Thermosets polymers

Polymers can be used as surface coatings. Linear polymers are applied as a solution the solvent evaporates leaving a protective film of the polymer. Thermosets are applied as a fluid mixture of resin and hardener which has to be mixed just before it is used, and cures almost as soon as it is applied. 

Volume 3 covers the performance of polymers, thermosets, elastomers, and composites. 

Polymers, 20 389-412. See also Ethylene-propylene polymers Filled polymers Higher olefin polymers Polymerization Polysaccharides Shape-memory polymers (SMPs) SiC>2 polymer Special polymers Sulfur-containing polymers Thermosetting reactive polymers Water-soluble polymers aging of, 20 167... 

Foamed polymers. Thermosets and thermoplastics formed into low density, cellular materials containing bubbles of gas. Rigid foams have their gas bubbles in closed cells, inhibiting flexibility flexible foams have the bubbles in open cells, permitting the gas to escape as the foam is flexed. 

Among polymers, thermosets are especially difficult to study for many reasons structural complexity, making difficult the chemical analysis, lack of rigorous tools to investigate the macromolecular structure lack of physical theories to interpret the change of properties (e.g., embrittlement) against structural changes. 

Among the variety of polymer thermosets, epoxies enjoy the most widespread use and are certainly the most studied. They are usually synthesized from oligomeric, end-functional epoxy resins and multifunctional curing agents or hardeners . In addition, catalysts sometimes are employed to speed the crosslinking reactions or allow them to take place at lower temperatures. 

Dimensional stability, especially on spun rayon and AVRIL when run in conjunction with the low polymer thermosetting resins. 

A thermosetting plastic is a polymer that can be caused to undergo a chemical change to produce a network polymer, called a thermoset polymer. Thermosetting polymers can often be shaped with the application of heat and pressure, but the number of such cycles is severely limited. Epoxies, for which cross-linking reactions are illustrated in Eqs. (1 -9) and (I -10), are thermosetting polymers. The structurally similar phenoxies (1-22) are usually not cross-linked and are considered to be thermoplastics. 

Amorphous Polymer, amorphous Polymer, thermosetting Polymer, thermosetting Polymer, thermosetting Polymer, thermoplastic Polymer, thermoplastic... 

These reactions have been explained in detail in the sections of Chapter 1 indicated and they are all identified by permanent, covalent bonds between polymeric chains. These chemical-network polymer systems are an important sub-class of network polymers and are sometimes referred to as thermoset polymers. Thermoset polymers cannot be re-melted or undergo flow under the influence of heat once they have been polymerized (i.e. they have a thermosef morphology, unlike thermoplastic polymers, which can be re-melted and flow under application of heat). Owing to their excellent properties at high temperatures (and under extreme environmental conditions) thermoset polymers are suitable for a wide variety of high-performance applications such as electronic packaging, automotive panelling and... 

Atlac . [Reichhold/Reactive Polymers] Thermoset polyester resins for fiberglass-reinforced structures, glass-reinforced coatings, mortars in pulp and paper, caustic-chlorine, metal treatment, filament winding, centrifugal casting of large tanks and pipe. 

Hetron 800. [Ashland/Congrosite Polymers] Thermosetting furan resin for corrosion-resistant fiberglass-reinforced plastic laminates. 

Ricon. [Ricon Resins] Polybutadiene polymers thermoset for potting, molding oonqi. and castings, rubber modi-fim, wire coating, laminates, coatings. 

Xycon Hybrid Resin. [Amoco] Two-component polymer thermoset for truck-body panels, after-market automotive parts, recreational vehicles, outdoor equip., tubs and showers, elec, parts. 

A thermoset is a polymer that, when heated, imdeigoes a chemical change to produce a cross-linked, solid polymer. Thermosets usually exist initially as liquids called prepolymers they can be shaped into desired forms by the application of heat and pressure, but are incapable of undergoing repeated cycles of softening and hardening. Examples of thermosetting polymers include urea-formaldehyde, phenol-formaldehyde, and epoxies. 

Some plastics, called thermoplastics, are able to repeatedly undergo this shape-changing treatment. Others, known as thermoset, can be shaped only once because they form irreversible covalent bonds between chains during the setting process and consequently will no longer melt and flow. Vulcanized rubber is an example of a thermoset polymer. Thermoset polymers tend to have relatively high chemical resistance and excellent mechanical properties. However, the vast majority of plastics used in packaging are thermoplastics. 

---