cm-1 - Prof. Yusuf Yagci
Transkript
cm-1 - Prof. Yusuf Yagci
YALOVA UNIVERSITY FACULTY OF ENGINEERING DEPARTMENT OF ENGINEERING TEST METHODS FOR POLYMERS I PLM 305 Assoc. Prof. Dr. Mehmet Atilla TAŞDELEN tasdelen@yalova.edu.tr www.POLYMAT.org COURSE OUTLINE Week 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Topic Introduction, Preliminary Identification Methods: Solubility, Density, Behaviour on Heating (Atilla) Determination of Water uptake and moisture, Determination of ash amount, Thermal Expansion Coefficient (Hamit) Electrical and Optical Properties and Their Measurement, Thermal Conductivity (Hamit) Surface Tension, Surface Resistance, Refractometry, Refractive Index Measurement in Transparent Plastics, Colour Determination (Hamit) Fire Resistance, Aging: Thermal Aging, UV Aging, Aging under Atmospheric Conditions and Ozone Effects (Hamit) Determination of Structure of Polymers. Spectroscopic Methods: Ultraviolet-Visible Spectroscopy (Atilla) Infrared Spectroscopy (Atilla) Infrared Spectroscopy (Atilla) Nuclear Magnetic Resonance Spectroscopy (1H and 13C NMR) III (Hamit) Midterm Nuclear Magnetic Resonance Spectroscopy (1H and 13C NMR) III (Hamit) Colligative Properties, Determination of Molecular Weight of Polymers : End-Group Analysis, Viscosity Measurements (Atilla) Gel Permeation Chromatography (GPC), Light Scattering (Atilla) Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) (Hamit) Where in the spectrum are these transitions? Where in the spectrum are these transitions? Basics of Light, E&M Spectrum, and X-rays Light can take on many forms. Radio waves, microwaves, infrared, visible, ultraviolet, X-ray and gamma radiation are all different forms of light. The energy of the photon tells what kind of light it is. Radio waves are composed of low energy photons. Optical photons--the only photons perceived by the human eye--are a million times more energetic than the typical radio photon. The energies of X-ray photons range from hundreds to thousands of times higher than that of optical photons. The speed of the particles when they collide or vibrate sets a limit on the energy of the photon. The speed is also a measure of temperature. (On a hot day, the particles in the air are moving faster than on a cold day.) Very low temperatures (hundreds of degrees below zero Celsius) produce low energy radio and microwave photons, whereas cool bodies like ours (about 30 degrees Celsius) produce infrared radiation. Very high temperatures (millions of degrees Celsius) produce X-rays. Techniques and information content Molecular Molecular Libration vibrations (hindered rotations) Electronic Absorption Infrared, Raman, EELS Microwave, THz Valence band and shallow electronic levels (atoms) Deep electronic core levels (atoms) UV absorption UV photoemission Electron loss Visible Fluorescence Luminescence X-ray photoemission (XPS, ESCA) Auger Electron (AES) What is Infrared? • Infrared radiation lies between the visible and microwave portions of the electromagnetic spectrum. • Infrared waves have wavelengths longer than visible and shorter than microwaves, and have frequencies which are lower than visible and higher than microwaves. • The Infrared region is divided into: near, mid and far-infrared. • Near-infrared refers to the part of the infrared spectrum that is closest to visible light and far-infrared refers to the part that is closer to the microwave region. • Mid-infrared is the region between these two. • The primary source of infrared radiation is thermal radiation. (heat) • It is the radiation produced by the motion of atoms and molecules in an object. The higher the temperature, the more the atoms and molecules move and the more infrared radiation they produce. What is Infrared? (Cont.) Humans, at normal body temperature, radiate most strongly in the infrared, at a wavelength of about 10 microns (A micron is the term commonly used in astronomy for a micrometer or one millionth of a meter). In the image to the left, the red areas are the warmest, followed by yellow, green and blue (coolest). The image to the right shows a cat in the infrared. The yellow-white areas are the warmest and the purple areas are the coldest. This image gives us a different view of a familiar animal as well as information that we could not get from a visible light picture. Notice the cold nose and the heat from the cat's eyes, mouth and ears. Vibrational Spectroscopy: Theory In IR spectroscopy, IR photons is absorbed and converted by a molecule into energy of molecular vibration m1 m2 r A simple harmonic oscillator is a mechanical system consisting of a point mass connected to a massless spring. The mass is under the action of a restoring force proportional to the displacement of the particle from its equilibrium position and the force constant k of the spring (under the classical Hooke’s law) Infrared Spectroscopy • The bonds between atoms in the molecule stretch and bend, absorbing infrared energy and creating the infrared spectrum. Symetric Streching Simetrik Gerilme Asymetric Streching Asimetrik Gerilme There are four bending vibrations Scissoring Twisting Rocking Düzlem içi eğilme Düzlem içi eğilme Düzlem dışı eğilme (Makaslama) (Sallanma) (Yana sallanma) Wagging Düzlem dışı eğilme (Bükülme) IR Spectrum • Plot IR energy vs. %transmittance (%T) – Energy scale in wave numbers, wn (cm-1) – %T scale • Compares intensity of IR striking sample (Iin) with intensity of IR leaving sample (Iout) • 100%T no light absorbed by sample • 0% all light absorbed by sample IR Spectrum The History of Infrared Spectroscopy Infrared (IR) Spectroscopy: –Herschel first recognized the existence of IR and its relation to the heating of water –First real IR spectra measured by Abney and Festing in 1880’s –IR spectroscopy became a routine analytical method as spectra were measured and instruments developed from 1903-1940 (especially by Coblentz at the US NBS) –IR spectroscopy through most of the 20th century is done with dispersive (grating) instruments, i.e. monochromators –Fourier Transform (FT) IR instruments become common in the 1980’s, led to a great increase in sensitivity and resolution J. F. W. Herschel W. Coblentz Infrared Spectroscopy A molecule can be characterized (identified) by its molecular vibrations, based on the absorption and intensity of specific infrared wavelengths. Infrared Spectroscopy For isopropyl alcohol, the infrared absorption bands identify the various functional groups of the molecule. The Principles of FTIR Method Sample Analysis Process 1. The Source: Infrared energy is emitted from a glowing black-body source. This beam passes through an aperture which controls the amount of energy presented to the sample (and, ultimately, to the detector). 2. The Interferometer: The beam enters the interferometer where the “spectral encoding” takes place. The resulting interferogram signal then exits the interferometer. Sample Analysis Process 3. The Sample: The beam enters the sample compartment where it is transmitted through or reflected off of the surface of the sample, depending on the type of analysis being accomplished. This is where specific frequencies of energy, which are uniquely characteristic of the sample, are absorbed. 4. The Detector: The beam finally passes to the detector for final measurement. The detectors used are specially designed to measure the special interferogram signal. 5. The Computer: The measured signal is digitized and sent to the computer where the Fourier transformation takes place. The final infrared spectrum is then presented to the user for interpretation and any further manipulation. Sampling Gases: • high resolution is required to clarify the detailed structure inherent to a gas sample. • The cell internal pressure must be adjusted for quantitative analysis of the gas sample • Gas Cells with 5 cm or 10 cm Light Path. Numune Hazırlama Liquids Using NaCl disks Numune Hazırlama Solids Katı ise: 1-KBr peleti hazırlanması 2-Pasta hazırlanması 3-NaCl diski üzerinde katı film oluşturulması Eğer örnek katı ise spektroskopik potasyum bromür (KBr) yardımı ile birkaç tonluk basınç altında ince şeffaf bir tablet oluşturularak spektrum alınır. KBr’ün infrared bölgesinde absorpsiyonu olmadığı için kullanılması uygundur. Kullanılan KBr nem içermemelidir. Çünkü içerdiği nemin IR spektrumunda hatalı bantların gozlenmesine neden olur. Numune Hazırlama IR spektrumlarının alınması için yöntemler Çözelti ise: Çözeltilerin spektrumunun alınması sırasında dikkat edilmesi gereken en önemli şey, şeçilen çözücünün IR bölgesinin her yerinde ışığı geçirebilmesi gerekmektedir. Bu nedenle en fazla tercih edilen çözücüler karbontetraklorür, kloroform, karbondisülfür, siklohekzan, benzen, tetrakloroetilendir. Bu çözücülerden uygun olanı herhangi biri ile örneğin %0.1-10 ‘lük bir çözeltisi hazırlanır. Hazırlanan bu çözelti infrared hücrelerine koyulur. Ayrıca kullanılan çözücünün hücreninn yapıldığı maddeyi çözmemesine de dikkat edilmelidir. Numune Hazırlama IR spektrumlarının alınması için yöntemler Transmisyon-FTIR tekniğinde örnek, IR ışının geçiş yolu üzerine konulmaktadır. Buna karşılık ATR-FTIR (Hafifletilmiş Toplam Yansıtma, Attenuated Total Reflectance) yönteminde örnek, IR’ye geçirgen olan özel bir kristalin yüzeyi ile temas ettirilir. Numune Hazırlama IR spektrumlarının alınması için yöntemler Sampling IR spektrumlarının alınması için yöntemler Frekans Bağ Gerilme Frekans Tablosu Frekans atomlar ağırlatıkça düşer. Frekans bağ kuvveti veya bağ enerjisi arttıkça artar. Example Bağ Gerilme Frekans Tablosu Simetrik Gerilme Düzlem içi eğilme (Makaslama) Düzlem içi eğilme (Yana sallanma) Example Frekans Example Example O-H Band at 3300 cm-1. Example 3300 civarinda Secondary amine (R2NH), broad and one spike. Primary amine (RNH2), broad and two spike. Tersiyer amine (R3N), not detected. Example Ketones, Aldehydes and Carboxylic acids, C=O bağları ~1710 cm-1. Örnekler Aldehydes has additionally two C-H signals: ~ 2700 ve 2800 cm-1. Example Carboxylic acid has additionally O-H band. Example C=O bağlarının C=C bağlarıyla konjugasyonu gerilme frekansını ~1680 cm-1 ye düşürür. Bir amidin C=O grubu daha düşük frekansta absorblar: 1640-1680 cm-1. Bir esterin C=O grubu daha yüksek frekansta absorblar: ~1730-1740 cm1. Küçük halkalardaki karbonil grupları (5 C veya daha az C) daha da yüksek frekansta absorblar. Example C - N ~ 1200 cm-1 C = N ~ 1660 cm-1 more stronger than C = C bands C ≡ N ~ 2200 cm-1 Alkyne C ≡ C has a weak absorption at 2200 cm-1. FT-IR Bands Interpretation of infrared spectra Applications of Infrared Analysis • • • • • • • Pharmaceutical research Forensic investigations Polymer analysis Lubricant formulation and fuel additives Foods research Quality assurance and control Environmental and water quality analysis methods • Biochemical and biomedical research • Coatings and surfactants • Etc. Capabilities of Infrared Analysis Identification and quantitation of organic solid, liquid or gas samples. Analysis of powders, solids, gels, emulsions, pastes, pure liquids and solutions, polymers, pure and mixed gases. Infrared used for research, methods development, quality control and quality assurance applications. Samples range in size from single fibers only 20 microns in length to atmospheric pollution studies involving large areas. Polyethylene Polyethylene Low-density polyethylene (LDPE) % 50 cristallinity High-density polyethylene (HDPE) % 70 cristallinity Polypropylene Polypropylene (a) atactic (b) syndiotactic (c) isotactic The absorbance values at 970 and 1460 cm-1 do not depend upon the tacticity, whereas the absorbances at 840, 1000 and 1170 cm-1 are characteristic of isotactic PP, and the absorbance at 870 cm-1 is characteristic of syndiotactic PP. Polyisobutylene Polytetrafluoroethylene Poly(vinylidene fluoride) Poly(vinyl chloride) Polystyrene Poly(para-xylene) Poly(vinylidene chloride) Poly(vinyl acetate) Poly(vinyl alcohol) Poly(cis-isoprene) Poly(chloroprene) Poly(methyl methacrylate) Poly(butyl acrylate) Poly(methacrylic acid) Nylon 66 vs Nylon 610 nylon 6 6 nylon 6 10 Poly(dimethyl siloxane) Poly(acrylamide) Poly(ethylene oxide) Mn=8000 Poly(ethylene oxide) Mn=400 Poly(epichlorohydrin) Polycarbonate Poly(ethylene terephthalate) Poly(caprolactam) Copolymer Composition The absorbance values at 2250 and 1600 cm−1 in this spectrum were 0.205 and 0.121, respectively. Copolymer Composition The absorbance values at 1020 and 720 cm−1 in this spectrum were 0.301 and 0.197, respectively. Estimate the composition of this sample. Isocyanate Amount The absorbance values at 1020 and 720 cm−1 in this spectrum were 0.301 and 0.197, respectively. Estimate the composition of this sample.