Copolymers aromatic

By far the largest group of liquid crystalline polymers containing imide groups are copoly(esterimide)s (PEIs). These have been sub-divided into flexible copolymers containing aliphatic spacers and wholly aromatic copolymers. There are several reports of copoly(amide-imide)s and copoly(ether-imide)s (both thermotropic and lyotropic) and these are treated separately. There are only a few examples of wholly aromatic imide containing LCPs, as polyimides frequently melt well above their decomposition temperature. Successful attempts have been made to incorporate flexible spacers, but in most instances the spacers are based on ether units, and the polymer is more strictly classified as a poly(etherimide). 

Liquid crystals formed through pressure change have been named barotropic. Barotropic behavior is observed not only for flexible polymers, it is also rather popular for conventional thermotropic liquid crystalline compounds and polymers. It has been reported by several research groups (e.g., Herrmann et al, 1983 Chandrasekhar and Shashidhar, 1979 Stevens et al., 1984). As an example, Hsiao et al. (1988) claimed that for the aromatic copolymer of 4-hydroxybenzoic acid (20 mol %), hydroquinone (40 mol %) and 1,3-phthalic acid (40mol %), not only would the temperature range of the liquid crystalline phase formed at normal pressure increase with increasing pressure, it would also form a new liquid crystal phase at high pressure. 

Table 9. Soluble and low melting aromatic copolymer compositions3...

H. J. Harwood in Problems in Aromatic Copolymer Structure in Natural and Synthetic High Polymers — NMR, bL 4, P. Diehl (ed.). Springer-Verlag, Bolin. 1970... 

Aromatic copolymers bearing the sulfide linkage and the amine linkage in the backbone have been synthesized, i.e., poly(l,4-phenylene sulfide-1,4-phenyleneamine) (PPSA). The reaction is sketched in Figure 5.6. 

Incarnate and co-workers [2004] reported that at constant clay content the CPNC modulus increases with the extrusion rate. Addition of clay shifted the main E" peak position by about 60 to 70°C. The same authors [2003] also investigated the viscoelastic properties of a PA-6 and its statistical, partially aromatic copolymer, ADS, with 3, 6 and 9wt% C30B. In tensile mode the low-T relative modulus, increased from 1.15 to 1.54 (at 1 Hz and 5°C/min). The influence of clay on Tg might be attributed to the confinement of polymer chains in silicate galleries, which partially hinders the molecular motion [Ash et al., 2002]. It is significant that Tg does not always increase with organoclay content, as the outcome is influenced by the type, quantity, and miscibility of the plasticizing intercalant. 

Polymer H is the aromatic copolymer from 2,5-dimethylpiperazine and 3.3 -dimethyl-4,4 -diisocyanato-diphenylene ... 

Aromatic copolymers bearing the sulfide linkage and the amine linkage in the backbone, i.e., poly-... 

Another aromatic copolymer of maleic acid with a-methyl styrene (MA-MSt)n was also confirmed to undergo the conformational transition... 

Norsten et al. reported highly fluorinated sulfonated comb-shaped aromatic copolymers with different side-chain weight fractions [178], prepared by condensation copolymerization of aromatic fluorinated monomers such as 6F-BPA and decafluorobi-phenyl with abisphenol macromonomer (synthesized by anionic polymerization method) containing an oligomeric polystyrene side chain, as shown in... 

Owing to their pronounced hydrolytic instability, polyanhydrides have therefore been explored as degradable implant materials. Aliphatic polyanhydrides degrade within days whereas some aromatic polyanhydrides degrade over several years. Thus, aliphatic-aromatic copolymers, having intermediate rates of degradation, are usually employed. 

D.-Y. Park, P.A. Kohl, H.W. Beckham, Anion-conductive multiblock aromatic copolymer membranes structure-property relationships, J. Phys. Chem. C 117 (2013) 15468-15477. 

Table 2 Soluble and Low Melting Aromatic Copolymer Compositions ... 

In the remainder of this paper we will discuss studies on the resonance of methoxy, a-methyl, aromatic, methine and methylene protons in aromatic copolymers. 

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