Fully Aliphatic Copolyesters Based on Poly(butylene 1,4-cyclohexanedicarboxylate) with Promising Mechanical and Barrier Properties for Food Packaging Applications

Abstract

Poly(butylene cyclohexanedicarboxylate/diglycolate) random copolymers (P(BCEmBDGn)) of various compositions were synthesized and characterized from the molecular, thermal, structural, and mechanical point of view. Barrier properties to different gases (oxygen and carbon dioxide) were also evaluated. All the polymers showed good thermal stability and appeared as semicrystalline materials at room temperature. The main effect of copolymerization was a lowering in the crystallinity and a decrease of T m with respect to homopolymers. The dependence of T m on composition for copolymers with high butylene cyclohexanedicarboxylate unit content was well described by Baur’s equation. X-ray diffraction (XRD) measurements indicated that two different crystalline phases are present, depending on composition: copolymers with high BCE unit content were characterized by PBCE crystal phase, whereas those rich in BDG counits crystallized in PBDG lattice. The samples displayed different surface hydrophilicity: the water contact angle regularly decreased with the increasing mol % of BDG. The mechanical properties were found strictly related to crystallinity degree (χc); the copolymers containing 60–75 mol % of BDG showed the lowest elastic modulus and the highest elongation at break. Lastly, the chemical composition of the copolymer strongly influenced permeability to CO2 and O2. Moreover, the selectivity ratios for the examined samples increased with the increasing of BDG mol %, confirming the existence of a correlation between the permeability and the chemical composition. Almost all copolymers showed improved barrier properties with respect to polylactide films tested under the same conditions.

Poly(butylene cyclohexanedicarboxylate/diglycolate) random copolymers reinforced with SWCNTs for multifunctional conductive biopolymer composites

“…The DSC curves after melt quenching are shown in Figure 4. As it can be seen from the data reported in Table 2, the glass transition temperature and &C p values were not influenced by the presence of nanofillers and the results here presented are in good agreement with those previously obtained for neat polymers [24]. During the second heating scan, DSC traces of neat polymers showed multiple melting peaks, due to melt-recrystallization processes [26].…”

“…The compression moulding process limited the crystallization rate and crystal phase perfection, since a rapid cooling from the melt was adopted; on the other hand the solvent casting method allowed the polymer to develop a higher amount of a more perfect crystal phase. This was evidenced by the absence of the double melting peak in the 1 st scan DSC traces, and by the absence of the small reflections at 16.2 and 19.5° in the diffraction patterns of the films obtained by solvent casting, as well as by the &H m and X c values reported in Table 2, as compared to those previously obtained [24].…”

“…Poly(butylene cyclohexanedicarboxylate/diglycolate) random copolymers (P(BCEmBDGn)) were synthesized in bulk by the usual two step melt polycondensation, as reported elsewhere [24]. Briefly, 1,4-butanediol (BD) and different molar ratios of DMCE and DMDG, were employed in the syntheses, using 20% mol in excess of glycol with respect to dimethylesters and a concentration of catalyst (Ti(OBu) 4 ) of about 150 ppm of Ti/g of polymer.…”

New eco-friendly random copolyesters based on poly(propylene cyclohexanedicarboxylate): Structure-properties relationships

“…Therefore, polymers derived, for example, from 1,4-cyclohexane dicarboxylic acid and a diol obtainable from biomass (as 1,3-propanediol, obtainable by renewable feedstocks, such as corn) can be considered as fully sustainable materials. Moreover, the presence of the 1,4-cyclohexylene units along a macromolecule does not hinder the attack of microorganisms in some homopolymers and copolymers [7][8][9]. Therefore, the polyesters containing the 1,4-cyclohexylene units can be considered biodegradable materials and are very promising, environmentally friendly polyesters.…”

Crystallization kinetics, mechanical properties, and hydrolytic degradation of novel eco‐friendly poly(butylene diglycolate) containing ether linkages

“…In recent years, the synthesis and physical properties of poly(diethylene glycol succinate) (PDEGS), poly(triethylene dodecanoate) (PTED), and poly(butylene diglycolate) (PBDG) containing ether linkages have been reported in literature . It should be emphasized that all of these polyesters are highly hydrophilic and flexible.…”