Butyl rubber is a copolymer of isobutylene and isoprene. Simple copolymers are known as “regular” or “clear” butyl rubber, or simply “butyl.” When butyl rubbers are modified after polymerization with the halogens bromine or chlorine, a second family, known as halobutyl rubber (or halobutyls), results.

Significant advances have been made over the past 20 years in the development of biodegradable polymers. These materials have been developed in a variety of forms, and thus have potential use in a range of industries, including adhesives.

Completely cured adhesives and sealants are generally considered safe and non-toxic, although caution must be exercised when machining or grinding joints due to airborne particles. Also, decomposition products may exhibit substantial vapor pressures that present health and safety issues. However, it is exposure to uncured components that can be the most harmful, and that is the subject of this article.

Pressure-sensitive adhesives (PSAs) are a combination of several materials that come together to form a "construction." A PSA construction is a combination of layers including a facestock (label) or backing (tape), an optional primer coat, an adhesive, and a silicone release coating on a protective liner. The PSA construction—whether a label, tape or transfer adhesive—is manufactured through several coating and laminating steps, including liner-release coating, adhesive coating/drying/curing, optional facestock or backing primer coating, and lamination of the facestock or backing to the liner.

With ongoing advances in structural adhesive formulation, designers in every industry have increasing alternatives to mechanical fasteners for assembly of metal, composites, plastics, rubber, glass and more.

The harsh conditions of space place a set of constraints on the technologies that take us there. Of primary concern when it comes to space system design is the adhesive chosen to hold everything together. What does it take to perform in the vacuum of space, and why do silicone adhesives continue to be the adhesive of choice in many aerospace applications?