Thermoplastics, definition

Classification Thermoplastic Definition Polymer exhibiting anisotropy during processing while behaving as a liq. exc. fire resist, toughness, chem. inertness good elec. 

Tbe term structural foam was originally coined by Union Carbide to describe an injection moulded thermoplastic cellular material with a core of relatively low density and a high-density skin. The term has also been used to describe rigid foams that are load bearing. Today it is commonly taken to imply both of the above requirements, i.e. it should be load bearing and with a core of lower density than the skin. In this section the broader load-bearing definition will be used. Whilst structural foams are frequently made from polymers other than polystyrene, this polymer is strongly associated with such products and it is convenient to deal with the topic here. 

Plastics are subidivided into two types thermoplastic and thermosetting. The thermoplastics can be softened by heat and hardened again by subsequent cooling. This process is reversible and can be repeated many times. By contrast, the thermosetting resins are first softened and melted and, at subsequent heating to a definite temperature, they are irreversibly hardened, becoming insoluble [53]. 

Silicone co-polymer networks and IPNs have recently been reviewed.321 The development of IPNs is briefly described, and the definitions of the main (non-exclusive) classes of the IPNs are cited. Examples of latex IPNs, simultaneous and sequential IPNs, semi-IPNs, and thermoplastic IPNs are provided. The use of silicone-silicone IPNs in studies of model silicone networks is also illustrated. Networks in which siloxane and non-siloxane components are connected via chemical bonds are considered co-polymer networks, although some other names have been applied to such networks. Today, some of the examples in this category should, perhaps, be discussed as organic-inorganic hybrids, or nanocomposites. Silicone IPNs are discussed in almost all of the major references dealing with IPNs.322-324 Silicone IPNs are also briefly discussed in some other, previously cited, reviews.291,306... 

Chapter 22 didn t give you a very satisfying definition of resins. But its useful here to talk about two classes of polymers called resins thermosets and engineering thermoplastics. 

Usually an indication of molecular mixing can be theoretically calculated based on composite Tg s. When the glass transition temperature of the SIPN was between that of the neat components, molecular interactions were assumed. A definite increase in Tg resulted in these materials. No calculated Tg can be compared since the thermoset did not show a Tg. It was interesting to note that the beta transition of the triazine network was unaffected, but the Tg for the composite was much higher relative to the thermoplastic alone. System II showed a 20 C increase in Tg, while I showed a large increase, changing from 62 C to 125°C. 

Sheets of a substrate that have been impregnated with a curable polymer, curable polymers, or liquid reactants, or a thermoplastic, and are ready for fabrication of laminates. Note 1 See Definition 1.16 notes 2 and 3. 

Thermal stability as measured by these ramped TGA experiments of the sort previously described are not the definitive test of a polymer s utility at elevated temperature. Rather, for a polymer to be useful at elevated temperatures, it must exhibit some significant retention of useful mechanical properties over a predetermined lifetime at the maximum temperature that will be encountered in its final end use application. While many of the bisbenzocyclobutene polymers have been reported in the literature, only a few have been studied in detail with regards to their thermal and mechanical performance at both room and elevated temperatures. Tables 7-10 show some of the preliminary mechanical data as well as some other physical properties of molded samples of polymers derived from amide monomer 32, ester monomer 40, diketone monomer 14 and polysiloxane monomer 13. The use of the term polyamide, ester etc. with these materials is not meant to imply that they are to be regarded as merely modified linear thermoplastics. Rather, these polymers are for the most part highly crosslinked thermosets. 

The term ionomer was originally introduced in 1964 by Dupont to indicate a thermoplastic polymer containing both covalent and ionic bonds (5-7). By definition, ionomers are statistical thermoplastic copolymers consisting of (8) ... 

In such a flexible definition of engineering thermoplastics, the exact list and number of materials and/or families of materials will vary with the viewpoint of the specialist who prepares the list. For purposes of illustration, let us consider 13 thermoplastics, developed during the past decade or two, which are produced in small to moderate volume at medium to high prices, and are finding growing application in products where their superior properties justify their higher costs. Most of these descriptions of engineering thermoplastics are taken from the manufacturers bulletins and unpublished discussions with manufacturers and users of these materials. 

Commercial Plastisols, Accdg to definition given in Ref 2, a plastisol is a liquid dispersion of finely divided resin in a plasticizer. It is usually 100% solid with no volatiles when volatile content exceeds 5% of the total wt it is called organosol. When the plastisol is heated, the plasticizer solvates the resin particles, and the mass gels. With continued application of heat the mass fuses to become a conventional thermoplastic material... 

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