Eco-friendly poly(butylene 1,4-cyclohexanedicarboxylate): relationships between stereochemistry an crystallization behavior

Poly(butylene 1,4-cyclohexanedicarboxylate) (PBCHD) is an environmentally friendly material, as it can be obtained from biomass (although nowadays it is prepared from petroleum resources) and is potentially biodegradable. Moreover, the aliphatic rings along the chains lend interesting characteristics, for example good mechanical properties and resistance to weather for outdoor applications. As many properties, such as biodegradability, strongly depend on crystallinity, a study of the crystallizability of PBCHDs is very meaningful. Equilibrium melting temperatures and crystallization rates are strongly affected by the cis/trans ratio of the 1,4-cyclohexylene units. Indeed, only the trans isomer can form crystals, whereas the cis isomer is fully excluded from the crystalline phase. All thermal data can be well understood by considering PBCHD as a random copolymer with crystallizable (trans isomer) and noncrystallizable (cis isomer) components, which only differ for the stereochemistry of the aliphatic rings.