Linear amorphous polycarbonate

Linear amorphous polymers exist in a number of characteristic physical states depending on the timescale of the measurement and temperature. These are illustrated in Fig. 5.2 in terms of an arbitrary modulus function and are classified as glassy, leathery, rubbery, rubbery flow, and viscous (Tobolsky 1960 Collins et al. 1973). All linear amorphous polymers exhibit these five physical states when they are observed over a wide range of time or temperature. Materials of this type are typical of amorphous thermoplastics, such as polystyrene (PS), poly(methyl methacrylate) (PMMA), or polycarbonate (P(i ) polymers. Polymers that are either crosslinked or crystalline do not exhibit the rubbery flow and viscous liquid responses as illustrated. Crystalline polymers, however, will exhibit a viscous response at temperatures above the melting transition. 

In paper [43] acceleration of the stress relaxation process was found at loading of epoxy polymers under the conditions similar to those described above (Figure 6.8, curves 2-4). The authors [43] explained the observed effect by the partial rupture of chemical bonds. In order to check this conclusion in paper [39] repeated tests on compression of samples, loaded up to the cold flow plateau and then annealed at T < T, were carried out. It has been established that in the diagram o-e tooth of yield is restored. This can occur at the expense of the restoration of unstable clusters, since the restoration of failed chemical bonds at T < is scarcely probable. In this connection it is also necessary to note that yield tooth suppression as a result of preliminary plastic deformation was observed earlier for linear amorphous polymers, for example, polycarbonate [44], for which the chemical bonds network is obviously absent. 

In Figure 9.14 the dependence K (D ) is adduced, which has shown linear decay with growth in and at = 3, i.e., at nanostructure formation in Euclidean space, K = 0 and the structure of epoxy polymers does not undergo changes (formation of nanoclusters) in its creation process. Let us note that such treatment is confirmed by the data for particulate-filled polymer nanocomposites, for which the structure formation proceeds in Euclidean space and the polymer matrix dimension of nanocomposites is constant and equal to this parameter for a matrix polymer [40]. The similar, but weaker, dependence K (D ) was found for a linear amorphous polymer (polycarbonate, a dashed line in Figure 9.14), which is due to the absence of such a powerful factor as chemical crosslinking nodes network. 

Examples of crystalline polymers are nylons, cellulose, linear polyesters, and high-density polyethylene. Amorphous polymers are exemplified by poly(methyl methacrylate), polycarbonates, and low-density polyethylene. The student should think about why these structures promote more or less crystallinity in these examples. 

By definition, thermoplastics have limitations at elevated temperatures. It is in this particular property that fibrous glass can lead to remarkable improvements. However, a sharp division exists for reinforced thermoplastics. The various reinforced thermoplastics can be put in two groups relative to DTUL. These consist of amorphous and crystalline or semicrystalline polymers. The amorphous polymers such as styrene-acrylonitrile, polystyrene, polycarbonate, poly (vinyl chloride), and acrylo-nitrile-butadiene-styrene are generally limited to modest DTUL improvements, usually on the order of 20°F with 20% glass. However, crystalline polymers such as the nylons, linear polyethylene, polypropyl-... 

ABA ABS ABS-PC ABS-PVC ACM ACS AES AMMA AN APET APP ASA BR BS CA CAB CAP CN CP CPE CPET CPP CPVC CR CTA DAM DAP DMT ECTFE EEA EMA EMAA EMAC EMPP EnBA EP EPM ESI EVA(C) EVOH FEP HDI HDPE HIPS HMDI IPI LDPE LLDPE MBS Acrylonitrile-butadiene-acrylate Acrylonitrile-butadiene-styrene copolymer Acrylonitrile-butadiene-styrene-polycarbonate alloy Acrylonitrile-butadiene-styrene-poly(vinyl chloride) alloy Acrylic acid ester rubber Acrylonitrile-chlorinated pe-styrene Acrylonitrile-ethylene-propylene-styrene Acrylonitrile-methyl methacrylate Acrylonitrile Amorphous polyethylene terephthalate Atactic polypropylene Acrylic-styrene-acrylonitrile Butadiene rubber Butadiene styrene rubber Cellulose acetate Cellulose acetate-butyrate Cellulose acetate-propionate Cellulose nitrate Cellulose propionate Chlorinated polyethylene Crystalline polyethylene terephthalate Cast polypropylene Chlorinated polyvinyl chloride Chloroprene rubber Cellulose triacetate Diallyl maleate Diallyl phthalate Terephthalic acid, dimethyl ester Ethylene-chlorotrifluoroethylene copolymer Ethylene-ethyl acrylate Ethylene-methyl acrylate Ethylene methacrylic acid Ethylene-methyl acrylate copolymer Elastomer modified polypropylene Ethylene normal butyl acrylate Epoxy resin, also ethylene-propylene Ethylene-propylene rubber Ethylene-styrene copolymers Polyethylene-vinyl acetate Polyethylene-vinyl alcohol copolymers Fluorinated ethylene-propylene copolymers Hexamethylene diisocyanate High-density polyethylene High-impact polystyrene Diisocyanato dicyclohexylmethane Isophorone diisocyanate Low-density polyethylene Linear low-density polyethylene Methacrylate-butadiene-styrene... 

The mechanical properties of poly(methyl methacrylate), PMMA, have been studied for quite a long time and, in addition to its industrial interest, PMMA constitutes a kind of reference material. Indeed, among the amorphous linear polymers it represents an intermediate between the very brittle polystyrene and the tough bisphenol A polycarbonate considered in Sect. 4. Furthermore, as shown in [1] (Sect. 8.1), the molecular motions responsible for its large p transition are precisely identified, as well as the nature of the cooperativity that develops in the high temperature range of the p transition. 

Figure 30. Mobility, g, plotted linearly in In, as a function of electric field strength (E), plotted as for holes in tri-/ -tolylamine (TTA) (40 wt.%) in bisphenol-A polycarbonate. The range of field strengths is approximately 10 -10 V cm (1-100 V pm ). The mobility depends exponentially on With increasing temperature, the overall magnitude of/r increases while the dependence on E weakens. These dependences are observed in nearly all amorphous molecular solids. (Reprinted with permission from Ref. [73r].)...

In a series of related publications, Hennig has reported the measurements of elastic constants for oriented polymers which are either amorphous or of low crystallinity. In his earliest work." Hennig showed that in polyvinyl chloride and polymethylmethacrylate the relationship 3/Eo = S33 + 2S11, where is the modulus of the isotropic polymer, holds to a good approximation. Results for the anisotropy of the linear compressibility y in polyvinyl chloride, polymethylmethacrylate, polystyrene and polycarbonate were also reported. In this experiment Hennig measured the linear compressibility parallel to the draw direction 7ii, and that in the plane perpendicular to the draw direction Vi. For uniaxially oriented polymers yn = 2Si3 + S33 = S i -I-Si2-I-S 3. It was... 

Early developments in aliphatic and aromatic polycarbonates. The first significant documentation of aromatic polycarbonates synthesis began with Einhom [24]. He reacted hydroquinone, resorcinol, and catechol with phosgene in a pyridine solution, obtaining linear polymers from hydroquinone (an insoluble crystalline powder that melted above 280°C) and resorcinol (an amorphous material that melted with decomposition at 190 to 200°C), and a cyclic carbonate from catechol. Subsequent research was focused on finding more efficient preparation methods and on improving material properties [25]. 

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