Recently developed polymers

Organic polymers have been used to increase the viscosity of acids. The primary application is in fracture acidizing. Binary and ternary acrylamide copolymers are the most commonly used chemicals for this application. Many of these polymers degrade rapidly in strong acids at temperatures >130 F development of more stable polymers suitable for high temperatures is desirable. Recently developed polymers for this application include acrylamide copolymers with ... 

A number of investigations on radiation effects of polymers at ambient temperature have been carried out and summarized in some recent publications [38-40]. However, there are very few experimental results on cryogenic temperature irradiation of conventional polymers. Figure 5 shows the summary of early experiments on irradiation of polymers at 77 K up to y-ray dose of 2 x 106 Gy [41,42]. As is evident from Fig. 5, the candidate polymers that can be used at cryogenic temperatures are only aromatic based epoxy resins, poly-imides, and polystyrene. This means that the choice of polymers for superconducting magnets to be operated in a radiation environment is rather limited. Therefore, the intention of this chapter is to give information on the radiation tolerance of recently developed polymers. 

There was recently developed polymer-supported palladium catalyst that can be used in aqueous medium and can be recovered for reuse simply by filtration [2751. To avoid precipitation of insoluble palladium black on the polymer support, a quite stable palladium complex 6 is proposed (Scheme 73) [276, 277]. Mathey reported that their complex with tetraphosphole-based macrocyclic ligand is even more stable and good for reuse (Structure 2) [278]. 

Heller, J. Poly(ortho esters)—some recent developments. Polym. Mater. Sci. Eng. 2003, 89, 189. 

J. Kirchhoff and F. Kraushaar, Triacetoneamine derivatives Industrial applications and recent developments, Polym. Polym. Compos. 2000, 8, 245-254. 

Polyvinyl Pyrrolidone. This recently developed polymer has found its major industrial applications as a consequence of its solubility in water and its low toxicity. Its monomer is prepared by the vinylation o( pyrrolidone by acetylene ... 

The recently developed polymers and some examples of optical applications introduced here make us confident that polymer materials appears to be very promising in optics, appears to be as novel optical materials. 

Although most of the everyday, high-tonnage polymers in present use are insulators, this book is devoted to an important class of recently developed polymers that conduct. Many polymeric materials can be formed into thin, mechanically strong films, and it is obviously desirable to confer the additional property of electrical conductivity on polymers that already benefit from being flexible and compact. Consequently, much ingenuity has been displayed over the past decade or more in developing plastic and elastomeric materials which conduct ions and/or electrons [1-5]. 

The second part describes recent information on the properties and biological effects of already well-known natural polyelectrolytes such as heparin and DNA and recently developed polymers such as pyran and polyionenes. The effects of polyanions and polycations on normal and transformed cells as well as on acetylcholine receptors follow. This part is of particular interest to scientists involved in biological research. 

J. Meissner, Polymer melt elongation—methods, results, and recent developments, Polym. Eng. Sci. 27, 537-546 (1987). 

Therefore, there is a strong requirement to develop high-performance polymer membranes with superior thermal, chemical, mechanical and long-term stabilities for CO2 separation. Thus recently developed polymer materials are suggested to be the excellent candidates. In this chapter, gas transport mechanism with respect to sorption and diffusion through polymeric membrane materials will be introduced followed by a recent literature review on the chemical structure, physical properties, gas permeabilities and selectivities of membrane materials as well as up-to-date high performance and highly permeable membranes especially for CO2 separation. 

Liquid Membranes. A number of reviews summarize the considerable research effort ia the 1970s and 1980s on Hquid membranes containing carriers to faciUtate selective transport of gases or ions (58,59). Although stiU being explored ia a number of laboratories, the mote recent development of much mote selective conventional polymer membranes has diminished interest ia processes using Hquid membranes. 

Poly(phenylene sulfide) (PPS) is another semicrystalline polymer used in the composites industry. PPS-based composites are generally processed at 330°C and subsequently cooled rapidly in order to avoid excessive crystallisation and reduced toughness. The superior fire-retardant characteristics of PPS-based composites result in appHcations where fire resistance is an important design consideration. Laminated composites based on this material have shown poor resistance to transverse impact as a result of the poor adhesion of the fibers to the semicrystalline matrix. A PPS material more recently developed by Phillips Petroleum, AVTEL, has improved fiber—matrix interfacial properties, and promises, therefore, an enhanced resistance to transverse impact (see PoLYAffiRS containing sulfur). 

Hydrogenated nitnle is a more recent development, in which the unsaturation of the polymer is markedly reduced leading to better aging. 

S.J. Shuttleworth, S.M. Allin and P.K. Sharma, Functionalised Polymers - Recent Developments and New Applications in Synthetic Organic Chemistry, Synthesis 1217-1239 7997. 

Bl) The metrics effect is very significant in special theoretical examples, like a freely joined chain. In simulations of polymer solutions of alkanes, however, it only slightly affects the static ensemble properties even at high temperatures [21]. Its possible role in common biological applications of MD has not yet been studied. With the recently developed fast recursive algorithms for computing the metric tensor [22], such corrections became affordable, and comparative calculations will probably appear in the near future. 

The use of quenching agents in polymers is a recent development. Of particular interest are the nickel(II) chelates in polypropylene film and fibre and the even newer hindered amines which appear to combine the roles of antioxidant cmd quenching agent. 

The more recently developed so-called linear low-density polyethylenes are virtually free of long chain branches but do contain short side chains as a result of copolymerising ethylene with a smaller amount of a higher alkene such as oct-1-ene. Such branching interferes with the ability of the polymer to crystallise as with the older low-density polymers and like them have low densities. The word linear in this case is used to imply the absence of long chain branches. 

Much of recent development in polymerisation technology has been devoted to establishing control of the MWD of LLDPE polymers. With such polymers, naiTowing the MWD confers higher toughness, greater clarity, lower heat seal... 

Another recent development is the preparation of a polyester-polycarbonate copolymer. The polymers involve a polyester component based on the reaction between bis-phenol A and iso- or terephthalic acid with the carbonate component arising from the reactions described in Section 20.3 (see Section 20.9). 

Yet another recent development has been the alloying of polycarbonates with liquid crystal polymers such as Vectra (see Section 25.8.1). These alloys are notable for their very good flow properties and higher strength and rigidity than conventional bisphenol A polycarbonates. 

It is usual to think that plastics are a relatively recent development but in fact, as part of the larger family called polymers, they are a basic ingredient of animal and plant life. Polymers are different from metals in the sense that their structure consists of very long chain-like molecules. Natural materials such as silk, shellac, bitumen, rubber and cellulose have this type of structure. However, it was not until the 19th century that attempts were made to develop a synthetic... 

A recent development of the insulated runner principle is the distribution tube system. This overcomes the possibility of freezing-off by insertion of heated tubes into the runners. However, this system still relies on a thick layer of polymer forming an insulation layer on the wall of the runner and so this system is not suitable for heat sensitive materials. 

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