DMCD 99% trans, CHDA 99% trans, CHDM 66% trans, titanium tetrabutoxide (TBT) (all from Aldrich chemicals) were high purity products and not purified before use.
The same procedure was used to produce prepolymers starting from DMCD as monomer.
In order to better understand the isomerization behavior of CHDA, DMCD, and of the polymers obtained using these monomers, we have performed a new set of tests to complete our previous study on the isomerization kinetics of CHDA and DMCD at 250[degrees]C .
The results obtained show that no isomerization takes place on CHDA, while DMCD starts to isomerize above 230[degrees]C.
5 also show a catalytic effect of the carboxylic groups in the isomerization reaction, since the polymer obtained using CHDA as monomer is more prone to isomerization with respect to that obtained using DMCD. Indeed, as we have previously reported , it is more difficult to obtain a PCCD with high trans content, by melt polycondensation, starting from CHDA with respect to starting from DMCD.
The prepolymers were prepared by polycondensation starting from CHDA or DMCD 99% trans and CHDM 66% trans using TBT as a catalyst.
The characteristics of PCCDs obtained from SSP have been compared (Table 3) with those of PCCDs obtained from DMCD and CHDA using the multi-step melt process reported in our previous work .
PCCD aliphatic polyester has been prepared by a novel process that comprises a SSP step, using CHDA or DMCD, and CHDM as monomers.
Mechanism for DMCD isomerization proposed by Kricheldorf [261 in the presence of acid catalyst.
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