Polymer blends systems

Note 1 Phase inversion may be observed during the polymerization or melt processing of polymer blend systems. 

Harrats, C., Groeninckx, G., and Thomas, S. 2006. Micro- and Nanostructured Multiphase Polymer Blend Systems. Taylor Francis, Boca Raton, FL. 

Phase separation through NG mechanism cannot be observed for polymer-polymer blend systems that show interfacial tension lying in the range 0.5-11 mN/m. In addition, they predicted that a secondary phase separation could take place inside dispersed rubber particles in the case when the average composition of dispersed domains lies in the unstable region at the end of the phase separation [2], They were not able to observe a phase separation inside dispersed domains with TEM micrographs however, they concluded that there are two phases inside the dispersed domains by the fact that the glass transition temperature of the rubber-... 

The CP experiments on polymer blend systems, using a mixture of two polymers in which one is deuterated and another is protonated, have been carried out in order to elucidate their miscibility. This information is given by whether protons in the protonated polymer are cross-polarized to deute-rons of the other deuterated polymer or not. These studies show that effective CP transfer may be limited to about 10 A. In the... 

Harrats S, Thomas S, Groeninckx G (2006) Micro and nano structured multiphase polymer blend systems - phase morphology and interface. CRC, Boca Raton... 

The examples described in this chapter were chosen to give the reader an overview of the science and technology of polymer blending as well as insights into specific polymer blend systems chosen to correct or tailor specific processing or performance deficiencies. 

The question immediately raised is would this technique portray an opposite or negative adhesion response if applied to a polymer blended system where no interfacial bonding could be present Such a system would be cis-polybutadiene and high molecular weight polyisobutylene restricted to that portion of the blend system where polyisobutylene is the minor dispersed phase in cis-polybutadiene. A high molecular weight polyisobutylene [L-300 Vistanex (Enjay Chemical Co.)] was compounded with zinc oxide, sulfur, and TMTDS and then dissolved in hexane. cis-Polybutadiene (Phillips Chemical Co.) was also mixed with... 

Later reports [49-51] provided further insight into the blend morphology for several of the cellulose/synthetic polymer blend systems fisted in Table 1. In particular, refining efforts were devoted to precise quantification of the scale of homogeneity in the blends. A dielectric relaxation... 

Consequently, the presence of an intensity of the Yoneda peak, split along the -direction is present over a rather broad range of nano-dot distance distributions. It should be noted, that in polymer systems, a very high degree of order as shown in Fig. 4a is only rarely present. In polymer blend systems it is not expected at all. 

Over the last decade, the poor economics of new polymer and copolymer production and the need for new materials whose performance/ cost ratios can be closely matched to specific applications have forced polymer researchers to seriously consider purely physical polymer blend systems. This approach has been comparatively slow to develop, however, because most physical blends of different high molecular weight polymers prove to be immiscible. That is, when mixed together, the blend components are likely to separate into phases containing predominantly their own kind. This characteristic, combined with the often low physical attraction forces across the immiscible phase boundaries, usually causes immiscible blend systems to have poorer mechanical properties than could be achieved by the copolymerization route. Despite this difficulty a number of physical blend systems have been commercialized, and some of these are discussed in a later section. Also, the level of technical activity in the physical blend area remains high, as indicated by the number of reviews published recently (1-10). 

The basic issue confronting the designer of polymer blend systems is how to guarantee good stress transfer between the components of the multicomponent system. Only in this way can the component s physical properties be efficiently used to give blends with the desired properties. One approach is to find blend systems that form miscible amorphous phases. In polyblends of this type, the various components have the thermodynamic potential for being mixed at the molecular level and the interactions between unlike components are quite strong. Since these systems form only one miscible amorphous phase, interphase stress transfer is not an issue and the physical properties of miscible blends approach and frequently exceed those expected for a random copolymer comprised of the same chemical constituents. 

Miscible Blends. Both Components Amorphous. Certainly one of the most commercially important and publicized examples of a miscible polymer blend system is that based on polystyrene and poly(phenylene oxide), which is sold under the trade name Noryl by General Electric. Many fundamental studies of this system have been published, many of which were devoted to proving that these two components are miscible in a thermodynamic sense (see chapter 5 of Ref. 10 by MacKnight, Karasz, and Fried). Commercial interest in this system involves both... 

Kobayashi, Y., Wang, C.L., Hirata, K., Zheng, W., Zhang, C. (1998) Effects of composition and external electric fields on positron formation in a polymer blend system . Phys. Rev. B. 38(9), 5384. 

By analogy with small molecule liquid crystals, where the type of liquid crystal formed is used as a test for miscibility, it is expected that all polymer molecules that form the same type of liquid crystalline phase will be miscible (4). This is in contrast to more traditional polymers where miscibility is the exception rather than the rule. The present work will suggest which of these concepts is applicable to liquid crystal polymer blend systems. 

The purpose of the present work is to extend the above studies to blend systems consisting of two components, each of which is capable of forming a liquid crystalline phase in the melt. Such blends become of increasing importance with the recently reported finding (6) that it is possible to observe synergisms in mechanical properties in these systems. Our previous studies in this area have suggested that the theories of traditional polymer blend systems (7.8) are applicable to these blends. This paper is a further study of the applicability of these concepts. 

The suggestion that two liquid crystal polymers are incompatible with each other is contrary to ideas which are well established for small molecule liquid crystals (4). In fact, miscibility with other liquid crystals is one of the criteria sometimes used to establish the type of liquid crystal being dealt with. On the other hand, if the rheological criteria established for other polymer blend systems are valid for liquid crystal polymer blend systems as well, the two materials being discussed in the present work must be incompatible. 

The next sections of this paper contain the results of solid state structure investigations of these blend samples. The suggestion which will be advanced is that ideas concerning traditional polymer blend systems are more applicable for providing an understanding of these results than are ideas concerning small molecule liquid crystals. 

The usefulness of inverse gas chromatography for determining polymer-small molecule interactions is well established (1,2). This method provides a fast and convenient way of obtaining thermodynamic data for concentrated polymer systems. However, this technique can also be used to measure polymer-polymer interaction parameters via a ternary solution approach Q). Measurements of specific retention volumes of two binary (volatile probe-polymer) and one ternary (volatile probe-polymer blend) system are sufficient to calculate xp3 > the Flory-Huggins interaction parameter, which is a measure of the thermodynamic... 

This paper reviews the application of IGC in determining interaction parameters for three polymer blend systems polystyrene-poly(n-butyl methacrylate) (PS-PnBMA), polystyrene-poly(2,6-dimethyl-1,4-phenylene oxide) (PS-PPO), and poly(vinylidene fluoride)-poly(methyl methacrylate) (PVF2-PMMA)... 

Polymerization of the alkoxyallene with macromonomers having a poly (ethyleneglycol) group by [(7r-allyl)Ni(OCOCF3)]2/PPh3 produces a graft copolymer with narrow molecular weight distribution [129]. The products serve as polymeric surfactants in the polymer blend system of polystyrene and poly(methyl methacrylate). 

Le Menestrel, C. Bhagwagar, D.E. Graf, J.F. Painter, P.C. Coleman, M.M. Hydrogen bonding in ternary polymer blend systems determination of association parameters. Macromolecules 1992, 25, 7101. 

Some cellulose derivatives and P(3HB) and P(3HB-co-3HV) have been found to show good compatibility [114-116]. These are chemically modified natural and natural biodegradable polymer blend systems. Blends obtained by melts compounding P(3HB) with cellulose acetate butyrate (CAB, degrees of butyrate and acetate substitution are 2.50 and 0.18, respectively) have been found to be miscible over the whole composition range by DSC and dynamic mechanical spectroscopy [116]. 

This review summarizes our work at the University of Bayreuth over the last few years on improving the electret performance of the commodity polymer isotactic polypropylene (Sect. 3) and the commodity polymer blend system polystyrene/polyphenylene ether (Sect. 4) to provide electret materials based on inexpensive and easily processable polymers. To open up polymer materials for electret applications at elevated temperatures we concentrated our research on commercially available high performance thermoplastic polyetherimide resins and synthesized several fluorinaled polyetherimides to identify structure-property relations and to improve further the performance at elevated temperatures (Sect. 5). 

Table 3.19. Expressions for the dissipation energy terms and corresponding spherulite growth rates in a crystalline/amorphous polymer blend system [Martuscelli, 1984 Baitczak et al., 1984]...

The general influence of a compatibilizer on the crystallization behavior of an immiscible polymer blend system is stiU far from being well understood. However, abstract can be made between two main classes. A first class consists of compatibilizers that form a kind of immiscible interlayer between the two phases. Examples are given by Holsti-Miettinen et al. [1992], and... 

Polyolefin-polyamide melt blends are striking in not only the lack of miscibility, but also the large interfacial tensions between the two melt phases. Investigations of these phenomena in our laboratories (118,124-126) have made numerous studies of these polymer blend systems and found that their phase morphology are quite unstable and trend to coalesce especially under quiescent or low deformation rate conditions. Similar to polyolefin-polystyrene blends, they also show weak interfacial adhesion (118,124,127) (as shown in Fig. 2.9). The mechanical properties of the... 

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