Building Design and Construction Handbook - Merritt - Ventech!

BUILDING MATERIALS 4.93
sistance. It is therefore used in making gaskets, electrical insulation, and similar
products that maintain their properties at both high and low temperatures.
Additional elastomers include polyethylene, cyclized rubber, plasticized polyvinyl
chloride, and polybutene. A great variety of materials enters into various
rubber compounds and therefore provide a wide range of properties. In addition,
many elastomeric products are laminated structures of rubber-like compounds combined
with materials like fabric and metals (Art. 4.76).
COMBINATIONS OF PLASTICS AND OTHER
MATERIALS
Plastics often are used as part of a composite construction with other materials. The
composites may be in the form of laminates, matrix systems, sandwich structures,
or combinations of these.
4.74 HIGH-PRESSURE LAMINATES
Laminated thermosetting products consist of fibrous sheet materials combined with
a thermosetting resin, usually phenol formaldehyde or melamine formaldehyde. The
commonly used sheet materials are paper, cotton fabric, asbestos paper or fabric,
nylon fabric, and glass fabric. The usual form is flat sheet, but a variety of rolled
tubes and rods is made.
Decorative Laminates. These high-pressure laminates consist of a base of phenolic
resin-impregnated kraft paper over which a decorative overlay, such as printed
paper, is applied. Over all this is laid a thin sheet of melamine resin. When the
entire assemblage is pressed in a hot-plate press at elevated temperatures and pressures,
the various layers are fused together and the melamine provides a completely
transparent finish, resistant to alcohol, water, and common solvents. This material
is widely used for tabletops, counter fronts, wainscots, and similar building applications.
It is customarily bonded to a core of plywood to develop the necessary
thickness and strength. In this case, a backup sheet consisting of phenolic resin and
paper alone, without the decorative surface, is employed to provide balance to the
entire sandwich.
4.75 REINFORCED PLASTICS
These are commonly made with phenolic, polyester, and epoxide resins combined
with various types of reinforcing agents, of which glass fibers in the form of mats
or fabrics are the most common. Because little or no pressure is required to form
large complex parts, rather simple molds can be employed for the manufacture of
such things as boat hulls and similar large parts. In buildings, reinforced plastics
have been rather widely used in the form of corrugated sheet for skylights and side
lighting of buildings, and as molded shells, concrete forms, sandwiches, and similar
applications.