MateriaIs of construction
Plastics comprise many different materials based on their polymer structure, additives, and so on. Practically all plastics at some stage in their fabrication can be formed into simple to extremely complex shapes that can range from being extremely flexible to extremely strong. Polymers, the basic ingredients in plastics, are high molecular weight organic chemical compounds, synthetic or natural substances consisting of molecules. Practically all of these polymers use virtually an endless array of additives, fillers, and reinforcements to perform properly during product fabrication and/or in service. There are many compounded base polymer combinations so that new materials are always on the horizon to meet new industry requirements that now total over 35,000 plastics worldwide. Table 1.1 provides examples of their manufacturing stages from raw materials to products. Examples of the diversified use of different plastics are shown in Figs. 1.2 and 1.3. Plastic, polymer, resin, elastomer, and reinforced plastic (RP) are somewhat synonymous terms. The most popular term worldwide is plastics.
Polymer denotes the basic material. Whereas plastic pertains to polymers or resins (as well as elastomers, RPs, etc.) containing additives, fillers, and/or reinforcements. An elastomer is a rubber-like material (natural
or synthetic). Reinforced plastics (also called plastic composites) are plastics with reinforcing additives such as fibers and whiskers, added principally to increase the product’s mechanical properties but also provides other benefits such as increased heat resistance and improved tolerance control.
There are thermoplastics (TPs) that melt (also called curing) during processing. Cure occurs only with thermoset plastics (TSs) or when a TP is converted to a TS plastic and in turn processed. The term curing
TPs occurred since at the beginning of the 20th century the term curing was accurately used for TSs. At that time TSs represented practically all the plastic used worldwide. Thus TPs took on the incorrect term curing even though there is no chemical reaction or curing action.
Appreciate the polymer chemist’s ability to literally rearrange the molecular structure of the polymer to provide an almost infinite variety of compositions that differ in form, appearance, properties, cost, and
other characteristics. One must also approach the subject with a completely open mind that will accept all the contradictions that could make it difficult to pin common labels on the different families of plastics or even on the many various types within a single family that are reviewed in this book. Each plastic (of the 35,000 available) has specific performance and processing capabilities.
Plastics Engineered Product Design
Dominick Rosato and Donald Rosato
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