Structure of thermoplastic

Figure 4.131(a) displays schematic structures of thermoplastics and crosslinked rubbers, while Figure 4.131(b) displays two possible schematic structures of thermoplastic elastomers. 

Figure 4.131. (a) Schematic structures of thermoplastics and crosslinked rubbers (b) Schematic structure ofTPEs... 

Unlike the thermosetting resins, the thermoplastic resins will soften on heating or on contact with solvents. They will then harden on cooling or on evaporation of the solvent from the material. This is a result of the noncrosslinked chemical structure of thermoplastic molecules. The following are important characteristics of thermoplastic resins that can affect their joining capability. 

Figure 1.4 Schematic structures of thermoplastic and thermoset polymers.

Figure 1 Structure of thermoplastic rubber. Copyright 2003 by Taylor Francis Group, LLC...

FIGURE 2.3 Structure of thermoplastic elastomers from ABA triblock copolymers. (From Morton, 1971.)... 

Table 3.1 Chemical structures of thermoplastic polymers in biomedical applications... 

A reinforced structure of thermoplastics, named as the in situ hybrid composite, consists of three components in principle macroscopic fibers such as glass fiber, carbon fiber, or aramid fiber microscopic LCP fibrils and a matrix resin [157]. Macroscopic fibers are in their fibrous form before the fabrication of the reinforced composite, while LCP fibrils are generated in situ during the melt processing of the ternary composite. 

Rg.19 Chemical structures of thermoplastic SMPs. (a) Aliphatic polyetherurethane TFX, which is prepared from methylene bis(p-cyclohexyl isocyanate) (H12 MDI), 1,4-butanediol (BD), and poly(tetramethylene glycol) (PTMG). (b) Multiblock copolymer PDC prepared from PPDO-diol, poly(p-dioxanone-diol) TMDl, 2,2(4),4-trimethylhexanediisocyanate PCL-diol, poly(f-caprolactone-diol). Reprinted by permission from ref. [85]. Copyright 2006, Nationtil Academy of Sciences, U.S.A. 

Fig. 4. Droplet-like structure of thermoplastic com starch/EVOH blend in film from, after disagregation in boiling water (129).

Fig. 5. Layered structure of thermoplastic waxy maize/EVOH film after 3 days of soil burial test (129).

Figure 1.5 Examples of molecular structures of thermoplastic (A) and thermosetting (B) stimuli-responsive monomers.

The structure of thermoplastic rubber is unique. It does not behave like conventional elastomers such as natural rubber or styrene-butadiene rubber (SBR) in a number of important respects. The next several sections explain the fundamental principles of its behavior. 

Much work has been published on the physical structure of thermoplastic rubber. Two glass transition temperature T peaks are found in dynamic mechanical tests with an S-B-S block copolymer. In contrast, only one peak is found in a random SBR copolymer with the same sty-rene/butadiene ratio. This difference is shown in Fig. 4. 

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