Polyesteramides

In Chapter 25 it will be shown that polyesters, condensation polymers containing the repeat -COO- group, may be produced by reactions analogous to the methods used to produce polyamides as summarised in the first section of this chapter. It 

In the 1940s ICI introduced a material marketed as Vulcaprene made by condensing ethylene glycol, adipic acid and ethanolamine to a molecular weight of about 5000 and then chain extending this with a diisocyanate. This rubbery material found some use as a leathercloth and is dealt with further in Chapter 25. 

Some 50 years later, in the 1990s Bayer produced their BAK polyesteramides by co-reacting either hexamethylene diamine or e-caprolactam with adipic acid and butane glycol. These materials do have sufficient regularity to be crystallisable and are of interest as biodegradable plastics and are discussed further in Chapter 31. 

FREiDLNA, R. K. and KARAPETYAN, s. A., Tdomerization and New Synthetic Materials, Pergamon, Oxford (1961) 

Fibres from Synthetic Polymers, Elsevier, London (1953) 

PEAs can be synthesized by statistical condensation copolymerization of polyamide monomers (PA 6 or PA 6.6), adipic acid, and 1,4-butanediol. One of the main drawbacks for this class of polymers is their inherently high water permeability, which makes the use of nanofillers necessary to improve hydrophobicity, particularly if such materials are used in packaging [87]. 

Nanoscale fillers, specifically nano-CaCOj and nano-SiOj were added to PEA by liu et al. [320] who found that improved mechanical properties were obtained around a critical filler concentration, specifically the concentration at the onset of percolation. Moreover, when the composites underwent hydrolysis, the inert filler played a role as a mechanical obstacle in the matrix and retarded the hydrolysis on the other hand, the interfacial area between the filler particle and the matrix resin increased with the filler, which would accelerate the hydrolysis. As a result of these two inverse effects, a minimum and a maximum value appeared in the plot of the degradation rate-fiUer content graph. 

Bionanocomposites based on PEA and OMMT (Cloisite C25A), prepared by twin-screw corotating extrusion revealed three degradation steps instead of the two decomposition processes detected in the pristine sample [321]. The onset mass loss temperature decreased in the nanocomposite as a result of the presence of 

Deng et al. [322] prepared bionanocomposites of ahphatic PEA reinforced with hydrothermally synthesized nano-hydroxyapatite (n-HA) which was added to PEA at concentrations ranging from 10% to -30%. It was found that the shape and size of the n-HA crystals were similar to those of the apatite crystals in natural bone and that bionanocomposites with enhanced mechanical property and bioactivity were produced, indicating that the PEA/n-HA bionanocomposites may serve as potential candidate scaffold for tissue engineering. 

Morales et al. [323] prepared bionanocomposites of PEA (derived from glycohc acid and 6-aminohexanoic add by in situ polymerization) reinforced with OMMTs. The most dispersed structure was obtained by addition of C25A organoclay. Evaluation of thermal stability and crystallization behavior of these samples showed significant differences between the neat polymer and its nanocomposite with C25A. Isothermal and nonisothermal calorimetric analyses of the polymerization reaction revealed that the kinetics was highly influenced by the presence of the silicate particles. Crystallization of the polymer was observed to occur when the process was isothermally conducted at temperatures lower than 145 °C. In this case, dynamic FTIR spectra and WAXD profiles obtained with synchrotron radiation were essential to study the polymerization kinetics. Clay particles seemed to reduce chain mobility and the Arrhenius preexponential factor. 

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This is often a convenient route to produce polyesteramides. 

A further approach is used by Bayer with their polyesteramide BAK resins. A film grade, with mechanical and thermal properties similar to those of polyethylene is marketed as BAK 1095. Based on caprolactam, adipic acid and butane diol it may be considered as a nylon 6-co-polyester. An injection moulding grade, BAK 2195, with a higher melting point and faster crystallisation is referred to as a nylon 66-co-polyester and thus presumably based on hexamethylene diamine, adipic acid and butane diol. 

Anodier ordered polyesteramide is polyester containing a small amount of diamides (amide units of uniform length) ... 

PAs have also been copolymerized with other polymer systems and, in particular", with polyesters and poly ethers. In the copoly esteramides the crystallinity is decreased by copolymerization, as the crystalline structure of the amide unit is very different from the ester unit. However, alternating polyesteramides behave as homopolymers with a glass ttansition temperature and a melting temperature intermediate to the polyester and the PA polymer (Figs. 3.10 and 3.11).23,24 Polyesters, such as PBT and PET, modified with a small amount of diamide are also copolymers that have a high order.24,73... 

Aliphatic hyperbranched polyesters, 56 Aliphatic isocyanate adducts, 202 Aliphatic isocyanates, 210, 225 Aliphatic polyamides, 138 Aliphatic polyesteramides, 56 Aliphatic polyesters, 18, 20, 29, 32, 87 degradable, 85 hyperbranched, 114-116 melting points of, 33, 36 structure and properties of, 40-44 syntheses of, 95-101 thermal degradation of, 38 unsubstituted and methyl-substituted, 36-38... 

Silylated diamines, 156, 187-188 Silylated monomers, 72 Silylation, distillation and, 338 6NT6 alternating polyesteramide, synthesizing, 189-190 6,6 -linked polymers, 480 Size exclusion chromatography (SEC) analyses, 90, 490 Slabstock foam, 233-234 Slow monomer addition, 57 Small-angle neutron scattering (SANS), 282... 

Muscat D, van Benthem RATM (2001) Hyperbranched Polyesteramides - New Dendritic Polymers. 212 41-80... 

Many diols and polyols like 1, 4-butanediol and hydroxy-terminated polyesters or polyethers or polyesteramides are used for reaction with diisocyanates commercially. 

Figure 6.2 The polyesteramide structure proposed by Gaymans and co-workers E, ester group A, amide group [21]. Reprinted from Polymer, 38, van Bennekom, A. C. M. and Gaymans, R. J., Amide-modified polybutylene terephthalate structure and properties, 657-665, Copyright (1997), with permission from Elsevier Science...

Other, rigid-rod monomers can be incorporated into PET, to increase chain stiffness, and therefore the Tg (Figure 6.5). A prime example of such a rigid copolyester is a multi-ring poly(ethylene terephthalate-imide) [43], As was the case with the polyesteramides of Gaymans, the imide-containing diol monomer, A,A-bis[p-(2-hydroxyethoxycarbonyl)phenyl]-biphenyl-3,3,4,4-tetracarboxy-diimide, was preformed prior to polycondensation, where this monomer is free... 

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