RUBBER CEMENT Vegetable adhesives include starches and dextrins derived from corn, wheat, potatoes, and rice, used for bonding paper, wood, and textiles; gums such as gum arabic, agar, and algin, which when moistened provide adhesion in such products as stamps and gummed envelopes; cellulose adhesives, used to bond leather, cloth, and paper; rubber cements; and resins such as tree pitch and mastic. Synthetic adhesives, used either alone or as modifiers of natural adhesives, perform better and have a greater range of application than the natural products. Most of them form polymers, huge molecules incorporating large numbers of simple molecules to form strong chains and nets that link surfaces in a firm bond. Thermosetting adhesives, which are transformed into tough, heat-resistant solids by the addition of a catalyst or the application of heat, are used in such structural functions as bonding metallic parts of aircraft and space vehicles. Thermoplastic resins, which can be softened by heating, are used for bonding wood, glass, rubber, metal, and paper products. Elastomeric adhesives, such as synthetic or natural rubber cements, are used for bonding flexible materials to rigid materials.
Posted on: Wed, 30 Jul 2014 19:07:42 +0000
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