Copolyesteramides

The dimethyl ester of a carboxy-terminated diamide is reacted with 1,2-ethanediol in the conditions of PBT synthesis. The amide functions are unaffected while the hydroxy-ester interchange reaction proceeds to the formation of an alternating copolyesteramide (Scheme 2.60). The procedures given below are reproduced from ref. 430. (Copyright 1997 Elsevier Science Ltd, with permission of the copyright owner.)... 

Another important type of condensation polymer are the linear polyesters, such as poly (ethylene terephthalate) (PET) and poly (butylene terephthalate) (PBT). Copolymers of polyesters and PA have been studied in detail, and it has been shown that random copolyesteramides have a low structural order and a low melting temperature. This is even the case for structurally similar systems such as when the group between the ester unit is the same as that between the amide unit, as in caprolactam-caprolactone copolymers (Fig. 3.10).22 Esters and amide units have different cell structures and the structures are not therefore isomorphous. If block copolymers are formed of ester and amide segments, then two melting temperatures are present. 

The situation can be different if the comonomer distribution is not random. For example, if each type of repeat unit occurs in blocks above a certain length, then blocks of different types of repeat units generally segregate into separate phases unless they happen to be miscible [4], and the crystallization behavior of each phase is similar to that of the corresponding homopolymer. See also Gaymans et al [171,172] for some very interesting copolyesteramides with short amide... 

The LCP system Vectra B950 (an aromatic copolyesteramide) from Hoechst-Celanese was intended to be used as such a reinforcing fibre phase in a polypropylene (PP) matrix. We were requested to determine the thermal transition effects of Vectra B950 in order to use these effects to determine small amounts of Vectra B950 in a PP matrix by DSC. 

S. C. Tjong, R. K. Y. Li, and X. Xie. Properties of in situ composites based on semiflexible thermotropic liquid crystalline copolyesteramide and polyamide 66 blends. Polym. J. (Tokyo), 32 907-914,2000. 

Nagata, M., and Kiyotsukuri, T., 1994, Biodegradability of copolyesteramides from hexamethylene adipate and hexamethylene adipamide. Eur. Polym. J. 30 1277-1281. 

The thermal expansivity and thermal conductivity of thermotropic liquid crystalline copolyesteramides (Vectra B950 and Vectra A950), with a draw ratio X from 1.3 to 15, have been measured parallel and... 

The elastic moduli of an extruded PLC are largely determined by its molecular orientation, so we first consider the orientation parameters calculated from the observed meridional X-ray reflections. For liquid crystalline copolyesters and copolyesteramides, the sharpness of these reflections gives an indication of the coherence length, a value corresponding to 10 monomers being typical. Therefore, the orientation parameter obtained from the meridional reflection is not specific to the crystalline regions but instead reflects the average orientation of all the chains in the polymer. 

J Schillings, Neue Copolyesteramide filr die Anwendung als Biomaterial Synthese, Charakterisierung, Degradation und Zytokompatibilittlt , Dissertation an der RWTH Aachen, 2003... 

Three commercially available thermotropic liquid crystalline polymers (TLCPs) were presented as examples in this section. They are Hoechst Celanese Vectra A950 and Vectra B950 as well as Amoco Xydar . Vectra A950 is a random copolymer of 73 mol% 4-hydroxybenzoic acid and 27 mol% 6-hydroxy-2-naphthoic acid, and Vectra B950 is a random copolyesteramide consisting of 60 mol% of 6-hydroxy-2-naphthoic acid, 20 mol% terephthalic acid, and 20 mol% p-aminophenol. Xydar is made from p-hydroxybenzoic acid, isophthalic and/or terephthalic acids, and 4,4 -biphenol. The repeating unit structures of the three LCPs are shown in Figure 6.2. 

In addition to mechanical reinforcement, LCP addition improved the dimensional stability and thermal resistance of the PP matrix. The former appeared as remarkably reduced post-shrinkage and lower linear thermal expansion coefficient, the latter as significantly increased heat deflection temperature (HDT). The HDT values increased from the level of 52°C for neat PP to 78°C for PP/LCP 70/30 and 110°C for 50/50 blends. Even greater improvements were found for blends with another, copolyesteramide-type LCP (Vectra B950) the HDT value for PP/ 30wt.% B950 was as high as 132°C [4]. 

The strongest modulus improvement is found for NY, especially when a wholly aromatic copolyesteramide (VB) is added into it (E ratio = 2.75, for an LCP content of 20%). However, even with a semi-aromatic copolyester (SBH), NY experiences fairly good reinforcement. The behavior of the rc based blends is very similan the comparatively lower values of the E ratios of the PC blends, with respect to the NY blends, can be explained considering that the tensile modulus of neat PC fibers, prepared under comparable conditions, is much higher than that of neat NY fibers (6.0 GPavs. 0.8 Gpa). 

Fakirov S, Sarkissova M and Denchev Z (1996) Sequential reordering in condensation copolymers. 3. Miscibility-induced sequential reordering in random copolyesteramides, Macromol Chem Phys 197 2889-2907. 

LCP are fully aromatic copolyesters or copolyesteramides which have become the standard high performance polymers used in certain new electrical/electronic applications notably fuel cells. Thermosetting LCP are also available. 

They calculated the coefficients of an expansion of the Kij(S, T) up to fourth order in the order parameter S and the degree of biaxiality T. In case of weak biaxiality Telastic moduli (/= /, m, n)) are predominant and the deformation state may be described satisfactorily with three bulk and one surface elastic constant, as in the uniaxial case. Recently, these three quasi-uni-axial bulk elastic constants of slightly biaxial nematic copolyesteramide have been determined by De Neve et al. [313] from an optical observation of the Freedericksz transition in different geometries. 

In a few cases, the addition of minor amounts of immiscible or miscible polymers results in the nucleation of a crystalline polymer. The nucleation of PP by PE and polyamides (e.g., PAl 1) (immiscible) as well as the addition of PP to poly(butene-l) (miscible) has been noted in the literature [138-141 ]. The addition of LDPE to PP showed a reduction in the spherulite size of PP, attributed to an increase in nucleation density of the a-crystalline form along with an increase in the rate of growth of the -crystalline form [141]. The nucleation of polycarbonate by the zinc salt of sulfonated polystyrene ionomers was noted to occur with both miscible and phase separated blends [142]. Nanometer sized ionic aggregates appeared to contribute to the polycarbonate nucleation. A liquid crystalline copolyesteramide (Vectra-B950 ) was shown to accelerate the crystallization of poly(phenylene sulfide) [143]. This effect was not concentration dependent and did not change the level of crystallinity. 

Copolyesteramides with poly(ethylene oxide) segments as phase transfer catalysts... 

Mumcu S, Burzin K, Felsmann R and Feinauer R (1978) Copolyesteramide aus laurinlactam, 1,10-decandicarbonshure und a,to- dihydroxy-(polytetrahydrofuran), Angew Makromol Chem 74 49-60. 

Goodman I, Rodriguez M T (1996), Copolyesteramides, 9. Random 6-iminohexanoyl 12-oxydodecanoyl copolyesteramides , Macromol. Chem. Phys., 197 (3), 881-894. 

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