thermoplastic

…as an adhesive, as with thermoplastic elastomers such as styrene-isoprene-styrene block copolymers. Polymers impart strength, flexibility, and the ability to spread and interact on an adherend surface—properties that are required for the formation of acceptable adhesion levels.

Thermoplastics provide strong, durable adhesion at normal temperatures, and they can be softened for application by heating without undergoing degradation. Thermoplastic resins employed in adhesives include nitrocellulose, polyvinyl acetate, vinyl acetate-ethylene copolymer, polyethylene, polypropylene, polyamides, polyesters, acrylics, and cyanoacrylics.

Thermoplastics, on the other hand, are melted and then solidified, a process that can be repeated numerous times for reprocessing. Although the manufacturing technologies for thermoplastics are generally not as well developed as those for thermosets, thermoplastics offer several advantages. First, they do not have…

…processed by methods common to thermoplastics.

When many bituminous coals are heated, they soften and form a plastic mass that swells and resolidifies into a porous solid. Coals that exhibit such behaviour are called caking coals. Strongly caking coals, which yield a solid product (coke) with properties suitable for…

Other rubbery materials consist of elastomers having strong intermolecular associations but no real chemical interlinks. Examples are molecules containing a few hydrogen-bonding groups. If the associations between the molecules are strong enough to prevent flow under moderate stresses, such materials can…

…fibres, all natural fibres are nonthermoplastic; that is, they do not soften when heat is applied. At temperatures below the point at which they will decompose, they show little sensitivity to dry heat, and there is no shrinkage or high extensibility upon heating, nor do they become brittle if cooled…

…they are defined as either thermoplastic resins or thermosetting resins. This fundamental distinction is seen in the organization of the table, and its origin in the chemical composition and molecular structure of plastic polymers is described below.

Most thermoplastics are therefore recycled into somewhat less-demanding applications. HDPE from thin-walled grocery bags, for example, may be converted into thick-walled flowerpots; polyvinyl chloride (PVC) recovered from bottles may be used in traffic cones; and PET recovered from beverage bottles may be washed, dried, and melt-spun…

…can be melted are called thermoplastic polymers. Thermoplasticity is found in linear and branched polymers, whose looser structures permit molecules to move past one another. The network structure, however, precludes the possibility of molecular flow, so that network polymers do not melt. Instead, they break down upon reheating. Such polymers…

As mentioned above, polymers that are classified as plastics can be divided into two major categories: thermoplastics and thermosets. Thermoplastics such as polyethylene and polystyrene are capable of being molded and remolded repeatedly. Thus, a foamed-polystyrene cup can be heated and reshaped…

Shellac is a natural thermoplastic; that is, a material that is soft and flows under pressure when heated but becomes rigid at room temperature. This property makes it useful either by itself or in combination with such fillers as flaked mica and asbestos in manufactured molding compositions, used for…

…are divided into two classes, thermoplastic resins, which remain plastic after heat treatment, and thermosetting resins, which become insoluble and infusible on heating.