5 августа, 2015 
Malyar Since natural rubber is the foundation of the rubber industry, all materials that are so — called elastomers, or rubber, are essentially compared against it. Therefore, elastomers are, generally, high molecular weight polymers that elongate or stretch, are crosslinkable, have the unique cured property of rebound or the ability to snap back to an original configuration upon release of stress, have high resilience and compression strength, and have high tensile strength and modulus when stretched. All uncured rubber materials exhibit the characteristic of viscoelasticity, which combines the properties of both solids and liquids, being both stretchable and ‘‘liquid-like,’’ or viscous, in the solid state. Rubbery polymers, in addition, also have a high degree of resistance to water in both the uncured and cured states, as well as fairly good resistance to heat and cold when properly compounded and cured. The long chain crosslinked polymers also generally have relatively high tear resistance, are usually quite flexible, and highly resistant to fatigue stress.
Now, while many rubber polymers exhibit many of these properties, none of them exhibits all of them, nor equally well. Each polymer type has its own unique set of properties and characteristics, which allows for an expanding array of choices for assembly applications. Listed below are the major areas in which elastomeric adhesives provide an advantage over other polymer types.
Fast strength development Whether used as a base for pressure sensitive adhesives or for contact bond adhesives, most rubber polymer-based adhesives exhibit the characteristic of green strength, or the ability to virtually instantaneously develop holding power to a surface. Few other polymer systems have this property to as high a degree, or to as wide an array of surfaces and process conditions. This quick bond feature is a great asset to many assembly processes and manufacturing operations.
Versatility Rubber-based adhesives can be compounded to stick to almost anything under almost any conditions. Bond strength can vary from a temporary holding pressure sensitive product, with a few grams per linear centimeter of peel strength, to a high strength structural bond exhibiting hundreds of kilograms per square centimeter of lap shear strength.
Variety Although there are only a few basic categories of rubber polymers that make up the majority of applications, these polymers come in a wide array of distinct product grades within each category. In addition, most of these polymers are compatible with, and can be mixed freely with, other rubbery polymers to provide even more choices of properties, not to mention the virtually endless numbers of fillers, additives, reinforcing and tackifying resins, other polymer types, plasticizers, and other ingredients that can be used to further modify basic properties.
Economy For many applications, rubber-based adhesives and sealants are inexpensive relative to the base cost of many other polymer systems. In addition, the costs for dispensing and application tooling are often low. The speed of assembly operations with quick-stick adhesives often provides a labor and total cost advantage, and may even lower tooling costs.
Flexibility The inherent resilience of rubber polymers often provides protection in expansion/contraction modes due to product temperature cycling and flex stress from repetitive work cycles. Plus this flexibility improves the assembly’s resistance to vibration, fatigue, impact, shear, elongation, and peel forces.
Variety of forms Rubber-based adhesives can be supplied to the user in solvent or water-based formulations, as a solid hot melt or a soft tacky extrusion, as a tape (reinforced or not, single or double-sided), as a film, and even pre-applied to a surface for later solvent or heat activation. Products can be single or multiple component, depending on the application requirements.
Variety of bonding methods The numerous forms and types of rubber-based adhesives and sealants also provide for numerous mechanisms for developing bonds to surfaces. Contact bond, pressure sensitive, wet bond, heat reactivation, and solvent reactivation are all feasible modes of product assembly with these products.
Ease of modification Most elastomeric adhesives can be readily modified in viscosity, tack, drying time (for solvent-based products), strength properties, heat resistance, aging characteristics and other properties to fit process and user requirements, usually without significant changes to basic characteristics or costs.
Thermoplastic or thermosetting A property often available in the same compound. However, typically, low strength requirements and ambient applications usually are solved with thermoplastic noncuring elastomeric adhesives, while high strength and high heat resistance are obtained from rubber polymers that are crosslinked. Thermoplastic adhesives will often begin losing strength at temperatures above 70°C. Some adhesives actually operate as a thermoplastic until the ambient temperature rises, at which time the adhesive will gain strength through a crosslinking mechanism and function as a thermoset thereafter. There is usually a time limit on the ability of an adhesive to function in this manner, since most curing functions are time-temperature dependent and most of these dual type products will achieve some limited crosslinking at ambient conditions. Some curing mechanisms for elastomers do require exposure to elevated temperatures to effect a suitable cure.
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