Polyme Analysis 2010 Part 12 pps

ü Examine surface irregularities or fracture areas in a part for plastics applications. ü Measure the thickness (in cross section) of thin coatings. üStudy surface topography and failure analysis üTest specimens are sputter coated with gold, then placed in a vacuum chamber for viewing on the computer monitor at up to 10,000x magnification. ü Polaroid photos are taken for a permanent record. Approximately 0.25" x 0.25" Polaroid photos can be scanned into electronic documents. Scanning Electron Microscopy (SEM) Untreated jute NaOH-treated jute NaOH/PAPS-jute PP/jute composite without treatment PP/jute composite with treatment Fourier Transform Infrared Spectrometry (FTIR) -ASTM E1252 -Identify of polymer -Detect organic layers or fiberglass -Detect surface coatings -Also examine contaminants and some fillers within the polymers -A small amount (few grams) of sample is needed. -Three basic spectrometer components: +Radiation source +Interferometer (giaothoakế), +and detector Simplified optical layout of a typical FTIR spectrometer Fourier Transform Infrared Spectrometry (FTIR) -The sample is inserted into a detector and the amount of Infrared Light absorbed at each frequency is determined. The most commonly used interferometer is a Michelson interferometer. üConsists of 3 active components: a moving mirror, a fixed mirror, and a beamsplitter üThe two mirrors are perpendicular to each other. üThe beamsplitteris often made by depositing a thin film of germanium onto a flat KBr substrate üRadiation from the broadband IR source impinges on the beamsplitter ü At the beamsplitter, half the IR beam is transmitted to the fixed mirror and the remaining half is reflected to the moving mirror üAfter the divided beams are reflected from the two mirrors, theyare recombined at the beamsplitter. Due to changes in the relative position of the moving mirror to the fixed mirror, an interference pattern is generated. üThe resulting beam then passes through the sample and is eventually focused on the detector. Fourier Transform Infrared Spectrometry (FTIR) Wavenumber( ): =1 / λ ['gæmə] ['reidiou] ultraviolet Infrared Region(IR) electromagnetic spectrum λ ch hνE • == The energy of the wave (E): ν: frequency λ :wavelength The infrared region (14,000 cm -1 to 10 cm -1 ): near, mid and far-infrared region üMid-infrared region (4,000 cm-1 to 400 cm-1): →themost interest region →corresponds to changes in vibrational energies within molecules üThe far infrared region (400 cm -1 to 10 cm -1 ): →useful for molecules containing heavy atoms such as inorganic compounds →requires rather specialisedexperimental techniques. FTIR Symmetrical stretching Asymmetrical stretching In-plane bending Out-of -plane bend Molecular Vibrations Major vibrationalmodes for a nonlinear group, CH 2 Stretching vibration Bending vibration Out-of-plane bending (When a compound absorbs the energy of Infrared radiation) FTIR Single Bonds to Hydrogen FTIR . Spectrometry (FTIR) -ASTM E1252 -Identify of polymer -Detect organic layers or fiberglass -Detect surface coatings -Also examine contaminants and some fillers within the polymers -A small amount. irregularities or fracture areas in a part for plastics applications. ü Measure the thickness (in cross section) of thin coatings. üStudy surface topography and failure analysis üTest specimens are sputter