CHDM-based Copolyesters with 4- tetramethyl-l,3-cyclobutanediol

Although TMCD is not commercially available, technology for its preparation from isobutyric acid or isobutyric anhydride has been reported [79-83], A process for separation of the individual cis- and trans-isomers of TMCD has also been reported [84], TMCD is usually prepared with an approximate 50/50 cis/trans ratio, and this is the usual equilibrium isomer ratio used for polyester preparation, although polyesters prepared from other isomer ratios and from the pure m-isomer have been reported [77, 78], 

4 CHDM-BASED COPOLYESTERS WITH OTHER SELECTED MONOMERS 

The selection of monomers for preparation of copolyesters is based on applying established structure/property principles and is usually driven by new market needs and applications with specific end-use properties in mind. Thus, attempts to develop amorphous or semicrystalline CHDM-based polyester compositions for applications requiring greater heat resistance or higher heat deflection temperatures have generally followed the theme of incorporating bulky or rigid constituents to further enhance the desirable thermal properties of CHDM-based 

CHDM copolyesters containing residues of 2,6-naphthalenedicarboxylate, 4,4 -biphenyldicarboxylic acid and CHDM are reported to exhibit high heat resistance [91]. 

The authors acknowledge Drs James Scanlan and Peter Shang of Eastman Chemical Company for providing unpublished dynamic mechanical analyses data and DSC data, respectively 

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