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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.

Novel aliphatic, random copolyesters, containing counits derived from a polyalkylene dicarboxylate and a polybutylene 1,4cyclohexanedicarboxylate, have been synthesized and characterized in terms of molecular structure and thermal properties. In particular, the effects of the molar composition, the length of the aliphatic sequences, and the cistrans ratio of the 1,4cyclohexylene units on the characteristics of the crystalline and amorphous phases are discussed. Some interesting structureproperty relationships have been found. The materials result to be very promising new biopolymers as they are characterized by a potential biodegradability and good physical properties, which can be easily modified, according to the requests of specific applications, by little changes in the molecular structure.