on an account of growing demand in the Asia-Pacific region. China and India are the biggest consumers of adhesives and sealants due to rapid industrialization and infrastructure growth.
Further information:
Gums, adhesives & sealants technology (with formulae & their applications) 2nd edition describe detailed information on subject. The major contents of this book are: introduction to adhesives, animal glue, casein and mixed protein adhesives, starch based adhesives, natural rubber adhesives, butyl rubber and polyisobutylene, styrene-butadiene rubber adhesives, polysulfide sealants and adhesives, epoxy resin adhesives, polyvinyl acetal adhesives chemistry, dissolution, laminaran, gum Arabic introduction production, foods, pectin introduction production, natural rubber adhesive, styrene-butadiene rubber adhesives, neoprene (polychloroprene), phenolic resin adhesives.
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