Abstract Poly(ε-caprolactone) (PCL) is one of the leading biocompatible and biodegradable polymers. However, the mechanical property of PCL is relatively poor as compared with that of polyolefins, which has limited the active applications of PCL as an industrial material. In this study, to enhance the mechanical property of PCL, cellulose nanofibers (C-NF) with high mechanical property, were employed as reinforcement materials for PCL. The C-NF were fabricated via the electrospinning of cellulose acetate (CA) followed by the subsequent saponification of the CA nanofibers. For the enhancement of the mechanical property of the PCL composite, the compatibility of C-NF and PCL was investigated: the surface modification of the C-NF was introduced by the ring-opening polymerization of the ε-caprolactone on the C-NF surface (C-NF-g-PCL). The polymerization was confirmed by the Fourier transform infrared (FTIR) spectroscopy. Tensile testing was performed to examine the mechanical properties of the C-NF/PCL and the C-NF-g-PCL/PCL. At the fiber concentration of 10 wt%, the Young’s modulus of PCL compounded with neat C-NF increased by 85% as compared with that of pure PCL, while, compounded with C-NF-g-PCL, the increase was 114%. The fracture surface of the composites was analyzed by scanning electron microscopy (SEM). From the SEM images, it was confirmed that the interfacial compatibility between PCL and C-NF was improved by the surface modification. The results demonstrated that the effective surface modification of C-NF contributed to the enhancement of the mechanical property of PCL.
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Thermal, mechanical, and topographical evaluation of nonstoichiometric α‐cyclodextrin/poly(ε‐caprolactone) pseudorotaxane nucleated poly(ε‐caprolactone) composite films
Three pseudorotaxanes (PpR) comprised of poly (ε‐caprolactone) (PCL) and α‐cyclodextrin (α‐CD) with varying stoichiometric ratios were synthesized and characterized. Wide‐angle X‐ray diffraction (WAXD) and thermogravimetric (TGA) analyses provided conclusive evidence for complexation between the guest PCL and host α‐CD. The as‐synthesized and characterized PpRs were used at 10 and 20% concentrations as nucleants to promote the bulk PCL crystallization in composite films. Both WAXD and TGA provided evidence for intact PpR structures in the composite films. Isothermal differential scanning calorimetric (I‐DSC) analyses, performed at various crystallization temperatures demonstrated significant differences in the crystallization patterns among the composite films. In addition, I‐DSC analyses showed higher Avrami constant values (n) in the PpR‐nucleated composite PCL films (n ~ 3), indicating 3‐dimensional crystal growth. In the case of neat PCL films, however, lower n values indicated crystal growth in 1‐dimensions or 2‐dimensions. Moreover, atomic force microscopic analyses showed large crests and pits in PpR‐nucleated PCL composites, with irregular morphologies leading to higher surface roughness. To the contrary, the crests and pits were much smaller in the neat PCL films, resulting in lower surface roughness values. Finally, mechanical testing revealed higher tensile strength for PpR‐nucleated PCL composites films, demonstrating larger load bearing capabilities. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys.
- NSF-PAR ID:
- 10078091
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Journal of Polymer Science Part B: Polymer Physics
- Volume:
- 56
- Issue:
- 22
- ISSN:
- 0887-6266
- Page Range / eLocation ID:
- p. 1529-1537
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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