Polymer properties polycarbonate

The properties of elastomeric materials are also greatly iafluenced by the presence of strong interchain, ie, iatermolecular, forces which can result ia the formation of crystalline domains. Thus the elastomeric properties are those of an amorphous material having weak interchain iateractions and hence no crystallisation. At the other extreme of polymer properties are fiber-forming polymers, such as nylon, which when properly oriented lead to the formation of permanent, crystalline fibers. In between these two extremes is a whole range of polymers, from purely amorphous elastomers to partially crystalline plastics, such as polyethylene, polypropylene, polycarbonates, etc. 

A Comparison of Polyiminocarbonates and Polycarbonates The Effect of the NH Group on Polymer Properties. The replacement of the carbonyl oxygen by an NH group presents the only molecular difference between polyiminocarbonates and polycarbonates. In spite of the overall structural similarity between these two types of polymers, we found very significant differences between their respective material properties. In general, polyiminocarbonates and polycarbonates tend to complement each other in several aspects. 

How does the molecular architecture of the bisphenol molecule affect the physical properties of the final polycarbonate polymer ... 

J. Katajisto, M. Linnolahti, and T.A. Pakkanen, Effect of branching of cyclo-olefin copolymers and polycarbonate polymers on mechanical and optical properties Ab initio and molecular simulation study, /. Mol. Struct., 758(2-3) 189-194, 2006. 

In the examples provided in this section, combinatorial methods were used to improve the properties of an industrial aromatic polymer, such as melt-polymerized bisphenol-A polycarbonate. The reactions were performed in 96-well microtiter glass plates that served as 96-microreactor arrays in a sequence of steps of increasing temperature with a maximum temperature of 280°C. An example of one of the 96-microreactor arrays after melt-polymerization is shown in Figure 5.3A. For melt-polymerization of bisphenol-A polycarbonate, the starting reaction components included diphenyl carbonate and bisphenol-A monomers and a catalyst (e.g., NaOH). The materials codes used in the examples are presented in Table 5.2. Intermediate species include polycarbonate oligomers and phenol. The bisphenol-A polycarbonate polymer often contains a branched side product that produces a detectable fluorescence signal and other species that can include nonbranched end-groups and cyclics. We used fluorescence spectroscopy for nondestructive chemical analysis of melt-polymerized bisphenol-A polycarbonate. The key attractive... 

One of the reasons for the changes in the mechanical properties can be attributed to the changes in crystallinity. It has been reported " that the addition of 10 wt% of polyhy-droxyalkanoate reduced the crystallinity of a polycarbonate polymer from a 50-90% range down to 30%. 

The deterioration of polymer properties by ESC has been studied for several decades. But the actual mechanism is not certainly established (Hansen 2002). It is believed that in the presence of the stress, the active fluid causes local plasticization that generates crazes and eventually catastrophic cracks. The ultimate result in many cases is brittle fracture, even in normal ductile polymers like polyethylene, ABS, and polycarbonate. Since failure by ESC can be induced by environmental fluids like cleaning agents and lubricants and the mechanical stress can be the residual (molded-in) stresses, it was considered to be a silent killer (Sepe 1999). 

Asalti s polycarbonates are colorless with good transparency other excellent features include, for example, heat stability and leworkability, in contrast to polycarbonates produced by the phosgene process. Asahi s polycarbonates are hi er quality because they are from impurities such as chlorinated compounds, which are difficult to remove from polycarbonates obtained from the phosgene process and which have a negative effect on polymer properties. 

Jeon CH, Ryu SH, Chang YW (2003) Optical properties of plasticized polycarbonate. Polym Int 53 153-155... 

Note Property values such as those listed in this table vary widely and should not be used for design purposes without validating by testing tbe exact polymer to be used. ASTM Standard testing procedures offer reliable experimental protocols for such experiments. Mechanical properties of polymers can also be found in reference handbooks such as The Polymer Handbook (2006) and other textbooks such as Rodriguez, 1996 (p. 696-710) as well as various online databases such as plasticsusa.com. Variability of polymer properties can be seen for example in Fig. 3.7, where the true stress and strain at rupture for polycarbonate differ from the values tabulated here. 

The two types of plastics are thermoplastics and thermosetting plastics. Thermoplastics can be softened melt and recyclable. Recyclable plastics include Polyethylene Terephthalate (PET), Low Density Polyethylene (LDPE), High Density Polyetltylene (HDPE), and Polypropylene (PP). Thermosets can melt and take the shape only once and not used for repeated work. Sometimes, they are termed as non-recyclable plastics, and include polycarbonate, bakelite, nylon, and so on. Table 3shows synthetic polymer properties and their uses in packaging. 

Tjandraatmadja, G.F., Burn, L S., Jollands, M.C. Evaluation of commercial polycarbonate optical properties after QUV-A radiation - the role of humidity in photodegradation, Polymer Degradation and Stability 78 (2002) 435-448... 

Because polymer properties are governed by the constitution and orientation of the side chains, a great deal of research has been aimed at controlling and modifying these features in aliphatic polycarbonates. Initial research focused on catalyst discovery thus PO and CHO were the model epoxides. A modest amount of research, however, has been directed at the synthesis of other polycarbonates, and more recently, the properties of such materials have been examined. 

While the ROP of five-membered cycUc carbonates is thermodynamically unfavorable and results in a poly(ether carbonate) via decarboxylation of part of the monomer [37], six-, seven- and higher-membered cyclic carbonates and dicarbonates [38-45] were polymerized to obtain polycarbonates without ether sequences. Several 2,2-disubstituted trimethylene carbonate and spirocarbonate monomers were prepared and polymerized in order to tune the polymer properties highly crystalline materials or materials with variable Tg-values were obtained [46-56]. 

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