Block copolymers stress-strain curves

Proportion of Hard Segments. As expected, the modulus of styrenic block copolymers increases with the proportion of the hard polystyrene segments. The tensile behavior of otherwise similar block copolymers with a wide range of polystyrene contents shows a family of stress—strain curves (4,7,8). As the styrene content is increased, the products change from very weak, soft, mbbedike materials to strong elastomers, then to leathery materials, and finally to hard glassy thermoplastics. The latter have been commercialized as clear, high impact polystyrenes under the trade name K-Resin (39) (Phillips Petroleum Co.). Other types of thermoplastic elastomers show similar behavior that is, as the ratio of the hard to soft phase is increased, the product in turn becomes harder. 

Figure 1. Stress-strain curves of polycarbonate-polydimethyl-siloxane block copolymers (Crosshead Speeds 5 cm/min). (Reproduced from Refs. 15 18. Copyright 1980, 1984 American Chemical Society.)...

Figure 10.1. USAXS observation during straining of an SBS block copolymer. Right monitor Intensity maxima on an ellipse. Raw-data coordinate system (x,y) and radial cuts for data analysis are indicated. Middle Videotaping of sample. Left Stress-strain curve. Control booth of beamline BW4, HASYLAB, Hamburg...

Likewise, the mechanical properties of the copolymers were nearly identical or even somewhat enhanced towards the polyimide homopolymer in terms of the modulus and tensile strength values [44,47]. For most of the block copolymers, the elongations to break were substantially higher than that of PMDA/ODA polyimide (Table 4). The shape of the polyimide stress-strain curve is similar to that of a work-hardened metal with no distinguishable yield point... 

Fig. 19. The stress-strain curves recorded for the two triblock copolymer samples during cold drawing of films with a constant rate of 1 mm/min. ABA-isolated clean pnBA central block Mn=65,200 pMMA outer blocks, Mn=13,150, overall Mw/Mn=1.34. ABA-sequential clean pnBA central block, Mn=67,500 pMMA-grad-pnBA outer blocks 13mol% nBA and 87 mol% MMA, Mn=10,600, overall Mw/Mn=1.24. Inset small angle X-ray scattering intensities for these samples. Reprinted with permission from [94]. Copyright (2000) John Wiley Sons, Inc.

Figure 4.18. Stress-strain curve for SBS block copolymer (Kraton 101) deposited from solution (90/10 THF/MEK). Note behavioral changes brought about by altered morphology. (Beecher et al, 1969.)...

Figure 2.14. First and second stress-strain curves for a block copolymer thermoplastic elastomer. When the polystyrene phase continuity is destroyed during the first elongation, a soft elastomer results. " ...

Stress-strain curves of PE, PC, PA, and polybntylene terephthalate [92], and styrene-butadiene block copolymers [93]. 

Figure 4. Typical stress-strain curves of nylon 6 and the graft and block copolymers.

The mechanical behavior of these linear block copolymers is directly related to the composition and morphology (correlated stress-strain curves are presented in Fig. 3.8 in Part II). By changing the macromolecular architecture and processing conditions in block copolymers, very different morphologies with modified mechanical properties and partly new micromechanical mechanisms can be obtained (see Chapter II.3). 

Figure 18.17 Stress-strain curves of block copolymers shown in Figure 18.16. The behavior of linear symmetric block copolymer LN1 is chosen as a reference (a) solution cast films (b) injection-molded bars (c) solution cast films. Adhikari [40]. Reproduced with permission of Elsevier.

FIGURE 16.3 Stress-strain curves for different samples of block copolymers of caprolactone with -butyl acrylate tested at (a) room temperature and (b) 70 °C. Polymer compositions were 0, 20, 39, 50 and 71 wt% n-butyl acrylate from top to bottom in (a). Reprinted with permission from Referenece 1. Copyright 2001 National Academy of Sciences, USA. 

Fig. 2. Stress-strain behavior of MDI-based siloxane-urea segmented copolymers as a function of siloxane block molecular weights (PSX-Mn g/mole), [1. PSX-1140, 2. PSX-1770, 3. PSX-2420, 4. PSX-3670] and their comparison with unfilled (curve 7) and silica filled (curves 5 and 6) conventional silicone rubbers51 158,358,359)...

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