Applications of polymers blends and composites

Bhattacharyya D and Fakirov S (2009) Organoclay, particulate and nanofibril reinforced polymer-polymer composites Manufacturing, modeling and application, in Nano- and Micromechanics of Polymer Blends and Composites (Eds. Karger-Kocsis and Fakirov S) Hanser Publishers, Munich, Germany, pp. 167-205. 

Both ethylene (e.g., LLDPE) and propylene copolymers, because of their superior mechanical properties, are widely applicable in polymer blends and composites with excellent results. 

Technical and financial incentives make polymeric materials an attractive alternative in an ever-increasing number of applications. The development of new resins, which, for several decades, attracted most of research efforts, now tends to be snpplemented by new approaches [1-3]. The strength of these new tendencies is clearly shown by the rapid emergence of polymer blends and composites as engineering materials [4]. 

Mohammed, Z. H., Hember, M. W. N., Richardson, R. K., and Morris, E. R. 1998. Application of polymer blending laws to composite gels of agarose and crosslinked waxy maize starch. Carbokydr. Polym. 36 27-36. 

Nowadays, the microhardness technique, being an elegant, non-destructive sensitive and relatively simple method, enjoys wide application, as can be concluded from the publications on the topic that have appeared during just the last five years - they number more than 100, as is shown by a routine computer-aided literature search. In addition to some methodological contributions to the technique, the microhardness method has also been successfully used to gain a deeper understanding of the microhardness-structure correlation of polymers, copolymers, polymer blends and composites. A very attractive feature of this technique is that it can be used for the micromechanical characterization of some components, phases or morphological entities that are otherwise not accessible for direct determination of their microhardness. 

The tunable metallocene catalyst with a well-defined polymerization mechanism provides distinctive advantages in the preparation of new polymers with well-controlled molecular structures, especially functional polyolefins that are very difficult to prepare by other methods. Since the discovery of HDPE and i-PP about half a century ago, functionalization of polyolefin has been a scientifically challenging and industrially important area. The constant interest, despite lack of effective functionalization chemistry, is due to the strong desire to improve polyolefin s poor interactive properties. The hydrophobicity and low surface energy of polyolefin has limited its applications, especially in the areas of coating, blends, and composites, in which adhesion, comparability, dispersion, and paintability are paramount. 

Polymer blends (mixtures of structurally different polymers (10-19)) are of interest because synthesized polymers have not satisfied increasing application demands. Polyolefin blends are a subset of polymer blends and may be classified into two groups. The first group contains polyolefins only, which are formulated to broaden the range of structures, properties, and applications offered by polyolefins. The second group contains polyolefins and nonpolyolefins, which are formulated to mitigate some of the property drawbacks of the polyolefin or the nonpolyolefin. For a blend to be classified as a polyolefin blend, it is presumed that the polyolefin component is of significant composition in the blend. 

Numerous polymers have been studied for their potential apphcation in PEMFCs. Based on their chemical structure, these polymers can be categorized into (a) vinylic polymers, (b) aromatic polymers, and (c) polymer blends and composite/hybrid polymers. Generally, vinylic polymers are synthesized by addition polymerization, while aromatic polymers are synthesized by step-growth polymerization. The most studied vinylic polymers for PEMFC applications are perfluorosulfonic acid ionomers (PFSls), in particular Nation , and styrene sulfonic acid-based polymers. Chemical structures of representative vinyhc PEMs are shown in Scheme 2. 

Parveen Saini (PhD Thesis) Synthesis, Characterization and Evaluation of Conducting Polymer Blends and Composites for Microwave Shielding and Antistatic Application, 2012 (Copyright Indian Institute of Technology, New Delhi, India). 

Dawsey X.R., Application and limitations of lithium chlotide/iVjV-dimethylacetamide in the homogeneous derivatization of cellulose, in Cellulosic Polymers, Blends and Composite, Ed. Gilbert R.D., Hanser, Munich, 1994, pp. 157-171. 

Yamanaka S., Watanabe K., Applications of bacterial cellulose, in Cellulosic Polymers - Blends and Composites, Ed. Gilbert R., Hanser Gardner, Mtinchen, 1994, p. 207. 

Yamanaka, S. and Watanabe, K. 1994. Applications of bacterial cellulose. In Cellulose Polymers, Blends and Composites, ed. R.D. Gibert, pp. 207-215. Cincinnati, OH Hanser/Gardner Publications. 

As shown above, H spin-diffusion may be detected via observation has also been used to follow H spin-diffusion in fluoropolymers [71]. An interesting case of homonuclear spin-diffusion between nuclei has been reported for domain size determination in phosphazene polymers [72]. In general, most researchers still use traditional HTip and T measurements to indirectly access the limits of spin-diffusion in an approximate fashion, as reported in many recent applications of these methods to a variety of semicrystalline polymers, blends, and composites [73-78]. 

As the use of polymers continues to increase in multi-component and multiphase applications, such as in polymer blends and composites, the behavior of polymers at interphases and the degree of mixing polymer segments in their blends become critical issues. Understanding how the conformations and mobilities of polymer chains in these heterogeneous systems compare with those observed in their homogeneous bulk systems may provide a point of departure in the discussions of their physical characteristics. 

This book. Micro- and Nanostnictured Polymer Systems From Synthesis to Applications, describes the recent advances in the development and characterization of multicomponent polymer blends and composites. It covers occurrence, synthesis, isolation and production, properties and applications, modification, and also the relevant analysis techniques to reveal the stractures and properties of polymer systems. Bio-based polymer blends and composites occupy a unique position in the dynamic world of new biomaterials. Namral polymers have attained their cutting-edge technology through various platforms yet, there is a lot of novel information about them, that is discussed in this book. 

Diblock copolymers are known to be the most effective compatibilizers for improving the interfacial interactions between two polymers that are immiscible. This is particularly interesting for iPP, since its lack of functionality and the poor compatibility between iPP and other materials have imposed limitations for iPP applications in many areas, including polymer blends and composites. The synthesis of iPP with terminal functional groups (OH, NH2, etc.) offers a good opportunity to carry out chain extensions through simple coupling reactions with suitable polymers. These may be carried out in solution or in the polymer melt. Reactive extrusion of two chain-end reactive polymers... 

The application of the Porod equation or of the Debye-Bueche approach are particularly attractive because they offer the possibility to evaluate the interfacial area between the phases of the blend, and they are probably the only way to quantify such feature in polymer blends and composites. In fact, when the two polymers are mixed together in a blend, traditional methods based on the adsorption of small molecules, i.e. the BET approach, are inapplicable. Image analysis of TEM micrographs can in principle be an option, but it is extremely time consuming and it suffers from a number of limitations, such as dependence on sample preparation, on projection effects, and on image defocus. The validity of SAXS for the study of interpenetrating networks has been shown for several systems. ... 

The approaches to the new polymer developments cover a multitude of areas such as new polymer systems such as the liquid crystalline polymers, new applications of old polymers such as carbon fibers which were used in Edison s light bulbs in the 1800 s to their use today and in the future as advanced composites in aerospace structures and the exploding field of polymer blends and alloys. 

The research devoted to the study of different chemical and physical aspects of polypyrroles is largely justified by their potential technological applications. The full range of techniques available from polymer chemistry and physics (copolymerization, processable precursors, inclusion of substituents, blend and composite or latex formation, and the versatility of electrochemical methods of film production, as well as the relatively high level of environmental stability in its doped state, processability and high mechanical integrity) can be applied to the development of useful materials for specific applications. In fact, fabrication of conducting... 

Electrical conductivities required for antistatic applications are not very high, and a wide range of conductive blends and composites is being developed. The required surface conductances for those applications are typically in the range lO tolQ- Scm-. Many chemical companies that manufacture plastic foils are in the process of making films coated with conducting polymers. 

Selected applications for polymers, polymer blends, and composites are shown in Tables 13.11,13.12, and 13.13, respectively. In Table 13.9, poly(ethyl-ene terephthalate) (PET) used for soft drink containers incorporates a bit of comonomer to reduce crystallinity just to the incipient point, rendering it optically clear for esthetic purposes. Most important, PET has an exceedingly low permeability to carbon dioxide (see Section 4.4), allowing for a relatively long shelf life of the sodas. The crystalline homopolymer makes the fiber widely known as polyester. 

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