Polyesters and Polycarbonates

Polybutylene terephthalate, shown in the following, is a hydrophobic plastic used in automotive ignition systems. What monomers would you use to make it, and what conditions would you suggest  

Polycarbonates can be formed by nucleophilic aromatic substitution involving aromatic difluorides and carbonate ion. Give a structure for the polymer produced from the monomers shown in the following, and propose a mechanism for its formation  

10 This could be made from terephthalic acid (benzene-l,4-dicarboxylic acid) and butane 1,4-diol. Although the reaction between the diol and the diacid chloride would be more rapid, it would not be commercially viable. 

11 Because of the electron-accepting nature of the carbonyl group, the fluorines attached to the aromatic rings can be substituted by the carbonate dianion (review Section 13.4 if necessary)  

Copolymerization of approximately 2% 2,6-naphthalenedicarboxylate with poly-(ethylene terephthalate) resulted in photostabilization of the polyester. The photodecomposition of polymer from a phenolphthalein-terephthalic acid copolymer has been studied.  

The photochemical and photophysical processes taking place on irradiation of the polycarbonate of bisphenol A have been thoroughly investigated. Xenotester treatment of the polycarbonate Makrofol resulted in a combination of scission and rearrangement reactions primarily on the surface of the sample.  

Margolin and L. M. Postnikov, Russ. Chem. Rev. (Engl. Transl.), 1980,585. 

Abbaas, J, Appl. Polym. Sci., Appl. Polym. Symp., 1979, 35, 345. 

Studies of the photo-oxidation and stabilization of poly (but-1-ene) have been reported in a series of papers. The products of breakdown of poly(2-methylpropylene) resulting from high-energy and vacuum-u.v. irradiation have been determined. The effect of u.v. radiation in the presence of oxygen on the viscoelastic behaviour of poly(2-methylpropylene oxide) (3) has been measured. It was noted that in the absence of oxygen no changes took place. 

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Polymerization by Transimidization Reaction. Exchange polymerization via equihbrium reactions is commonly practiced for the preparation of polyesters and polycarbonates. The two-step transimidization polymerization of polyimides was described in an early patent (65). The reaction of pyromellitic diimide with diamines in dipolar solvents resulted in poly(amic amide)s that were thermally converted to the polyimides. High molecular weight polyimides were obtained by employing a more reactive bisimide system (66). The intermediate poly(amic ethylcarboamide) was converted to the polyimide at 240°C. 

Propylene oxide can be copolymerized with other epoxides, such as ethylene oxide (qv) (25,29,30) or tetrahydrofiiran (31,32) to produce copolymer polyols. Copolymerization with anhydrides (33) or CO2 (34) results in polyesters and polycarbonates (qv), respectively. 

In the case of polar polymers the situation is more complex, since there are a large number of dipoles attached to one chain. These dipoles may either be attached to the main chain (as with poly(vinyl chloride), polyesters and polycarbonates) or the polar groups may not be directly attached to the main chain and the dipoles may, to some extent, rotate independently of it, e.g. as with poly(methyl methacrylate). 

Films have been used for insulating electric motors, in capacitors requiring a heat resistance not met by conventional polyester and polycarbonate dielectrics and as a soldering-resistant base for flexible printed circuits. 

Polyesters and polycarbonate polyols show improved resistance to oxidative attack, compared with that of the polyethers. Stress relation studies run at 130°C, comparing a urethane based on a poly(oxypropylene) polyol and a urethane based on poly(butane adipate) polyol show that, after 60 h, the urethane based on PPG lost most of its strength, while the polyester retained most of its strength [83], Urethanes made from poly(butadiene) polyols are also susceptible to oxidation, but they show good resistance to air-oven aging with antioxidants present (see p. 290 in [45],... 

The lower thermal stability of natural fibers, up to 230°C, the thermal stability is only small, which limits the number of thermoplastics to be considered as matrix materials for natural fiber composites. Only those thermoplastics whose processing temperature does not exceed 230°C are usable for natural fiber reinforced composites. These are, most of all, polyolefines, such as polyethylene and polypropylene. Technical thermoplastics, such as poyamides, polyesters, and polycarbonates, require... 

During the course of this study, styrylpyridine based polyesters and polycarbonates as well as their related model compounds were synthesized and characterized by TGA, 01, and UV irradiation to determine the effect of the structure on thermal and UV stability. 

Flammability Characterization of Styrylpyridine Polyesters and Polycarbonates and Their Related Model Compounds... 

An increase of char yield is generally reflected as an improvement in oxygen index. In the styrylpyridine based polyesters and polycarbonate an intermolecular thermally induced Diels-Alder reaction has occurred through the double bond, this increased the char yield and decreased the flammability. The Fries rearrangement, as well as dimerization and isomerization, occurred simultaneously during the UV irradiation of p-VPPB, but no dimerization or isomerization occurred for p,p -BVPDPC, probably due to steric effects. 

Most polyester alloys are polyester/polycarbonates and properties, processability and prices are intermediate between those of polyester and polycarbonate. A few alloys are poly-ester/ASA and properties, processability and prices are intermediate between those of polyester and ASA. 

Summary of some general assessments concerning the chemical behaviour at room temperature of polyester and polycarbonate, which are not necessarily representative of polyester/PC alloys or of all grades of polyester and PC. These general indications should be verified by consultation with the producer of the selected alloys and by tests under operating conditions. 

In this chapter, polymerization of epoxides and co-polymerization of epoxides with GO or GO2, which give polyethers, polyesters, and polycarbonates, respectively, are reviewed. During the last decade, significant advances... 

The quoted values are an estimate from data for polystyrene, polypropene, polyester and polycarbonate capacitors. 

The current organic photoreceptors are triarylamines, triarylmethanes, hy-drazones, oxadiazoles, pyrazolines, oxazoles, and more recently, stilbene derivatives. The polymer matrix, on the other hand, is constituted by polyesters and polycarbonates (Fig. 5). The common presence of aromatic amines as substituents in all these materials contributes to efficient hole transport [44]. The nonbonding electron pair on the nitrogen atom, in fact, confers on these molecules a low oxidation potential, and consequently, the production of a chemically stable radical cation with the possibility of an effective overlap of nonbonding molecular orbitals between neighboring molecules. 

Polyamides, polyesters, and polycarbonates are formed by substitution reactions at carbonyl groups... 

Gross, R.A. Kalra, B. Kumar, A. Polyester and polycarbonate synthesis by in vitro enzyme catalysis. Appl. Microbiol. Biotechnol. 2001, 55 (6), 655-660. 

Sodium antimonate must be used with halogen containing compounds for it to act as effective fire retardant. The source of chlorine may come from polymer (e.g., PVC, chlorinated rubber, etc.) or other chlorinated or brominated material. The benefits of using sodium antimonate over antimony oxide include its low tinting strength and the acid scavenging capability. For these reasons, it is used in semi-opaque or dark colored materials and in polymers such as polyesters and polycarbonates which are acid sensitive. 

When I started working at Victor Chemical Works in 1942, my boss. Dr. Howard Adler, wanted me to look into the possibility of making some phosphorus-containing polymers. It is known that organic phosphorus compounds have flame retarding properties. To put things in the proper historical perspective, at that time vinyl polymers and nylon were relatively new commercial products. (Polymers such as the ethylene terephthalate polyesters and polycarbonate were not introduced to the market place until many years later.)... 

Polymeric membranes are prepared from a variety of materials using several different production techniques. Table 5 summarizes a partial list of the various polymer materials used in the manufacture of cross-flow filters for both MF and UF applications. For microfiltration applications, typically symmetric membranes are used. Examples include polyethylene, polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE) membrane. These can be produced by stretching, molding and sintering finegrained and partially crystalline polymers. Polyester and polycarbonate membranes are made using irradiation and etching processes and polymers such as polypropylene, polyamide, cellulose acetate and polysulfone membranes are produced by the phase inversion process.f Jf f ... 

Russell et al. [38] also studied Novozym 435-catalyzed A-A/B-B type condensation polymerizations to prepare aromatic polyesters and polycarbonates. Polymerizations between divinylesters or dicarbonates with aromatic diols, conducted for 24h in bulk catalyzed by Novozym 435 (lOwt %) at preferably 70°C, gave low molecular weight polycarbonates and polyesters. The aromatic diols included 1,2-benzenedimethanol, 1,3-benzenedimethanol, 1,4-benzenedimethanol, 2,6-pyridinedimethanolor4,4-isopropylidenebis(2-(2,6-dibromophenoxy)ethanol) and bisphenol-A. The Mw of polycarbonates and polyesters did not exceed 5200 and 3500 (yields <35%), respectively. When various isomers of benzenedimethanol... 

Matsumura, S. (2003) Depolymerization and Polymerization of polyester and polycarbonate in supercritical fluid,... 

A similiar comparison can be made between permeability data of polyesters and polycarbonates containing "polyester-like" monomers. For example, polycarbonates 26 and 27, which contain predominantly bisphenols which are structurally similiar to the repeat unit (circled) of an alkyl terephthalate polymer (PBT), possess essentially the same low permeability as that polyester (Table V). Furthermore, there has been a recent announcement (3 ) that aliphatic polycarbonates, such as polypropylene and polyethylenecarbonate, are being developed as potential gas barrier materials. In summary these results suggest that the relative low permeabilities of commercial polyesters and high permeabilities of commerical polycarbonates are not a direct consequence of the ester or carbonate links, but are due instead to the structure of the monomers they are prepared from, i.e., the aliphatic diol and aromatic bisphenol, respectively. 

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