Carbon-13 solid state NMR study on uniaxially oriented poly(l-lactic acid) films

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ABSTRACT:The results of a study of the relation between the oriented structure and drawn Poly(-caprolactone) specimens including CaCO 3 particles and their dynamic mechanical properties are presented. The loss elasticity, EЉ, showed almost the same curve for both undrawn sheets and drawn sheets as a function of CaCO 3 content. On the other hand, the storage modulus, EЈ, of drawn sheets increased nonlinearly with increasing CaCO 3 content, and their curve showed lower EЈ values than those of undrawn sheets. By simulation of 13 C CP NMR spectra of drawn PCL/CaCO 3 sheets, both oriented and unoriented components were observed. The distribution parameter, p, of drawn PCL/CaCO 3 sheets was 13°, which was larger than those (8°) of drawn PCL. Further, the fraction of the unoriented component increased with increasing CaCO 3 content. Thus, adding CaCO 3 particles into the PCL, the arrangement of the oriented component was disturbed and decreased. In addition, from the line shape analyses of 13 C CP MAS NMR spectra, four peaks were obtained in not only undrawn sheets but also in drawn sheets of both PCL and PCL/CaCO 3 compounds. Besides, structural change occurred at only drawn PCL/CaCO 3 sheets. Therefore, the change in dynamic mechanical properties observed only for drawn PCL/CaCO 3 sheets were strongly dependent on the orientational structure, which was formed under shear stress of the stretching drawn process.

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structural analysis of oriented poly(ε‐caprolactone) including CaCO₃ particles with ¹³C solid‐state NMR

Ito

Yamaguchi

Watanabe

et al. 2001

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“…The NMR spectroscopy, which is a powerful tool for the study of the structure and molecular dynamics in polymers, was also used for the study of PLA structure. The solid‐state MAS 13 C‐NMR spectra for amorphous, crystalline and semicrystalline PLA samples are preferably detected using the cross‐polarization (CP) NMR technique since the sufficient signal to noise ratio in the CP MAS 13 C‐NMR spectra can be obtained during much shorter time than the time which is needed for the single pulse (SP) MAS 13 C‐NMR spectra. On the other hand, in general, only the latter measurements reflect the polymer structure quantitatively.…”

Section: Introductionmentioning

confidence: 99%

Morphology and molecular mobility of plasticized polylactic acid studied using solid‐state ¹³C‐ and ¹H‐NMR spectroscopy

Kovaľaková

Olčák

Hronský

et al. 2016

MAS 13 C-NMR measurements were used for the study of morphology and molecular mobility in amorphous quenched and triacetine-plasticized PLA samples and PLA samples which underwent cold crystallization during annealing at 80 and 100 8C. The single pulse MAS 13 C-NMR spectra indicate that plasticizer promotes cold crystallization which results in the decrease of the temperature of crystallization and formation of more perfect crystalline domains. The T 1 ( 13 C) spin-lattice relaxation times show that the presence of plasticizer molecules leads to an increase of local mobility in PLA chains but plasticized PLA after annealing at 100 8C shows more rigid structure. The series of broad line 1 H-NMR spectra performed at temperatures up to 100 8C provided information on the changes in relaxation processes and morphology of the studied samples. The interpretation of the results obtained using the techniques of NMR spectroscopy were supported by WAXD and DSC measurements.

“…7 On the other hand, solid state NMR studies on poly(L-lacide) (PLA) in ''fiber form'' are very limited; to our knowledge, only the draw direction of PLA films has been investigated by solid state 13 C NMR to date. 8 In regard to ''materials'' based on PLA, however, solid state 13 C NMR analyses and relaxation time measurements are also effective for structural and molecular motion analyses, since PLA has multiple components, including the crystalline and amorphous phases. 9,10 Several reports have been published on the relaxation time analysis of PLA materials, including stereocomplex material, polymer blends, and a copolymer.…”

Section: Introductionmentioning

confidence: 99%

Solid state NMR analysis of poly(L‐lactide) random copolymer with poly(ε‐caprolactone) and its reactive extrusion process

Nishida

Nishimura

Tanaka

et al. 2011

A random copolymer based on poly(L-lactide) (PLA) with poly(e-caprolactone) (PCL) was prepared and characterized by mechanical testing and solid state NMR, compared with a polymer blend. For a monofilament sample consisting of PLA/PCL random copolymer, there were negative correlations between the CL content and the mechanical properties: tensile strength, tensile elastic modulus, flexural rigidity, and flexural hysteresis decreased with increasing CL content. In contrast, the mechanical properties of the polymer blend were only slightly changed by addition of the CL unit. For the random copolymer, the addition of a small amount of CL reduced relaxation times, T 1 C and T 1q H, gradually. The T 1 C and T 1q H values correlated closely with the tensile elastic modulus and the tensile strength, respectively.