Blend experimental

Figure 3. Fraction blends experimental vs. calculated chromatograms...

This article reviews the phase behavior of polymer blends with special emphasis on blends of random copolymers. Thermodynamic issues are considered and then experimental results on miscibility and phase separation are summarized. Section 3 deals with characteristic features of both the liquid-liquid phase separation process and the reverse phenomenon of phase dissolution in blends. This also involves morphology control by definite phase decomposition. In Sect. 4 attention will be focused on flow-induced phase changes in polymer blends. Experimental results and theoretical approaches are outlined. 

The first is to develop thermodynamic issues to understand the complex phase behavior of polymer blends. Experimental determination of miscibility regions provides the individual segmental interaction parameters necessary for predictions of various phase equilibria. 

TOM Tomova, D., Kressler, J., and Radusch, H.-J., Phase behaviour in ternary polyamide 6/polyamide 66/elastomer blends (experimental data by D. Tomova), Polymer, 41, 7773, 2000. 

In addition, Piggott and Leidner (34) have criticized the validity of the simple geometrical considerations upon which Eq. 7 is based. As shown in Fig. 12 for the composition range in which brittle failure is observed to occur in the PpClS/PPO blends, experimental values for break elongation consistently fall far above the curve calculated by use of Eq. 7. The usefulness of Eq. 7 in predicting... 

A) Conventional DSC first and second heating eurves for a PET/ABS blend. Experimental parameters sample mass 9.2 mg, heating/cooling rate 10 K/min. (B) TMDSC first heating curves for an identical sample of the PET/ABS blend. TMDSC experimental parameters sample mass 8.5 mg,/ = 2 K/min,/ = 60 s and Aj = 1 K (courtesy of TA Instruments Inc.)... 

Fig. 3.34 Thennal properties of the second scan of the MCDEA-cured ER/PEO blends. ( ) Experimental plot of Tg versus overall blend composition, ( ) plot of Tg versus calculated amorphous...

Blends of PCL with linear low-density polyethylene have been prepared and their rheological properties were investigated. Data demonstrated that in variations of In(viscosity) with composition of the blends experimental values fell below the weighted average values. A model was proposed to describe this negative deviation [153]. 

FIGURE 16.7 (a) DSC thermograms in the second heating runs for solution/precipitation PDLLA/PMMA blends with compositions from 100 0 to 0 100, and (b) Tg versus composition in solution/ precipitation PDLLA/PMMA blends. ( ) Experimental results. Line A corresponds to the weight average, and line B is drawn according to Equation 16.1 with k — 0.5. Reprinted from Ref. 71. Copyright 2002, with permission from John Wiley Sons, Inc. 

Taipalus, R., Harmia, T, Zhang, M. Q. et al. 2001. The electrical conductivity of carbon-fibre-reinforced polypropylene/polyaniUne complex-blends Experimental characterisation and modelling. Composite Science and Technology 61 801-814. 

Figure 4.11 Theoretically calculated phase diagram of PVDF/PMMA blend. Experimental and material parameters were determined by Nishi and Wang (O) [56].

Fig. 5 Experimental setup (left) and result (right) of mean (line scan) refraction intensities of polystyrene and polystyrene blend (right).

Physical or chemical vapor-phase mechanisms may be reasonably hypothesized in cases where a phosphoms flame retardant is found to be effective in a noncharring polymer, and especially where the flame retardant or phosphoms-containing breakdown products are capable of being vaporized at the temperature of the pyrolyzing surface. In the engineering of thermoplastic Noryl (General Electric), which consists of a blend of a charrable poly(phenylene oxide) and a poorly charrable polystyrene, experimental evidence indicates that effective flame retardants such as triphenyl phosphate act in the vapor phase to suppress the flammabiUty of the polystyrene pyrolysis products (36). 

Initial evaluations of chemicals produced for screening are performed by smelling them from paper blotters. However, more information is necessary given the time and expense required to commercialize a new chemical. No matter how pleasant or desirable a potential odorant appears to be, its performance must be studied and compared with available ingredients in experimental fragrances. A material may fail to Hve up to the promise of its initial odor evaluation for a number of reasons. It is not at all uncommon to have a chemical disappear in a formulation or skew the overall odor in an undesirable way. Some materials are found to be hard to work with in that their odors stick out and caimot be blended weU. Because perfumery is an individuaHstic art, it is important to have more than one perfumer work with a material of interest and to have it tried in several different fragrance types. Aroma chemicals must be stable in use if their desirable odor properties are to reach the consumer. Therefore, testing in functional product appHcations is an important part of the evaluation process. Other properties that can be important for new aroma chemicals are substantivity on skin and cloth, and the abiHty to mask certain malodors. 

Ternary Blends. Discussion of polymer blends is typically limited to those containing only two different components. Of course, inclusion of additional components may be useful in formulating commercial products. The recent Hterature describes the theoretical treatment and experimental studies of the phase behavior of ternary blends (10,21). The most commonly studied ternary mixtures are those where two of the binary pairs are miscible, but the third pair is not. There are limited regions where such ternary mixtures exhibit one phase. A few cases have been examined where all three binary pairs are miscible however, theoretically this does not always ensure homogeneous ternary mixtures (10,21). 

A variety of experimental techniques have been used to prepare and characterize polymer blends some of the mote important ones for estabHshing the equiHbtium-phase behavior and the energetic interactions between chain segments ate described here (3,5,28,29). 

Fig. 3. Phase-separation temperatures for 50 50 PVC—a-MSAN blends, where (-------) represents the blend drying temperature, ( ) are experimentally...

In the depolymeri2ed scrap mbber (DSR) experimental process, ground scrap mbber tines produce a carbon black dispersion in ok (35). Initially, aromatic oks are blended with the tine cmmb, and the mixture is heated at 250—275°C in an autoclave for 12—24 h. The ok acts as a heat-transfer medium and swelling agent, and the heat and ok cause the mbber to depolymeri2e. As more DSR is produced and mbber is added, less aromatic ok is needed, and eventually virtually 100% of the ok is replaced by DSR. The DSR reduces thermal oxidation of polymers and increases the tack of uncured mbber (36,37). Depolymeri2ed scrap mbber has a heat value of 40 MJ/kg (17,200 Btu/lb) and is blended with No. 2 fuel ok as fuel extender (38). 

In addition to the somewhat sophisticated triblock thermoplastic elastomers described above, mention should be made of another group of thermoplastic diene rubbers. These are physical blends of polypropylene with a diene rubber such as natural rubber. These may be considered as being an extension to the concept of thermoplastic polyolefin rubbers discussed in Section 11.9.1 and although extensive experimental work has been carried out with these materials they do not yet appear to have established themselves commercially. 

The objeetive of the following model is to investigate the extent to whieh Computational Fluid Mixing (CFM) models ean be used as a tool in the design of industrial reaetors. The eommereially available program. Fluent , is used to ealeulate the flow pattern and the transport and reaetion of ehemieal speeies in stirred tanks. The blend time predietions are eompared with a literature eonelation for blend time. The produet distribution for a pair of eompeting ehemieal reaetions is eompared with experimental data from the literature. 

V3.03. The tank diameter was T = 1 m. Furthermore, Z/T = 1, D/T = 0.33, C/T = 0.32, and rpm = 58. The flow pattern in this tank is shown in Figure 10-9. Experimental data were used as impeller boundary eonditions. Figure 10-10 shows the uniformity of the mixture as a funetion of time. The model predietions are eompared with the results of the experimental blend time eorrelation of Fasano and Penny [6]. This graph shows that for uniformity above 90% there is exeellent agreement between the model predietions and the experimental eorrelation. Figure 10-1 la shows the eoneentration field at t = 0 see. Figures 10-1 lb through 10-1 Id show the eoneentration field at t = 0,... 

It is possible to distinguish between SBR and butyl rubber (BR), NR and isoprene rubber (IR) in a vulcan-izate by enthalpy determination. In plastic-elastomer blends, the existence of high Tg and low Tg components eases the problems of experimental differentiation by different types of thermal methods. For a compatible blend, even though the component polymers have different Tg values, sometimes a single Tg is observed, which may be verified with the help of the following equation ... 

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