Copolyamides, aryl-aliphatic

Aryl-aliphatic copolyamides (Ar-Al-PA) are industrial technical polymers whose uses as transparent plastics require performances in terms of temperature behaviour, or resistance to solvents and stress cracking. The transparency of materials necessitates a completely amorphous structure, which is obtained by using not only para-substituted phenyl rings, but also meta-substituted phenyl rings that decrease the chain regularity. 

Fig. 74 Chemical formulae and code names of the aryl-aliphatic copolyamides studied...

The combined investigations of a series of aryl-aliphatic copolyamides (xTyl -y and MT) by dielectric relaxation, solid-state 13C and 2H NMR, and dynamic mechanical experiments demonstrate the existence of three secondary transitions y, ft and co, in order of increasing temperature. 

Finally, it is interesting to point out that, whereas for poly(ethylene tere-phthalate), bisphenol A polycarbonate and the aryl-aliphatic copolyamides (Sects. 4 to 6, respectively), the phenyl ring flips plays an important role in the p transition processes. In the case of the aryl-aliphatic epoxy networks such 7t-flips exist but they are only indirectly involved in the [J> transition. 

Methyl methacrylate-co-N-methyl glutarimide copolymer Bisphenol A polycarbonate Tetramethyl bisphenol A polycarbonate Aryl-aliphatic copolyamides... 

Aryl-aliphatic copolyamide Bisphenol A polycarbonate Chain disentanglement craze N-Cyclohexyl maleimide unit... 

The purpose of this paper is to investigate the mechanical properties (plastic deformation, micromechanisms of deformation, fracture) of several amorphous polymers considered in [1], i.e. poly(methyl methacrylate) and its maleimide and glutarimide copolymers, bisphenol A polycarbonate, aryl-aliphatic copolyamides. Then to analyse, in each polymer series, the effect of chemical structure on mechanical properties and, finally, to relate the latter to the motions involved in the secondary transitions identified in [ 1] (in most cases, the p transition). 

Fig.6 SDZs at 25 °C. a Optical microscopy of localised SDZs in aryl-aliphatic copolyamide, b TEM photograph of diffuse SDZs in MGIM copolymer...

However, the situation is different when we are interested in a series in which the chemical structure of the polymer is gradually changed, as will be the case in this paper when dealing with poly(methyl methacrylate) and its maleimide and glutarimide copolymers (Sect. 3), or with the aryl-aliphatic copolyamides (Sect. 5). In these cases, one can take one of the polymers in the series as a reference and use the corresponding experimental transition temperature for determining the proportionality constant. 

Along this line, the analysis of the plastic deformation, the micromechanisms of deformation, and the fracture behaviour of the series of aryl-aliphatic copolyamides studied in [1] (Sect. 6) is quite suitable. 

The mechanical properties of aryl-aliphatic copolyamides, both xTyl y and MTyli-y series, present interesting features. 

A first approach was to consider amorphous polymers with quite different chemical structures, either containing side groups responsible for the /> transition (PMMA and its copolymers), or only a chain backbone without side chains (BPA-PC, aryl-aliphatic copolyamides) in which the ft transition results from motions of some of the main-chain units (typically phenyl ring, carbonate, or amide groups). 

In order to achieve a more accurate analysis of the chemical structure effect, gradual changes of chemical structure were performed for each polymer type, e.g. MMA-co-maleimide (CMIMx) and MMA-co-glutarimide (MGIMx) copolymers, BPA-PC and TMBPA-PC, and the content and nature (iso-(l) or fere(T)) of phthalic units in aryl-aliphatic copolyamides (xTyli.y and... 

---