The distribution of crystallinity and the crystalline orientation of a poly(ɛ-caprolactone) (PCL) film have been studied using terahertz (THz) imaging. Terahertz images were developed by using the intensity ratio of the two spectral peaks at 1.42 and 2.03 THz that are assigned to the crystalline modes parallel and perpendicular to the c-axis (I⊥/I||) of the PCL film. The obtained THz images show that the distribution of crystallinity and crystalline orientation vary considerably between the different regions in the PCL film, even though this inhomogeneity is not visible in the corresponding optical image. Our results clearly illustrate that THz imaging is a promising technique to characterize the physical properties of semi-crystalline polymers.
HerrmannM.TaniM.SakaiK.FukasawaR.“Terahertz Imaging of Silicon Wafers”. J. Appl. Phys2002; 91(3): 1247–1250.
3.
AjitoK.UenoY.“THz Chemical Imaging for Biological Applications.” IEEE Trans. Terahertz Sci. Technol2011; 1(1): 293–300.
4.
ShenY.C.“Terahertz Pulsed Spectroscopy and Imaging for Pharmaceutical Applications: A Review”. Int. J. Pharm2011; 417(1): 48–60.
5.
SonJ.-H.Terahertz Biomedical Science and Technology, Boca Raton, FL: CRC Press/Taylor and Francis Group, 2014.
6.
FukunagaK.PicolloM.“Terahertz Spectroscopy Applied to the Analysis of Artists Materials”. Appl. Phys. A.: Mater. Sci. Process2010; 100(3): 591–597.
7.
NagatsumaT.NishiiH.IkeoT.“Terahertz Imaging Based on Optical Coherence Tomography”. Photonics Res2014; 2(4): B64–B69.
8.
JansenC.WietzkeS.PetersO.SchellerM.ViewegN.SalhiM.KrumbholzN.JördensC.HochreinT.KochM.“Terahertz Imaging: Applications and Perspectives”. Appl. Opt2010; 49(19): E48–E57.
9.
RutzF.KochM.KhareS.MonekeM.RichterH.EwertU.“Terahertz Quality Control of Polymeric Products”. Int. J. Infrared Millimeter Waves2006; 27(4): 547–556.
10.
WietzkeS.JansenC.RutzF.MittlemanD.M.KochM.“Determination of Additive Content in Polymeric Compounds with Terahertz Time-Domain Spectroscopy”. Polym. Test2007; 26(5): 614–618.
WietzkeS.JördensC.KrumbholzN.BaudritB.BastianM.KochM.“Terahertz Imaging: A New Non-Destructive Technique for the Quality Control of Plastic Weld Joints”. J. Eur. Opt. Soc. Rapid2007; 2: 07013.
13.
StoikC.D.BohnM.J.BlackshireJ.L.“Nondestructive Evaluation of Aircraft Composites Using Transmissive Terahertz Time Domain Spectroscopy”. Opt. Exp.2008; 16(21): 17039–17051.
14.
KawaseK.OgawaY.WatanabeY.InoueH.“Non-Destructive Terahertz Imaging of Illicit Drugs Using Spectral Fingerprints”. Opt. Exp2003; 11(20): 2549–2554.
15.
KawaseK.“Terahertz Imaging for Drug Detection and Large-Scale Integrated Circuit Inspection”. Opt. Photonics News2004; 15(10): 34–39.
16.
YamashitaM.OtaniC.KawaseK.MatsumotoT.NikawaK.KimS.MurakamiH.TonouchiM.“Backside Observation of Large-Scale Integrated Circuits with Multilayered Interconnections Using Laser Terahertz Emission Microscope”. Appl. Phys. Lett2009; 94(19): 191104.
17.
BaragwanathA.J.FreemanJ.R.GallantA.J.ZeitlerJ.A.BeereH.E.RitchieD.A.ChamberlainJ.M.“Terahertz Near-Field Imaging Using Subwavelength Plasmonic Apertures and a Quantum Cascade Laser Source”. Opt. Lett2011; 36(13): 2393–2395.
18.
HoshinaH.MorisawaY.SatoH.MinamideH.NodaI.OzakiY.OtaniC.“Polarization and Temperature Dependent Spectra of Poly(3-hydroxyalkanoate)s Measured at Terahertz Frequencies”. Phys. Chem. Chem. Phys2011; 13(20): 9173–9179.
19.
HoshinaH.IshiiS.MorisawaY.SatoH.NodaI.OzakiY.OtaniC.“Isothermal Crystallization of Poly(3-hydroxybutyrate) Studied by Terahertz Two-Dimensional Correlation Spectroscopy”. Appl. Phys. Lett2012; 100(1): 011907.
20.
HoshinaH.MorisawaY.SatoH.KamiyaA.NodaI.OzakiY.OtaniC.“Higher Order Conformation of Poly(3-hydroxyalkanoates) Studied by Terahertz Time-Domain Spectroscopy”. Appl. Phys. Lett2010; 96(10): 101904.
21.
HoshinaH.IshiiS.YamamotoS.MorisawaY.SatoH.UchiyamaT.OzakiY.OtaniC.“Terahertz Spectroscopy in Polymer Research: Assignment of Intermolecular Vibrational Modes and Structural Characterization of Poly(3-hydroxybutyrate)”. IEEE Trans. Terahertz Sci. Technol2013; 3(3): 248–258.
22.
SuzukiH.IshiiS.SatoH.YamamotoS.MorisawaY.OzakiY.UchiyamaT.OtaniC.HoshinaH.“Brill Transition of Nylon-6 Characterized by Low-Frequency Vibration Through Terahertz Absorption Spectroscopy”. Chem. Phys. Lett2013; 575: 36–39.
23.
FuseN.SatoR.MizunoM.FukunagaK.ItohK.OhkiY.“Observation and Analysis of Molecular Vibration Modes in Polylactide at Terahertz Frequencies”. Jpn. J. Appl. Phys2010; 49(10R): 102402.
GassnerF.OwenA.J.“Physical Properties of Poly(β-Hydroxybutyrate)–Poly(ɛ-caprolactone) Blends”. Polymer1994; 35(10): 2233–2236.
26.
EstellésJ.M.VidaurreA.DuenasJ.M.M.CortázarI.C.“Physical Characterization of Polycaprolactone Scaffolds”. Sci. Mater. Med2008; 19(1): 189–195.
27.
NishidaH.TokiwaY.“Distribution of Poly(β-hydroxybutyrate) and Poly(ɛ-caprolactone) Aerobic Degrading Microorganisms in Different Environments”. J. Environ. Polym. Degrad.1993; 1(3): 227–233.
28.
KomatsuM.MizunoM.SaitoS.FukunagaK.OhkiY.“Terahertz Spectral Change Associated with Glass Transition of Poly-ɛ-caprolactone”. J. Appl. Phys2015; 117(13): 133102.
29.
ChataniY.OkitaY.TadokoroH.YamashitaY.“Structural Studies of Polyesters. III. Crystal Structure of Poly-ɛ-caprolactone”. Polym. J1970; 1(5): 555–562.
30.
BittigerH.MarchessaultR.H.“Crystal Structure of Poly-ɛ-caprolactone”. Acta Cryst. B1970; 26(12): 1923–1927.
31.
HuH.DorsetD.L.“Crystal Structure of Poly(iɛ-caprolactone)”. Macromolecules1990; 23(21): 4604–4607.
32.
F. Brisse, R.H. Marchessault. “Contribution of Electron Diffraction on Single Crystals to Polymer Structure Determination”. In: A.D. French and K.H. Gardner, editors. Fiber Diffraction Method. Washington, DC: 1980. ACS Symposium Series Vol. 141, Chap. 16, 267–277.
