Thermoplastics semicrystalline

Poly(phenylene sulfide). Poly(phenylene sulfide) (PPS) is a semicrystalline thermoplastic with a T of 85°C and a of 285°C. The nominal... 

Currently, important TPE s include blends of semicrystalline thermoplastic polyolefins such as propylene copolymers, with ethylene-propylene terepolymer elastomer. Block copolymers of styrene with other monomers such as butadiene, isoprene, and ethylene or ethylene/propy-lene are the most widely used TPE s. Styrene-butadiene-styrene (SBS) accounted for 70% of global styrene block copolymers (SBC). Currently, global capacity of SBC is approximately 1.1 million tons. Polyurethane thermoplastic elastomers are relatively more expensive then other TPE s. However, they are noted for their flexibility, strength, toughness, and abrasion and chemical resistance. Blends of polyvinyl chloride with elastomers such as butyl are widely used in Japan. ... 

In the case of poly(alkoxyphosphazenes) (IV) or poly(aryloxyphos-phazenes) (V) a dramatic change in properties can arise by employing combinations of substituents. Polymers such as (NP CHjCF ) and (NP CgH,).) are semicrystalline thermoplastics (Table I). With the introduction of two or more substituents of sufficiently different size, elastomers are obtained (Figure 4). Another requirement for elastomeric behavior is that the substituents be randomly distributed along the P-N backbone. This principle was first demonstrated by Rose (9), and subsequent work in several industrial laboratories has led to the development of phosphazene elastomers of commercial interest. A phosphazene fluoroelastomer and a phosphazene elastomer with mixed aryloxy side chains are showing promise for military and commercial applications. These elastomers are the subject of another paper in this symposium (10). 

A truncation of the term thermoplastics. Generally organic materials which in the manufacturing stage are caused to flow by the application of heat and pressure and thus take up a desired shape, which shape is retained when the applied heat and pressure are removed. Plastics are high polymers and are classified into amorphous and semicrystalline thermoplastics and thermosetting materials. 

Semicrystalline polymers, 20 351, 352, 588 toughness of, 20 354 Semicrystalline resins, 19 537 Semicrystalline thermoplastics, melting temperature of, 19 538t Semiefficient (semi-EV) sulfur... 

Experimental results are presented that show that high doses of electron radiation combined with thermal cycling can significantly change the mechanical and physical properties of graphite fiber-reinforced polymer-matrix composites. Polymeric materials examined have included 121 °C and 177°C cure epoxies, polyimide, amorphous thermoplastic, and semicrystalline thermoplastics. Composite panels fabricated and tested included four-ply unidirectional, four-ply [0,90, 90,0] and eight-ply quasi-isotropic [0/ 45/90]s. Test specimens with fiber orientations of [10] and [45] were cut from the unidirectional panels to determine shear properties. Mechanical and physical property tests were conducted at cold (-157°C), room (24°C) and elevated (121°C) temperatures. 

Graphite/ Thermo- plastic AS4/PPS Phillips Petroleum Phillips Petroleum Polyphenylene sulfide, semicrystalline thermoplastic... 

For semicrystalline thermoplastics there is an upper limit set by the melting temperature and a lower limit set by the acceptable duration of testing, typically one year or 8,760 hours. This limits the test temperatures to a narrow band, increasing both the effect of scatter and the temperature interval over which the results have to be extrapolated. 

Poly(butylene terephthalate) (PBT) (1) resins are semicrystalline thermoplastics used in a wide variety of applications, most commonly in durable goods that are formed by injection molding. Applications include electronic and communications equipment, computers, televisions, kitchen and household appliances, industrial equipment, lighting systems, gardening and agricultural equipment, pumps, medical devices, food handling systems, handles, power and hand tools, bobbins and spindles, and automotive parts in both under-the-hood and exterior applications. Additionally, PBT is very widely used to form electrical connectors. PBT, through its many blended products, can be tailored to suit numerous applications. 

Poly(butylene terephthalate) (PBT) is a semicrystalline, thermoplastic polyester which is completely analogous to PET except that it has a longer, more flexible butylene chain linkage which imparts a rapid crystallization rate, thus making PBT well suited to injection moulding processes. This polyester is used widely for electrical and electronic components due to its high temperature resistance and good electrical properties (Chapter 8). 

Figure 3.1. Examples of modulus variations versus temperature for an amorphous and a semicrystalline thermoplastic...

Atlanta,18-21 April 1988,p.719-22. 012 PRODUCTION OF MICROCELLULAR FOAMS IN SEMICRYSTALLINE THERMOPLASTICS... 

The phenomenological ordering of polymers projected for use as constructing materials is not an easy matter. Sometimes the temperature stability is used as a criterion, i.e., the temperature up to which the mechanical properties remain more or less constant. Another attempt for classification, uses the E modulus or the shape of the curve of stress-strain measurements (see Sect. 2.3.5.1). In general one can say that semicrystalline thermoplastics are stiff, tough, and impact-resistant while amorphous thermoplastics tend to be brittle. Their E... 

Thus, a brief survey of the current understanding of the molecular and super-molecular structures of common thermoplastics is presented first. This review starts with a brief description of the current state-of-the-art knowledge of the constitution, configuration, conformation and supermolecular structure of common glassy and semicrystalline thermoplastics. Later in this chapter, specific features of the structure-property relationships are discussed in greater detail for the most frequently filled thermoplastics. Effects of fillers on the structural variables in polypropylene, considered the most commercially important matrix, are especially emphasized. 

Since the chain regularity is an attribute of a development of higher levels of structural hierarchy, namely crystalline domains, stereoisomerism affects greatly the morphology and, thus, the mechanical properties of semicrystalline thermoplastics. 

The importance of spherulites and spherulitic morphology for the mechanical response of semicrystalline thermoplastics rests on experimental evidence that... 

The time needed for polymer chains of amorphous thermoplastics above Tg and semicrystalline thermoplastics above Tm to diffuse across the interface and randomize is relatively short compared with the time needed for resin flow. It is believed, therefore, that diffusion bonding is completed immediately after the two molten surfaces merge, and that the microstructure of the contact zone is also assumed to be identical to that of the intraply sections [12,13],... 

Recently, a new concept in the preparation of TPVs has been introduced, based on the reaction-induced phase separation (RIPS) of miscible blends of a semicrystalline thermoplastic in combination with an elastomer, with the potential for obtaining submicrometer rubber dispersions. This RIPS can be applied to a variety of miscible blends, in which the elastomer precursor phase was selectively crosslinked to induce phase separation. Plausible schematic representation of the morphological evolution of dynamic vulcanization of immiscible and miscible blends is shown in Fig. 9. For immiscible blends, dynamic vulcanization leads to a decrease in the size... 

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