Crystal Structure and Tensile Fracture Morphology of Poly(ethylene terephthalate)-co-poly(ethylene 2,6-naphthalate) Block Copolyesters and Fibers

Abstract

Poly­(ethylene terephthalate) (PET) and poly­(ethylene 2,6-naphthalate) (PEN) homopolyesters were synthesized and then copolymerized at different molar feed ratios into PET-co-PEN (TN) block copolyesters. The sequence distribution of the TN copolyesters was analyzed through proton nuclear magnetic response spectroscopy. The results demonstrated that the block segments of PET and PEN are highly miscible and tend to be randomly or nearly randomly distributed in the synthesized TN molecular chains. For TN block copolyesters with PET as the main component and number-averaged sequence length of PET > 3, wide-angle X-ray diffraction (WAXD) profiles indicated that all TN copolyester crystals were related to PET. TN block fibers were produced from a TN block copolyester through melt spinning at a 90:10 PET-to-PEN molar feed ratio and then subjected to different heat treatments. The relaxation of the oriented amorphous chain at elevated temperatures reduced the birefringence of the TN fiber. When the relaxation heat treatment time or stretching was longer, the oriented amorphous molecular chains were reoriented and crystallized, which increased the birefringence of the TN fiber. The differences in the segmental mobility of PET and PEN led to a multinecking and a mushroom-head morphology with transverse striations along the fiber axis because of the snapback effect after tensile failure.

Next-Generation High-Performance Bio-Based Naphthalate Polymers Derived from Malic Acid for Sustainable Food Packaging

“…All samples (unannealed and annealed) were tested at room temperature, as shown in Figure . After annealing, the para-substituted polymers (i.e., 2,6-PEN and PET) presented strong scattering peaks over a range of 11.5° ≤ 2θ ≤ 32.8°, in agreement with the results of previous studies, , whereas PEI and 2,7-PEN presented weaker scattering peaks. These results indicate that meta-substitution in conjunction with additional aromatic and cycloalkyl rings in PEI and naphthalate-based polymers disrupt crystallization .…”

“…It is known that 2,6-PEN and poly­(ethylene isophthalate)­(PEI) are commercially available comonomers used for the production of high-performance PET as well as PET drinking bottles and food packaging. , Note however that the existence of a naphthalene group and a meta-substitution structure within the polymer chains can disrupt the formation of a coherent crystal structure. , Thus, we expected that 2,7-PEN and 2,7-PETHN would have a similar (or perhaps more pronounced) effect on crystallinity, due to their meta- (as opposed to para-) substitution and fused ring system. We used temperature-controlled WAXS to observe both the crystallinity and the crystallization behavior as a function of temperature.…”

Intrinsically Flexible and Aging Resistant Fluorene‐Based Rod‐Coil Copolymer for Bendable Deep‐Blue PLEDs

“…The copolymer has strong viscosity and chain segment activity, so it shows higher elongation at break and good tensile properties. [33,34] In short, the copolymerization method is more suitable for biomimetic flexible optoelectronic devices in terms of mechanical properties.…”

Kinetics of Ternary Copolycondensation for High-Performance PCTG Copolyester with Ester Interchange, Polycondensation, and Mass Transfer

“…Poly­(ethylene terephthalate) (PET) has excellent physical and chemical properties and is widely used in bottles, textiles, and films . Currently, PET has been developed for functionalization and high performance, mainly involving copolymerization, blending, and surface modification.…”