Polymers thermoplastics, thermosets, elastomer

Flame Retardation of Polymeric Materials. The suitability of a particular flame-retarding method is often determined by the nature of the polymer type (e.g., thermoplastic or thermoset). A brief and general discussion regarding the flame retardation of thermoplastics, thermosets, elastomers, and fibers follows. 

According to lUPAC nomenclature rules, the trivial names of common polymers do not necessarily have to be replaced by structural names. Therefore, both trivial and structural names of polymers will be used in this book. In general, the standard abbreviations of trivial names will only be used in diagrammatic illustrations (see, for example. Table VII-6). Trade names of thermoplasts, thermosets, elastomers, and fibers will not be used in the text. 

Part VI is totally new. It is an introduction into polymer technology and thus discusses thermoplasts, thermosets, elastomers, fibers, coatings, and adhesives with respect to their end-use properties. It also contains chapters on additives, blends and composites. 

Chem. Descrip. PTFE fluoroadditive CAS 9002-84-0 EINECS/ELINCS 204-126-9 Uses Modifier for inks, coatings, lubricants, and sealants lubricant for thermoplastics, thermosets, elastomers Properties Wh. powd., odorless 1.8-4 p avg. particle size 90% > 0.3 p insol. in water sp.gr. 2.1-2.3 bulk dens. 200-425 g/L surf, area 5-10 mV g m.p. 342 C flash pt. none > 99% assay Toxicohgy OSHA PEL 15 mg/m (8 h TW/, total dust), 5 mg/m (8 h TWA, respirable dust) nonirritating to skin TSCA listed Envronmental Aquatic toxicity expected to be low Precaution Nonflamm. in air, but will bum if or en cone, exceeds 95% heating or burning may evolve fumes which cause polymer fume fever and small amts, of carbonyl fluoride and hydrogen fluoride incompat. with finely divided metal pc s. and oxidizers Storage Keep containers closed to avoid contamination Teflon MP 1200 [DuPont DuPont Canada]... 

Paints or lacquers are composites of, in general, three components pigments, binders, and solvents. Depending on application, the nature of the pigment can vary between extremely wide limits (see also Chapter 34). The binders are also known as film formers they are exclusively polymers or prepolymers, that is, thermoplasts, thermosets, elastomers, and elastoplasts. The nature of the solvent can also vary within wide limits according to the type of film former and the desired application. Here, solvents are described as good in the paints industry when they lead to low-viscosity paints or lacquers. Such good solvents are usually poor solvents in the thermodynamic sense (see also Chapters 4 and 6). 

Carbon black is the most extensively used filler in terms of volume in thermoplastic/ thermoset elastomers. One method of quantifying carbon black dispersion is through the reduction in resistivity of insulating polymer matrices that occurs by virtue of the CB s ability to create a conductive three-dimensional particulate network. As the amount of carbon black is increased, the resistivity is decreased. In addition, the efficiency of a fixed amount of carbon black is increased as a result of the increased dispersion offered by the use of titanates. As an example. Table 5.8 shows the effect of increasing amounts of LICA 09 on the resistivity of a CB-filled styrene/butadiene block copolymer. 

Dynamic mechanical analysis techniques permit measurement of the ability of materials to store and dissipate mechanical energy during deformation. DMA is used to determine the modulus, glass transition, mechanical damping and impact resistance, etc., of thermoplastics, thermosets, elastomers and other polymer materials. Information regarding the phase separation of polymers is also available by DMA [2]. In DMA, viscoelastic materials are deformed in a sinusoidal, low strain displacement and their responses are measured. Elastic modulus and energy dissipation are the measured properties. 

There are four main polymer classes (thermoplastics, thermosets, elastomers and thermoplastic elastomers) but thermoplastics fall into two distinct classes as amorphous thermoplastics and semi-crystalline thermoplastics (Figure 2.1). 

Table 1.4 gives a list of major polymers and common abbreviated symbols, subdivided into the four types thermoplastics, thermosets, elastomers, and thermoplastic... 

As with all thermoplastic elastomers, the copolyesterethers can be processed as thermoplastics. They are linear polymers and contain no chemical cross-links, thus the vulcanisation step needed for thermosetting elastomers is eliminated and scrap elastomer can be re-used in the same process as virgin material (176—180). 

The chemistry of synthetic polymers is similar to the chemistry of small molecules with the same functional groups, but the physical properties of polymers are greatly affected by size. Polymers can be classified by physical property into four groups thermoplastics, fibers, elastomers, and thermosetting resins. The properties of each group can be accounted for by the structure, the degree of crystallinity, and the amount of cross-Jinking they contain. 

Thermoplastics are more suitable for recycling than elastomers or thermosetting polymers. Thermoplastics can be heated above their melting temperatures and then recast into new shapes. Elastomers and thermosets, on the other hand, have extensive cross-linking networks that must be destroyed and then reformed in the process of recycling. Processes that destroy cross-linking, however, generally break down the polymer beyond the point at which it can be easily reconstituted. 

When a thermoplastic polyurethane elastomer is heated above the melting point of its hard blocks, the chains can flow and the polymer can be molded to a new shape. When the polymer cools, new hard blocks form, recreating the physical crosslinks. We take advantage of these properties to mold elastomeric items that do not need to be cured like conventional rubbers. Scrap moldings, sprues, etc. can be recycled directly back to the extruder, which increases the efficiency of this process. In contrast, chemically crosslinked elastomers, which are thermosetting polymers, cannot be reprocessed after they have been cured. 

Both thermoplastics and thermosets can be used in four of the five major application areas plastics, elastomers, coatings, and adhesives. But, only thermoplastics can be used in making fibers. During the spinning and drawing process of fiber processing, it s necessary to orient the molecules. Only unbranched, linear polymers (not thermosets) are capable of orientation. 

Therefore, rotary kilns are the special application of this chapter and are compared with competing technologies. A closer look is given to the treatment of thermoplastic, thermosetting or elastomer-based polymers, containing heteroatoms such as nitrogen, chlorine or bromine. 

In general, polymers can be divided into four major categories, depending on their physical behavior thermoplastics, fibers, elastomers, and thermosetting resins. Thermoplastics are the polymers most people think of when the word plastic is mentioned. These polymers have a high T, and are therefore hard at room temperature, but they become soft, and viscous when heated. As a result, they can be molded into toys, beads, telephone housings, or into any of a thousand other items. Because thermoplastics have little or no cross-linking, the individual chains can slip past one... 

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