Modulus-temperature behavior

Fig. 6. Influence of composition on the modulus-temperature behavior of perfectly alternating block copolymers [52]...

Unlike the random copolymers, block and graft copolymers separate into two phases, with each phase exhibiting its own Tg (or TM).40 The modulus-temperature behavior of a series of... 

Figure 5. Dynamic shear modulus-temperature behavior (torsion pendulum, 1 Hz) of 50% w/w HS copolyurethanes based on diisocyanates FDI-a (F) and MDI (M). Soft segment glass transition and hard-segment melting are in the temperature regions indicated, respectively, by and Tm.

Modulus-temperature behavior of amorphous polymers is also affected by admixture with plasticizers. These are the soluble diluents described briefly in Section 12.3.2. As shown in Fig. 11-11, the incorporation of a plasticizer reduces Tg and makes the polymer more flexible at any temperature above Tg. In polyfvinyl chloride), for example, T can be lowered from about 85°C for unplaslicized material to —30°C for blends of the polymer with 50 wt % of dioctyl phthalate plasticizer. A very wide range of mechanical properties can be achieved with this one polymer by variations in the type and concentration of plasticizers. 

Novel sulfonated and carboxylated ionomers having "blocky" structures were synthesized via two completely different methods. Sulfonated ionomers were prepared by a fairly complex emulsion copolymerization of n-butyl acrylate and sulfonated styrene (Na or K salt) using a water soluble initiator system. Carboxylated ionomers were obtained by the hydrolysis of styrene-isobutyl-methacrylate block copolymers which have been produced by carefully controlled living anionic polymerization. Characterization of these materials showed the formation of novel ionomeric structures with dramatic improvements in the modulus-temperature behavior and also, in some cases, the stress-strain properties. However no change was observed in the glass transition temperature (DSC) of the ionomers when compared with their non-ionic counterparts, which is a strong indication of the formation of blocky structures. 

With this background, it will be easy to proceed with the analysis of the modulus-temperature behavior of more complicated systems. 

Figure 6.6. Loss modulus-temperature behavior of PU(PTM02000)/UPMI(PEG600) IPNs at various PU/UBMI ratios ------ 100/0,----- 90/10,---------- 70/30,...0/100.

Figure 17.1. Generalized mechanical loss (tan 5) and modulus-temperature behavior for various types of polymer blends. Case 1 (dashed-dotted line), miscible Case 2 (dashed line), partially miscible Case 3 (dotted line), microheterogenous Case 4 (solid line) phase separated. Reproduced with permission from O. Olabisi, L. M. Robeson, and M. T. Shaw, Polymer-Polymer Miscibility , Academic Press, New York, 1979.

This Figure notes that combinations of amorphous (high T ) engineering polymers (e.g., PPE, polycarbonate, polyarylate) with lower T crystalline polymers (e.g., polyamide-66, polybutyleneterephthalate), offers the modulus-temperature behavior desired for the noted application. 

FIGURE 15.7 Modulus-temperature behavior of polyester-polystyrene bloek copolymers 1, polyester 2, polyester containing 20% of polystyrene 3, containing 45% polystyrene 4, containing 60% polystyrene 5, pure polystyrene. 

Figure 2.6. Modulus-temperature behavior of blends of polystyrene with a 30/70 butadiene/ styrene copolymer. Dashed lines delineate change in Tg with composition. (Tobolsky, 1960.)...

Cooper and Tobolsky (1966a) showed (Figure 5.6) that the modulus-temperature behavior of polyurethanes is characteristic of block copolymers... 

Figure 5.12. Modulus-temperature curves of poly acrylic acid), a buta-diene-acrylonitrile-methacrylic ter-polymer (69 25 6), and their zinc salts. The polyacids have normal modulus-temperature behavior,...

Figure 7.4. Modulus-temperature behavior of nylon 6/polystyrene graft copolymers. —, 50% N 75% N O, Nylon 6 A, polystyrene. (Matzner et al, 1973.)...

Figure 8.12. Modulus-temperature behavior of cis-PB/PS IPN s (Curtius et al, 1972). Two transitions are observed for all IPN compositions. The IPN s with midrange compositions behave in a leathery manner at room temperature. The sharp rise at — 80°C for the pure ds-PB is due to crystallization. The fact that none of the IPN s shows PB crystallization indicates the existence of molecular mixing. (Modulus taken at 10 sec, using a Gehman torsional tester.)...

Figure 8.13. Modulus-temperature behavior of PEA/PMMA IPN s. Numerical values indicate wt % PEA. All compositions were found to exhibit only one broad transition region. (Sperling et al, 1970a.)...

To test the results of the model developed here, results are compared with room temperature tensile loading data for a porous cordierite. The modulus-temperature behavior for this ceramic is shown in Figure 2. From this data, values for and were computed. The coefficient of friction for this material is not known, but reported values for ceramics range from 0.6 -1.8 For this work, a nominal value of / = 1.0 was selected. The other needed parameters of interest are given in Tabie 1 along with the method nsed for determining their values. 

Fig. 6.6 Loss modulus temperature behavior of PU (PTM02000)/UPMI (PEG600) IPNs at various...

The following observations emerge from the Young s-modulus/ temperature behavior shown in Figs. 5 to 7 for the graphite epoxies ... 

L. H. Sperling and D. W. Friedman, Synthesis and Mechanical Behavior of Interpenetrating Polymer Networks Poly(ethyl acrylate) and Polystyrene, J. Polym. Sci. A-2 7, 425 (1969). Synthesis of sequential IPNs. Modulus-temperature behavior. Modulus-composition behavior. 

Fig. 1-26 Effect of cross-linking on modulus-temperature behavior [36].

Figure 1.6 Idealized modulus-temperature behavior of an amorphous polymer. Young s modulus, stress/strain, Is a measure of stiffness.

Figure 2. Modulus-temperature behavior of polystyrene SINs. ...

Figure4.25 Generalized modulus-temperature behavior for plasticized PVC compared to unmodified PVC...

FigureS.S Generalized modulus-temperature behavior for various types of polymer blends...

The viscoelastic properties of polymer blends determined by dynamic mechanical analysis to yield E, E" and tand has been reviewed in Section 5.2. The modulus-temperature behavior of polymer blends is a strong function of the phase behavior. In Fig. 6.2, the generalized modulus-temperature behavior of miscible versus immiscible blends is compared for the case of two amorphous polymers with different glass transition temperatures. The phase separated blend exhibits a modulus plateau between the TgS of the components with the plateau position dependent upon the composition. The miscible blends show single Tg behavior, with the Tg position dependent upon the composition. 

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