Phenylenes physical properties

Some of the common types of plastics that ate used ate thermoplastics, such as poly(phenylene sulfide) (PPS) (see Polymers containing sulfur), nylons, Hquid crystal polymer (LCP), the polyesters (qv) such as polyesters that ate 30% glass-fiber reinforced, and poly(ethylene terephthalate) (PET), and polyetherimide (PEI) and thermosets such as diaHyl phthalate and phenoHc resins (qv). Because of the wide variety of manufacturing processes and usage requirements, these materials ate available in several variations which have a range of physical properties. 

Poly(p-pheny lene)s, PPPs, constitute the prototype of rigid-rod polymers and are currently being intensively investigated [1]. The key role of PPPs follows from their conceptually simple and appealing molecular structure, from their chemical stability, and from their superior physical properties [2], In turn, this is the result of important advances made in aromatic chemistry over the last few years. The following section gives an overview of the most common methods to generate poly(p-phenylene)s via different synthetic approaches. 

Poly(2,6-dimethyl-l,4-oxyphenylene) (poly(phenylene oxide), PPG) is a material widely used as high-performance engineering plastics, thanks to its excellent chemical and physical properties, e.g., a high 7 (ca. 210°C) and mechanically tough property. PPO was first prepared from 2,6-dimethylphenol monomer using a copper/amine catalyst system. 2,6-Dimethylphenol was also polymerized via HRP catalysis to give a polymer exclusively consisting of 1,4-oxyphenylene unit, while small amounts of Mannich-base and 3,5,3, 5 -tetramethyl-4,4 -diphenoquinone units are always contained in the chemically prepared PPO. 

Cyclic enone, 12 185 Cyclic ethers, 10 567, 569 12 663 polymerization, 14 271 Cyclic fatigue, in ceramics, 5 633-634 Cyclic gas generators, 6 786-787, 789, 827 Cyclic halides, 19 56 Cyclic hexakis(thio-l,4-phenylene), melt polymerization of, 23 705 Cyclic hydrocarbons, 13 687 Cyclic hydroxyalkyl alkyl peroxide, 18 454 Cyclic ion exchange operation, 14 408-413 Cyclic ketones, 12 176, 177 14 590-592. See also Cyclic 1,2-diketones physical properties of, 14 591t hydroxyalkyl hydroperoxides from, 18 450... 

Fujimoto, C. H., Hickner, M. A., Cornelius, C. J. and Loy, D. A. 2005. lonomeric poly(phenylene) prepared by Diels-Alder polymerization Synthesis and physical properties of a novel polyelectroylte. Macromolecules 38 5010-5016. 

General Physical Properties of Poly(Phenylene Oxide) (PPO)... 

As in the case of nylons, the flexibility of PUs is increased as the number of methylene groups is increased, and the rigidity is related to the number of stiffening groups, such as phenylene groups in the chain. As the number of methylene units increases (Table 14.6), the Tm decreases. The Tm generally increases as the flexible units are replaced by nonflexible units, such as phen-ylenes and piperazines. Thermal and physical properties of aliphatic PUs are shown in Table 14.7. 

The most common advanced composites are made of thermosetting resins, such as epoxy polymers (the most popular singlematrix material), polyesters, vinyl esters, polyurethanes, polyimids, cianamids, bismaleimides, silicones, and melamine. Some of the most widely used thermoplastic polymers are polyvinyl chloride (PVC), PPE (poly[phenylene ether]), polypropylene, PEEK (poly [etheretherketone]), and ABS (acrylonitrile-butadiene-styrene). The precise matrix selected for any given product depends primarily on the physical properties desired for that product. Each type of resin has its own characteristic thermal properties (such as melting point... 

Ambrosch-Draxl, C., Majewski, J.A., Vogl, P. and Leising, G. (1995) First-prindples studies of the structural and optical properties of crystalline poly (para-phenylene). Physical Review. B, Condensed Matter, 51, 9668-76. 

In order to prepare non-styrenic polymer-supported organotin chlorides, which are expected to show physical properties such as mechanical strength, polarity and porosity different from those of polystyrene-based supports, Deleuze and coworkers copolymerised dibutyl[3-(allyloxy)propyl]tin chloride with N-phenylmaleimide (PMI) and l,l/-(methylene-4,l-phenylene)bismaleimide (MPBMI) to prepare the polymers 88a and 88b180. 

Recently, preparation of well-ordered periodic meso-structured hybrid materials was reported with (MeO)3Si-R-Si(OMe)3(R = alkylene, phenylene and 2-butylene) precursors210. Using an evaporation-induced self-assembly, thin films with a mesoporous organization can be prepared, and their physical properties (thickness, dielectric constant, modulus and hardness) are closely dependent on the nature of the R group. 

The polymerization reactions of bistetracyclone monomers XXIa-e with both m- and p-diethynylbenzene (XVII and XVIII) produced a series of polymers (XXII, Reaction 15) containing short blocks of phenylene units connected by methylene chains. High molecular weight polymers were obtained (Table II), and a range of physical properties was observed. 

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