Study on the crystallization of poly(alkylene dicarboxylate)s derived from 1,9-nonanediol and mixtures with different ratios of azelaic acid and pimelic acid units

Abstract

Polyalkylene dicarboxylates derived from 1,9-nonanediol and mixtures with different ratios of pimelic acid and azelaic acid were synthesized by thermal polycondensation.All samples had a high degree of crystallinity although it was found to decrease with the comonomer content.Crystallization kinetics of the two homopolymers and the copolymer with the eutectic composition was studied by calorimetric and optical microscopy techniques. Similar Avrami parameters were determined for the three samples and a spherulitic growth with heterogeneous nucleation was deduced. Spherulites showed negative birefringence and a fibrillar or ringed texture depending on the sample. Furthermore, clear differences were found in the primary nucleation density, the spherulitic growth rate and even in the secondary nucleation constant deduced from the Lauritzen-Hoffman treatment.The three studied samples had a similar arrangement of molecular chains, and consequently their WAXD patterns showed the same strong reflections related to the molecular packing. SAXS data revealed that a lamellar insertion mechanism was characteristic for non-isothermal crystallization from the melt. In addition, significant differences were found between the crystal lamellar thicknesses of the homopolymer and copolymer samples. Diffraction and spectroscopic data suggested that the lamellar crystals of the eutectic copolymer were mainly constituted by azelate units whereas the pimelate units were preferentially located in the amorphous regions including the interlamellar amorphous layer associated with the chain folds.

Unique isodimorphism and isomorphism behaviors of even-odd poly(hexamethylene dicarboxylate) aliphatic copolyesters

“…It is well known that some structural and thermodynamic properties are sensitive to the parity, even or odd, of the number of atoms contained in the molecular skeleton. [28][29][30][31][32] In recent years, some emerging odd diacid and/or diol monomers are explored for the synthesis of polyesters. 33,34 Azelaic acid one of the naturally occurring dicarboxylic acids, has been industrially producted by ozonolysis cleavage of the alkene double bond of oleic acid 35 and can be directly extracted in barley, rye, sorghum, or wheat through an adequate biocatalysis-based process.…”

“…Several works have recently been addressed to study the aliphatic copolyesters based on these odd diacids, 31,32,[39][40][41][42] however, there has been no attempt to create new even-odd copolyesters derived from 1,6-hexanediol and azelaic acid, pimelic acid or glutaric acid. The odd-chain segments of polyesters make packing of polymer chains difficult as compared to the even segments, and consequently lead to reduced crystallinity and increased biodegradability as it depends to a large extent on polymer crystallinity.…”

Crystallization Kinetics, Morphology, and Mechanical Properties of Novel Biodegradable Poly(ethylene succinate-co-ethylene suberate) Copolyesters

“…Scheme 1 displays the chemical structure of the copolymer. 1 HNMR from a spectrometer (Bruker AV 600) was used to determine the composition of the synthesized copolymers using deuterated chloroform (CDCl 3 ) as the solvent. The three copolymers containing 4.8, 9.9, and 15.3 mol % of ESub were named PESSub5, PESSub10, and PESSub15, respectively.…”