Research on Polymer Processing

The effect of mechanical deformation on polymer crystallization, which is a very complex topic at the frontiers of research on polymer processing, will be discussed briefly in Chapter 19. 

These three topics were also recommended as high-priority, frontier areas for research in a recent National Research Council (NRC) study. Polymer Science and Engineering The Shifting Research Frontiers (National Academy Press, Washington, D.C., 1994). (In addition. Polymer Science and Engineering recommended research on polymer processing and manufacturing, but the present panel concluded that work in this field was less directly suited to NRL.)... 

Thorough colloidal/surface characterisation is fundamental to the success of research on polymer colloids. A wide range of complementary techniques are available for colloidal/surface characterisation of polymer colloids and access to several is necessary since no single technique can provide full characterisation. There is an ongoing need for experimental and theoretical work on improvements to existing methods and on development of new techniques to support the needs of research. Additionally, the necessary improvements in process modelling will naturally lead to a demand for advances in on-line analysis to support feedback loops for process control and manufacturing. Thus, further developments in on-line methods for measurement of particle... 

Based on these results, our recent research on polymer electret materials focuses on the understanding of (1) the role of the chemical structure of the polymer, (2) the influence of additives, and (3) the variation of processing parameters on the electret performance. As schematically illustrated in Fig. 7, the objective of our research is to provide concepts and methods to improve substantially the electret performance of polymer materials. 

New Directions in Academic Research. The future of academic research on polymer-supported catalysts and reagents may depend on the success of currently available species in industrial processes. Large scale successes would encourage many more chemists to employ polymer-supported species routinely in the laboratory and to invent new polymeric catalysts and reagents. 

By the mid-80s it was clear to most researchers that success on the conductivity side had taken its toll on polymer processability. Attention turned back to restoring the solubility and mechanical properties of the polymer. Polyaniline received the most attention initially. The nonconductive emeraldine base form is soluble in A-methylpyrrolidone [28] and films can be cast. Subsequent doping with a protonic acid from aqueous solution, or in situ with a photo-acid generator [45], is necessary to achieve conductivity. Polyaniline is also soluble in sulfuric acid, not the most convenient of solvents. Nevertheless it proved possible to spin fibers [46], cast films and extmde sheets of conductive polyaniline sulfate, but the laboratory experiments did not make the transition into large-scale manufacmring. 

Research on the process technology for precast products using polymer-impregnated mortar and concrete and for field polymer impregnation systems [12, 50, 51]... 

Polymer-capped bimetallic nanoclusters are very effective as catalysts. The combination of various metals can produce many kinds of bimetallic nanoclusters of various structures. We can now freely control the structure of bimetallic nanoclusters. Recently, we have succeeded in preparing triple core/shell structured trimetallic nanoclusters which have much higher catalytic activity than the corresponding bimetallic nanoclusters. Thus, the present author believes that researches on polymer-capped bi- or tri-metallic nanoclusters are progressing rapidly and that the results will be applied to various practical chemical processes in the near future. 

In terms of polymer design, side groups have been added to PPV to make it solution-processable and to time the emission color. Additionally, the class of polymers utilized in PLEDs has expanded beyond substituted p-phenylenevinylenes to include homopolymers and copolymers of p-phenylenes [8-10], 2,7-fluorenes [11,12], and 2,5-thienylenes [13,14] (see Chart 5.1 for structures of polymers and abbreviations used through out this text). A quick review of the literature reveals that there has been a plethora of research on polymers for use as active layers in PLEDs. It is now possible to tune the emission of the polymer from blue to green to red, to engineer the HOMO and LUMO levels and, to vary the architecture of the chain from linear to dendritic. 

Research on polymer fabrication is used to develop parameters that allow obtaining polymer processing parameters from a determined set of macroscopic properties, which yields parameters that are suitable for the thermodynamic properties and phase behavior of polymeric materials during its melt condition. It is necessary to have an extensive experimental detail to minimize the troubles during polymer processing. Therefore,... 

Putrescine (diaminobutane, DAB) is a widely abundant biogenic diamine [7]. It found early apphcation in the polymer industry as a building block for the synthesis of PA4.6, though not of biological origin [25]. Indeed, current production relies on propylene from petrochemistry, ammonium, and hydrocyanic acid [25]. The common occurrence in bacteria [7], however, promised a reasonable basis for bio-based production, thus stimulating research on fermentation processes. 

Progress in the research on polymers for photorefractive applications during the past 4 years has been encouraging. In addition to the material properties addressed above, however, photorefractive polymers must demonstrate other properties such as good optical quality, reproducibility, stability, processibility, and long grating... 

The focus of commercial research as of the mid-1990s is on catalysts that give desired and tailored polymer properties for improved processing. Development of metallocene catalyst systems is an example. Exxon, Dow, and Union Carbide are carrying out extensive research on this catalyst system for the production of polyethylene and polypropylene. 

Light wave technologies provide a number of special challenges for polymeric materials. Polymer fibers offer the best potential for optical communications in local area network (LAN) applications, because their large core size makes it relatively cheap to attach connectors to them. There is a need for polymer fibers that have low losses and that can transmit the bandwidths needed for LAN applications the aciylate and methacrylate polymers now under study have poor loss and bandwidth performance. Research on monomer purification, polymerization to precise molecular-size distributions, and weU-controlled drawing processes is relevant here. There is also a need for precision plastic molding processes for mass prodnction of optical fiber connectors and splice hardware. A tenfold reduction in the cost of fiber and related devices is necessaiy to make the utilization of optical fiber and related devices economical for local area networks and tlie telecommunications loop. 

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