Molecular Order in Cold Drawn, Strain-Recrystallized Poly(ε-caprolactone)

Abstract

Biaxial order in free-standing films of poly(εcaprolactone) (PCL), induced by plastic deformation and fibrillation, is studied by infrared transition moment orientational analysis (IR-TMOA) and X-ray diffraction (pole figures). This enables one to determine the order parameter tensor for the different molecular moieties with respect to the sample coordinate system. The main chains of the polymers are aligned with the stretching direction (x), leading to a strong order of the crystallites (Hermans orientation function, S xx = 0.9 ± 0.1), and less ordered, amorphous regions (S xx = 0.34 ± 0.1). The microscopic biaxiality of the system, |S yy − S zz | ≈ 0.1, is caused by the macroscopically asymmetric deformation perpendicular to the stretching direction. Cold drawing leads to a reduction in crystallinity and distorted crystallites in the fibrils, indicating the absence of "melting and recrystallization" or "fine slip" processes.

Selectively Deuterated Poly(ε-caprolactone)s: Synthesis and Isotope Effects on the Crystal Structures and Properties

“…H-PCL displays two main peaks centered at 2945 and 2868 cm −1 that can be assigned to asymmetric and symmetric stretching of methylene groups in PCL, respectively. 54 The small peak at 2895 cm −1 is either not assigned in the literature 54 or assigned to a symmetric CH 2 stretching in the crystalline phase; 53 however, the lack of this signal in D4-PCL suggests that it is related to stretching of the methylene group(s) adjacent to the ester group. Two sharp peaks of D4-PCL in the C−H stretching region match well with those of H-PCL and are likely from asymmetric and symmetric stretching of the nondeuterated methylene groups.…”

“…The a, b lattice parameters of PCL are slightly larger than those of PE due to the presence of carbonyl groups in PCL that are perpendicular to the polymer chain. 47,53 Both polymers display similar degrees of volume isotope effects upon full deuteration as represented by their comparable V H /V D ratios. Despite these similarities, only a, b lattice parameters of PE decrease by deuteration with no change in the c parameter observed within experimental resolution, 16 while PCL shows the largest reduction in the caxis.…”

Strong, transparent composites based on glass‐fiber textile and a polycarbonate–polycaprolactone blend with matching refractive indices

“…PC is a representative transparent amorphous polymer and has a higher refractive index than E‐glass fiber 24 . The other matrix component used in this study, polycaprolactone (PCL), has a lower refractive index than E‐glass fiber, 25,26 thus, the refractive index of a PC–PCL blend should be adjustable to that of E‐glass fiber. Moreover, PC and PCL are known to be fully miscible, and blends of these polymers are morphologically homogeneous and exhibit no light scattering 27–29 .…”

Energy Harvesting Applications from Poly(ε-caprolactone) Electrospun Membranes

“…The carbonyl stretching (ν­(CO)) mode is easily detected at 1727 cm –1 (Figure b). Moreover, PCL presents an absorption band at 1293 and 1157 cm –1 , assigned to C–O and C–C stretching in the crystalline and amorphous phase, , respectively.…”

“…The carbonyl stretching (ν(CO)) mode is easily detected at 1727 cm −1 (Figure 1b). Moreover, PCL presents an absorption band at 1293 and 1157 cm −1 , assigned to C−O and C−C stretching in the crystalline and amorphous phase, 18,19 respectively. It was observed that the melting transition of the PCL membrane presents a double shoulder with maxima at 63 °C (Figure 1c), suggesting a distribution of the size of the crystalline unit or the presence of fragmented crystallites.…”